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2.
Int J Hyg Environ Health ; 215(2): 196-201, 2012 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-22197023

RESUMO

From 1996/1997 to 2008/2009, blood and urine were sampled from 9- to 11-year-old pupils in the state of Baden-Württemberg, South-West Germany. In blood samples the chlororganics DDE, HCB, PCB-138, PCB-153 and PCB-180 were analysed by gas chromatography and ECD detection. PCDD/PCDF were measured in pooled blood samples using GC/MS. Lead concentrations in blood were quantified by graphite furnace atomic absorption spectrometry (AAS), mercury in urine by using cold vapour AAS. For all chlororganics and heavy metals a distinct decrease of the internal concentration could be shown within the 12-year investigation period. For DDE, the median decreased from 0.32 µg/l to 0.11 µg/l. The median of HCB fell from 0.19 µg/l to 0.07 µg/l. The median of the sum of the three PCB-congeners PCB-138, PCB-153 and PCB-180 decreased from 0.47 µg/l to 0.18 µg/l. The burden of PCDD/PCDF in pooled blood samples resulted in approximately half the concentration after the 12-year period. The internal concentrations of the chlororganics were distinctly higher in breastfed children than in non-breastfed children. In 2008/2009, these differences were strongest for PCB and DDE (2-fold), moderate for PCDD/PCDF (1.6-fold), and slight for HCB (1.2-fold). The median of lead concentrations in blood dropped from 23.6 µg/l to 15.9 µg/l. The median of mercury concentrations in urine decreased from 0.25 µg/l to a value below the limit of quantification of 0.2 µg/l; the 95th percentile was reduced from 3.1 µg/l to less than 0.2 µg/l. The decline of amalgam fillings in children during the investigation period had a strong influence on internal concentrations of mercury. The internal concentration of the persistent xenobiotics investigated here decreased to a low level not likely to be of concern for human health.


Assuntos
Exposição Ambiental/análise , Exposição Ambiental/estatística & dados numéricos , Monitoramento Ambiental/métodos , Hidrocarbonetos Clorados/sangue , Chumbo/sangue , Mercúrio/urina , Aleitamento Materno/estatística & dados numéricos , Criança , Cromatografia Gasosa , Feminino , Seguimentos , Alemanha , Humanos , Masculino , Metais Pesados/sangue , Metais Pesados/urina , Compostos Orgânicos/sangue , Compostos Orgânicos/urina , Fatores de Risco
3.
Radiologe ; 49(11): 1033-9, 2009 Nov.
Artigo em Alemão | MEDLINE | ID: mdl-19855950

RESUMO

Endoleaks following endovascular aneurysm repair (EVAR) are common and present a diagnostic challenge in the follow-up after EVAR. Contrast-enhanced ultrasound (CEUS) is a promising new method for the diagnosis and follow-up of endoleaks. CEUS with SonoVue allows a rapid and non-invasive diagnosis in the follow-up after EVAR. The sensitivity and specificity of conventional ultrasound compared to the multislice CT angiography is estimated to be 33-63% and 63-93%, respectively. These values can be increased through the use of CEUS in up to 98-100% (sensitivity) and 82-93% (specificity). This article describes the etiology, classification and importance of different types of endoleaks. The value of CEUS in this clinical scenario will be discussed.


Assuntos
Aneurisma Roto/diagnóstico por imagem , Aneurisma Roto/etiologia , Aneurisma/diagnóstico por imagem , Aneurisma/cirurgia , Fosfolipídeos , Hexafluoreto de Enxofre , Ultrassonografia/métodos , Procedimentos Cirúrgicos Vasculares/efeitos adversos , Meios de Contraste , Humanos , Sensibilidade e Especificidade , Resultado do Tratamento
5.
Public Health Nutr ; 8(6): 642-9, 2005 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-16236194

RESUMO

OBJECTIVE: The study aimed to assess the relationship of various types of kindergarten differing in length of care and food availability with the development of overweight in pre-school children. DESIGN, SETTING AND SUBJECTS: A cross-sectional study was carried out in 2002 in Stuttgart, Germany, as part of the school entrance examination. Height and weight of 2140 children (participation 70.2%) were measured and information on type of kindergarten and other potential determinants of overweight was collected by a parental questionnaire. Change in relative body mass index (BMI) position between the ages of 4 and 6 years was assessed using medical records. RESULTS: The prevalence of overweight or change in relative BMI position did not differ according to the type of kindergarten. For the prevalence of overweight in German children, adjusted odds ratios (OR) comparing institutions that open only in the morning with those opening in the morning and afternoon or for the full day were 0.86 (95% confidence interval (CI) 0.40, 1.83) and 0.63 (95% CI 0.25, 1.58), respectively. Parental BMI and duration of television watching were positively associated, and maternal educational status and duration of breast-feeding were negatively associated, with overweight and/or change in relative BMI position. The prevalence of overweight was substantially higher among non-German than among German children (adjusted OR 2.17 (95% CI 1.53, 3.07)). CONCLUSIONS: These data show no association between different types of kindergarten and the development of overweight in early childhood. Duration of television watching and breast-feeding, as well as the relatively high prevalence of overweight in ethnic minorities, deserve further attention.


Assuntos
Serviços de Alimentação , Obesidade/epidemiologia , Obesidade/etiologia , Instituições Acadêmicas , Índice de Massa Corporal , Aleitamento Materno/epidemiologia , Criança , Pré-Escolar , Intervalos de Confiança , Estudos Transversais , Escolaridade , Feminino , Alemanha/epidemiologia , Humanos , Masculino , Razão de Chances , Fatores de Risco , Inquéritos e Questionários , Televisão
6.
Gesundheitswesen ; 67(4): 302-11, 2005 Apr.
Artigo em Alemão | MEDLINE | ID: mdl-15856391

RESUMO

Although PCB and PCB-containing materials are not processed for a long time, PCB is under discussion again and again caused by the pollution of indoor environments. To objectify the discussion, the dates of the PCB-biomonitoring, the organochlorine-compounds (DDE, HCB, beta-/gamma -HCH, PCDD/PCDF) and the polybrominated biphenyl ethers concerning the investigations within the project "Sentinel Health Departments" in Baden-Wurttemberg are represented. Additionally results from children from Kazakhstan (Aral-Sea area) and from teachers which are working in PCB polluted schools as well as from a long term investigated test person are reported. Blood concentrations of the following compounds decreased from 1996/97 to 2002/03: the sum of the concentration of PCB 138,153 and 180 decreased from 0.46 microg/L to 0.20 microg/L, DDE from 0.32 microg/L to 0.17 microg/, HCB from 0.20 microg/L to 0.08 microg/L, beta-HCH below the level of detection, I-TEQ NATO to 4.8 pg/g blood fat, TEQ WHO (without PCB) to 5.5 pg/g blood fat, PCB 126 to 18,8,pg/g blood fat and PCB 169 to 12.8 pg/g blood fat. The influence of breast feeding and the gender on the level of the pollution is conspicious. No local correlations were found in Baden-Wurttemberg, but they were found in comparison with the results of Kazakhstan (Aral-Sea area). The difficulty to produce time series while the analyzing pollutants are more and more decreasing, as well as the change of the calculation base of the summation of parameters like I-TEQ NATO to TEQ WHO are discussed.


Assuntos
Compostos de Bifenilo/sangue , Monitoramento Ambiental , Poluentes Ambientais/sangue , Hidrocarbonetos Clorados/sangue , Praguicidas/sangue , Dibenzodioxinas Policloradas/análogos & derivados , Adulto , Fatores Etários , Benzofuranos/sangue , Carga Corporal (Radioterapia) , Aleitamento Materno , Criança , Pré-Escolar , Cromatografia Gasosa , Interpretação Estatística de Dados , Diclorodifenil Dicloroetileno/sangue , Feminino , Fungicidas Industriais/sangue , Alemanha , Hexaclorobenzeno/sangue , Humanos , Inseticidas/sangue , Cazaquistão , Masculino , Bifenil Polibromatos/sangue , Bifenilos Policlorados/sangue , Dibenzodioxinas Policloradas/sangue , Fatores Sexuais , Poluentes do Solo/sangue
7.
Gesundheitswesen ; 66(8-9): 528-35, 2004.
Artigo em Alemão | MEDLINE | ID: mdl-15372355

RESUMO

So far there have been rather few reliable and comparable data available on indoor pollution with mould. Following the publication of the Federal Environmental Agency and the Health Agency Baden-Württemberg which supports the assessment of mould pollution of indoor air, it seemed advisable to investigate as to how far these criteria can be used for the assessing the mould pollution in daily practice. The results of investigations of 130 homes and 117 classrooms in Baden-Württemberg. will be represented.


Assuntos
Poluição do Ar em Ambientes Fechados/análise , Poluição do Ar em Ambientes Fechados/estatística & dados numéricos , Monitoramento Ambiental/métodos , Fungos/isolamento & purificação , Características de Residência/estatística & dados numéricos , Medição de Risco/métodos , Instituições Acadêmicas/estatística & dados numéricos , Cidades/epidemiologia , Monitoramento Epidemiológico , Alemanha/epidemiologia , Fatores de Risco , Esporos Fúngicos/isolamento & purificação
8.
Gesundheitswesen ; 65(7): 457-63, 2003 Jul.
Artigo em Alemão | MEDLINE | ID: mdl-12891478

RESUMO

The study examined the exposure to biological indoor air agents and their possible role for allergies and respiratory tract illnesses of children. It was conducted as a case control study (atopic vs non-atopic children) at the four surveillance public health departments in Baden-Württemberg in the winter season 1999/2000 and included 379 children of the fourth class. The concentrations of the house dust mite antigens Der F1, Der p1, and Der Gr2 as well as cat allergen Fel d1 were determined in the children's bedrooms on the ground and in the mattress. Specific IgE-antibodies against allergens from house dust, mites and cat were determined in the serum of the children. For mite allergens the following medians ( micro g/g) were estimated in floor dust: Der p1 = 0.6, Der f1 = 2.3, Gr2 = 0.1; in mattresses: Der p1 = 1.2, Der f1 = 3.4, Gr2 = 0.3. The median of Fel d1 in floor dust was 0.2 microg/g, in mattresses 0.1 microg/g. Sensitisation to dust mite allergen was found to be more prevalent than sensitisation to cat. The distribution of sensitisation among the cases and controls is different. Among the cases, more subjects were sensitised to dust mites (32.9 %) and cat (13.1 %). Among the controls, 17.1 % were sensitised to dust mites and 4.1 % to cat. The results showed no direct association between the prevalence of allergies or respiratory tract illnesses and the indoor concentrations of the allergens. Possible reasons for these findings are discussed.


Assuntos
Alérgenos , Gatos/imunologia , Dermatite Atópica/diagnóstico , Ácaros/imunologia , Hipersensibilidade Respiratória/diagnóstico , Alérgenos/análise , Alérgenos/imunologia , Animais , Roupas de Cama, Mesa e Banho , Estudos de Casos e Controles , Criança , Interpretação Estatística de Dados , Dermatite Atópica/etiologia , Dermatite Atópica/imunologia , Poeira/imunologia , Ensaio de Imunoadsorção Enzimática , Alemanha , Humanos , Hipersensibilidade Respiratória/etiologia , Hipersensibilidade Respiratória/imunologia , Inquéritos e Questionários
9.
Gesundheitswesen ; 65(5): 327-35, 2003 May.
Artigo em Alemão | MEDLINE | ID: mdl-12772075

RESUMO

Since 1992, in Baden-Württemberg, ten-year old children have been surveyed in the project "Sentinel Health Departments" to study their exposure to environmental pollutants and possible health effects. In the four study areas 1200 children have been investigated every year initially, since 1996 every second year. The data for mercury in body fluids are reported here. The decrease in the body burden of mercury as a result of the declining usage of dental amalgam fillings, was been verified. In 1992/93, of all the children who had been surveyed, the 95 percentile for the body burden of mercury was 3.1 microg/l and in 2000/01 1.35 microg/l. Also to be discussed is the reason why mercury-based cosmetic ointments seriously exceed the HBM-II-intervention-value. Because of using these ointments, concentrations of mercury in urine up to 1400 microg/l were found. A study within the project "Sentinel Health Departments" compared the concentrations of mercury in the urine of adults with those in blood and salvia. The results support the opinion that mercury in urine is appropriate for estimating the mercury uptake from dental amalgam fillings. It can be assumed that these results reflect the situation in the entire Federal Republic of Germany. The ten years' experience confirms that the concept of the "Sentinel Health Departments" is excellently suited to obtain data relevant for environmental health of children. Environmental health protection and the essential gathering of data for future health observation in Baden-Württemberg.


Assuntos
Amálgama Dentário/efeitos adversos , Monitoramento Ambiental/estatística & dados numéricos , Poluentes Ambientais/farmacocinética , Intoxicação por Mercúrio/epidemiologia , Mercúrio/farmacocinética , Saúde Pública/estatística & dados numéricos , Adulto , Carga Corporal (Radioterapia) , Criança , Poluentes Ambientais/toxicidade , Monitoramento Epidemiológico , Feminino , Alemanha/epidemiologia , Humanos , Masculino , Mercúrio/toxicidade , Intoxicação por Mercúrio/diagnóstico , Intoxicação por Mercúrio/prevenção & controle , Fatores de Risco , Saliva/metabolismo , Vigilância de Evento Sentinela
10.
J Pharm Biomed Anal ; 20(1-2): 225-39, 1999 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-10704027

RESUMO

The present report describes how pharmacological assays may be validated and sets a basis for a discussion on the validation of biological test systems. The note for guidance on the validation of analytical procedures published by the European agency for the evaluation of medicinal products was adapted to the validation of a pharmacological test system. The presently described rat lung lavage test (RLL-test) is an animal model that has great similarities to the pathophysiology of the acute respiratory distress syndrome of humans. In this RLL-test, the activity of surfactants can be tested in a standardised fashion. The usefulness of the point estimator and the corresponding confidence intervals (CI) as a statistical test procedure for equivalence was demonstrated. A validation can be based on the above mentioned guidance but should be adjusted to pharmacological needs. Based on the presented experiences, it can be concluded that a specific guideline for validation of pharmacological or biological tests is desirable.


Assuntos
Pulmão/metabolismo , Surfactantes Pulmonares/farmacologia , Anestesia , Animais , Bioensaio , Pulmão/efeitos dos fármacos , Masculino , Modelos Biológicos , Oxigênio/sangue , Surfactantes Pulmonares/administração & dosagem , Ratos , Ratos Sprague-Dawley , Proteínas Recombinantes/administração & dosagem , Proteínas Recombinantes/farmacologia , Padrões de Referência , Reprodutibilidade dos Testes , Irrigação Terapêutica
11.
Am J Phys Anthropol ; 105(3): 315-32, 1998 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-9545075

RESUMO

The activity of 17 hand muscles was monitored by electromyography (EMG) in three subjects during hard hammer percussion manufacture of Oldowan tools. Two of the subjects were archaeologists experienced in the replication of prehistoric stone tools. Simultaneous videotapes recorded grips associated with the muscle activities. The purpose of the study was to identify the muscles most likely to have been strongly and repeatedly recruited by early hominids during stone tool-making. This information is fundamental to the identification of skeletal features that may reliably predict tool-making capabilities in early hominids. The muscles most frequently recruited at high force levels for strong precision pinch grips required to control the hammerstone and core are the intrinsic muscles of the fifth finger and the thumb/index finger regions. A productive search for skeletal evidence of habitual Oldowan tool-making behavior will therefore be in the regions of the hand stressed by these intrinsic muscles and in the joint configurations affecting the relative lengths of their moment arms.


Assuntos
Osso e Ossos/anatomia & histologia , Hominidae/anatomia & histologia , Músculo Esquelético/anatomia & histologia , Animais , Antropologia Física , Eletromiografia , Dedos/anatomia & histologia , Fósseis , Mãos , Humanos , Destreza Motora , Músculo Esquelético/fisiologia , Polegar/anatomia & histologia
12.
J Clin Endocrinol Metab ; 81(6): 2335-7, 1996 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-8964873

RESUMO

Digitalis glycosides and a putative ouabain-like substance act by inhibiting Na,K-adenosine triphosphatases and could regulate aldosterone secretion. We studied the effects of ouabain on basal and angiotensin II (AII)-induced aldosterone in rat and human adrenal glomerulosa cells. In the rat, ouabain at doses as high as 10(-4) mol/L had no effect on basal aldosterone secretion, but caused a dose-related inhibition of AII and ACTH secretion. In human glomerulosa cells, ouabain was 1000 times more potent on both basal and AII stimulation, with action at 10(-8) mol/L. The effect of ACTH was also blunted by 10(-8)-10(-7) mol/L ouabain. However, the effect of potassium (8.7 mmol/L) on aldosterone was not altered by these doses of ouabain. These results suggest that nanomolar levels of ouabain can reduce aldosterone secretion from human zona glomerulosa cells.


Assuntos
Glândulas Suprarrenais/efeitos dos fármacos , Aldosterona/metabolismo , Angiotensina II/antagonistas & inibidores , Antagonistas de Receptores de Mineralocorticoides/farmacologia , Ouabaína/farmacologia , Glândulas Suprarrenais/metabolismo , Hormônio Adrenocorticotrópico/farmacologia , Angiotensina II/farmacologia , Animais , Humanos , Masculino , Potássio/farmacologia , Ratos , Ratos Sprague-Dawley , Zona Glomerulosa/citologia , Zona Glomerulosa/efeitos dos fármacos , Zona Glomerulosa/metabolismo
13.
Cytotechnology ; 19(2): 111-24, 1995 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-22359012

RESUMO

A murine hybridoma cell line producing a monoclonal antibody against penicillin-G-amidase and a murine transfectoma cell line secreting a monovalent chimeric human/mouse Fab-antibody fragment were cultivated in three different media (serum-containing, low protein serum-free, and iron-rich protein-free) in flask cultures, stirred reactors and a fixed bed reactor. In static batch cultures in flasks both cell lines showed similar good growth in all three media.In suspension in a stirred reactor, the hybridoma cell line could be cultivated satisfactory only in serum-containing medium. In low protein serum-free medium, Pluronic F68 had to be added to protect the hybridoma cells against shear stress. But even with this supplement only batch, not chemostat mode was possible. In iron-rich protein-free medium the hybridoma cells grew also in continuous chemostat mode, but the stability of the culture was low. The transfectoma cell line did not grow in stirred reactors in any of the three media.Good results with both cell lines were obtained in fixed bed experiments, where the cells were immobilized in macroporous Siran(®)-carriers. The media, which were optimized in flask cultures, could be used without any further adaptation in the fixed bed reactor. Immobilization improved the stability and reliability of cultures of non-adherent animal cells in serum-free media tremendously compared to suspension cultures in stirred reactors. The volume-specific glucose uptake rate, an, indicator of the activity of the immobilized cells, was similar in all three media. Deviations in the metabolism of immobilized and suspended cells seem to be mainly due to low oxygen concentrations within the macroporous carriers, where the cells are supplied with oxygen only by diffusion.

14.
Science ; 264(5167): 1907-10, 1994 Jun 24.
Artigo em Inglês | MEDLINE | ID: mdl-8009220

RESUMO

Fossils and artifacts recovered from the middle Awash Valley of Ethiopia's Afar depression sample the Middle Pleistocene transition from Homo erectus to Homo sapiens. Ar/Ar ages, biostratigraphy, and tephrachronology from this area indicate that the Pleistocene Bodo hominid cranium and newer specimens are approximately 0.6 million years old. Only Oldowan chopper and flake assemblages are present in the lower stratigraphic units, but Acheulean bifacial artifacts are consistently prevalent and widespread in directly overlying deposits. This technological transition is related to a shift in sedimentary regime, supporting the hypothesis that Middle Pleistocene Oldowan assemblages represent a behavioral facies of the Acheulean industrial complex.


Assuntos
Fósseis , Hominidae/anatomia & histologia , Animais , Etiópia , Geologia/história , História Antiga , Humanos , Crânio/anatomia & histologia
15.
Strahlenther Onkol ; 170(1): 36-41, 1994 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-8303576

RESUMO

PURPOSE: Experimental in vivo radiotherapy frequently aims at the imitation of clinically applied fractionation schedules. However, the reliability of the anesthetic procedure and limited access to the treatment machines in clinical departments are major factors complicating the practical realisation of the experiment. Therefore, a reliable and time saving system for irradiations of xenografted tumors has been developed, which allows repeated irradiations, even in relatively short intervals available for experimental irradiations. MATERIAL AND METHODS: The system presented here consists of an acrylic distributor for an anesthetic gas mixture employing enflurane (Ethrane) in the center of the set-up. Ten mice are positioned radially around the midpoint of the set-up so that they can be irradiated simultaneously. The xenotransplanted tumors growing on the right hind leg of mice are placed in a predefined position, which was found to be of advantage in order to position the tumors for fractionated treatments in identical setting. Tumor-bearing mice are irradiated with 15 MeV photons generated by a linear accelerator at a dose rate of 2.5 Gy/min. One of the significant feature of the setup is the ability to irradiate in acute hypoxia which is obtained by use of an integrated tourniquet. The dose modifying effects of different gases can be investigated by simply using them as carrier for the enflurane. RESULTS: With the use of the set-up several different experiments were performed so far. At most ten fractions were given, one fraction per day. Even after these repeated treatment the loss of animals due to narcosis was less than 2%. The dose variation within the treatment field was found to be less than 4% as measured with TLD dosimetry. The remaining body of the mice is shielded effectively from the direct beam as the whole body dose of mice is 8% of the total tumor absorbed dose. The efficacy of the tourniquet technique for acute hypoxic irradiations was illustrated with the use of 99mTc-labelled albumin showing a complete stop of blood flow in the clamped leg. The steep dose-response curve obtained for single dose irradiation of a neurogenic sarcoma is based on the physical and experimental precision which can be reached with the technique suggested here. CONCLUSION: Due to the high dose rate and the possibility to irradiate ten animals simultaneously the set-up introduced here is greatly time saving. The versatile applicability makes the new set-up a valuable tool for tumor radiobiology.


Assuntos
Neoplasias Experimentais/radioterapia , Anestesia por Inalação/instrumentação , Animais , Enflurano , Camundongos , Fatores de Tempo , Transplante Heterólogo
16.
Biophys J ; 64(5): 1559-66, 1993 May.
Artigo em Inglês | MEDLINE | ID: mdl-8324191

RESUMO

It has recently been reported that polymer actin made from monomer containing ATP (ATP-actin) differed in EM appearance and rheological characteristics from polymer made from ADP-containing monomers (ADP-actin). Further, it was postulated that the ATP-actin polymer was more rigid due to storage of the energy released by ATP hydrolysis during polymerization (Janmey et al. 1990. Nature 347:95-99). Electron micrographs of our preparations of ADP-actin and ATP-actin polymers show no major differences in appearance of the filaments. Moreover, the dynamic viscosity parameters G' and G" measured for ATP-actin and ADP-actin polymers are very different from those reported by Janmey et al., in absolute value, in relative differences, and in frequency dependence. We suggest that the relatively small differences observed between ATP-actin and ADP-actin polymer rheological parameters could be due to small differences either in flexibility or, more probably, in filament lengths. We have measured nucleotide exchange on ATP-actin and ADP-actin polymers by incorporation of alpha-32P-ATP and found it to be very slow, in agreement with earlier literature reports, and in contradiction to the faster exchange rates reported by Janmey et al. This exchange rate is much too slow to cause "reversal" of ADP-actin polymer ATP-actin polymer as reported by Janmey et al. Thus our results do not support the notion that the energy of actin-bound ATP hydrolysis is trapped in and significantly modifies the actin polymer structure.


Assuntos
Actinas/química , Difosfato de Adenosina/análogos & derivados , Trifosfato de Adenosina/análogos & derivados , Actinas/isolamento & purificação , Actinas/ultraestrutura , Difosfato de Adenosina/química , Trifosfato de Adenosina/química , Animais , Fenômenos Biofísicos , Biofísica , Elasticidade , Microscopia Eletrônica , Coelhos , Reologia , Termodinâmica , Viscosidade
17.
Appl Radiat Isot ; 44(1-2): 253-60, 1993.
Artigo em Inglês | MEDLINE | ID: mdl-8386041

RESUMO

A single radiation-sensitive ESR signal at g = 2.0018 occurs in fossil tooth enamel, but not in modern teeth. In dating fossil teeth, the equivalent radiation dose (AD) needed to produce the observed ESR signal is the integral with respect to time of the natural, environmental dose rate (ED) experienced by the tooth during burial. Since the age depends on the U uptake history assumed, three dates are normally calculated assuming early U uptake (EU), continuous (linear) U uptake (LU), or recent U uptake (RU). Generally the LU ages agree best with known ages determined by other methods, but the EU and RU ages are respectively the minimum and maximum ages. Longola Spring Mound, in Central Zambia, contains a Late Stone Age collection occurs on the mound surface. Embedded in layer near the base is a much older layer containing Middle Stone Age artifacts and bone material. Four ungulate teeth collected from the lower layer were ESR dated. EU, LU, and RU ages for each tooth agree very closely, but ages range from 14 to 96 ka. Although the layer may be a two component deposit with teeth averaging 18 +/- 2 ka and 91 +/- 3 ka, high sedimentary Th concentrations and ESR isochrons suggest that gamma ext dose estimates are in error. LU dates estimated from isochron plots average 204 +/- 86 ka, while LU ages calculated with the average isochron-derived gamma ext = 10.79 +/- 1.89 mrad/a average 220 +/- 62 ka. More excavation and dating are necessary to determine if the isochron data is reasonable.(ABSTRACT TRUNCATED AT 250 WORDS)


Assuntos
Esmalte Dentário , Fósseis , Animais , Espectroscopia de Ressonância de Spin Eletrônica , História Antiga , Mamíferos , Zâmbia
18.
Biopolymers ; 31(11): 1265-71, 1991 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-1663797

RESUMO

Dynamic light scattering was used to characterize the diffusion of monodisperse polystyrene latex spheres (PLS) of different sizes (55-, 105-, and 265-nm radii) in column-purified 0.65 mg/mL actin solutions polymerized with 100 mM KCl in the absence and presence of various amounts of the actin-binding protein gelsolin. The gelsolin and its interaction with actin was initially studied to ensure that the gelsolin could be used to produce filament populations with well-defined mean lengths. Measurements with PLS diffusion probes present showed, in the absence of gelsolin, that the effective local microviscosity in the actin solutions was 5-20 times that of water and that a large fraction of the PLS are trapped within the pores of the actin filament network, as found previously [J. Newman, K. L. Schick, & K. S. Zaner, (1989) Biopolymers 28, 1969-1980]. As the molar ratio of gelsolin to actin was increased, the diffusion coefficients of the PLS approached those in pure water while the degree of PLS trapping went to zero. Measurements of the dependence of the PLS diffusion coefficients on the ratio of actin concentration to the semidilute overlap concentration showed, for the smaller PLS, a transition occurring near the mean global overlap concentration. These results reflect the dissolution of the actin network as the gelsolin concentration is increased and illustrate the role of gelsolin/actin interactions in the control of macromolecular transport within the periphery of cells.


Assuntos
Actinas/química , Proteínas de Ligação ao Cálcio/química , Proteínas dos Microfilamentos/química , Difusão , Gelsolina , Luz , Microesferas , Espalhamento de Radiação , Soluções
19.
Biopolymers ; 28(11): 1969-80, 1989 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-2597742

RESUMO

The diffusion of monodisperse polystyrene latex spheres (PLS) in column-purified 0.65 mg/mL actin solutions, polymerized with 100 mM KCl in the absence and presence of a cross-linker, actin binding protein (ABP), has been studied using dynamic light scattering. Measurements over a wide range of scattering angles from 90 degrees to 8 degrees, corresponding to inverse scattering vector probing distances of about 40-400 nm, respectively, give a measure of both the fraction of PLS mobile over the probing distance (from the normalized time autocorrelation function amplitude) and the average diffusion coefficient of the mobile PLS. Both 100- and 500-nm diameter PLS are fully mobile in polymerized actin solutions over distances of less than 100 nm, as reported previously (Newman, J., Schick, K. S. & Gukelberger, G. Biophys. J. 53, 573a, and Newman, J., Mroczka, N. & Schick, K. L. Biopolymers, 28, 655-666). At increasing probing distances, or when ABP is added at molar ratios of 1:750 or 1:150, greater fractions of the PLS are immobilized, up to almost 99% at the conditions of a 400-nm probing distance with 500-nm probes and at a ratio of 1:150 added ABP to actin. The degree of immobilization correlated well with the amount of added ABP, the size of the PLS, and the probing distance. At increasing probe distances, as the degree of immobilization increases, the remaining mobile fraction of PLS has an increasing average diffusion coefficient. These results suggest a range of pore sizes in the actin gels with a mean size of a few hundred nanometers.


Assuntos
Actinas , Difusão , Animais , Reagentes de Ligações Cruzadas , Géis , Luz , Proteínas dos Microfilamentos , Coelhos , Espalhamento de Radiação
20.
Int J Cardiol ; 23(2): 258-60, 1989 May.
Artigo em Inglês | MEDLINE | ID: mdl-2722293

RESUMO

In a 47-year-old male with hypertrophic cardiomyopathy, coronary angiography revealed three myocardial bridges associated with significant systolic narrowing of the left coronary artery. Measurements during pacing and exercise demonstrated no sign of myocardial ischemia. Ten-year follow-up was uneventful. Thus, the prognosis of myocardial bridges, even when located at multiple sites across the left coronary artery, seems benign.


Assuntos
Cardiomiopatia Hipertrófica/patologia , Miocárdio/patologia , Angiografia , Cardiomiopatia Hipertrófica/diagnóstico por imagem , Angiografia Coronária , Vasos Coronários/patologia , Coração/diagnóstico por imagem , Humanos , Masculino , Pessoa de Meia-Idade
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