Novel chelating agents for iron, manganese, zinc, and copper mixed fertilisation in high pH soil-less cultures

BACKGROUND

Studies about simultaneous fertilisation with several micronutrients have increased in recent years, as Fe, Mn and Zn deficiencies may appear in the same culture conditions. In fertigation, the replacement of sulfates by synthetic chelates is essential in areas with high pH irrigation water and substrates. Ethylenediamine-N-(2-hydroxyphenylacetic acid)-N'-(4-hydroxyphenylacetic acid) (o,p-EDDHA) and ethylenediamine disuccinic acid (EDDS) are novel chelating agents whose efficacy in simultaneous fertilisation of Zn, Mn and Cu is unknown. This work evaluates the effectiveness of both ligands compared to traditional ligands (EDTA, HEEDTA and DTPA) applied as micronutrient chelate mixtures to soybean and navy bean plants grown in soil-less cultures at high pH by analysing the SPAD and micronutrient nutritional status, including the Composition Nutritional Diagnosis (CND) analysis tool.

RESULTS

The application of micronutrients using o,p-EDDHA was more effective in providing Mn and Zn than traditional ligands or sulfates. The application using EDDS increased the Zn nutrition. The results are well correlated with the chemical stability of the formulations.

CONCLUSION

The combined application of Mn and Zn as o,p-EDDHA chelates can represent a more effective source than traditional chelates in micronutrient fertiliser mixtures in soil-less cultures at a high pH.

Reactivity and effectiveness of traditional and novel ligands for multi-micronutrient fertilization in a calcareous soil

This study compares the effectiveness of multi-micronutrient formulations containing iron (Fe), manganese (Mn), and zinc (Zn) with traditional (EDTA, DTPA, HEEDTA, and EDDHAm) or novel chelates (o,p-EDDHA, S,S-EDDS, and IDHA) and natural complexing agents (gluconate and lignosulfonate). The stability and reactivity of the formulations were studied on batch experiments with calcareous soil and by speciation modeling. Formulations containing traditional ligands maintained higher Mn but lower Zn concentration in soil solution than the novel ligands. The gluconate and lignosulfonate maintained low concentrations of both Mn and Zn in soil solution. Selected formulations were applied into calcareous soil and their efficacy was evaluated in a pot experiment with soybean. The formulation containing DTPA led to the highest Zn concentration in plants, as well as the formulation containing S,S-EDDS in the short-term, which correlated with its biodegradability. The application of traditional or novel ligands in formulations did not result in sufficient plant Mn concentrations, which was related to the low Mn stability observed for all formulations under moderate oxidation conditions. The results highlight the need to consider the effect of metals and ligands interactions in multi-nutrient fertilization and the potential of S,S-EDDS to be used for Zn fertilization. Furthermore, it is necessary to explore new sources of Mn fertilization for calcareous soils that have greater stability and efficiency, or instead to use foliar fertilization.

Root iron uptake efficiency of Ulmus laevis and U. minor and their distribution in soils of the Iberian Peninsula

The calcifuge and calcicole character of wild plants has been related to nutrient availability shortages, including iron (Fe)-deficiency. Surprisingly, just a few studies examined the relation between root Fe uptake and plant distribution in different soil types. We assessed the root Fe acquisition efficiency of two Ulmus species with calcareous (Ulmus minor) and siliceous (U. laevis) soil distribution patterns in the Iberian Peninsula. Seedlings of both elm species were grown hydroponically with different Fe concentrations during 6 weeks. Plant physiological responses to Fe-limiting conditions were evaluated as were the ferric reductase activity and proton (H(+)) extrusion capacity of the roots. Iron deprived elm seedlings of both species were stunted and suffered severe Fe-chlorosis symptoms. After Fe re-supply leaf chlorophyll concentrations rose according to species-dependent patterns. While U. minor leaves and seedlings re-greened evenly, U. laevis did so along the nerves of new growing leaves. U. minor had a higher root ferric reductase activity and H(+)-extrusion capability than U. laevis and maintained a better nutrient balance when grown under Fe-limiting conditions. The two elm species were found to have different Fe acquisition efficiencies which may be related to their natural distribution in calcareous and siliceous soils of the Iberian Peninsula.

FRET-based dimeric aptamer probe for selective and sensitive Lup an 1 allergen detection

A sensitive method for the rapid and sensitive detection of the anaphylactic food allergen Lup an 1 (β-conglutin) exploiting fluorescence resonance energy transfer (FRET) has been developed. A high affinity dimeric form of a truncated 11-mer aptamer against β-conglutin was used, with each monomeric aptamer being flanked by donor/acceptor moieties. The dimeric form in the absence of target yields fluorescence emission due to the FRET from the excited fluorophore to the proximal second fluorophore. However, upon addition of β-conglutin, the specific interaction induces a change in the bi-aptameric structure resulting in an increase in fluorescence emission. The method is highly specific and sensitive, with a detection limit of 150 pM, providing an effective tool for the direct detection of the toxic β-conglutin subunit in foodstuffs in just 1 min at room temperature.

Selection of 2'F-modified RNA aptamers against prostate-specific antigen and their evaluation for diagnostic and therapeutic applications

Currently, prostate-specific antigen (PSA) is considered to be the most sensitive marker available for prostate cancer detection and for monitoring of disease progression. In addition to its importance as a tumor marker, PSA has a role in the biological activity of cancer growth and proliferation. Therefore, the inhibition or activation of its biological activity may be used in prostate cancer therapy. Here, we describe the isolation and characterization of new 2'F-modified RNA aptamers directed against PSA. Binding studies demonstrate the ability of these new aptamers to specifically recognize their target with dissociation constants in the nanomolar range. In order to demonstrate the functionality of the selected aptamers, an apta-PCR approach was used for the quantitative detection of PSA, achieving a limit of detection of 11 nM. Furthermore, the potential use of the selected aptamers in therapeutics was demonstrated with the 2'F-modified aptamers being highly stable in human serum and having the ability to moderate the activity of PSA, which will be explored for the treatment of prostate cancer.

Comparison of different methods for generation of single-stranded DNA for SELEX processes

Single-stranded DNA (ssDNA) generation is a crucial step in several molecular biology applications, such as sequencing or DNA chip and microarray technology. Molecules of ssDNA also play a key role in the selection of ssDNA aptamers through Systematic Evolution of Ligands by EXponential enrichment (SELEX). With particular interest for this application, herein we present a comparative study of the most used methods for generation of ssDNA used in SELEX, such as asymmetric PCR, enzyme digestion and magnetic separation with streptavidin beads. In addition, we evaluate a new technique that combines asymmetric PCR and enzyme digestion with the aim to achieve the maximum efficiency in ssDNA generation. The methods studied were compared in terms of quality of ssDNA using electrophoretic analysis and generated ssDNA yields were quantitatively measured using an Enzyme-Linked OligoNucleotide Assay (ELONA).

Structure and fertilizer properties of byproducts formed in the synthesis of EDDHA

The synthesis of commercial EDDHA produces o,o-EDDHA as the main reaction product, together with a mixture of regioisomers (o,p-EDDHA and p,p-EDDHA) and other unknown byproducts also able to complex Fe3+. These compounds have been obtained by direct synthesis, and their structures have been determined by ESI-MS analysis as oligomeric EDDHA-like products, formed by polysubstitution in the phenolic rings. Short-term experiments show that the iron complexes of samples enriched in these oligomeric byproducts have adequate stability in solution, but a significant amount of them is lost after interaction with soils and soil materials. Mildly chlorotic cucumber plants are able to reduce iron better from o,p-EDDHA/Fe3+ than from the iron complexes of the oligomeric byproducts. In hydroponics, the chlorotic soybean susceptible plants have a lower potential for Fe absorption from these byproducts than from o,o-EDDHA/Fe3+ and from o,p-EDDHA/Fe3+. In the studied conditions, the iron chelates of EDDHA byproducts do not have the long-lasting effect shown by o,o-EDDHA/Fe3+ and present a less efficient fast-action effect than the o,p-EDDHA/Fe3+.

Single cell variability of L. monocytogenes grown on liver pate and cooked ham at 7oC: comparing challenge test data to predictive simulations

AIMS

The variability in growth between individual Listeria monocytogenes cells was investigated on liver pâté and cooked ham. These results were compared to Monte Carlo simulations based on data collected previously in broths (Francois et al., submitted for publication).

METHODS AND RESULTS

Single cells were isolated by a dilution protocol and inoculated on 15 g samples of liver pâté and cooked ham, pasteurized in the packaging. Of each product, 250 samples were inoculated, of which 50 samples were analysed for L. monocytogenes on each analysis day. Results were compared to simulations, based on distributions that describe the variability of the individual cell lag phases and generation times of L. monocytogenes cultivated in broths. Based on the same simulation techniques, the variability effect was investigated for different inoculum levels (10, 100, 10,00 and 10,000 cells). It was demonstrated that the expected variability of the outgrowth of L. monocytogenes in a challenge test is very high for low inoculum levels.

CONCLUSIONS

The variability in growth characteristics observed between different single L. monocytogenes cells on foods is very large. The simulations based on the previously collected optical density data in broths, could be confirmed by foods inoculated with single L. monocytogenes cells.

SIGNIFICANCE AND IMPACT OF THE STUDY

The large variability between different individual L. monocytogenes cells has serious consequences for the experimental design of a challenge test. One thousand cells per portion are necessary in order to reduce the variability to acceptable levels and quantify the behaviour of the pathogen consistently with a reasonable number of challenge tests.

Treatment of severe nosocomial pneumonia: a prospective randomised comparison of intravenous ciprofloxacin with imipenem/cilastatin

BACKGROUND

A prospective multicentre study was undertaken to compare the efficacy of intravenous ciprofloxacin or imipenem in the treatment of severe nosocomial pneumonia requiring mechanical ventilation.

METHODS

Patients with a clinical suspicion of pneumonia were randomised to receive either ciprofloxacin (800-1200 mg/day) or imipenem (2-4 g/day) in doses adjusted for renal function and specimens of the lower respiratory tract were taken. Patients were included in the study when specimens showed significant growth for potentially pathogenic microorganisms in quantitative bacterial cultures (n = 75, ciprofloxacin 41/75 (55%); imipenem 34/75 (45%)). The clinical and bacteriological success rates were the primary and secondary efficacy variables. An intent-to-treat analysis was performed for all randomised patients who received at least one dose of the study medication (n = 149, ciprofloxacin 72/149 (48%), imipenem 77/149 (52%)).

RESULTS

The success rates were generally good, but neither the clinical success rates (ciprofloxacin, 29/41 (71%), imipenem, 27/34 (79%); 95% CI -10.8 to 28.1; p = 0.435) nor the bacteriological response rate (ciprofloxacin, 20/41 (49%), imipenem, 17/34 (50%); 95% CI -21.5 to 23.9; p = 1.0) were significantly different between the study arms. Pseudomonas aeruginosa was recovered in 26/75 patients (35%) and clinical (ciprofloxacin, 10/14 (71%), imipenem, 8/12 (67%); 95% CI -40.4 to 30.9; p = 1.0) and bacteriological response rates (ciprofloxacin, 7/14 (50%), imipenem, 3/12 (25%), 95% CI -60.9 to 10.9, p = 0.247) were not significantly different in this subgroup of patients. Resistance of Pseudomonas aeruginosa developed in 5/26 cases (19%), 1/14 (7%) to ciprofloxacin and 4/12 (33%) to imipenem (p = 0.147), and the mortality was 12/75 (16%) with no difference between treatment groups (ciprofloxacin, 8/41(24%), imipenem 4/34 (17%); p = 0.362). The clinical response was evaluable in 109/149 patients (73%) in the intent-to-treat analysis and was successful in 74/109 patients (68%). The clinical response rates were also not significantly different in the intent-to-treat analysis (ciprofloxacin, 34/52 (65%), imipenem, 40/57 (70%); 95% CI -12.8 to 22.3; p = 0.746).

CONCLUSIONS

Treatment with either ciprofloxacin or imipenem was effective in a selected group of patients with microbiologically confirmed, severe nosocomial pneumonia requiring mechanical ventilation. Although no differences between the study medication could be documented in this trial, smaller differences between treatment arms may have been missed because of sample size limitations.

[Severe Plasmodium falciparum malaria. Description of 5 cases]

In the last few years a considerable number of imported malaria has been reported in Spain, probably due the increased tourism to areas with endemic malaria, particularly with P. falciparum. This is the species more frequently associated with severe complications and the only one capable of causing cerebral malaria. In this report we review five cases of malaria which required intensive care because of their severity. None of the patients had received chemoprophylaxis. In all cases the admission criterion to the intensive care unit was the organic failure of one or more systems (renal failure and disseminated intravascular coagulation [DIC] mainly) or the presence of changes in the central nervous system. Parasitemia at admission was higher than 5% in all patients. One patient died on account of cerebral malaria. Only one patient had severe complications not directly associated with malaria. In patients who already have severity criteria, a negative parasitemia test during the clinical course does not necessarily implies a clinical improvement nor does it exclude the emergence of complications. On the other hand, a low parasitemic degree is never a contraindication for admission to the intensive care unit when severity criteria are present.

Pneumonia in ventilated head trauma patients: the role of thiopental therapy

The role of barbiturate therapy in the development of pneumonia in head trauma patients in the intensive care unit of a university hospital was studied retrospectively. A total of 151 ventilated head trauma patients were included in the study. Intravenous thiopentone was administered to 75 patients (Group A), and 76 patients were managed without thiopentone therapy (Group B). Pneumonia was diagnosed when a new persistent pulmonary infiltrate appeared, with at least two of the following: (a) fever greater than 38 degrees C, (b) a white blood cell count greater than 15,000/mm3, or (c) the presence of purulent bronchial secretions. On admission, there were no differences in the acute physiology and chronic health evaluation 2 revision (APACHE II) and Glasgow Coma Score between Groups A and B. Fifty-three per cent of the patients treated with thiopentone (Group A) developed pneumonia compared with 35% in Group B (odds ratio 1.85, 95% confidence interval 0.97-3.51). Gram-negative and Staphylococcus aureus organisms were the most frequently isolated in all cases. No differences in age, sex, APACHE II, Glasgow Coma Score, nutritional status or dexamethasone treatment were observed between the groups with and without pulmonary infection. In the multivariate analysis, prolonged mechanical ventilation before pneumonia and thiopentone treatment remained as the only independent risk factors for the appearance of pneumonia in head trauma patients (p = 0.001 for both). Nevertheless, thiopentone did not increase the rate of mortality in patients with pneumonia. In conclusion, head trauma victims treated with thiopentone have a greater risk for the development of nosocomial pneumonia independent of mechanical ventilation.

[Acute myopathy related to the administration of glucocorticoids and neuromuscular blockers]

Two cases of acute myopathy following the administration of high doses of glucocorticoids in patients requiring mechanical ventilation and who were also administered neuromuscular blockers are presented. The patients were two women of 57 and 73 years of age. The doses of methylprednisolone administered were of 810 and 1,180 mg during the first 7 and 17 days, respectively. With regard to the total doses of neuromuscular blockers the first patient received 76 mg of pancuronium over 4 days while the second received 1,180 mg of atracurium over 17 days. This myopathy is characterized by a clinical and histological picture which differs from that associated to the chronic use of glucocorticoids being attributed to a toxic action of these drugs somewhat favored by immobilization due to the use of neuromuscular blockers. Given the lack of references in the literature on this entity in Spain a review was undertaken with the need for correct early diagnosis allowing differentiation from other causes of weakness such as ischemia of the cerebral trunk, polyradiculoneuritis and polyneuritis of critical patients being of note. Muscular biopsy is therefore very useful since very suggestive signs of this myopathy may be found. The disease is reversible with no effective treatment. An early rehabilitation program is the only method of shortening the convalescence period.

Posthypoxic myoclonus in intensive care

Posthypoxic myoclonus (Lance-Adams' syndrome) is a rare complication of cardiorespiratory arrest. It has a better prognosis than other movement disorders secondary to brain ischaemia. We report a case of posthypoxic myoclonus in a 66-year-old woman after acute myocardial infarction and cardiopulmonary arrest. She had action and intention myoclonus, and these movements were also initiated by acoustic and pain stimuli. The origin of the myoclonus was probably subcortical, and it improved with clonazepam 2 mg t.i.d. We emphasize that early diagnosis is necessary in intensive care units in order to avoid misinterpretation of this syndrome and to start appropriate treatment.

Trichosporon beigelii fungemia and metastatic pneumonia in a trauma patient

Trichosporon beigelii is a fungus which usually produces cutaneous involvement in immunocompetent hosts, being rarely reported to cause systemic infection. A case of fungemia and metastatic pneumonia caused by Trichosporon beigelii in a trauma patient is reported.

Statistical modeling of prognostic indices for evaluation of critically ill patients

OBJECTIVE

To identify the most predictive association of variables from the usual indices of severity of illness by statistical objective analysis.

DESIGN

Logistic regression analysis of the different variables of the most important indices.

SETTING

A general critical care medicine group practice in a university hospital.

PATIENTS

A total of 630 critical care patients age 12 to 87 yrs were evaluated. The most important indices of severity of illness and the corresponding variables were recorded and the patient's course was followed for 3 months after ICU admission.

MEASUREMENTS AND MAIN RESULTS

One of our hypotheses was that the inclusion of an excessive number of variables to obtain the most common prognostic indices of mortality in critical care patients results in an underestimation of mortality and a redundancy of prognostic information. We performed a logistic regression analysis using the variables of the currently used indices of critical care prognosis: Acute Physiology Score, Simplified Acute Physiology Score, Acute Physiology Score-II, and Mortality Prediction Model. This mathematical approach resulted in a model of five variables: organ system failure, blood glucose, serum calcium, serum prothrombin activity, and serum osmolality. The score obtained from this model gave accurate prognostic criteria:sensitivity 91.2% and specificity 90%, using a cutoff point of 0.7; sensitivity 86% and, specificity 94%, using a cutoff point of 0.5.

CONCLUSIONS

Our results show that suitable statistical management of the discriminant prognostic variables allows reduction of the number of variables of the severity indices currently used, obtaining five more predictive variables.

[Predictive factors of mortality in a series of 61 patients with severe acute pancreatitis]

The predictive value of eight clinical variables and 20 analytical variables on mortality was retrospectively analyzed in 61 patients with severe acute pancreatitis, fulfilling at least three Ranson criteria, admitted to the ICU between 1977 and 1987. The mean age of the series was 57 +/- 16.6 years. Twenty seven were males and 34 females. The mortality rate was 60%. Univariate analysis demonstrated that the variables with greater predictive value of mortality were: age, days of hospitalization, presence of associated diseases, plasma lactodehydrogenase, more than 10% hematocrit decrease during the first 48 hours, plasma ureic nitrogen on admission and a value greater than 1.8 mmol/l during the first 48 hours, calcemia, arterial oxygen pressure, plasma albumin, and prothrombin time. A logistic regression multivariate analysis disclosed that the variables with independent predictive value of mortality were: age, serum ureic nitrogen, calcemia, arterial oxygen pressure, plasma albumin, and hematocrit decrease after 48 hours. When the patients were grouped according to the presence of less than three, three, four or more than four of these risk factors (being, the average the cutting point) we obtained a good prognostic discriminative power since the mortality in those groups was 0, 30%, 60%, and 100%, respectively.

Acute thallium poisoning: an evaluation of different forms of treatment

Hemodialysis, forced potassium diuresis, chelating agents per os, and Dithiocarb given intravenously during short periods of time were used for the treatment of acute thallium poisoning (ingestion of 750 mg of thallium sulfate), and the effectiveness of these different therapeutic procedures was analyzed. Chelating agents per os (Prussian blue, Dithiocarb, and Dithiozone) were ineffective in our patient, since fecal excretion of thallium was very low and unmodified by them. Forced potassium diuresis and hemodialysis were very useful therapeutic measures, especially in the first 12 days following ingestion. Dithiocarb perfusion seems to be the most effective method for enhancing urinary thallium excretion. This method might be most useful in the treatment of thallium poisoning if its deleterious effects could be eliminated.

[Oliguric and non-oliguric renal failure in high risk patient in intensive care units (author's transl)]

Oliguric and non-oliguric acute renal failure was studied in a group of 28 high risk patients in an intensive care unit. Of these, 15 (53.5%) presented oliguric and 13 (46.4%) non oliguric acute renal failure. Causal agents of the renal failure were postoperative in 14 cases, mainly peritonitis; medical in 10 and posttraumatic in 4. Oliguric renal failure was most commonly medical, while non-oliguric renal failure was predominantly postoperative in origin (p less than 0.05). Results of urinalysis indicative of renal failure were similar in both groups: NAO, osmolarity, FeNa, BUN o/p and creatinine o/p, as were degree and course of renal failure, and the appearance of complications and indications for dialysis. There was no significant difference in mortality rate between oliguric (93%) and non-oliguric (85%) patients; total mortality was 89%. The results of this study clearly show that non-oliguric acute renal failure carries the same poor prognosis in high risk patients in intensive care units as do the oliguric forms of the entity.

Metabolic acidosis and coma due to an overdose of nalidixic acid

A case of severe metabolic acidosis and coma after taking 28 g of nalidixic acid is described. After administration of 600 mEq of sodium bicarbonate the patient developed a respiratory alkalosis with secondary tetany. She recovered her state of consciousness nine hours later and the acid-base disturbance resolved after sixty hours.