Denitrifying pathways dominate nitrous oxide emissions from managed grassland during drought and rewetting.

Nitrous oxide is a powerful greenhouse gas whose atmospheric growth rate has accelerated over the past decade. Most anthropogenic N2O emissions result from soil N fertilization, which is converted to N2O via oxic nitrification and anoxic denitrification pathways. Drought-affected soils are expected to be well oxygenated; however, using high-resolution isotopic measurements, we found that denitrifying pathways dominated N2O emissions during a severe drought applied to managed grassland. This was due to a reversible, drought-induced enrichment in nitrogen-bearing organic matter on soil microaggregates and suggested a strong role for chemo- or codenitrification. Throughout rewetting, denitrification dominated emissions, despite high variability in fluxes. Total N2O flux and denitrification contribution were significantly higher during rewetting than for control plots at the same soil moisture range. The observed feedbacks between precipitation changes induced by climate change and N2O emission pathways are sufficient to account for the accelerating N2O growth rate observed over the past decade.

[Metformin-associated lactic acidosis: incidence, diagnosis, prognostic factors and treatment]. / Acidosis láctica asociada a metformina: incidencia, diagnóstico, factores pronóstico y tratamiento.

We describe the case of a patient with severe lactic acidosis, as well as presenting some data on its incidence, diagnosis, prognostic factors, and the most appropriate treatment. A 76 year-old male patient with diabetes on treatment with metformin, hypertension, dyslipaemia, and with mild cognitive impairment, was admitted to the Intensive Care Unit in a state of circulatory shock, requiring aggressive treatment with vasopressors and volume. The patient had acute kidney injury with an anuria of 3 days, probably secondary to dehydration to vomiting and to NSAIDs. As a result of the acute renal damage, the patient suffered a severe metformin-associated lactic acidosis. The rest of the causes of metabolic acidosis with an increased anion gap were ruled out, as well as a possible sepsis or rhabdomyolysis. Metformin-associated lactic acidosis is an uncommon metabolic condition, but with a high mortality. To reduce the mortality of these patients, it is important to make an early diagnosis using the clinical records, physical examination, and laboratory tests, with an early resuscitation with volume, vasopressors, bicarbonate, and renal replacement therapy.

Acidosis láctica asociada a metformina: incidencia, diagnóstico, factores pronóstico y tratamiento / Metformin-associated lactic acidosis: incidence, diagnosis, prognostic factors and treatment

Describimos el caso de un paciente con acidosis láctica grave y presentamos algunos datos acerca de su incidencia, diagnóstico, factores pronósticos y tratamiento más adecuado. Un paciente varón de 76 años diabético en tratamiento con metformina, hipertenso, dislipémico y con ligero deterioro cognitivo, ingresó en la Unidad de Cuidados Intensivos en estado de shock circulatorio requiriendo tratamiento agresivo con vasopresores y volumen. El paciente presentaba un daño renal agudo con anuria de 3 días probablemente secundario a la deshidratación por vómitos y a la toma de AINES. A consecuencia del daño renal agudo el paciente padeció una acidosis láctica grave asociada a metformina. Se descartó el resto de causas de acidosis metabólica con anion gap aumentado, así como una posible sepsis o rabdomiolisis. La acidosis láctica asociada a metformina es una condición metabólica poco frecuente pero de alta mortalidad. Para disminuir la mortalidad de estos pacientes, es importante hacer un diagnóstico precoz mediante la historia clínica, la exploración física y la analítica con una rápida reanimación mediante volumen, vasopresores, bicarbonato y técnica de depuración extra-renal(AU)

We describe the case of a patient with severe lactic acidosis, as well as presenting some data on its incidence, diagnosis, prognostic factors, and the most appropriate treatment. A 76 year-old male patient with diabetes on treatment with metformin, hypertension, dyslipaemia, and with mild cognitive impairment, was admitted to the Intensive Care Unit in a state of circulatory shock, requiring aggressive treatment with vasopressors and volume. The patient had acute kidney injury with an anuria of 3 days, probably secondary to dehydration to vomiting and to NSAIDs. As a result of the acute renal damage, the patient suffered a severe metformin-associated lactic acidosis. The rest of the causes of metabolic acidosis with an increased anion gap were ruled out, as well as a possible sepsis or rhabdomyolysis. Metformin-associated lactic acidosis is an uncommon metabolic condition, but with a high mortality. To reduce the mortality of these patients, it is important to make an early diagnosis using the clinical records, physical examination, and laboratory tests, with an early resuscitation with volume, vasopressors, bicarbonate, and renal replacement therapy(AU)

Osteomyelitis at the injection site of adrenalin through an intraosseous needle in a 3-month-old infant.

Intraosseous (IO) puncture is considered for the administration of drugs and fluids when vascular access cannot be achieved rapidly. Adrenaline/epinephrine, adenosine, crystalloids, colloids and blood products can be applied and administered effectively using this route during resuscitation of children. This technique is relatively simple with complications of <1%. These may include tibial fracture, lower extremity compartment syndrome and osteomyelitis. A case is described in which a 3-month-old male infant presented for emergency resuscitation requiring IO infusion utilising both tibial bones. High doses of adrenaline (1:1000; 0.1 mg/kg) were administered in the right tibial epiphysis only after the standard initial concentration (1:10000; 0.01 mg/kg) had minimal effect. A local inflammatory reaction was noted 24 h later in the right tibial region, which developed into cutaneous necrosis, and was eventually resected. Radiologically, no osseous lesion could be demonstrated, however, a bone scintigram revealed osteomyelitis. Upon surgical revision, purulent destruction was evident requiring removal of the epiphysis and part of the metaphysis. Although osteomyelitis is a rare complication which may be caused by sepsis, or contamination during insertion, we speculate that adrenaline in high concentrations may promote the development of osteomyelitis and the drug should be applied cautiously in more diluted concentrations.

A new filtering algorithm for medical magnetic resonance and computer tomography images.

Inner views of tubular structures based on computer tomography (CT) and magnetic resonance (MR) data sets may be created by virtual endoscopy. After a preliminary segmentation procedure for selecting the organ to be represented, the virtual endoscopy is a new postprocessing technique using surface or volume rendering of the data sets. In the case of surface rendering, the segmentation is based on a grey level thresholding technique. To avoid artifacts owing to the noise created in the imaging process, and to restore spurious resolution degradations, a robust Wiener filter was applied. This filter working in Fourier space approximates the noise spectrum by a simple function that is proportional to the square root of the signal amplitude. Thus, only points with tiny amplitudes consisting mostly of noise are suppressed. Further artifacts are avoided by the correct selection of the threshold range. Afterwards, the lumen and the inner walls of the tubular structures are well represented and allow one to distinguish between harmless fluctuations and medically significant structures.

Too little concern for breast cancer risk in radiation protection estimates?

Risk estimates of radiogenic breast cancer from recent consensus reports are found to depend as much on the models used as on the data. Some features of the models of BEIR V and the ICRP 1990 Recommendations are hardly supported in the literature and tend to underrate breast cancer risk in radioprotection.

Some notions and units in radioepidemiology and radiation protection. A structured list for the epidemiologist.

An annotated list of some notions and units used in radioepidemiology is presented, with special emphasis on differentiating between the realms of radiation physics, radiation biology, radioepidemiology and radiation protection.

Scanning tunneling microscopy of recA-DNA complexes coated with a conducting film.

A link between scanning tunneling microscopy (STM) and conventional transmission electron microscopy has been established for biological material by applying STM on freeze-dried recA-DNA complexes coated with a conducting film. The topography of the complexes observed by means of STM revealed a right-handed single helix composed of about six recA monomers per helical turn.

[Course and quantitative evaluation of the lung involvement in cystic fibrosis]. / Verlauf und quantitative Erfassung des pulmonalen Befalls bei zystischer Fibrose.

On the basis of clinical observations the course of pulmonary involvement in cystic fibrosis is studied, and an attempt at classification into three severity groups is made. Clinical and radiological findings, quantified by special scores, are presented and correlations between scores and lung function data are demonstrated. Although respiratory function tests - in particular the ratio of residual volume to total lung capacity (RV/TLC) - correlate with the clinical and chest radiographic scores, division into three severity degrees is only reliable for groups of patients. In the individual patient the clinical, radiological and lung function findings must be taken into account together. Assessment according to a scoring system may be helpful.

Avian myeloblastosis virus RNA is terminally redundant: implications for the mechanism of retrovirus replication.

We have determined the terminal heteropolymeric sequences of AMV RNA by the following procedures: first, RNA sequence determination on the 5' terminal and the poly(A)-linked 3' terminal T1 oligonucleotides, and second, analysis by the Maxam and Gilbert (1977) method of AMV strong stop DNA and of DNA complementary to the poly(A)-linked T1 oligonucleotide, synthesized with reverse transcriptase and (pdT)13 as primer. The structure deduced for the 5' terminal region is (5')7mGpppGmCCAUUCUACCUCUCACCACAUUGGUGUGCACCUGGGUUGAUGGCCGGACCGUCGAUUCCCUGACGACUACGAGCACCUGCAUGAAGCAGAAGGCUUCAU... Two distinct 3' terminal sequences were deduced: GCCAUUCUACCUCUCAAA...AOH and GCCAUUCUACCUCUCACCAAA...AOH. The two termini, differing by a C-C-A sequence, may reflect genetic heterogeneity of the AMV stock or, more probably, may be generated at or after RNA transcription. These results demonstrate a terminal redundancy of the hetero polymeric sequence of 16 and 19 nucleotides, respectively. The terminal redundancy allows for mechanisms which involve transfer of the DNA segment synthesized on the 5' terminal redundant sequence to the 3' terminal redundant sequence.