Strategies for Cd accumulation in Dittrichia viscosa (L.) Greuter: role of the cell wall, non-protein thiols and organic acids

Dittrichia viscosa (L.) Greuter is plant species commonly found in degraded zones of Asturias (Spain), where it accumulates high levels of Cd, but the mechanisms involved in this response in non-model plants have not been elucidated. In this way, we analysed the fraction of the total Cd bound to the cell walls, the ultrastructural localization of this metal, and non-protein thiol and organic acid concentrations of two clones of D. viscosa: DV-A (from a metal-polluted soil) and DV-W (from a non-polluted area). After 10 days of hydroponic culture with Cd, fractionation and ultrastructural localisation studies showed that most of the Cd accumulated by D. viscosa was kept in the cell wall. The non-protein thiol content rose in D. viscosa with Cd exposure, especially in the non-metallicolous DV-W clone, and in both clones we found with Cd exposure a synthesis de novo of phytochelatins PC2 and PC3 in shoots and roots and also of other phytochelatin-related compounds, particularly in roots. Regarding organic acids, their concentration in both clones decreased in shoots after Cd treatment, but increased in roots, mainly due to changes in the citric acid concentration. Thus, retention of Cd in the cell wall seems to be the first strategy in response to metal entry in D. viscosa and once inside cells non-protein thiols and organic acids might also participate in Cd tolerance.

Cd-induced phytochelatin synthesis in Dittrichia viscosa (L.) Greuter is determined by the dilution of the culture medium

In this paper, we examined Cd accumulation and PC synthesis in two clones of Dittrichia viscosa, one with a metallicolous (DV-A) and the other with a non-metallicolous origin (DV-W). The clones were cultured in vitro with 0 and 10 mg Cd L(-1) in both short-term treatments (up to 72 h) and over 10 days. We also examined the influence of the culture medium dilution and the PC-synthesis inhibitor, L-buthionine-sulfoximine (BSO), on these parameters. Similar Cd accumulation values were found in the two clones. No synthesis of new thiolic compounds was observed in Cd-treated plants cultured in vitro in Murashige and Skoog medium up to 72 h when compared to controls. Dilution of the culture medium affected PC production, increasing it in 1/2 MS and especially in 1/4 MS. Cd uptake did not increase in the same way, but still hyperaccumulation levels were exceeded in all Cd treatments. BSO addition increased the sensitivity of D. viscosa to Cd and diminished Cd accumulation. Nevertheless, a poor correlation between PCs and Cd accumulation capacity was observed since the highest Cd content did not correspond to the highest PC levels. All these results obtained suggest that PCs are important in Cd accumulation and detoxification in D. viscosa and also that other mechanisms might be involved in these traits.

Functional group directed C–H borylation

Different strategies designed to enable directing group effects have been applied to achieve regioselective borylation of C(sp²)–H and C(sp³)–H bonds.

Implications of full-scale implementation of an anammox-based process as post-treatment of a municipal anaerobic sludge digester operated with co-digestion

The feasibility of treating the supernatant of a municipal sludge digester supplemented with co-substrates by means of an anammox-based process (ELAN(®)) was tested in Guillarei (NW of Spain). Ammonia concentration measured in the supernatant of the sludge digester varied in the range 800-1,500 g N/m(3) due to the fact that the sludge produced in the plant was co-digested with wastes coming from surrounding food industries. Treating this supernatant in the ELAN(®) reactor, nitrogen removal rates up to 1.1 kg N/(m(3) d) were reached in experiments run in a pilot plant reactor operated in batch mode. No nitrite oxidation was registered after several months of operation despite the average dissolved oxygen (DO) concentrations being 1.5 g O2/m(3) and the temperature reaching values as low as 18 °C. By keeping the DO set point at 1-2 g O2/m(3) and tuning the hydraulic retention time, the stability of the process was guaranteed and the presence of co-substrates in the anaerobic digester did not affect negatively the operation of the autotrophic nitrogen removal process. Due to the success of the pilot plant experiment, an upscale of the process to full scale is proposed. Mass balances applied to Guillarei wastewater treatment plant revealed that in the main stream line the average denitrification rate calculated with the data of year 2011 was 226 kg N/d. Since the nitrogen removal efficiency is limited by the amount of readily biodegradable organic matter available to carry out denitrification in the water line, the implementation of an anammox-based process to treat the supernatant seems the best option to improve the effluent quality in terms of nitrogen content. The nitrogen removal rate in the sludge line would be 30 times higher than the one in the water line. The implementation of the process would improve the energetic balance and the nitrogen removal performance of the plant.

Semi-continuous anaerobic co-digestion of orange peel waste and residual glycerol derived from biodiesel manufacturing

The manufacturing of orange juice generates high volumes of orange peel waste which should not be deposited in landfill according to current recommendations. Furthermore, glycerol is a compound co-generated in biodiesel manufacturing, but the volume generated is higher than the current demand for pure glycerol. The anaerobic co-digestion of orange peel waste with residual glycerol could reduce the inhibitory effect of some compounds and provide a correct nutrient balance. Under mesophilic temperature and semi-continuous conditions, a mixture of orange peel waste-residual glycerol of 1:1 (in COD) operated favorably for organic loads up to 2.10 g VS/L. At higher organic loads, the accumulation of volatile fatty acids (VFA) and a decrease in the pH caused process destabilization. The methane yield coefficient was quite constant, with a mean value of 330±51 mL(STP)/g VSadded, while the organic loading rate (OLR) reached a mean value of 1.91±0.37 kgVS/m3 d (17.59±2.78 kgmixture/m3 d) and the hydraulic retention time (HRT) varied in a range of 8.5-30.0 d.

Growth and physiological responses to cadmium stress of two populations of Dittrichia viscosa (L.) Greuter

Two clones of Dittrichia viscosa (L.) Greuter from contrasting populations, DV-A (metallicolous) and DV-W (non-metallicolous), were studied to compare Cd accumulation and tolerance. After 10 days of hydroponic culture with 0, 5, 10, and 15 mg Cd L(-1), metal accumulation and plant growth were measured as well as other stress markers such as decrease in the content of photosynthetic pigments, lipid peroxidation, phenols, H(2)O(2), and free proline. We also analyzed the activity of the antioxidant enzymes guaiacol and ascorbate peroxidases, catalase, superoxide dismutase, and glutathione reductase as well as their isoform patterns. Our results confirmed a high Cd tolerance and accumulation in both clones of D. viscosa, which suggests that these traits are constitutive in this species. However, when the Cd concentration in solution exceeded 10 mg Cd L(-1), DV-A was more tolerant than DV-W. The physiological mechanisms involved in Cd tolerance also differed between them, although phenols and guaiacol peroxidase played an important role in both clones. The effective Cd detoxification of DV-A consisted mainly in a promoted ascorbate peroxidase activity and better efficiency of catalase and glutathione reductase enzymes.

An automatic critical care urine meter

Nowadays patients admitted to critical care units have most of their physiological parameters measured automatically by sophisticated commercial monitoring devices. More often than not, these devices supervise whether the values of the parameters they measure lie within a pre-established range, and issue warning of deviations from this range by triggering alarms. The automation of measuring and supervising tasks not only discharges the healthcare staff of a considerable workload but also avoids human errors in these repetitive and monotonous tasks. Arguably, the most relevant physiological parameter that is still measured and supervised manually by critical care unit staff is urine output (UO). In this paper we present a patent-pending device that provides continuous and accurate measurements of patient's UO. The device uses capacitive sensors to take continuous measurements of the height of the column of liquid accumulated in two chambers that make up a plastic container. The first chamber, where the urine inputs, has a small volume. Once it has been filled it overflows into a second bigger chamber. The first chamber provides accurate UO measures of patients whose UO has to be closely supervised, while the second one avoids the need for frequent interventions by the nursing staff to empty the container.

[Life-sustaining treatment limitation criteria upon admission to the intensive care unit: results of a Spanish national multicenter survey]

OBJECTIVE

To determine the life-sustaining treatment limitation (LSTL) predisposition upon patient admission to the intensive care unit (ICU), the criteria upon which such predisposition is based, and whether these decisions are related to structural factors of the surveyed hospitals.

DESIGN

A descriptive multicenter study was made in 2010, involving the conduction of a survey in 90 hospitals, with a view to documenting the usual practice referred to LSTL upon admission in these centers.

SETTING

Spanish ICUs.

INTERVENTION

Opinion survey.

MAIN VARIABLES OF INTEREST

Type of hospital, number of hospital beds, ICU and semicritical patient beds, usual bed availability in the ICU, use of restrictive admission criteria, use of LSTL criteria upon admission, and type of criterion used to decide LSTL.

RESULTS

A total of 43 (48%) hospitals participated in the study, with LSTL being a common practice in these centers (93%). LSTL was fundamentally decided on the basis of the presence of prior severe chronic disease (95%), observation of previously declared patient will (95%), prior functional limitation (85%), and qualitative futility of care (82%). Frequent ICU bed availability (77% of the hospitals) and the use of restrictive criteria (79% of the hospitals) were also associated to patient admission with LSTL.

CONCLUSIONS

Admission to ICU with LSTL is a generalized practice in Spanish Hospitals. LSTL is decided based on physiological futility from an objective medical point of view, but also in observance of ethical and moral implications based on the qualitative futility of medical care.

[Impact of noninvasive ventilation failure upon patient prognosis. Subanalysis of a multicenter study]

OBJECTIVE

Noninvasive ventilation (NIV) constitutes first-line treatment for the exacerbation of obstructive pulmonary disease and cardiogenic lung edema. Several studies suggest that NIV failure could increase the risk of mortality, mainly due to the delay in tracheal intubation. We aimed to evaluate the negative impact of NIV failure in routine practice among Spanish ICUs.

PATIENTS

A subanalysis was made of the multicenter validation of the Sabadell Score study, extracting patients with acute respiratory failure requiring either invasive or noninvasive mechanical ventilation, with the exclusion of patients presenting "do not resuscitate and/or do not intubate" orders.

VARIABLES

We recorded demographic parameters, ICU-specific treatments and the development of acute renal failure or infections during ICU stay. Patients were followed-up on until hospital discharge or death. The statistic analysis included Cox multiple logistic regression.

RESULTS

We analyzed 4132 patients, of whom 1602 (39%) received only invasive mechanical ventilation (IMV), while 529 (13%) received NIV. The latter succeeded in 50% of the patients, but the other 50% required intubation. NIV failure was more common in neurological and postsurgical patients. Mortality was lower than predicted in NIV patients (22% vs. 33%) and similar to predicted in IMV patients (27% vs. 29%). Mortality was lower than predicted in patients in whom NIV proved successful (12% vs. 28%), and in those in whom NIV failed (32% vs. 38%).

CONCLUSION

NIV failure and the need of intubation as routinely used do not seem to imply a poorer patient prognosis.

The indication of tracheotomy conditions the predictors of time to decannulation in critical patients

OBJECTIVE

Variables predicting optimal timing for tracheostomy decannulation remain unknown. We aimed to determine whether classifying patients into two groups according to their indications for tracheostomy could identify variables associated with time to decannulation.

DESIGN

A prospective, observational cohort study was carried out.

LOCATION

Two medical-surgical ICUs.

PATIENTS

We included all patients tracheostomized during ICU stay, excluding patients with do-not-resuscitate orders, tracheostomies for long-term airway control, neuromuscular disease, or neurological damage. Patients were classified into two groups: patients tracheostomized due to prolonged weaning and/or prolonged mechanical ventilation (Group 1), and patients tracheostomized due to low level of consciousness or inability to manage secretions (Group 2).

INTERVENTIONS

Patients were weaned and decannulated according to established protocols.

MAIN VARIABLES

We recorded the following variables: time to tracheostomy, forced vital capacity, peak flow, suctioning requirements, Glasgow Coma Score (GCS), characteristics of respiratory secretions, and swallowing function. Statistical analyses included Cox-proportional multivariate analysis with time to decannulation as the dependent variable.

RESULTS

A total of 227 patients were tracheostomized in the ICUs; of these, 151 were finally included in the study. In the multivariate analysis, time to decannulation in Group 1 was associated with the male gender (HR 1.74 (1.04-2.89), p= 0.03), age>60 years (HR 0.58 (0.36-0.91), p= 0.02), high suctioning frequency (HR 0.81 (0.67-0.97), p= 0.02), low forced vital capacity (HR 0.48 (0.28-0.82), p<0.01), and low peak flow (HR 0.25 (0.14-0.46), p<0.01). In Group 2 time to decannulation was associated to GCS >13 (HR 2.73 (1.51-4.91), p<0.01), high suctioning frequency (HR 0.7 (0.54-0.91), p<0.01), and inadequate swallowing (HR 1.97 (1.11-3.52), p=0.02).

CONCLUSION

Variables associated with longer time to decannulation in ICU-tracheostomized patients differ with the indications for tracheostomy.

Acute physiologic effects of a stepwise recruitment maneuver in acute respiratory distress syndrome

BACKGROUND

Stepwise recruitment maneuvers (RM) applied with high airway pressures may optimize lung recruitment, but this kind of intervention may lead to widely heterogeneous responses with possible side effects. To assess the clinical impact of these maneuvers, we performed a stepwise maximal-recruitment strategy superimposed on routine mechanical ventilation.

METHODS

We studied 13 adults with early-phase acute lung injury/acute respiratory distress syndrome (ALI/ARDS). We used pressure-control ventilation at an FiO(2) of 1. Starting from a Pplat/positive end-expiratory pressure (PEEP) of 40/25, we sequentially increased airway pressure in 5 cmH(2)O steps until a PaO(2)/FiO(2) of 350 mmHg or a Pplat/PEEP of 60/40 cmH(2)O was reached. The PEEP was then progressively reduced until the PaO(2) decreased by more than 10% of the maximum PaO(2); the PEEP was subsequently set to 2 cmH(2)O above this level. An intra-arterial catheter continuously displayed blood gas measures. The respiratory mechanics and hemodynamics were monitored at each phase and during the two-hour follow-up.

RESULTS

Two hours after the RM, the PaO(2)/FiO(2) was higher than at baseline (187±102 versus 339±136 mmHg, P<0.001). In 8 patients, the PEEP increased from 12±3 cmH(2)O to 15±4 cmH(2)O after the RM (P<0.001). In the other five, it closely mirrored the basal PEEP. Seven patients did not reach the 350-mmHg PaO(2) target. The respiratory system compliance decreased in seven patients. The RM was discontinued due to severe complications in four patients.

CONCLUSION

Although stepwise-RM improves oxygenation, it has a heterogeneous impact on respiratory mechanics and may cause adverse hemodynamic effects and transient hypoxemia. If the use of this kind of RM is considered, it should be adapted to individual patient needs, applied carefully and closely monitored.

Risk factors for Giardia infection among hospitalized children in Cuba

The risk factors associated with Giardia infection, in children hospitalized in Havana, Cuba, were recently explored. Children aged ≥5 years were more likely to be positive for Giardia infection than the younger children, with an odds ratio (OR) of 3·41 [95% confidence interval (CI) = 1·36-9·69]. The risk factors found to be associated with Giardia infection in univariate analyses were rural residence (OR = 3·01; CI = 1·23-7·35), belonging to a household that did not receive water from an aqueduct (OR = 3·27; CI = 1·21-8·91), drinking unboiled water (OR = 3·64; CI = 2·14-6·26), nail biting (OR = 3·47; CI = 1·97-6·08), eating unwashed vegetables raw (OR = 4·84; CI = 2·33-10·14), and a personal (OR = 3·23; CI = 1·58-6·59) or family history (OR = 3·96; CI = 1·53-10·47) of previous parasitic infection. In multivariate analyses, however, only two (modifiable) risk factors were found to be independently and significantly associated with Giardia infection: nail biting and eating unwashed vegetables raw. It therefore seems that, at least at the individual level, giardiasis-prevention activities in Havana should be focussed on health education to improve personal hygiene and food-related practices. If appropriately managed, the surveillance of drinking water and foodstuffs, for Giardia and other parasites, might also help to reduce the hospitalization of Cuban children.

Incidence and influence on referral of primary stabbing headache in an outpatient headache clinic

Primary stabbing headache (PSH) is a pain, as brief, sharp, jabbing stabs, predominantly felt in the first division of trigeminal nerve. Population studies have shown that PSH is a common headache. However, most people suffer attacks of low frequency or intensity and seldom seek for medical assistance. There are few clinic-based studies of PSH, and its real influence as a primary cause for referral to neurology outpatient offices is to be determined. We aim to investigate the burden of PSH as main complaint in an outpatient headache clinic. We reviewed all patients with PSH (ICHD-II criteria), attended in an outpatient headache clinic in a tertiary hospital during a 2.5-year period (January 2008–June 2010). We considered demographic and nosological characteristics and if PSH was main cause of submission. 36 patients (26 females, 10 males) out of 725 (5%) were diagnosed of PSH. Mean age at onset 34.1 ± 2.9 years (range 10–72). Mean time from onset to diagnosis 68.8 ± 18.3 months. Twenty-four patients fulfilled ICHD-II criteria for other headaches (14 migraine, 6 tension-type headache, 2 hemicrania continua, 1 primary cough headache and 1 primary exertional headache). 77.7% of patients were submitted from primary care. In 14 patients (39%), PSH was main reason for submission, its intensity or frequency in 5 (35.7%) and fear of malignancy in 9 (74.3%). Only two patients of those who associated other headaches were submitted due to PSH. In conclusion, PSH is not an uncommon diagnosis in an outpatient headache office. However, and according to our data, it is not usually the main cause of submission to a headache clinic.

Bronchoscopic lung volume reduction in a single-lung transplant recipient with natal lung hyperinflation: a case report

After single lung transplantation for emphysema native lung hyperinflation is a common complication that may cause respiratory failure. Herein we have reported satisfactory bronchoscopic lung volume reduction in a left single-lung transplant recipient with native lung hyperinflation, who suffered from Medical Research Council (MRC) class 3 dyspnea and chest pain. Three endobronchial valves (Zephyr; Emphasys Medical, Redwood, Calif, United States) were placed into the segmental bronchi of the right upper lobe, using videobronchoscopy under general anesthesia. Postoperative chest computed tomography revealed subsegmental atelectasis in that lobe. The clinical benefit was an improved MRC dyspnea class from 3 to 2, which was still present at 4 months after the procedure, although there were no remarkable changes in spirometric parameters.