Hydrological control of river and seawater lithium isotopes

Seawater lithium isotopes (δ⁷Li) record changes over Earth history, including a ∼9‰ increase during the Cenozoic interpreted as reflecting either a change in continental silicate weathering rate or weathering feedback strength, associated with tectonic uplift. However, mechanisms controlling the dissolved δ⁷Li remain debated. Here we report time-series δ⁷Li measurements from Tibetan and Pamir rivers, and combine them with published seasonal data, covering small (<10²  km²) to large rivers (>10⁶ km²). We find seasonal changes in δ⁷Li across all latitudes: dry seasons consistently have higher δ⁷Li than wet seasons, by −0.3‰ to 16.4‰ (mean 5.0 ± 2.5‰). A globally negative correlation between δ⁷Li and annual runoff reflects the hydrological intensity operating in catchments, regulating water residence time and δ⁷Li values. This hydrological control on δ⁷Li is consistent across climate events back to ~445 Ma. We propose that hydrological changes result in shifts in river δ⁷Li and urge reconsideration of its use to examine past weathering intensity and flux, opening a new window to reconstruct hydrological conditions.

From modern seasonal to the deep time, global data show that continental hydrology has a direct and consistent effect on river and marine Li isotope compositions, highlighting a crucial role of climate on Earth’s weathering and the carbon cycle.

The Role of Crustal Buoyancy in the Generation and Emplacement of Magmatism During Continental Collision

During continental collision, considerable amounts of buoyant continental crust subduct to depth and subsequently exhume. Whether various exhumation paths contribute to contrasting styles of magmatism across modern collision zones is unclear. Here we present 2D thermomechanical models of continental collision combined with petrological databases to investigate the effect of the main contrasting buoyancy forces, in the form of continental crustal buoyancy versus oceanic slab age (i.e., its thickness). We specifically focus on the consequences for crustal exhumation mechanisms and magmatism. Results indicate that it is mainly crustal density that determines the degree of steepening of the subducting continent and separates the models' parameter space into two regimes. In the first regime, high buoyancy values (∆ρ > 500 kg/m3) steepen the slab most rapidly (to 45-58°), leading to opening of a gap in the subduction channel through which the subducted crust exhumes ("subduction channel crustal exhumation"). A shift to a second regime ("underplating") occurs when the density contrast is reduced by 50 kg/m3. In this scenario, the slab steepens less (to 37-50°), forcing subducted crust to be placed below the overriding plate. Importantly, the magmatism changes in the two cases: Crustal exhumation through the subduction channel is mainly accompanied by a narrow band of mantle melts, while underplating leads to widespread melting of mixed sources. Finally, we suggest that the amount (or density) of subducted continental crust, and the resulting buoyancy forces, could contribute to contrasting collision styles and magmatism in the Alps and Himalayas/Tibet.

Andean surface uplift constrained by radiogenic isotopes of arc lavas

Climate and tectonics have complex feedback systems which are difficult to resolve and remain controversial. Here we propose a new climate-independent approach to constrain regional Andean surface uplift. ⁸⁷Sr/⁸⁶Sr and ¹⁴³Nd/¹⁴⁴Nd ratios of Quaternary frontal-arc lavas from the Andean Plateau are distinctly crustal (>0.705 and <0.5125, respectively) compared to non-plateau arc lavas, which we identify as a plateau discriminant. Strong linear correlations exist between smoothed elevation and ⁸⁷Sr/⁸⁶Sr (R² = 0.858, n = 17) and ¹⁴³Nd/¹⁴⁴Nd (R² = 0.919, n = 16) ratios of non-plateau arc lavas. These relationships are used to constrain 200 Myr of surface uplift history for the Western Cordillera (present elevation 4200 ± 516 m). Between 16 and 26°S, Miocene to recent arc lavas have comparable isotopic signatures, which we infer indicates that current elevations were attained in the Western Cordillera from 23 Ma. From 23–10 Ma, surface uplift gradually propagated southwards by ~400 km.

Multiple complex tectonic and climatic processes have formed the Andes, which today provides a unique ecological niche. Here, Scott et al. investigate how the chemical composition of lavas from stratovolcanoes can be used to give insight on the uplift of the Andes over the last 200 million years.

Metamorphic records of multiple seismic cycles during subduction

Large earthquakes occur in rocks undergoing high-pressure/low-temperature metamorphism during subduction. Rhythmic major-element zoning in garnet is a common product of such metamorphism, and one that must record a fundamental subduction process. We argue that rhythmic major-element zoning in subduction zone garnets from the Franciscan Complex, California, developed in response to growth-dissolution cycles driven by pressure pulses. Using electron probe microanalysis and novel techniques in Raman and synchrotron Fourier transform infrared microspectroscopy, we demonstrate that at least four such pressure pulses, of magnitude 100-350 MPa, occurred over less than 300,000 years. These pressure magnitude and time scale constraints are most consistent with the garnet zoning having resulted from periodic overpressure development-dissipation cycles, related to pore-fluid pressure fluctuations linked to earthquake cycles. This study demonstrates that some metamorphic reactions can track individual earthquake cycles and thereby opens new avenues to the study of seismicity.

The Ethics of Promoting Living Kidney Donation Using Nonargumentative Influence: Applications, Concerns, and Future Directions

Recommendations from the 2014 Consensus Conference on Best Practices in Living Kidney Donation reflect increasing attention to overcoming barriers to donation as a means of expanding access to living donor kidney transplantation. "High priority" initiatives include empowering transplant candidates and their loved ones in their search for a living kidney donor. Transplant programs are assuming an unprecedented role as facilitators of patients' solicitation for donors, and nonprofits are promoting living kidney donation (LKD) in the community. New strategies to promote LKD incorporate "nonargumentative" forms of influence (i.e. approaches to shaping behavior that do not attempt to persuade through reason) such as appeals to emotion, messenger effects and social norms. These approaches have raised ethical concerns in other settings but have received little attention in the transplantation literature despite their increasing relevance. Previous work on using nonargumentative influence to shape patient behavior has highlighted implications for (1) the relationship between influencer and influenced and (2) patient autonomy. We argue that using nonargumentative influence to promote LKD is a promising strategy that can be compatible with ethical standards. We also outline potential concerns and solutions to be implemented in practice.

Strontium-90 Biokinetics from Simulated Wound Intakes in Non-human Primates Compared with Combined Model Predictions from National Council on Radiation Protection and Measurements Report 156 and International Commission on Radiological Protection Publication 67

This study had a goal to evaluate the predictive capabilities of the National Council on Radiation Protection and Measurements (NCRP) wound model coupled to the International Commission on Radiological Protection (ICRP) systemic model for 90Sr-contaminated wounds using non-human primate data. Studies were conducted on 13 macaque (Macaca mulatta) monkeys, each receiving one-time intramuscular injections of 90Sr solution. Urine and feces samples were collected up to 28 d post-injection and analyzed for 90Sr activity. Integrated Modules for Bioassay Analysis (IMBA) software was configured with default NCRP and ICRP model transfer coefficients to calculate predicted 90Sr intake via the wound based on the radioactivity measured in bioassay samples. The default parameters of the combined models produced adequate fits of the bioassay data, but maximum likelihood predictions of intake were overestimated by a factor of 1.0 to 2.9 when bioassay data were used as predictors. Skeletal retention was also over-predicted, suggesting an underestimation of the excretion fraction. Bayesian statistics and Monte Carlo sampling were applied using IMBA to vary the default parameters, producing updated transfer coefficients for individual monkeys that improved model fit and predicted intake and skeletal retention. The geometric means of the optimized transfer rates for the 11 cases were computed, and these optimized sample population parameters were tested on two independent monkey cases and on the 11 monkeys from which the optimized parameters were derived. The optimized model parameters did not improve the model fit in most cases, and the predicted skeletal activity produced improvements in three of the 11 cases. The optimized parameters improved the predicted intake in all cases but still over-predicted the intake by an average of 50%. The results suggest that the modified transfer rates were not always an improvement over the default NCRP and ICRP model values.

Donor Hemodynamics as a Predictor of Outcomes After Kidney Transplantation From Donors After Cardiac Death

Donation after cardiac death is an important source of transplantable organs, but evidence suggests donor warm ischemia contributes to inferior outcomes. Attempts to predict recipient outcome using donor hemodynamic measurements have not yielded statistically significant results. We evaluated novel measures of donor hemodynamics as predictors of delayed graft function and graft failure in a cohort of 1050 kidneys from 566 donors. Hemodynamics were described using regression line slopes, areas under the curve, and time beyond thresholds for systolic blood pressure, oxygen saturation, and shock index (heart rate divided by systolic blood pressure). A logistic generalized estimation equation model showed that area under the curve for systolic blood pressure was predictive of delayed graft function (above median: odds ratio 1.42, 95% confidence interval [CI] 1.06-1.90). Multivariable Cox regression demonstrated that slope of oxygen saturation during the first 10 minutes after extubation was associated with graft failure (below median: hazard ratio 1.30, 95% CI 1.03-1.64), with 5-year graft survival of 70.0% (95%CI 64.5%-74.8%) for donors above the median versus 61.4% (95%CI 55.5%-66.7%) for those below the median. Among older donors, increased shock index slope was associated with increased hazard of graft failure. Validation of these findings is necessary to determine the utility of characterizing donor warm ischemia to predict recipient outcome.

What are the harms of refusing to allow living kidney donation? An expanded view of risks and benefits

Recent Organ Procurement and Transplantation Network policies relating to living kidney donation (LKD)warrant renewed attention to the ethics of transplantation from living donors. These policies focus on risks related to potential donor evaluation, informed consent and follow-up. The ethical basis of living donation is a favorable risk/benefit ratio for the donor, but regulations and research have given less attention to the benefits of donation. Relatedly, the transplant field has also failed to consider potential harms from denying patients the opportunity to donate. These harms may be substantial in the setting of directed kidney donation to a spouse/partner, sibling or child.We argue that complete assessment of donor risks and benefits demands consideration of not only the risks and benefits of donation, but also those of refusing a donor. In contrast to the ever-expanding literature on risks of donation, there are no data describing outcomes for individuals who were turned down as kidney donors. We consider factors contributing to this omission in the transplant literature, argue that current regulations may perpetuate a narrow understanding of relevant risks and benefits in LKD, and identify areas for improvement in research and clinical practice.

WUS and STM-based reporter genes for studying meristem development in poplar

We describe the development of a reporter system for monitoring meristem initiation in poplar using promoters of poplar homologs to the meristem-active regulatory genes WUSCHEL (WUS) and SHOOTMERISTEMLESS (STM). When ~3 kb of the 5' flanking regions of close homologs were used to drive expression of the GUSPlus gene, 50-60% of the transgenic events showed expression in apical and axillary meristems. However, expression was also common in other organs, including in leaf veins (40 and 46% of WUS and STM transgenic events, respectively) and hydathodes (56% of WUS transgenic events). Histochemical GUS staining of explants during callogenesis and shoot regeneration using in vitro stems as explants showed that expression was detectable prior to visible shoot development, starting 3-15 days after explants were placed onto callus inducing medium. A minority of WUS and STM events also showed expression in the cambium, phloem, or xylem of regenerated, greenhouse grown plants undergoing secondary growth. Based on microarray gene expression data, a paralog of poplar WUS was detectably up-regulated during shoot initiation, but the other paralog was not. Both paralogs of poplar STM were down-regulated threefold to sixfold during early callus initiation. We identified 15-35 copies of cytokinin response regulator binding motifs (ARR1AT) and one copy of the auxin response element (AuxRE) in both promoters. Several of the events recovered may be useful for studying the process of primary and secondary meristem development, including treatments intended to stimulate meristem development to promote clonal propagation and genetic transformation.

Reproducibility of bronchodilator response for a reservoir dry powder inhaler following routine clinical use

The performance of dry powder inhaler (DPI) devices, particularly reservoir DPIs, may be influenced by environmental conditions. This study compared the bronchodilator efficacy and in vitro aerosol characteristics of salbutamol, delivered via a novel reservoir DPI (Clickhaler) and a conventional pressurized metered-dose inhaler (MDI) before and after use of the DPI in clinical practice. Following a screening visit, patients received cumulative doses of salbutamol (100, 200, and 400 microg) via DPI or MDI on separate days in a double-blind, crossover design before and after a 4-week period, during which the DPI was used as the patients' first-line bronchodilator. Lung function responses (forced expiratory volume in 1 sec [FEV1], forced vital capacity [FVC], and peak expiratory flow [PEF]) to salbutamol delivered by DPI and MDI and in vitro aerosol characteristics were not significantly different before and after the period of DPI patient use. DPI performance, assessed in vivo and in vitro, is maintained following an extended period of patient use.

Pulmonary toxicity of cardiac drugs

Pulmonary damage caused by the undesired effects of cardiac drugs is being increasingly recognized. With the symptoms of breathlessness, wheeze, cough and hemoptysis common to both cardiac and respiratory diseases, an adverse pulmonary reaction to a cardiac drug may be mistakenly attributed to deterioration of cardiac status. This is especially true if the onset of symptoms are subacute or chronic. The pulmonary side effects of cardiac drugs are varied and may actually mimic the disease being treated. It is essential that the clinician remain highly suspicious that new and unexplained pulmonary symptoms and signs may be drug-related. Most of the side effects are reversible with early drug cessation and subsequent challenge should be avoided if possible.

General practice spirometry in North Staffordshire

Spirometry is suggested, in North American and European guidelines, to be the most important measurement of lung function for the management of patients with chronic obstructive pulmonary disease (COPD). The aim of this study was to determine attitudes to and utilization of spirometry in general practices within North Staffordshire. All 95 practices in North Staffordshire were surveyed by telephone, using a standard proforma. Eighty-four practices (48 fundholding) containing 224 general practitioners (GPs) and serving 472,420 patients, agreed to take part. The survey was completed by practice nurses on 63 occasions, GPs on 14 and practice managers on seven. Eighteen practices possessed a spirometer, although eight did not use it. The measurements were performed by doctors in five of the practices, nurses in two and by both in three. Only two users had received formal training in the performance and interpretation of spirometry. Of the three practices using pneumotachograph spirometers, none knew how often the machine should be calibrated. Spirometry was used by five practices for diagnosis (although only four used it to determine forced expiratory volume in one second (FEV1)), three for monitoring and only one for bronchodilator reversibility testing. Although 44 (52%) practices thought that, ideally, spirometry should be available in the practice, only 10 of the 18 who had spirometers were currently providing this facility. Furthermore, the poor training puts into question the validity of some of the results obtained. Open access to hospital spirometry is one method of addressing these problems, and 73 (87%) practices, including 16 who already owned a spirometer, said that they would use such a service.

Compliance with oral corticosteroids during steroid trials in chronic airways obstruction

BACKGROUND

Corticosteroid trials are an important part of the assessment of patients with chronic airways obstruction, but false negative results will occur if the treatment is not taken. To determine compliance low dose phenobarbitone has been used as a marker.

METHODS

Thirty six patients referred to a chest clinic for assessment of their airways obstruction were studied. They were instructed to take eight capsules (each containing 5 mg prednisolone and 0.5 mg phenobarbitone) per day for two weeks. The response was assessed by home peak flow monitoring and clinic spirometric tests. Plasma phenobarbitone levels were measured after the trial to enable calculation of the dose to plasma concentration ratio (level to dose ratio, LDR) and the result was compared with the reference range for fully compliant individuals.

RESULTS

Five patients defaulted from follow up, 23 had LDR values within the expected range, and eight had low LDR values consistent with poor compliance. The nine patients with steroid responsive disease (> 20% improvement in peak flow or spirometric parameters) all had LDR values in the expected range.

CONCLUSION

Excluding those who defaulted whose compliance must be questionable, eight (26%) patients did not fully comply with the steroid trial. Not all patients who fail to respond to a two week home steroid trial have a steroid "unresponsive" disease.

Low incidence of red cell and HLA antibody formation by bone marrow transplant patients

BACKGROUND

Bone marrow transplant (BMT) patients, although immunosuppressed, are at risk for the development of red cell (RBC) and HLA antibodies, and they often are given filtered blood in an effort to prevent the latter complication. This study attempts to determine the rate of formation and the specificity of both RBC and HLA alloantibodies in this patient population.

STUDY DESIGN AND METHODS

BMT patients (148 received autologous marrow; 45 received allogeneic marrow) from an 18-month period, including patients with leukemia (57 patients), lymphoma (54), breast cancer (68), myeloma (8), myelodysplastic syndrome (5), and aplastic anemia (1), were studied to determine the rate of alloantibody formation to RBC and HLA antigens. A total of 2,410 RBC antibody screens were performed. The patients received 3,921 packed RBCs and 5,915 single-donor platelet units; all were irradiated and administered via white cell-reduction filters.

RESULTS

Seven (3.6%) of 193 patients had RBC antibodies upon hospital admission. Four (2.1%) of 193 developed RBC antibodies during the course of BMT: 3 patients had one RBC antibody and 1 patient had two RBC antibodies. RBC antibodies included anti-E (n = 2), anti-M (n = 1), anti-Jkb (n = 1), and anti-Lu14 (n = 1). Thus, 98 percent of patients (189/193) did not develop new (182/186) or additional (7/7) RBC antibodies during BMT. BMT patients were also screened weekly for HLA antibody formation (60-cell panel). Upon admission, 170 (85%) patients were negative. Of these, 8 (4.7%) developed persistent HLA antibodies (mean panel-reactive antibody score, 33 +/- 29%) and 9 (5.3%) were variably positive. Thus, in our setting and population, RBC antibody formation was 0.1 percent per unit transfused, and the HLA alloimmunization rate was 5 to 10 percent.

CONCLUSION

As RBC antibody screens are done every Monday, Wednesday, and Friday on this BMT service and as RBC antibody formation is low in these patients, screening for unexpected antibodies might be possible on a more infrequent basis. Also, the rate of HLA alloimmunization in this population receiving filtered blood components is low.

Childhood cancer in Britain: the National Registry of Childhood Tumours and incidence rates 1978-1987

The National Registry of Childhood Tumours contains population-based data on childhood cancers diagnosed throughout Great Britain from 1962 onwards. This paper describes the methodology of the Registry, presents incidence rates for 1978-1987 and describes other uses of the data. Total age-standardised annual incidence was 118.3 per million. The most frequent diagnostic groups were leukaemias (age-standardised rate 39.8), brain and spinal tumours (27.0), lymphomas (11.1), sympathetic nervous system tumours (8.3), kidney tumours (7.7) and soft-tissue sarcomas (7.5). Incidence rates were similar to those reported from other Western industrialised countries. The data are also used for a wide range of epidemiological and other studies. These include analyses of geographical variations in incidence, trends in survival, health of long-term survivors and their offspring and the genetics of childhood cancer. Information is frequently provided for clinicians and research workers, and series of specific types of cancer are compiled for further study. The Registry depends for the completeness and accuracy of its data on a wide range of organisations and individuals, and it is essential that this cooperation continues if the Registry is to be maintained.

Nasal surgery for snoring

Snoring is a common disorder usually presenting to otolaryngologists. Most patients who have any nasal symptoms would normally be offered nasal surgery, but there is a significant incidence of failure to control the snoring (approximately 25%). We analysed a group of patients, all having nasal surgery for snoring, with the aim of assessing whether any pre-operative factors would predict success or failure of the surgery. We found symptoms of excessively loud snoring, witnessed apnoeic episodes and hypersomnolence, or obstructive sleep apnoea diagnosed by overnight oxygen saturation measurements to be statistically associated with failure of nasal surgery to improve snoring.

Changes in nocturnal oximetry after treatment of exacerbations in cystic fibrosis

Sleep related arterial oxygen desaturation has been described in clinically stable young adults with cystic fibrosis. The incidence and severity of nocturnal oxygen desaturation in children during infective exacerbations and the changes that occur with treatment were examined. Forty five children with proved cystic fibrosis, median age 8.9 years, admitted to the Regional Cystic Fibrosis Unit underwent clinical evaluation, spirometry, and measurement of peak flow and nocturnal oxygen saturation on admission and after 10 days' treatment. There was a significant improvement in all the above measurements, with the averaged overnight saturation changing from a mean (SD) 92.7 (2.7)% to 94.3 (2.0)%, mean (SE) difference 1.58 (0.37). The time spent with a saturation 4% or more below their clinic value showed a marked improvement from 122 (152) minutes on the first night to 21 (30.7) on the second, mean (SE) difference 101 (22.4). Eight young children could not perform pulmonary function tests, all desaturated on the admission night. Nocturnal hypoxaemia is a common finding in young cystic fibrosis patients during infective exacerbations but improves with treatment. Overnight oximetry is simple to perform, well tolerated, and identifies patients with marked nocturnal desaturation.

Pulmonary and cutaneous vasculitis following hepatitis B vaccination

The case history is presented of a previously healthy non-atopic woman who developed cutaneous vasculitis, confirmed by biopsy, and pulmonary problems after inoculation with recombinant hepatitis B vaccine.

Pancoast syndrome: an unusual presentation of adenoid cystic carcinoma

We report on a patient with primary pulmonary adenoid cystic carcinoma presenting with Pancoast syndrome. Pancoast syndrome has not previously been described with this tumour. Other unusual features of this case include the peripheral origin and mediastinal involvement, with lack of proximal endobronchial spread.

Salbutamol output from two jet nebulizers

Nebulized bronchodilators are commonly used in the management of patients with airflow obstruction, although there is little information available on the bronchodilator output from the nebulizer unit. We have examined the fluid and salbutamol outputs of a single jet nebulizer from two commercial manufacturers at 1 min intervals up to 12 min. The drug and fluid output continued throughout the study period, with a greater fluid output leading to an increase in the concentration of salbutamol remaining within the nebulizer unit. This suggests that weight change is not a good indicator of drug output. Furthermore, there was a marked difference in peak salbutamol output between the two nebulizer units, being 2.9 mg (55%) with the Micro-Neb unit and 1.98 mg (38.7%) with the System 22 unit.

Pancoast syndrome: an unusual presentation of adenoid cystic carcinoma

We report on a patient with primary pulmonary adenoid cystic carcinoma presenting with Pancoast syndrome. Pancoast syndrome has not previously been described with this tumour. Other unusual features of this case include the peripheral origin and mediastinal involvement, with lack of proximal endobronchial spread.

Accuracy and significance of scoring hypopneas

We previously reported that the best definition of hypopneas in the sleep apnea/hypopnea syndrome (SAHS) is based on reduction in thoracoabdominal movement. However, the repeatability of scoring hypopneas from thoracoabdominal movement has not been assessed, nor has the need to record flow as well as thoracoabdominal movement. Thus, two polysomnographers independently scored both apneas and hypopneas on all-night polysomnograms of patients with SAHS. There was close agreement between the polysomnographers for the number of hypopneas (r = 0.98; mean difference 11%) and for the number of apneas (r = 0.99; mean difference 8%). The agreement was similar for the durations of both hypopneas (r = 0.99; mean difference 13%) and apneas (r = 0.99; mean difference 11%). There was also close agreement between the total number of respiratory events scored with and without reference to the flow signal (r = 0.99; mean difference 1.4%) with a maximum under-recognition of 18 events per night in a subject with 237 apneas per night. Thus, hypopneas can be scored reproducibly. In addition, the value of always recording and scoring flow as well as thoracoabdominal signals is questioned.

Obstructive sleep apnoea in adults presenting with snoring

Snoring is a common disorder, and may be associated with obstructive sleep apnoea, although there is little published information on the incidence of apnoea in snorers. This study aimed to assess the upper airway and to relate the findings to sleep study data in a population of patients referred by their general practitioners with loud snoring. Each patient had a full history, weight and height measurements, nasal examination, rhinomanometry, peroral grading of the oropharyngeal features, and fibreoptic pharyngoscopy with a modified Muller manoeuvre, followed by a sleep study. The results in our group of 35 patients demonstrate a high incidence of obstructive sleep apnoea (46%). Factors which correlated well with apnoea were excessively loud snoring, a narrow oropharynx, and marked obesity; 94% of patients with one or more of these features had evidence of sleep apnoea.