Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 298
Filtrar
1.
Rev Sci Instrum ; 92(6): 063902, 2021 Jun 01.
Artículo en Inglés | MEDLINE | ID: mdl-34243521

RESUMEN

Ultrasound is a powerful means to study numerous phenomena of condensed-matter physics as acoustic waves couple strongly to structural, magnetic, orbital, and charge degrees of freedom. In this paper, we present such a technique combined with single-turn coils (STCs) that generate magnetic fields beyond 100 T with the typical pulse duration of 6 µs. As a benchmark of this technique, the ultrasound results for MnCr2S4, Cu6[Si6O18]·6H2O, and liquid oxygen are shown. The resolution for the relative sound-velocity change in the STC is estimated as Δv/v ∼ 10-3, which is sufficient to study various field-induced phase transitions and critical phenomena.

4.
Carbon Balance Manag ; 11(1): 7, 2016 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-27330548

RESUMEN

BACKGROUND: Monitoring and managing carbon stocks in forested ecosystems requires accurate and repeatable quantification of the spatial distribution of wood volume at landscape to regional scales. Grid-based forest inventory networks have provided valuable records of forest structure and dynamics at individual plot scales, but in isolation they may not represent the carbon dynamics of heterogeneous landscapes encompassing diverse land-management strategies and site conditions. Airborne LiDAR has greatly enhanced forest structural characterisation and, in conjunction with field-based inventories, it provides avenues for monitoring carbon over broader spatial scales. Here we aim to enhance the integration of airborne LiDAR surveying with field-based inventories by exploring the effect of inventory plot size and number on the relationship between field-estimated and LiDAR-predicted wood volume in deciduous broad-leafed forest in central Germany. RESULTS: Estimation of wood volume from airborne LiDAR was most robust (R2 = 0.92, RMSE = 50.57 m3 ha-1 ~14.13 Mg C ha-1) when trained and tested with 1 ha experimental plot data (n = 50). Predictions based on a more extensive (n = 1100) plot network with considerably smaller (0.05 ha) plots were inferior (R2 = 0.68, RMSE = 101.01 ~28.09 Mg C ha-1). Differences between the 1 and 0.05 ha volume models from LiDAR were negligible however at the scale of individual land-management units. Sample size permutation tests showed that increasing the number of inventory plots above 350 for the 0.05 ha plots returned no improvement in R2 and RMSE variability of the LiDAR-predicted wood volume model. CONCLUSIONS: Our results from this study confirm the utility of LiDAR for estimating wood volume in deciduous broad-leafed forest, but highlight the challenges associated with field plot size and number in establishing robust relationships between airborne LiDAR and field derived wood volume. We are moving into a forest management era where field-inventory and airborne LiDAR are inextricably linked, and we encourage field inventory campaigns to strive for increased plot size and give greater attention to precise stem geolocation for better integration with remote sensing strategies.

5.
Oncogenesis ; 5: e210, 2016 Mar 14.
Artículo en Inglés | MEDLINE | ID: mdl-26974205

RESUMEN

We previously produced pigs with a latent oncogenic TP53 mutation. Humans with TP53 germline mutations are predisposed to a wide spectrum of early-onset cancers, predominantly breast, brain, adrenal gland cancer, soft tissue sarcomas and osteosarcomas. Loss of p53 function has been observed in >50% of human cancers. Here we demonstrate that porcine mesenchymal stem cells (MSCs) convert to a transformed phenotype after activation of latent oncogenic TP53(R167H) and KRAS(G12D), and overexpression of MYC promotes tumorigenesis. The process mimics key molecular aspects of human sarcomagenesis. Transformed porcine MSCs exhibit genomic instability, with complex karyotypes, and develop into sarcomas on transplantation into immune-deficient mice. In pigs, heterozygous knockout of TP53 was sufficient for spontaneous osteosarcoma development in older animals, whereas homozygous TP53 knockout resulted in multiple large osteosarcomas in 7-8-month-old animals. This is the first report that engineered mutation of an endogenous tumour-suppressor gene leads to invasive cancer in pigs. Unlike in Trp53 mutant mice, osteosarcoma developed in the long bones and skull, closely recapitulating the human disease. These animals thus promise a model for juvenile osteosarcoma, a relatively uncommon but devastating disease.

6.
Biol Lett ; 11(11)2015 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-26582842

RESUMEN

Hybridization can occur naturally among diverging lineages as part of the evolutionary process leading to complete reproductive isolation, or it can result from range shifts and habitat alteration through global warming and/or other anthropogenic influences. Here we report a molecular cytogenetic investigation of hybridization between taxonomically distinct species of the Alcelaphini (Alcelaphus buselaphus 2n = 40 × Damaliscus lunatus 2n = 36) and the Tragelaphini (Tragelaphus strepsiceros 2n = 31/32 × Tragelaphus angasii 2n = 55/56). Cross-species fluorescence in situ hybridization provides unequivocal evidence of the scale of karyotypic difference distinguishing parental species. The findings suggest that although hybrid meiosis of the former cross would necessitate the formation of a chain of seven, a ring of four and one trivalent, the progeny follow Haldane's rule showing F1 male sterility and female fertility. The tragelaphine F1 hybrid, a male, was similarly sterile and, given the 11 trivalents and chain of five anticipated in its meiosis, not unexpectedly so. We discuss these findings within the context of the broader evolutionary significance of hybridization in African antelope, and reflect on what these hold for our views of antelope species and their conservation.


Asunto(s)
Antílopes/genética , Análisis Citogenético , Animales , Antílopes/clasificación , Evolución Biológica , Femenino , Especiación Genética , Hibridación Genética , Hibridación Fluorescente in Situ , Infertilidad Masculina/genética , Cariotipificación , Masculino , Meiosis/genética , Aislamiento Reproductivo
7.
Nat Commun ; 5: 5282, 2014 Nov 19.
Artículo en Inglés | MEDLINE | ID: mdl-25407959

RESUMEN

Elevated concentrations of atmospheric greenhouse gases (GHGs), particularly carbon dioxide (CO2), have affected the global climate. Land-based biological carbon mitigation strategies are considered an important and viable pathway towards climate stabilization. However, to satisfy the growing demands for food, wood products, energy, climate mitigation and biodiversity conservation-all of which compete for increasingly limited quantities of biomass and land-the deployment of mitigation strategies must be driven by sustainable and integrated land management. If executed accordingly, through avoided emissions and carbon sequestration, biological carbon and bioenergy mitigation could save up to 38 billion tonnes of carbon and 3-8% of estimated energy consumption, respectively, by 2050.


Asunto(s)
Biodiversidad , Dióxido de Carbono , Secuestro de Carbono , Cambio Climático , Clima , Conservación de los Recursos Naturales , Ecosistema , Gases , Efecto Invernadero , Humanos
8.
Izv Akad Nauk Ser Biol ; (1): 65-75, 2014.
Artículo en Ruso | MEDLINE | ID: mdl-25735158

RESUMEN

Using direct measurements of CO2 fluxes by the method of turbulent pulsations, it was shown that the studied middle-taiga pine forest, raised bog, true steppe, and southern tundra along the Yenisei meridian (approximately 90 degrees E) are stocks of carbon of different capacity in the annual output. The tundra starts to function as a stock of carbon from June; the forest and bog, from May; and the steppe, from the end of April. In the transitional seasons and winter, the ecosystems are a weak source of carbon: the tundra already in September; the forest and bog, from October; and the steppe, from November. The photosynthetic productivity of the forest and steppe ecosys- tems (480-530 g C/(m x year) exceeds 2-2.5 times the productivity ofbogs and tundras (200-220 g C/(m x year). The relationships between the thermal balance structure and CO2 exchange are shown. Possible feedbacks between the carbon exchange between the ecosystems and the atmosphere as a result of climate warming in the region are assessed.


Asunto(s)
Dióxido de Carbono/metabolismo , Carbono/metabolismo , Ecosistema , Bosques , Fotosíntesis , Estaciones del Año , Siberia , Árboles
9.
AJNR Am J Neuroradiol ; 34(1): 74-9, 2013 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-22766668

RESUMEN

BACKGROUND AND PURPOSE: Postmortem studies of advanced PD have revealed disease-related pathology in the thalamus with an apparent predilection for specific thalamic nuclei. In the present study, we used DTI to investigate in vivo the microstructural integrity of 6 thalamic regions in de novo patients with PD relative to healthy controls. MATERIALS AND METHODS: Forty subjects (20 with early stage untreated PD and 20 age- and sex-matched controls) were studied with a high-resolution DTI protocol at 3T to investigate the integrity of thalamic nuclei projection fibers. Two blinded, independent raters drew ROIs in the following 6 thalamic regions: AN, VA, VL, DM, VPL/VPM, and PU. FA values were then calculated from the projection fibers in each region. RESULTS: FA values were reduced significantly in the fibers projecting from the AN, VA, and DM, but not the VPL/VPM and PU, in the PD group compared with the control group. In addition, there was a reduction in FA values that approached significance in the VL of patients with PD. These findings were consistent across both raters. CONCLUSIONS: The present study provides preliminary in vivo evidence of thalamic projection fiber degeneration in de novo PD and sheds light on the extent of disrupted thalamic circuitry as a result of the disease itself.


Asunto(s)
Imagen de Difusión Tensora/métodos , Fibras Nerviosas Mielínicas/patología , Enfermedad de Parkinson/patología , Tálamo/patología , Femenino , Humanos , Masculino , Persona de Mediana Edad , Reproducibilidad de los Resultados , Sensibilidad y Especificidad
10.
Ann Oncol ; 23(8): 1979-1985, 2012 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-22734013

RESUMEN

BACKGROUND: Malignant ascites (MA) is associated with poor prognosis and limited palliative therapeutic options. Therefore, quality of life (QoL) assessment is of particular importance to demonstrate new treatment value. Following the demonstration of the superiority of catumaxomab and paracentesis over paracentesis on puncture-free survival, this analysis aimed at comparing deterioration in QoL between both the treatment options. PATIENTS AND METHODS: In a randomised, multicentre, phase II/III study of patients with MA due to epithelial cell adhesion molecule (EpCAM) positive cancer, the QoL was evaluated using the European Organisation for Research and Treatment of Cancer Quality of Life Questionnaire-Core 30 items (EORTC QLQ-C30) questionnaire at screening, 1, 3 and 7 months after treatment and in the case of re-puncture on the day of paracentesis. Time to first deterioration in QoL was defined as a decrease in the QoL score of at least five points and compared between the catumaxomab (n=160) and control (n=85) groups using the log-rank test and Cox proportional hazards models adjusted for baseline score, country and primary tumour type. RESULTS: Deterioration in QoL scores appeared more rapidly in the control than in the catumaxomab group (median 19-26 days versus 47-49 days). The difference in time to deterioration in QoL between the groups was statistically significant for all scores (P<0.01). The hazard ratios ranged from 0.08 to 0.24 (P<0.01). CONCLUSIONS: Treatment with catumaxomab delayed deterioration in QoL in patients with MA. Compared with paracentesis alone, catumaxomab enabled patients to benefit from better QoL for a prolonged survival period.


Asunto(s)
Anticuerpos Biespecíficos/uso terapéutico , Ascitis/patología , Ascitis/terapia , Neoplasias/patología , Neoplasias/terapia , Paracentesis/métodos , Adulto , Anciano , Anciano de 80 o más Años , Antígenos de Neoplasias/metabolismo , Ascitis/metabolismo , Moléculas de Adhesión Celular/metabolismo , Terapia Combinada , Molécula de Adhesión Celular Epitelial , Femenino , Humanos , Masculino , Persona de Mediana Edad , Neoplasias/metabolismo , Neoplasias Ováricas/metabolismo , Neoplasias Ováricas/patología , Neoplasias Ováricas/terapia , Modelos de Riesgos Proporcionales , Calidad de Vida , Adulto Joven
11.
Ecol Lett ; 15(6): 520-6, 2012 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-22472207

RESUMEN

Trees with sufficient nutrition are known to allocate carbon preferentially to aboveground plant parts. Our global study of 49 forests revealed an even more fundamental carbon allocation response to nutrient availability: forests with high-nutrient availability use 58 ± 3% (mean ± SE; 17 forests) of their photosynthates for plant biomass production (BP), while forests with low-nutrient availability only convert 42 ± 2% (mean ± SE; 19 forests) of annual photosynthates to biomass. This nutrient effect largely overshadows previously observed differences in carbon allocation patterns among climate zones, forest types and age classes. If forests with low-nutrient availability use 16 ± 4% less of their photosynthates for plant growth, what are these used for? Current knowledge suggests that lower BP per unit photosynthesis in forests with low- versus forests with high-nutrient availability reflects not merely an increase in plant respiration, but likely results from reduced carbon allocation to unaccounted components of net primary production, particularly root symbionts.


Asunto(s)
Biomasa , Ciclo del Carbono , Árboles/crecimiento & desarrollo , Procesos Autotróficos , Carbono/metabolismo , Respiración de la Célula , Clima , Agricultura Forestal , Fotosíntesis , Raíces de Plantas/microbiología , Árboles/metabolismo , Árboles/microbiología
12.
Dtsch Med Wochenschr ; 136(38): 1889-94, 2011 Sep.
Artículo en Alemán | MEDLINE | ID: mdl-21915802

RESUMEN

OBJECTIVE: The challenge in diagnosing primary hyperparathyroidism (HPT) is to detect hereditary cases before first surgery. About 5% of cases are hereditary and integral component of multiple endocrine neoplasia type 1 and 2 (MEN1/MEN2), hyperparathyroidism-jaw tumor syndrome (HPT-JT), familial hypocalciuric hypercalcemia (FHH), and familial isolated hyperparathyroidism (FIHPT). Aim of this study was to evaluate similarities and differences in hereditary varieties of HPT. PATIENTS: 80 patients with hereditary HPT were evaluated in a retrospective analysis between 1980 and 2010 concerning clinical findings, family history, therapy, biochemical and molecular-genetic findings and follow-up. RESULTS: 80 patients with hereditary HPT are described, 52 belonged to MEN1, 15 to MEN2, 7 to HPT-JT, 4 to FHH and 2 to FIHPT kindreds. Penetrance of HPT was highest in MEN1 (85%), followed by HPT-JT (64%), FHH (28.5%), and MEN2 (8%). Youngest age at diagnosis of HPT was 7 and 16 years in the MEN2/HPT-JT group. Serum Calcium was highest in the HPT-JT group (3.6 mM), recurrencies of HPT were highest in the MEN1 group (40.5%). Parathyroid cancer solely occurred in the HPT-JT group. In single cases HPT occurs in FHH. CONCLUSION: Among the different varieties of hereditary HPT MEN1-HPT is most frequent and carries the utmost recurrence rate. Early diagnosis of HPT-JT syndrome is important because of the occurrence of parathyroid cancer. Single cases of HPT in FHH are described. Preoperative diagnosis of hereditary HPT has therapeutic consequences concerning extent of surgery and implications concerning patient and family care.


Asunto(s)
Hipercalcemia/congénito , Hiperparatiroidismo Primario/genética , Neoplasias Maxilomandibulares/genética , Neoplasia Endocrina Múltiple Tipo 1/genética , Neoplasia Endocrina Múltiple Tipo 2a/genética , Adenoma/diagnóstico , Adenoma/genética , Adolescente , Adulto , Anciano , Calcio/sangre , Preescolar , Análisis Citogenético , Análisis Mutacional de ADN , Diagnóstico Precoz , Femenino , Estudios de Seguimiento , Pruebas Genéticas , Humanos , Hipercalcemia/diagnóstico , Hipercalcemia/genética , Hiperparatiroidismo Primario/diagnóstico , Neoplasias Maxilomandibulares/diagnóstico , Masculino , Persona de Mediana Edad , Neoplasia Endocrina Múltiple Tipo 1/diagnóstico , Neoplasia Endocrina Múltiple Tipo 2a/diagnóstico , Neoplasias de las Paratiroides/diagnóstico , Neoplasias de las Paratiroides/genética , Penetrancia , Recurrencia , Estudios Retrospectivos , Síndrome , Adulto Joven
13.
Klin Monbl Augenheilkd ; 228(1): 66-9, 2011 Jan.
Artículo en Alemán | MEDLINE | ID: mdl-20714992

RESUMEN

BACKGROUND: Keratolysis is a rare severe complication following systemic autoimmunologic diseases. Despite of complex therapeutic treatments, the prognosis is very poor. PATIENTS: Ten eyes from seven patients with corneal ulcers were reported (age 45 - 73 years, mean 63 years; 6 women, 1 man). The corneal ulcer was perforated in 7 eyes. Five patients suffered from rheumatoid arthritis, and one patient developed a Sjögren's syndrome. Besides, one patient had shown both autoimmunologic diseases. After clinical attendance, visual acuity in the eyes with nonperforated ulcers was between 0.1 and 0.4, and in the eyes with perforated ulcers between light perception and 0.2. RESULTS: In 7 eyes with perforated corneal ulcers an emergency tectonic conjunctival plasty and, 1 - 2 days later, a keratoplasty had been performed. Postoperatively, local therapies had been initiated with antibiotic and immunosuppressive eyedrops as well as with conventional drops for dry-eye symptoms. Because of the autoimmunologic diseases of the patients, a systemic immunosuppressive therapy had been arranged. Follow-up period had been between 4 weeks and 3,5 years (mean 16 months). In the three eyes with nonperforated ulcers which received an antibiotic and immunosuppressive treatment, visual acuity was found at 1 / 20 and 0.4. However, in spite of stabilized findings in the 5 eyes with perforated ulcers, the visual acuity was in this case only between light perception and 0.05. One patient with a perforated ulcer and one patient with a recurrent corneal perforation after keratoplasty refused further operative procedures. Finally, both eyes had to undergo evisceration. CONCLUSIONS: Despite of intensive local and systemic immunosuppressive as well as operative therapies, corneal ulcers associated with autoimmunologic diseases (rheumatoid arthritis, Sjögren's syndrome) may cause a marked decrease of visual acuity or the loss of an eye. With regard to the healthy eye, an immunosuppressive therapy for life is most important.


Asunto(s)
Enfermedades Autoinmunes/diagnóstico , Enfermedades Autoinmunes/terapia , Úlcera de la Córnea/diagnóstico , Úlcera de la Córnea/terapia , Anciano , Enfermedades Autoinmunes/complicaciones , Úlcera de la Córnea/etiología , Femenino , Humanos , Masculino , Persona de Mediana Edad
14.
Plant Biol (Stuttg) ; 13(1): 134-44, 2011 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-21143734

RESUMEN

Positive species richness effects on aboveground community productivity in experimental grasslands have been reported to correlate with variable responses of individual species. So far, it is largely unknown whether more complete use of resources at the community level correlates with resource limitation of particular species and may explain their decreasing performance with increasing plant diversity. Using the subordinate grass species Lolium perenne L. as a model, we monitored populations in 82 experimental grasslands of different plant diversity (Jena Experiment) from year 2 to 6 after establishment, and measured ecophysiological leaf traits related to light and nutrient acquisition and use. Population and plant individual sizes of L. perenne decreased with increasing species richness. A decrease in transmitted light with increasing species richness and legume proportion correlated with increasing specific leaf area (SLA). Despite this morphological adaptation to lower light availability, decreasing foliar δ(13) C signatures with increasing species richness and low variation in leaf gas exchange and chlorophyll concentrations suggested a low capacity of L. perenne for adjustment to canopy shade. Leaf nitrogen concentrations and foliar δ(15) N signatures indicated a better N supply in communities with legumes and a shift in the uptake of different N forms with increasing species richness. Leaf blade nitrate and carbohydrate concentrations as indicators of plants nutritional status supported that light limitation with increasing species richness and legume proportions, combined with a N limitation in communities with increasing proportions of non-legumes, correlated with the decreasing performance of L. perenne in communities of increasing plant diversity.


Asunto(s)
Luz , Lolium/metabolismo , Lolium/efectos de la radiación , Nitrógeno/metabolismo , Clorofila/metabolismo , Ecosistema , Lolium/crecimiento & desarrollo
15.
Clin Genet ; 79(5): 489-94, 2011 May.
Artículo en Inglés | MEDLINE | ID: mdl-20681991

RESUMEN

The short stature homeobox (SHOX) gene is located in the pseudoautosomal region 1 of both sex chromosomes. Haploinsufficiency of SHOX leads to different phenotypes ranging from isolated short stature to Léri-Weill syndrome characterized by short stature, mesomelia and Madelung deformity. We describe a family with a SHOX deletion originally located on the Y chromosome and transmitted from father to daughter by crossover during meiosis. The male index patient presented with short stature, mesomelia and mild Madelung deformity. His father had a normal height but slightly disproportionate short legs. The sister of the index patient presented with marked Madelung deformity and normal height. A deletion of the SHOX gene was identified in the male index patient, his father and his sister. Metaphase fluorescence in situ hybridization (FISH) analyses showed a deletion of the SHOX gene on the Y chromosomes of the index patient and his father, and on the X chromosome of his sister, indicating that a meiotic crossover of the SHOX gene region between the X and Y chromosomes had occurred. The pseudoautosomal region 1 is a known recombination 'hot spot' in male meiosis. Published genetic maps indicate high recombination frequency of ∼40% for SHOX in male meiosis leading to pseudoautosomal inheritance.


Asunto(s)
Trastornos de los Cromosomas/genética , Preescolar , Femenino , Trastornos del Crecimiento/genética , Proteínas de Homeodominio/genética , Humanos , Hibridación Fluorescente in Situ , Masculino , Osteocondrodisplasias/genética , Linaje , Proteína de la Caja Homeótica de Baja Estatura
16.
Dtsch Med Wochenschr ; 135(30): 1477-83, 2010 Jul.
Artículo en Alemán | MEDLINE | ID: mdl-20648405

RESUMEN

BACKGROUND: The study was conducted to assess the rate of suspected pulmonary embolism (PE) prior to death and the diagnostic and therapeutic procedures performed. METHODS: Patients with autopsy-confirmed PE between 1998 and 2002 were included. Autopsy register and medical records were reviewed for history, diagnosis and therapy of PE. Patients were categorised into fatal and non-fatal PE according to the autopsy findings. RESULTS: 102 patients with fatal and 247 patients with non-fatal PE were eligible for analysis (median age 68 years; 24-95). In 58.8% with fatal and in 32% with non-fatal PE, disease was suspected pre-mortal. Clinical suspicion of PE was significantly enhanced in venous thrombosis (Odds Ratio [OR] = 12.17, p=0.004) and significantly decreased for chronic vascular disease (OR = 0.30, p=0.002). Recurrent PE was demonstrated in 31.4% fatal and in 4.5% non-fatal PE (OR = 9.81, p=0.001). 7% of all PE were localised centrally, 19% centrally and peripherally and 74% peripherally. Dyspnoea and tachycardia were the most frequent symptoms in fatal PE. About half of all patients suffered from malignancies. Suspicion of PE decreased after day 14 of hospitalisation (OR = 0.33, p=0.021). CONCLUSION: PE often is not diagnosed pre-mortally. Patients with chronic vascular disease and tumours as well as those hospitalised for over 14 days are at particular risk for PE.


Asunto(s)
Errores Diagnósticos/estadística & datos numéricos , Embolia Pulmonar/diagnóstico , Embolia Pulmonar/terapia , Adulto , Anciano , Anciano de 80 o más Años , Femenino , Alemania/epidemiología , Humanos , Incidencia , Masculino , Persona de Mediana Edad , Embolia Pulmonar/mortalidad , Medición de Riesgo , Factores de Riesgo , Análisis de Supervivencia , Tasa de Supervivencia , Adulto Joven
17.
Tree Physiol ; 30(6): 689-704, 2010 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-20453002

RESUMEN

The periodic production of large seed crops by trees (masting) and its interaction with stem growth has long been the objective of tree physiology research. However, very little is known about the effects of masting on stem growth and total net primary productivity (NPP) at the stand scale. This study was conducted in an old-growth, mixed deciduous forest dominated by Fagus sylvatica (L.) and covers the period from 2003 to 2007, which comprised wet, dry and regular years as well as two masts of Fagus and one mast of the co-dominant tree species Fraxinus excelsior (L.) and Acer pseudoplatanus (L.). We combined analyses of weather conditions and stem growth at the tree level (inter- and intra-annual) with fruit, stem and leaf production, and estimates of total NPP at the stand level. Finally, we compared the annual demand of carbon for biomass production with net canopy assimilation (NCA), derived from eddy covariance flux measurements, chamber measurements and modelling. Annual stem growth of Fagus was most favoured by warm periods in spring and that of Fraxinus by high precipitation in June. For stem growth of Acer and for fruit production, no significant relationships with mean weather conditions were found. Intra-annual stem growth of all species was strongly reduced when the relative plant-available water in soil dropped below a threshold of about 60% between May and July. The inter-annual variations of NCA, total NPP and leaf NPP at the stand level were low (mean values 1313, 662 and 168 g C m(-2) year(-1), respectively), while wood and fruit production varied more and contrarily (wood: 169-241 g C m(-2) year(-1); fruits: 21-142 g C m(-2) year(-1)). In all years, an annual surplus of newly assimilated carbon was calculated (on average 100 g C m(-2) year(-1)). The results suggest that stem growth is generally not limited by insufficient carbon resources; only in mast years a short-term carbon shortage may occur in spring. In contrast to common assumption, stem growth alone is not a sufficient proxy for total biomass production or the control of carbon sequestration by weather extremes.


Asunto(s)
Clima , Fagus/crecimiento & desarrollo , Tallos de la Planta/crecimiento & desarrollo , Árboles/crecimiento & desarrollo , Fraxinus/anatomía & histología , Fraxinus/crecimiento & desarrollo , Frutas/crecimiento & desarrollo , Hojas de la Planta/crecimiento & desarrollo , Estaciones del Año , Suelo , Árboles/anatomía & histología , Tiempo (Meteorología)
19.
Exp Clin Endocrinol Diabetes ; 118(8): 550-3, 2010 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-20013610

RESUMEN

UNLABELLED: Clinical studies are needed to classify rare and novel RET mutations associated with hereditary medullary thyroid carcinoma (MTC) into one of the clinical risk groups. Here we describe two new RET mutations/variants, R770Q and L881V, in patients with MTC and analyzed genotype-phenotype correlations associated with these RET mutations in the gene carriers. FAMILY 1: Calcitonin screening in a 42-year-old female patient with multinodular goiter showed elevated levels. RET mutation analysis revealed a new variant in exon 13 R770Q (CGA>CAA) in the patient. A thyroidectomy with central and lateral node dissection was done. Histology showed MTC in a mixed variance with follicular cancer of 2 cm diameter (T2N0M0). Postoperatively there was no increase of calcitonin after pentagastrin stimulation. The patient is biochemically cured concerning MTC and FTC after radioiodine therapy. In the sister of the index patient surprisingly another, previously not described amino-acid substitution Y791N (TAT><) in the RET protooncogene was found. In the parents the R770Q variant was detected in the mother, the Y791N mutation in the father. Another sister carries the R770Q variant. In all other gene carriers (aged 44-70 years), calcitonin levels were in the normal range, therefore, thyroidectomy had not yet been performed. FAMILY 2: In a 46-year-old female patient with nodular goiter thyroidectomy, central and left lateral lymph node dissection was done because of elevated calcitonin levels. Histology revealed a microcarcinoma with one lymph node metastasis (T1N1(1/8)Mx). RET analysis revealed a new mutation in exon 15 L881V (CTG>GTG). The L881V mutation was detected in five other family members. In the first generation stimulated calcitonin levels were in the normal range, therefore thyroidectomy had not yet been performed. In the sons of the index case thyroidectomy revealed CCH in the older one, no MTC in both. In a cousin thyroidectomy is intended because of elevated basal and stimulated calcitonin. CONCLUSION: Our clinical findings indicate that the L881V mutation may be associated with late-onset nonaggressive disease. If the germline RET R770Q variant has a causative role in the pathogenesis of the mixed medullar/follicular derived histology of the thyroid tumour in the index patient of family 1 has to be proven. The recommendations for prophylactic thyroidectomy in these mutations should be individualized depending on basal and stimulated calcitonin levels until more data are available.


Asunto(s)
Bocio Nodular/genética , Mutación , Proteínas Proto-Oncogénicas c-ret/genética , Nódulo Tiroideo/genética , Adenocarcinoma Folicular , Adulto , Anciano , Calcitonina/sangre , Carcinoma Neuroendocrino , Exones , Femenino , Bocio Nodular/sangre , Bocio Nodular/radioterapia , Bocio Nodular/cirugía , Humanos , Radioisótopos de Yodo/uso terapéutico , Metástasis Linfática , Masculino , Persona de Mediana Edad , Linaje , Pentagastrina , Neoplasias de la Tiroides/sangre , Neoplasias de la Tiroides/genética , Neoplasias de la Tiroides/radioterapia , Neoplasias de la Tiroides/cirugía , Nódulo Tiroideo/sangre , Nódulo Tiroideo/radioterapia , Nódulo Tiroideo/cirugía , Tiroidectomía
20.
Calcif Tissue Int ; 85(3): 211-20, 2009 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-19513579

RESUMEN

X-Linked hypophosphatemic rickets (HYP, XLH) is a disorder of phosphate homeostasis, characterized by renal phosphate wasting and hypophosphatemia, with normal to low 1,25-dihydroxy vitamin D3 serum levels. The purpose of our study was the detection of inactivating mutations in the PHEX gene, the key enzyme in the pathogenesis of XLH. The 16 patients, representing eight families, presented with suspected XLH from biochemical and clinical evidence. All 16 were referred for mutational analysis of the PHEX gene. We detected three novel disease-causing mutations, C59S, Q394X, and W602, for which a loss of function can be predicted. A G28S variation, found in two healthy probands, may be a rare polymorphism. Another mutation, A363 V, is localized on the same allele as the C59S mutation, thus its functional consequences cannot be proven. Furthermore, we detected a deletion of three nucleotides in exon 15 which resulted in the loss of amino acid threonine 535. Heterozygosity of this mutation in a male patient without any chromosomal aberrations suggests its presence as a mosaic. Novel large deletions were detected using multiplex ligation-dependent probe amplification (MLPA) analysis. Two of these deletions, loss of exon 22 alone or exons 21 and 22 together, may result in the translation of a C-terminal truncated protein. Two large deletions comprise exons 1-9 and exons 4-20, respectively, and presumably result in a nonfunctional protein. We conclude that molecular genetic analysis confirms the clinical diagnosis of XLH and should include sequence analysis as well as the search for large deletions, which is facilitated by MLPA.


Asunto(s)
Raquitismo Hipofosfatémico Familiar/diagnóstico , Raquitismo Hipofosfatémico Familiar/genética , Eliminación de Gen , Enfermedades Genéticas Ligadas al Cromosoma X , Predisposición Genética a la Enfermedad/genética , Endopeptidasa Neutra Reguladora de Fosfato PHEX/genética , Mutación Puntual/genética , Secuencia de Aminoácidos/genética , Preescolar , Análisis Mutacional de ADN , Exones/genética , Raquitismo Hipofosfatémico Familiar/fisiopatología , Femenino , Frecuencia de los Genes/genética , Marcadores Genéticos/genética , Genotipo , Humanos , Lactante , Masculino , Biología Molecular/métodos , Polimorfismo Genético/genética , Treonina/genética
SELECCIÓN DE REFERENCIAS
DETALLE DE LA BÚSQUEDA
...