碳、氧稳定同位素分析在古环境研究中的应用

A number of proxy records of paleoenvironment using stable isotopes could show the history of past environmental changes. These archives include peat and lake sediments, loess-paleosot sequence, fossil mammals and stalagmite, and so on. The stable isotopic composition of carbonate and organic matter and frequency magnetic susceptibility from Tianshuigou and Yuanlei loess-palesol sequence can be used to give estimates of the paleoenvironmental history of Dali, and even of the whole Chinese Loess Plateau during the last 250ka. Features of the High Temperature and Large Precipitation Event in the Tibet Plateau and its adjacent area during 40~30kaBP had been studied by Professor Shi Y. In this dissertation, its impact on Chinese Loess Plateau has been discussed again. Carbon and oxygen isotopic ratios, magnetic susceptibility and frequency magnetic susceptibility in Tianshuigou and Yuanlei profiles show that the Event in this area is not so stronger as the Tibet Plateau. The carbon isotopic composition of organic matter in Tianshuigou, Yuanlei, dingcun and Jingcun loess-palesol sequences are indicative of major changes in the paleovagetation between terrace and plain of the Chinese Loess Plateau. Water is one of the most important factors adjusting the relative biomass of C4 plant in terrestrial ecosystems. Stable carbon isotope ratio of vertebrate tooth enamel is used increasingly to reconstruct environmental and ecological information modern and ancient ecosystems. The SI3C value of tooth enamel bioapatites can distinguish between browsers and grazers. Data from typical grassland of Inter Mongolia, the Alpine meadow of Qinghai-Tibet Plateau and the Yaluzangbu Great Canyon indicate that diets of mammals could record the relative biomass of C4 plant only in the C4 dominated ecosystem. In a C3 dominated ecosystem, diet of mammals would include more C3 plants than vegetation. According to Professor Cerling, proxy records from North and South America, Africa and Pakistan show that at the end of the Miocene (between 8Ma to 6 Ma) there was a global expansion of CA biomass, probably when atmospheric CO2 levels declined. Thus, "C4 world" and "CO2 starvation" are put forward. In this dissertation, carbon isotopes of fossil tooth such as Equus sanmeniensis and Hipparion chiai from Linxia, China reveal that there is a C3 dominated ecosystem in the late Miocene. Diets of ancient mammals in Linxia are not evidence of global expansion of C4 biomass.

现代动物食谱及吕梁山北端全新世风成沉积研究

The carbon isotope compositions of plants in Xilinguole, Haibei and Jilong and the tooth enamel of animals in Jilong have been analyzed. The study of carbon isotope discrimination of plants along altitude gradient among the three areas has found decreased discrimination.The eolian deposits of Heyeping can be used to reconstruct Holocene climate variability in the region. Some proxies indicates that the 8. 2 ka event can be found in north China, and it is warm and arid in the 4900～6800(or 6900) cal. a BP.

Understanding and Modeling the Behavior of a Harmonic Drive Gear Transmission

In my research, I have performed an extensive experimental investigation of harmonic-drive properties such as stiffness, friction, and kinematic error. From my experimental results, I have found that these properties can be sharply non-linear and highly dependent on operating conditions. Due to the complex interaction of these poorly behaved transmission properties, dynamic response measurements showed surprisingly agitated behavior, especially around system resonance. Theoretical models developed to mimic the observed response illustrated that non-linear frictional effects cannot be ignored in any accurate harmonic-drive representation. Additionally, if behavior around system resonance must be replicated, kinematic error and transmission compliance as well as frictional dissipation from gear-tooth rubbing must all be incorporated into the model.

Characteristic infrared spectroscopic patterns in the protein bands of human breast cancer tissue

Infrared (IR) spectra of normal, hyperplasia, fibroadenoma and carcinoma tissues of human breast obtained from 96 patients have been determined and analyzed statistically. Several spectral differences were detected in the frequency regions of N-H stretching, amide I, II and III bands: (1) the bands in the region 3000-3600cm-1 shifted to lower frequencies for the carcinomatous tissue; (2) the A(3300)/A(3075) absorbance ratio was significantly higher for the fibroadenoma than for the other types of tissues; (3) the frequency of the a-helix amide I band decreased for the malignant tissue, while the corresponding beta -sheet amide I band frequency increased; (4) the A(1657)/A(1635) and A(1553)/A(1540) absorbance ratios were the highest for fibroadenoma and carcinoma tissues; (5) the A(1680)/A(1657) absorbance ratio decreased significantly in the order of normal > hyperplasia > fibroadenoma > carcinoma; (6) the A(1651)/A(1545) absorbance ratio increased slightly for the fibroadenoma and the carcinoma tissues; (7) the bands at 1204 and 1278 cm(-1), assigned to the vibrational modes of the collagen, did not appear in the original spectra as resolved peaks and were distinctly stronger in the deconvoluted spectra of the carcinoma tissue and (8) the A(1657)/A(1204) and A(1657)/A(1278) absorbance ratios, both yielding information on the relative content of collagen, increased in the order of normal < hyperplasia < carcinoma < fibroadenoma. The said differences imply that the information is useful for the diagnosis of breast cancer and malignant breast abnormalities, and may serve as a basis for further studies on conformational changes in tissue proteins during carcinogenesis. (C) 2001 Elsevier Science B.V. All rights reserved.

Pancreatic and adrenal development and function in an ovine model of polycystic ovary syndrome.

Polycystic Ovary Syndrome (PCOS) is a complex disorder encompassing reproductive and metabolic dysfunction. Ovarian hyperandrogenism is an endocrine hallmark of human PCOS. In animal models, PCOS-like abnormalities can be recreated by in utero over-exposure to androgenic steroid hormones. This thesis investigated pancreatic and adrenal development and function in a unique model of PCOS. Fetal sheep were directly exposed (day 62 and day 82 of gestation) to steroidal excesses - androgen excess (testosterone propionate - TP), estrogen excess (diethylstilbestrol - DES) or glucocorticoid excess (dexamethasone - DEX). At d90 gestation there was elevated expression of genes involved in β- cell development and function: PDX-1 (P<0.001), and INS (P<0.05), INSR (P<0.05) driven by androgenic excess only in the female fetal pancreas. β- cell numbers (P<0.001) and in vitro insulin secretion (P<0.05) were also elevated in androgen exposed female fetuses. There was a significant increase in insulin secreting β-cell numbers (P<0.001) and in vivo insulin secretion (glucose stimulated) (P<0.01) in adult female offspring, specifically associated with prenatal androgen excess. At d90 gestation, female fetal adrenal gene expression was perturbed by fetal estrogenic exposure. Male fetal adrenal gene expression was altered more dramatically by fetal glucocorticoid exposure. In female adult offspring from androgen exposed pregnancies there was increased adrenal steroidogenic gene expression and in vivo testosterone secretion (P<0.01). This highlights that the adrenal glands may contribute towards excess androgen secretion in PCOS, but such effects might be secondary to other metabolic alterations driven by prenatal androgen exposure, such as excess insulin secretion Thus there may be dialogue between the pancreas and adrenal gland, programmed during early life, with implications for adult health Given both hyperinsulinaemia and hyperandrogenism are common features in PCOS, we suggest that their origins may be at least partially due to altered fetal steroidal environments, specifically excess androgenic stimulation

Centenarians and their hearts: a prospective registry with comprehensive geriatric assessment, electrocardiogram, echocardiography, and follow-up

Background Data on the cardiac characteristics of centenarians are scarce. Our aim was to describe electrocardiogram (ECG) and echocardiography in a cohort of centenarians and to correlate them with clinical data. Methods We used prospective multicenter registry of 118 centenarians (28 men) with a mean age of 101.5 ± 1.7 years. Electrocardiogram was performed in 103 subjects (87.3%) and echocardiography in 100 (84.7%). All subjects underwent a follow-up for at least 6 months. Results Centenarians with abnormal ECG were less frequently females (72% vs 93%), had higher rates of previous consumption of tobacco (14% vs 0) and alcohol (24% vs 12%), and scored lower in the perception of health status (6.8 ± 2.0 vs 8.3 ± 6.8). Centenarians with significant abnormalities in echocardiography were less frequently able to walk 6 m (33% vs 54%). Atrial fibrillation/flutter was found in 27 subjects (26%). Mean left ventricular (LV) ejection fraction was 60.0 ± 10.5%. Moderate or severe aortic valve stenosis was found in 16%, mitral valve regurgitation in 15%, and aortic valve regurgitation in 13%. Diastolic dysfunction was assessed in 79 subjects and was present in 55 (69.6%). Katz index and LV dilation were independently associated with the ability to walk 6 m. Age, Charlson and Katz indexes, and the presence of significant abnormalities in echocardiography were associated with mortality. Conclusions Centenarians have frequent ECG alterations and abnormalities in echocardiography. More than one fifth has atrial fibrillation, and most have diastolic dysfunction. Left ventricular dilation was associated with the ability to walk 6 m. Significant abnormalities in echocardiography were associated with mortality.

Depolarization of sperm membrane potential is a common feature of men with subfertility and is associated with low fertilization rate at IVF

STUDY QUESTION. Are significant abnormalities in outward (K+) conductance and resting membrane potential (Vm) present in the spermatozoa of patients undertaking IVF and ICSI and if so, what is their functional effect on fertilization success? SUMMARY ANSWER. Negligible outward conductance (≈5% of patients) or an enhanced inward conductance (≈4% of patients), both of which caused depolarization of Vm, were associated with a low rate of fertilization following IVF. WHAT IS KNOWN ALREADY. Sperm-specific potassium channel knockout mice are infertile with defects in sperm function, suggesting that these channels are essential for fertility. These observations suggest that malfunction of K+ channels in human spermatozoa might contribute significantly to the occurrence of subfertility in men. However, remarkably little is known of the nature of K+ channels in human spermatozoa or the incidence and functional consequences of K+ channel defects. STUDY DESIGN, SIZE AND DURATION. Spermatozoa were obtained from healthy volunteer research donors and subfertile IVF and ICSI patients attending a hospital assisted reproductive techniques clinic between May 2013 and December 2015. In total, 40 IVF patients, 41 ICSI patients and 26 normozoospermic donors took part in the study. PARTICIPANTS/MATERIALS, SETTING, METHODS. Samples were examined using electrophysiology (whole-cell patch clamping). Where abnormal electrophysiological characteristics were identified, spermatozoa were further examined for Ca2+ influx induced by progesterone and penetration into viscous media if sufficient sample was available. Full exome sequencing was performed to specifically evaluate potassium calcium-activated channel subfamily M α 1 (KCNMA1), potassium calcium-activated channel subfamily U member 1 (KCNU1) and leucine-rich repeat containing 52 (LRRC52) genes and others associated with K+ signalling. In IVF patients, comparison with fertilization rates was done to assess the functional significance of the electrophysiological abnormalities. MAIN RESULTS AND THE ROLE OF CHANCE. Patch clamp electrophysiology was used to assess outward (K+) conductance and resting membrane potential (Vm) and signalling/motility assays were used to assess functional characteristics of sperm from IVF and ICSI patient samples. The mean Vm and outward membrane conductance in sperm from IVF and ICSI patients were not significantly different from those of control (donor) sperm prepared under the same conditions, but variation between individuals was significantly greater (P< 0.02) with a large number of outliers (>25%). In particular, in ≈10% of patients (7/81), we observed either a negligible outward conductance (4 patients) or an enhanced inward current (3 patients), both of which caused depolarization of Vm. Analysis of clinical data from the IVF patients showed significant association of depolarized Vm (≥0 mV) with low fertilization rate (P= 0.012). Spermatozoa with electrophysiological abnormities (conductance and Vm) responded normally to progesterone with elevation of [Ca2+]i and penetration of viscous medium, indicating retention of cation channel of sperm (CatSper) channel function. LIMITATIONS, REASONS FOR CAUTION. For practical, technical, ethical and logistical reasons, we could not obtain sufficient additional semen samples from men with conductance abnormalities to establish the cause of the conductance defects. Full exome sequencing was only available in two men with conductance defects. WIDER IMPLICATIONS OF THE FINDINGS. These data add significantly to the understanding of the role of ion channels in human sperm function and its impact on male fertility. Impaired potassium channel conductance (Gm) and/or Vm regulation is both common and complex in human spermatozoa and importantly is associated with impaired fertilization capacity when the Vm of cells is completely depolarized.

Restauração directa de classes II em pré-molares com compósitos

Tese de Doutoramento apresentada à Universidade Fernando Pessoa como parte dos requisitos para obtenção do grau de Doutor em em Biotecnologia e Saúde, Epidemiologia e Saúde Pública.

Sinusite odontogénica

Monografia apresentada à Universidade Fernando Pessoa para obtenção do grau de Licenciada em Medicina Dentária.

Avaliação retrospectiva da longevidade das restaurações, com compósito, realizadas por alunos de pré-graduação em Medicina Dentária da Universidade Fernando Pessoa, entre os anos de 2002 e 2006

Monografia apresentada à Universidade Fernando Pessoa para obtenção do grau de Licenciada em Medicina Dentária

Aferição de competências em Endodontia percepcionadas pelos finalistas em Medicina Dentária e pelos Médicos Dentistas licenciados na Faculdade de Ciências de Saúde da Universidade Fernando Pessoa

Monografia apresentada à Universidade Fernando Pessoa como parte dos requisitos para obtenção do grau de Licenciada em Medicina Dentária

Uso de equipamento auxiliar no preparo dentário para próteses

Trabalho apresentado à Universidade Fernando Pessoa como parte dos requisitos para obtenção do grau de Mestre em Medicina Dentária.

Enterococcus sp. considerações clínicas e microbiológicas em endodontia

Projeto de Pós-Graduação/Dissertação apresentado à Universidade Fernando Pessoa como parte dos requisitos para obtenção do grau de Mestre em Ciências Farmacêuticas

Perda de dimensão vertical de oclusão e estruturas dentárias remanescentes

Projeto de Pós-Graduação/Dissertação apresentado à Universidade Fernando Pessoa como parte dos requisitos para obtenção do grau de Mestre em Medicina Dentária

Estudo da prevalência da utilização de protetores bucais em praticantes da arte marcial Muay Thai

Projeto de Pós-Graduação/Dissertação apresentado à Universidade Fernando Pessoa como parte dos requisitos para obtenção do grau de Mestre em Medicina Dentária