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1.
J Environ Manage ; 347: 119149, 2023 Dec 01.
Artículo en Inglés | MEDLINE | ID: mdl-37783087

RESUMEN

The recent agricultural expansion in the Matopiba region, Brazil's new agricultural frontier, has raised questions about the risk of increasing soil organic carbon (SOC) loss as large areas of native vegetation (NV; i.e., Cerrado biome) have been replaced by large-scale mechanized agriculture. Although sustainable managements, such as integrated crop-livestock (ICL) systems, are considered strategic to counterbalance the SOC loss associated with land-use change (LUC) while keeping food production, little is known about their long-term effects on SOC stocks in the Matopiba region. To this end, we used the DayCent model to simulate the effects of converting the management commonly used in this region, i.e., soybean-cotton rotation under no-tillage (NT), into ICL systems with distinct levels of intensification (e.g., crop rotations: soybean-pasture and soybean-pasture-cotton; soil and crop management: grass irrigation, scarification/harrowing, and length of grass cultivation) on long term SOC dynamics. Additionally, data from two projected climate scenarios: SSP2-4.5 [greenhouse gases emissions (GHG) will not change markedly over time and global temperature will increase by 2.0 °C by 2060] and SSP5-8.5 (marked changes in GHG emissions are expected to occur resulting in an increase of 2.4 and 4.4 °C in global temperature in the middle and at the end of the century) were included in our simulations to evaluate climate change effects on SOC dynamics in this region. Based on a 50-yr-time frame simulation, we observed that SOC stocks under ICL systems were, on average, 23% and 47% higher than in the NV (36.9 Mg ha-1) and soybean-cotton rotation under NT (30.9 Mg ha-1), respectively. Growing grasses interlaid with crops was crucial to increase SOC stocks even when disruptive soil practices were followed. Although the irrigation of grass resulted in an early increase of SOC stocks and a higher pasture stoking rate, it did not increase SOC stocks in the long term compared to non-irrigated treatments. The SSP2-4.5 and SSP5-8.5 climate scenarios had little effects on SOC dynamics in the simulated ICL systems. However, additional SOC loss (∼0.065 Mg ha-1 yr-1) is predicted to occur if the current management is not improved. These findings can help guide management decisions for the Matopiba region, Brazil, to alleviate the anthropogenic pressure associated with agriculture development. More broadly, they confirm that crop-livestock integration in croplands is a successful strategy to regenerate SOC.


Asunto(s)
Cambio Climático , Suelo , Carbono/análisis , Brasil , Biodiversidad , Temperatura , Agricultura/métodos , Poaceae
2.
Phys Rev Lett ; 127(13): 131802, 2021 Sep 24.
Artículo en Inglés | MEDLINE | ID: mdl-34623867

RESUMEN

Searches for the lepton number violating K^{+}→π^{-}µ^{+}e^{+} decay and the lepton flavor violating K^{+}→π^{+}µ^{-}e^{+} and π^{0}→µ^{-}e^{+} decays are reported using data collected by the NA62 experiment at CERN in 2017-2018. No evidence for these decays is found and upper limits of the branching ratios are obtained at 90% confidence level: B(K^{+}→π^{-}µ^{+}e^{+})<4.2×10^{-11}, B(K^{+}→π^{+}µ^{-}e^{+})<6.6×10^{-11} and B(π^{0}→µ^{-}e^{+})<3.2×10^{-10}. These results improve by 1 order of magnitude over previous results for these decay modes.

3.
Public Health ; 141: 26-31, 2016 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-27932012

RESUMEN

OBJECTIVES: This study was carried out with two objectives. The first one was to have an insight into the prevalence of chronic noncommunicable diseases (CNCD) in undocumented migrants, and the second one was to evaluate if differences existed among different ethnic groups. STUDY DESIGN: The study is based on the collection of data on drug dispensation by a non-governmental organization (NGO) providing free medical assistance to undocumented migrants in Milan, Italy. All the prescriptions to adult subjects from January 1 to December 31 2014 (total 8438) were recorded and analyzed. All the data available for the patients receiving prescriptions (age, gender and country of birth) were also collected in anonymous form. Ethical approval for the study was given by the Ethics Committee of the NGO. METHODS: Drugs were grouped according to the anatomical therapeutic chemical (ATC) classification and their quantities expressed as daily defined doses (DDDs)/1000 patients/day. The 56 ATC levels were divided into three groups according to their use for acute, chronic, or both acute and chronic diseases. The statistical analysis of drug dispensation was performed for the whole population and for the five ethnic groups into which it had been divided. RESULTS: Prescription of medicines for chronic conditions was significantly greater than for acute (154.2 ± 45.9 vs 51.3 ± 18.4 DDD/1000 patients/day, P < 0.02) and for both acute and chronic conditions (57.9 ± 12.8 DDD/1000 patients/day, P < 0.02). Five ATC classes accounted for 60% of all chronic prescriptions. They were differently distributed among the five ethnic groups (e.g., Asians required more antihypertensives and antidiabetics, East Europeans required more lipid modifying drugs, antihypertensives and antithrombotics). CONCLUSIONS: Our data show an important use of medicines for chronic diseases in a population of undocumented migrants. Though with some limitations, this could be an indicator of a high prevalence of CNCD in this population, with significant differences among different ethnic groups. This situation should be considered when planning health interventions, also in consideration of the fact that it could have an impact on European Health Services in a short time.


Asunto(s)
Enfermedad Crónica/epidemiología , Costo de Enfermedad , Inmigrantes Indocumentados/estadística & datos numéricos , Adolescente , Adulto , Anciano , Enfermedad Crónica/tratamiento farmacológico , Prescripciones de Medicamentos/estadística & datos numéricos , Femenino , Humanos , Italia/epidemiología , Masculino , Persona de Mediana Edad , Organizaciones , Farmacia , Prevalencia , Encuestas y Cuestionarios , Adulto Joven
4.
Phys Rev Lett ; 110(20): 201801, 2013 May 17.
Artículo en Inglés | MEDLINE | ID: mdl-25167396

RESUMEN

The analysis of a combined data set, totaling 3.6 × 10(14) stopped muons on target, in the search for the lepton flavor violating decay µ(+) → e(+)γ is presented. The data collected by the MEG experiment at the Paul Scherrer Institut show no excess of events compared to background expectations and yield a new upper limit on the branching ratio of this decay of 5.7 × 10(-13) (90% confidence level). This represents a four times more stringent limit than the previous world best limit set by MEG.

5.
Bone Marrow Transplant ; 58(5): 526-533, 2023 05.
Artículo en Inglés | MEDLINE | ID: mdl-36774432

RESUMEN

Allogeneic hematopoietic stem cell transplantation (HSCT) is still needed for many children with very high-risk acute leukemia. An HLA-haploidentical family donor is a suitable option for those without an HLA-matched donor. Here we present outcomes of a novel HLA-haploidentical HSCT (haplo-HSCT) strategy with adoptive immunotherapy with thymic-derived CD4+CD25+ FoxP3+ regulatory T cells (Tregs) and conventional T cells (Tcons) performed between January 2017 and July 2021 in 20 children with high-risk leukemia. Median age was 14.5 years (range, 4-21), 15 had acute lymphoblastic leukemia, 5 acute myeloid leukemia. The conditioning regimen included total body irradiation (TBI), thiotepa, fludarabine, cyclophosphamide. Grafts contained a megadose of CD34+ cells (mean 12.4 × 106/Kg), Tregs (2 × 106/Kg) and Tcons (0.5-1 × 106/Kg). All patients achieved primary, sustained full-donor engraftment. Only one patient relapsed (5%). The incidence of non-relapse mortality was 15% (3/20 patients). Five/20 patients developed ≥ grade 2 acute Graft versus Host Disease (aGvHD). It resolved in 4 who are alive and disease-free; 1 patient developed chronic GvHD (cGvHD). The probability of GRFS was 60 ± 0.5% (95% CI: 2.1-4.2) (Fig. 6), CRFS was 79 ± 0.9% (95% CI: 3.2-4.9) as 16/20 patients are alive and leukemia-free. The median follow-up was 2.1 years (range 0.5 months-5.1 years). This innovative approach was associated with very promising outcomes of HSCT strategy in pediatric patients.


Asunto(s)
Enfermedad Injerto contra Huésped , Trasplante de Células Madre Hematopoyéticas , Leucemia Mieloide Aguda , Humanos , Niño , Adolescente , Inmunoterapia Adoptiva/efectos adversos , Trasplante de Células Madre Hematopoyéticas/efectos adversos , Enfermedad Injerto contra Huésped/etiología , Leucemia Mieloide Aguda/complicaciones , Células Madre Hematopoyéticas , Acondicionamiento Pretrasplante/efectos adversos
6.
Phys Rev Lett ; 107(17): 171801, 2011 Oct 21.
Artículo en Inglés | MEDLINE | ID: mdl-22107507

RESUMEN

We present a new result based on an analysis of the data collected by the MEG detector at the Paul Scherrer Institut in 2009 and 2010, in search of the lepton-flavor-violating decay µ(+)e(+)γ. The likelihood analysis of the combined data sample, which corresponds to a total of 1.8×10(14) muon decays, gives a 90% C.L. upper limit of 2.4×10(-12) on the branching ratio of the µ(+)→e(+)γ decay, constituting the most stringent limit on the existence of this decay to date.

7.
Pediatr Blood Cancer ; 53(1): 124-6, 2009 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-19309717

RESUMEN

We describe the case a 2-day-old female with congenital glioblastoma. Total resection was followed by adjuvant and high dose chemotherapy, as indicated by the current Italian infant protocol. The child is alive and well 18 months after diagnosis. A review of 67 selected congenital brain tumors showed the mortality rate was 82%. Even though the majority of patients had glioblastoma, only 5/67 had received adjuvant therapy. To ensure optimal outcomes, we recommend total or subtotal surgical resection, followed by adjuvant and high dose chemotherapy. Given the lack specific protocols for congenital brain tumors an international consensus seems to be needed, starting with congenital glioblastoma.


Asunto(s)
Neoplasias Encefálicas/congénito , Neoplasias Encefálicas/diagnóstico , Glioblastoma/congénito , Glioblastoma/diagnóstico , Protocolos de Quimioterapia Combinada Antineoplásica/efectos adversos , Protocolos de Quimioterapia Combinada Antineoplásica/uso terapéutico , Biopsia , Neoplasias Encefálicas/tratamiento farmacológico , Cateterismo Venoso Central , Quimioterapia Adyuvante , Craneotomía , Femenino , Glioblastoma/tratamiento farmacológico , Enfermedades Hematológicas/inducido químicamente , Humanos , Recién Nacido , Neoplasia Residual/diagnóstico , Neoplasia Residual/tratamiento farmacológico , Neoplasia Residual/cirugía , Segunda Cirugía
8.
J Clin Invest ; 68(5): 1119-24, 1981 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-6271806

RESUMEN

Malignant hyperthermia occurs in humans with several congenital myopathies, usually in response to general anesthesia. Commonly, individuals who develop this syndrome lack symptoms of muscle disease, and their muscle lacks specific pathological changes. A biochemical marker for this myopathy has not previously been available; we found activity of adenylate cyclase and content of cyclic AMP to be abnormally high in skeletal muscle. Secondary modification of protein phosphorylation could explain observed abnormalities of phosphorylase activation and sarcoplasmic reticulum function.


Asunto(s)
Adenilil Ciclasas/metabolismo , Hipertermia Maligna/enzimología , Músculos/enzimología , 3',5'-AMP Cíclico Fosfodiesterasas/metabolismo , Adolescente , Adulto , Niño , Preescolar , AMP Cíclico/metabolismo , Activación Enzimática , Femenino , Fluoruros/farmacología , Humanos , Cinética , Persona de Mediana Edad
10.
Eura Medicophys ; 42(2): 121-6, 2006 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-16767058

RESUMEN

AIM: The aim of the study was to evaluate the long-term efficacy of night-only splint wear therapy for carpal tunnel syndrome (CTS). METHODS: We conducted a randomized case-control trial with evaluation after three and six months of follow-up of outpatients with mild, recent onset symptoms of CTS recruited from the department clinic. Fifty patients (50 hands) were enrolled, of which 36 completed the study at 6 months. The case group utilized a thermoplastic neutral wrist splint for night-only wear. Outcome measures were instrumental parameters (sensory and motor nerve conduction velocity), symptom and function alterations (as measured by Levine's self-administered questionnaire), clinical parameters (pressure-provocative and Phalen tests). RESULTS: Improvements were observed in Levine's symptom status score at the three-month (P=0.001) and the six-month (P=0.001) follow-up visits, in functional score (P=0.0001) and (P=0.0004), in median distal sensory latency (P=0.01) and (P=0.02), in pressure-provocative test outcome (P=0.01) and (P=0.003), in Phalen test outcome (P=0.04) and (P=0.05) respectively. CONCLUSION: Symptom relief and neurophysiological improvement after night-only splint wear therapy lasted up to the six-month follow-up visit.


Asunto(s)
Síndrome del Túnel Carpiano/rehabilitación , Férulas (Fijadores) , Síndrome del Túnel Carpiano/fisiopatología , Estudios de Casos y Controles , Femenino , Humanos , Masculino , Nervio Mediano/fisiología , Persona de Mediana Edad , Conducción Nerviosa/fisiología , Encuestas y Cuestionarios , Resultado del Tratamiento
11.
Biochim Biophys Acta ; 770(2): 122-6, 1984 Mar 14.
Artículo en Inglés | MEDLINE | ID: mdl-6421324

RESUMEN

We found that adenylate cyclase activity of human erythrocytes is potentially labile during isolation of their plasmalemma. Addition of 1 mM EGTA to solution used to remove hemoglobin from lysed cells protected activity. Human erythrocyte adenylate cyclase is minimally activated by catecholamines, in the absence or presence of exogenous guanyl nucleotide, but substantially by 5'-guanylyl imidodiphosphate or sodium fluoride and concentration-dependently by Mg2+ or Mn2+. Basal catalytic activity is an age-dependent component of the human erythrocyte; 5'-guanylyl imidodiphosphate- or fluoride-activated activities decline with cellular maturation proportionally to the decrease in basal activity.


Asunto(s)
Adenilil Ciclasas/sangre , Eritrocitos/enzimología , Fraccionamiento Celular , Ácido Egtácico/farmacología , Envejecimiento Eritrocítico , Guanilil Imidodifosfato/farmacología , Humanos , Isoproterenol/farmacología , Magnesio/farmacología , Manganeso/farmacología , Fluoruro de Sodio/farmacología
12.
Chemosphere ; 119: 122-129, 2015 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-24973531

RESUMEN

Nitrous oxide (N2O) has become the prime ozone depleting atmospheric emission and the third most important anthropogenic greenhouse gas, with a global warming potential approximately 300 times higher than CO2. Nitrification and denitrification are processes responsible for N2O emission from the soil after nitrogen input. The application of a nitrification inhibitor can reduce N2O emissions from these processes. The objective of this study was to assess the effect of two different nitrification inhibitors (dicyandiamide (DCD) and a commercial formulation containing two pyrazole derivatives (PD), 1H-1,2,4-triazole and 3-methylpyrazole) on N2O emissions from cattle urine applications for summer grazing conditions in the UK. Experiments were conducted under controlled conditions in a laboratory incubator and under field conditions on a grassland soil. The N2O emissions showed similar temporal dynamics in both experiments. DCD concentration in the soil showed an exponential degradation during the experiment, with a half-life of the order of only 10d (air temperature c. 15 °C). DCD (10 kg ha(-1)) and PD at the highest application rate (3.76 kg ha(-1)) reduced N2O emissions by 13% and 29% in the incubation experiment and by 33% and 6% in the field experiment, respectively, although these reductions were not statistically significant (P>0.05). Under UK summer grazing conditions, these nitrification inhibitors appear to be less effective at reducing N2O emissions than reported for other conditions elsewhere in the literature, presumably due to the higher soil temperature.


Asunto(s)
Contaminantes Atmosféricos/análisis , Guanidinas/farmacología , Óxido Nitroso/análisis , Pirazoles/farmacología , Contaminantes del Suelo/metabolismo , Triazoles/farmacología , Contaminantes Atmosféricos/metabolismo , Animales , Bacterias/efectos de los fármacos , Bacterias/metabolismo , Bovinos/orina , Inglaterra , Pradera , Nitrificación/efectos de los fármacos , Óxido Nitroso/metabolismo , Estaciones del Año
13.
Arch Neurol ; 34(1): 12-3, 1977 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-188401

RESUMEN

Cyclic guanosine monophosphate (cGMP) levels have been measured in the cerebrospinal fluid of patients with various neurological diseases. The subjects with epilepsy or cerebrovascular diseases do not show any difference from the controls. Moreover, in the CSF of patients having cerebral tumors the levels of cGMP are markedly increased. This change is in line with previous in vitro studies on the increase of cGMP during cell growth and cell proliferation showing that the role of the nucleotide is important for the control of the life cycle of the cell.


Asunto(s)
Neoplasias Encefálicas/líquido cefalorraquídeo , Trastornos Cerebrovasculares/líquido cefalorraquídeo , GMP Cíclico/líquido cefalorraquídeo , Epilepsia/líquido cefalorraquídeo , Adolescente , Adulto , Anciano , Enfermedad de Alzheimer/líquido cefalorraquídeo , Femenino , Humanos , Hidrocéfalo Normotenso/líquido cefalorraquídeo , Masculino , Persona de Mediana Edad , Esclerosis Múltiple/líquido cefalorraquídeo
14.
J Gerontol A Biol Sci Med Sci ; 51(6): B439-47, 1996 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-8914494

RESUMEN

Hexarelin (HEXA; 500 micrograms/kg/die, s.c.) was administered for 16 weeks to six old beagle dogs. The treatment consisted of three on-drug periods spaced by two off-drug periods. During each on period, the growth hormone (GH) peak response to HEXA initially increased and then dropped to pretreatment values. Each time, a wash-out interval restored the same pattern of GH responsiveness. HEXA significantly augmented the indices of spontaneous pulsatility of GH, but plasma insulin-like growth factor I levels did not change during treatment. HEXA apparently reduced bone resorption since it significantly decreased the urinary concentration of lysylpyridinoline, a bone matrix component. Bone formation apparently was not affected since unchanged levels of alkaline phosphatase were recorded. In three of six old dogs, HEXA induced an improvement of some morphological and biochemical muscular indices, evaluated in muscle specimens that, instead, remained unchanged in a group of young untreated controls. These findings indicate that HEXA effectively releases GH and primes the pituitary of old dogs, and strengthen the view that in aging, GH secretion may be restored by pharmacological means. It would also appear that HEXA-induced GH release improves some indices of body composition in old dogs.


Asunto(s)
Huesos/efectos de los fármacos , Hormona del Crecimiento/metabolismo , Sustancias de Crecimiento/farmacología , Músculos/efectos de los fármacos , Oligopéptidos/farmacología , Animales , Huesos/metabolismo , Perros , Femenino , Hormona del Crecimiento/sangre , Masculino , Músculos/patología
15.
J Neurol ; 218(3): 149-56, 1978 Jun 16.
Artículo en Inglés | MEDLINE | ID: mdl-79642

RESUMEN

The carnitine content of the culture media for normal and pathological human muscles, including a case of systemic carnitine deficiency (SCD) was measured and the carnitine concentration was the same in all normal and pathological muscle culture media. Carnitine was never detected in growth medium. Some fibroblasts and myoblasts were filled with neutral lipids in SCD. 14C-palmitate added to the medium was incorporated by SCD fibroblasts or myoblasts to the same concentration as in normal or pathological cells. Factors other than carnitine seem to account for the lipid accumulation of SCD in cell culture.


Asunto(s)
Carnitina/biosíntesis , Músculos/metabolismo , Enfermedades Neuromusculares/metabolismo , Palmitatos/metabolismo , Ácidos Palmíticos/metabolismo , Carnitina/deficiencia , Células Cultivadas , Humanos
16.
J Neurol ; 221(1): 25-37, 1979 Jul 11.
Artículo en Inglés | MEDLINE | ID: mdl-92534

RESUMEN

A case of progressive extrinsic ophthalmoplegia associated with peripheral neuropathy and hypertriglyceridemia type IV is described. Motor and sensory conduction velocities of the spinal nerves were severely decreased, while the EMG of the facial muscles was more suggested of a myopathic disorder. Electron microscopic study of biopsies of biceps and peroneus brevis muscles disclosed many ragged red fibers, mainly type I, which contained typical abnormal mitochondria. Other fibers, all type II, contained increased amounts of glycogen between myofibrils or beneath the sarcolemmal membrane, but the mitochondria were normal. These fibers were more abundant in the peroneus brevis than in the biceps muscle. Nerve biopsy revealed marked loss of myelinated fibers, but neither mitochondrial changes nor glycogen storages were evident in Schwann's cells. Biochemical investigations confirmed the increased amount of glycogen in both muscle biopsies and revealed a decrease of guanilcyclase. Phosphorylase, phosphorylase b kinase, adenilcyclase, and carnitine concentrations were all normal. The pathogenesis of this syndrome is discussed and the relationship between mitochondrial abnormalities and glycogen accumulation in muscle tissue are considered.


Asunto(s)
Oftalmoplejía/patología , Enfermedades del Sistema Nervioso Periférico/patología , Adulto , Glucógeno/metabolismo , Humanos , Masculino , Mitocondrias Musculares/ultraestructura , Músculos/metabolismo , Músculos/ultraestructura , Conducción Nerviosa , Oftalmoplejía/metabolismo , Enfermedades del Sistema Nervioso Periférico/metabolismo
17.
J Neurol Sci ; 43(3): 421-7, 1979 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-230321

RESUMEN

Cyclic nucleotide phosphodiesterase activity has been measured in muscle biopsies taken from healthy controls and from cancer patients. In both groups the muscles were clinically and morphologically normal. The phosphodiesterase activity was significantly increased in muscles from cancer patients using both cyclic AMP and cyclic GMP as substrate. These findings are in line with previous reports indicating that malignancy may interfere with metabolism of the host muscular tissues, and suggest the possibility that the observed biochemical changes might be an aspect of an early muscle neurogenic involvement.


Asunto(s)
2',3'-Nucleótido Cíclico Fosfodiesterasas/metabolismo , Carcinoma/enzimología , Músculos/enzimología , Hidrolasas Diéster Fosfóricas/metabolismo , AMP Cíclico/metabolismo , GMP Cíclico/metabolismo , Humanos , Neoplasias Hepáticas/enzimología , Neoplasias Pulmonares/enzimología , Neoplasias del Recto/enzimología , Neoplasias Gástricas/enzimología
18.
Clin Chim Acta ; 111(2-3): 133-46, 1981 Apr 09.
Artículo en Inglés | MEDLINE | ID: mdl-7226546

RESUMEN

The wide range of values reported for activity of adenylate cyclase (AC) in human skeletal muscle prompted re-evaluation of conditions used for homogenization and assay. Adenylate cyclase activity in the same normal muscle differed with different techniques of homogenization. In pH 7.5 isotonic Tris buffer, basal and catecholamine-activated activities declined rapidly in homogenates kept at 4 degrees C. Loss of basal activity was prevented by addition of a chelator of divalent cations. Loss of response to isoproterenol was prevented by addition of guanylnucleotides. Enzyme activity was maximal at 37 degrees C and pH 7.6. Enzyme activity was lower when theophylline was used to prevent degradation of labelled 3',5' cyclic adenosine monophosphate (cyclic AMP) than when unlabelled cyclic AMP was used to this purpose. Basal activity increased with increased MgCl2 concentration up to 50 mmol/l, but isoproterenol-activated activity was maximal at 4 mmol/l MgCl2. AC was inhibited by exogenous adenosine, but addition of adenosine deaminase to the assay mixture did not increase AC activity. Based upon these observations, standardized procedures of homogenization and assay were devised and used to measure AC activity in muscles of boys with Duchenne muscular dystrophy: basal and isoproterenol-stimulated activities were abnormally low.


Asunto(s)
Adenilil Ciclasas/análisis , Músculos/enzimología , Distrofias Musculares/enzimología , Adenosina Trifosfato/metabolismo , Calcio/metabolismo , Humanos , Concentración de Iones de Hidrógeno , Magnesio/análisis , Métodos , Temperatura
19.
J Neurosurg ; 55(4): 550-3, 1981 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-6792325

RESUMEN

To determine the effect of mannitol on blood viscosity, serial measurements were carried out on venous blood in patients undergoing craniotomies for intracranial aneurysms. Blood samples were drawn immediately prior to, and 30 minutes, 2, and 4 hours after administration of mannitol. Complete blood counts, serum osmolarities, and erythrocyte microsieving studies were also performed on each sample. Whole-blood viscosity decreased at 30 minutes and 2 hours, but not at 4 hours after mannitol administration. This decreased appeared at high shear rates only, where erythrocyte deformability is critical viscosity. This effect was independent of the hematocrit. Removal of mannitol from the suspension returned red cell deformability to preadministration values indicating that the increased erythrocyte deformability required the presence of mannitol and the relative hyperosmolarity induced by this agent. The reduced erythrocyte rigidity and subsequent decreased whole-blood viscosity should enhance tissue perfusion in the microcirculation.


Asunto(s)
Viscosidad Sanguínea/efectos de los fármacos , Manitol/farmacología , Agregación Eritrocitaria/efectos de los fármacos , Índices de Eritrocitos/efectos de los fármacos , Eritrocitos/fisiología , Humanos , Aneurisma Intracraneal/sangre , Plasma/efectos de los fármacos
20.
Oecologia ; 106(3): 376-381, 1996 May.
Artículo en Inglés | MEDLINE | ID: mdl-28307325

RESUMEN

Paleoecological and geomorphological studies indicate that, during the middle Holocene, there was a predominance of drier conditions with grassy savannahs replacing forests across the South American continent. Modern savannahs are composed mainly of C4 plants and soils developed under this type of vegetation show enrichment in 13C compared to soils under C3 vegetation cover. If soils contain stabilized organic matter formed in the middle Holocene, we hypothesize that former C4 vegetation would be evidenced by a large enrichment of 13C in soil organic matter (SOM). We investigate this possibility examining the depth variation of carbon isotopic composition in 21 soil profiles collected by different researchers at 14 different sites in Brazil. Of these, profiles from only three sites showed a marked increase of 13C with depth (9-10‰ enrichment in δ13C difference between the surface soil and deepest depth); two sites showed intermediate enrichment (4-5‰), and nine sites showed a small enrichment of approximatelly 2.5‰. The majority of sites showing all-C3 derived SOM were in the Amazon region. Possible causes for the absence of a large 13C enrichment with depth are: (1) dominance of C3 rather than C4 grasses in mid-Holocene savannahas, (2) soil profiles did not preserve organic matter derived from mid-Holocene plants, (3) the retreat of forest areas did not occur on a regional scale, but was a much more localized phenomenon.

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