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1.
Dig Dis Sci ; 2024 Apr 02.
Artigo em Inglês | MEDLINE | ID: mdl-38564148

RESUMO

BACKGROUND: Cholesterol ester storage disorder (CESD; OMIM: 278,000) was formerly assumed to be an autosomal recessive allelic genetic condition connected to diminished lysosomal acid lipase (LAL) activity due to LIPA gene abnormalities. CESD is characterized by abnormal liver function and lipid metabolism, and in severe cases, liver failure can occur leading to death. In this study, one Chinese nonclassical CESD pedigree with dominant inheritance was phenotyped and analyzed for the corresponding gene alterations. METHODS: Seven males and eight females from nonclassical CESD pedigree were recruited. Clinical features and LAL activities were documented. Whole genome Next-generation sequencing (NGS) was used to screen candidate genes and mutations, Sanger sequencing confirmed predicted mutations, and qPCR detected LIPA mRNA expression. RESULTS: Eight individuals of the pedigree were speculatively thought to have CESD. LAL activity was discovered to be lowered in four living members of the pedigree, but undetectable in the other four deceased members who died of probable hepatic failure. Three of the four living relatives had abnormal lipid metabolism and all four had liver dysfunctions. By liver biopsy, the proband exhibited diffuse vesicular fatty changes in noticeably enlarged hepatocytes and Kupffer cell hyperplasia. Surprisingly, only a newly discovered heterozygous mutation, c.1133T>C (p. Ile378Thr) on LIPA, was found by gene sequencing in the proband. All living family members who carried the p.I378T variant displayed reduced LAL activity. CONCLUSIONS: Phenotypic analyses indicate that this may be an autosomal dominant nonclassical CESD pedigree with a LIPA gene mutation.

2.
Sci Rep ; 10(1): 19226, 2020 11 05.
Artigo em Inglês | MEDLINE | ID: mdl-33154528

RESUMO

Since fetal programming is sex-specific, there may also be sex-specific in parental influences on newborn birth weight. We aimed to investigate the influence of parental factors on small-for-gestational-age (SGA) infants of different sexes. Based on a pre-pregnancy cohort, multivariate logistic regression was used. 2275 couples were included for analysis. Significant associations were observed among paternal height, pre-pregnancy body mass index (BMI), and SGA in male infants; among maternal height, pre-pregnancy BMI, and SGA in female infants, and among other maternal factors and SGA in both male and female infants. Such sex specificity may be related to genetic, epigenetic, or hormonal influences between parents and infants. In conclusion, there is a sex specificity in the effect of parental height and pre-pregnancy BMI on SGA. The data suggest that future studies on infants should consider the sex-specific differences between the effects of genetic or environmental factors and infants.


Assuntos
Peso ao Nascer/fisiologia , Estatura/fisiologia , Índice de Massa Corporal , Desenvolvimento Fetal/fisiologia , Recém-Nascido Pequeno para a Idade Gestacional , Pais , Adulto , Feminino , Idade Gestacional , Humanos , Recém-Nascido , Masculino , Gravidez , Fatores de Risco
3.
World J Clin Cases ; 8(19): 4320-4330, 2020 Oct 06.
Artigo em Inglês | MEDLINE | ID: mdl-33083391

RESUMO

BACKGROUND: mTOR gene is a key component of the PI3K/Akt/mTOR signaling pathway, and its dysregulation is associated with various diseases. Several studies have demonstrated that tea drinking is a protective factor against tuberculosis (TB). This study was designed to explore five single nucleotide polymorphisms (SNPs) of mTOR in the Han population of China to determine how their interactions with tea drinking affect susceptibility to TB. AIM: To investigate if the polymorphisms of mTOR gene and the gene-tea interaction are associated with susceptibility to TB. METHODS: In this case-control study, 503 patients with TB and 494 healthy controls were enrolled by a stratified sampling method. The cases were newly registered TB patients from the county-level centers for disease control and prevention, and the healthy controls were permanent residents from Xin'ansi Community, Changsha city. Demographic data and environmental exposure information including tea drinking were obtained from the study participants. We genotyped five potentially functional SNP sites (rs2295080, rs2024627, rs1057079, rs12137958, and rs7525957) of mTOR gene and assessed their associations with the risk of TB using logistic regression analysis, and marginal structural linear odds models were used to estimate the gene-environment interactions. RESULTS: The frequencies of four SNPs (rs2295080, rs2024627, rs1057079, and rs7525957) were found to be associated with susceptibility to TB (P < 0.05). Genotypes GT (OR 1.334), GG (OR 2.224), and GT + GG (OR 1.403) at rs2295080; genotypes CT (OR 1.562) and CT + TT (OR 1.578) at rs2024627, genotypes CT (OR 1.597), CC (OR 2.858), and CT + CC (OR 1.682) at rs1057079; and genotypes CT (OR 1.559) and CT + CC (OR 1.568) at rs7525957 of mTOR gene were significantly more prevalent in TB patients than in healthy controls. The relative excess risk of interaction between the four SNPs (rs2295080, rs2024627, rs1057079, and rs7525957) of mTOR genes and tea drinking were found to be -1.5187 (95%CI: -1.9826, -1.0547, P < 0.05), -1.8270 (95%CI: -2.3587, -1.2952, P < 0.05), -2.3246 (95%CI: -2.9417, -1.7076, P < 0.05) and -0.4235 (95%CI: -0.7756, -0.0714, P < 0.05), respectively, which suggest negative interactions. CONCLUSION: The polymorphisms of mTOR (rs2295080, rs2024627, rs1057079, and rs7525957) are associated with susceptibility to TB, and there is a negative interaction between each of the four SNPs and tea drinking.

4.
World J Clin Cases ; 7(5): 585-599, 2019 Mar 06.
Artigo em Inglês | MEDLINE | ID: mdl-30863758

RESUMO

BACKGROUND: Resistin is most likely involved in the pathogenesis of gestational diabetes mellitus (GDM), but the existing findings are inconsistent. AIM: To review the literature investigating the associations of the risk of GDM with serum level of resistin. METHODS: A systematic literature search was performed using MEDLINE, EMBASE, and Web of Science (all databases). This meta-analysis included eligible studies that: (1) investigated the relationship between the risk of GDM and serum resistin; (2) included GDM cases and controls without GDM; (3) diagnosed GDM according to the oral glucose-tolerance test; (4) were performed in humans; (5) were published as full text articles in English; and (6) provided data with median and quartile range, median and minimum and maximum values, or mean and standard deviation. The pooled standardized mean difference (SMD) and 95% confidence interval (CI) were calculated to estimate the association between the risk of GDM and serum resistin. To analyze the potential influences of need for insulin in GDM patients and gestational age at blood sampling, we performed a subgroup analysis. Meta-regression with restricted maximum likelihood estimation was performed to assess the potentially important covariate exerting substantial impact on between-study heterogeneity. RESULTS: The meta-analysis for the association between serum resistin level and GDM risk included 18 studies (22 comparisons) with 1041 cases and 1292 controls. The total results showed that the risk of GDM was associated with higher serum resistin level (SMD = 0.250, 95%CI: 0.116, 0.384). The "after 28 wk" subgroup, "no need for insulin" subgroup, and "need for insulin" subgroup indicated that higher serum resistin level was related to GDM risk ("after 28 wk" subgroup: SMD = 0.394, 95%CI: 0.108, 0.680; "no need for insulin" subgroup: SMD = 0.177, 95%CI: 0.018, 0.336; "need for insulin" subgroup: SMD = 0.403, 95%CI: 0.119, 0.687). The "before 14 wk" subgroup, "14-28 wk" subgroup, and "no information of need for insulin" subgroup showed a nonsignificant association between serum resistin level and GDM risk ("before 14 wk" subgroup: SMD = 0.087, 95%CI: -0.055, 0.230; "14-28 wk" subgroup: SMD = 0.217, 95%CI: -0.003, 0.436; "no information of need for insulin" subgroup: SMD = 0.356, 95%CI: -0.143, 0.855). The postpartum subgroup included only one study and showed that higher serum resistin level was related to GDM risk (SMD = 0.571, 95%CI: 0.054, 1.087) The meta-regression revealed that no need for insulin in GDM patients, age distribution similar between cases and controls, and ELISA all had a significant impact on between-study heterogeneity. CONCLUSION: This meta-analysis supports that the maternal serum resistin level is associated with GDM risk.

5.
World J Clin Cases ; 6(15): 995-1006, 2018 Dec 06.
Artigo em Inglês | MEDLINE | ID: mdl-30568954

RESUMO

AIM: To compare the accuracy of the scoring systems Child-Turcotte-Pugh (CTP), Model for End-stage Liver Disease score (MELD), MELD-Na, and MELD to Serum Sodium ratio (MESO) to predict the mortality in decompensated liver cirrhosis. METHODS: The PubMed, Web of Science, Cochrane Library, EMBASE, and Ovid databases were systematically searched from inception to September 2018 for relevant articles, and we evaluated the quality of the included studies. The accuracy of scoring systems was analyzed with Stata 12 and MetaDiSc 1.4. RESULTS: Sixteen studies involving 2337 patients were included. The pooled areas under the summary receiver operating characteristic curves (AUROCs) of CTP, MELD, MELD-Na, and MESO to predict mortality were 0.81, 0.78, 0.85, and 0.86, respectively. Within 3 mo, the AUROCs of CTP, MELD, and MELD-Na in predicting mortality were 0.78, 0.76, and 0.89, respectively. The AUROCs of CTP, MELD, and MELD-Na at 3 mo were 0.86, 0.78, and 0.86, respectively. The AUROCs of CTP, MELD, and MELD-Na at 6 mo were 0.91, 0.83, and 0.90, respectively. The AUROCs of CTP, MELD, and MELD-Na at 12 mo were 0.72, 0.75 and 0.84, respectively. In cirrhotic patients with bleeding, the AUROCs of CTP and MELD were 0.76 and 0.88, respectively. CONCLUSION: MESO has the highest AUROC in all assessed scoring systems. Considering the different time points, MELD-Na has good accuracy in predicting the mortality of decompensated liver cirrhosis. Compared to CTP, MELD is better in predicting variceal bleeding.

6.
J Sci Food Agric ; 96(8): 2660-7, 2016 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-26300406

RESUMO

BACKGROUND: Different carbohydrates elicit various effects on the digestibility and the glucose release rate, so it is of interest to develop a sustained-release noodle based on the combination of different carbohydrates and reveal the sustained-release mechanism. RESULTS: The data obtained suggest that xanthan and konjac gum exhibited excellent and synergistic sustained-release properties, whereas cornstarch showed the lowest average digestion rate. The sustained release was particularly evident when the noodle consisted of the following components: 50 g of 25 g kg(-1) hydrophilic colloid mixture solution composed of a 1:1 mass ratio of xanthan:konjac gum and 100 g of reconstructed flour consisting of 200 g kg(-1) buckwheat flour, 400 g kg(-1) cornstarch, and 400 g kg(-1) plain flour. The morphological structure of noodles revealed that the composite hydrophilic colloids strengthened the interaction between the gluten network and starch granules. This buried starch within the three-dimensional structure thereby releasing glucose in a slow and sustained way. The most suitable model to describe glucose release from noodles was the Ritger-Peppas equation, which revealed that matrix erosion contributed to the release mechanism. CONCLUSION: These findings indicate that the controlled use of hydrophilic colloids and starches in manufacturing noodles could modulate the glucose sustained-release. © 2015 Society of Chemical Industry.


Assuntos
Fagopyrum/química , Manipulação de Alimentos/métodos , Coloides , Análise de Alimentos , Glucose , Amido
7.
Zhonghua Liu Xing Bing Xue Za Zhi ; 32(7): 664-8, 2011 Jul.
Artigo em Chinês | MEDLINE | ID: mdl-21933535

RESUMO

OBJECTIVE: To study the features, safe sex behavior and the size of men who have sex with men (MSM) population in actual and virtual venues in one city. METHODS: We carried out a cross-sectional study in actual and virtual venues, using the Estimated Size of Population from a Single Sample (LMS method) to estimate the size of MSM population. RESULTS: Most MSM in actual venues were 24 - 43 year olds and had received high school education, whereas in virtual venues, the majority of this population were younger than 29 years old and had higher education, including some college students. The awareness of AIDS of the two groups from different venues showed no statistically significant difference, neither the safe sex behaviors. Proportions of the MSM population in actual and virtual venues were 21.22% (16 383, 95%CI: 11 514 - 21 252) and 78.78% (60 830, 95%CI: 57 327 - 64 329), respectively. After adjusting the overlapping part of the MSM from both venues, the total number was between 60 830 and 77 213, constituting a proportion of 5.03% - 6.38% in the sexually active male population (15 - 64 year olds) in this city. CONCLUSION: The size of the MSM population was large but the characteristics were different in the actual or virtual venues. As most MSM preferred going to the virtual venues, intervention program on AIDS-specific strategy in this area, in particular dealing with the Internet, should be strengthened.


Assuntos
Homossexualidade Masculina/estatística & dados numéricos , Adolescente , Adulto , China/epidemiologia , Estudos Transversais , Humanos , Internet , Masculino , Pessoa de Meia-Idade , Densidade Demográfica , Assunção de Riscos , Sexo Seguro , Fatores Socioeconômicos , Adulto Jovem
8.
Zhonghua Liu Xing Bing Xue Za Zhi ; 31(2): 151-4, 2010 Feb.
Artigo em Chinês | MEDLINE | ID: mdl-21215073

RESUMO

OBJECTIVE: To determine the risk factors related to tuberculosis infection among people living with HIV/AIDS and to develop strategies for preventing the co-infection. METHODS: A 1:2 matched nested case-control study was carried out to analyze the influencing factors of tuberculosis among people living with HIV/AIDS. RESULTS: 1018 people living with HIV/AIDS were followed up for one year with a total number of 736.75 person-years, among them 62 tuberculosis cases were diagnosed. The incidence density of tuberculosis among people living with HIV/AIDS was 8.42 persons per 100 person-years. Factors as education level(OR = 0.483), vaccination history of Bacille Calmette Guerin (OR = 0.561), CD(4)(+) count T-lymphocyte (OR = 0.356), unemployment (OR = 1.976), living alone (OR = 2.646), and smoking (OR = 2.215) were significantly related to the prevalence of tuberculosis among people living with HIV/AIDS. CONCLUSION: High education level, with vaccination history of Bacille Calmette Guerin and high level of CD(4)(+) T-lymphocyte count were protective factors while being unemployed, living alone, and smoking habit were risk factors related to the prevalence of tuberculosis among people living with HIV/AIDS.


Assuntos
Infecções Oportunistas Relacionadas com a AIDS/epidemiologia , Síndrome da Imunodeficiência Adquirida/complicações , Infecções por HIV/complicações , Tuberculose/epidemiologia , Síndrome da Imunodeficiência Adquirida/epidemiologia , Adulto , Estudos de Casos e Controles , China/epidemiologia , Coinfecção , Feminino , Infecções por HIV/epidemiologia , Humanos , Incidência , Masculino , Pessoa de Meia-Idade , Fatores de Risco
9.
Zhonghua Liu Xing Bing Xue Za Zhi ; 30(7): 672-5, 2009 Jul.
Artigo em Chinês | MEDLINE | ID: mdl-19957587

RESUMO

OBJECTIVE: to explore the current situation and related influencing factors on the retention time of patients receiving methadone maintenance treatment (MMT). METHODS: Information on basic situation and daily treatment of the patients were collected from the 7 MMT clinics opened in the pro-two batch in Hunan province. Retention rate and influencing factors were analyzed. RESULTS: (1) The retention rates after 6 and 12 months of MMT became 72.06% and 49.65% respectively. (2) The retention rates of high-dosage group and low-dosage group were 85.03% and 68.03% after 6 months on MMT program while became 60.48% and 46.28% after 12 months of MMT respectively. (3) The mean retention time of HIV+ patients and HIV patients were 9.46 months and 8.62 months respectively during the 12 months follow-up observation, showing a significant difference. (4) Patients who took large dose methadone, did not share needles, at older age or HIV+, were prone to keep MMT at a long period. CONCLUSION: The retention rates for 6 months and 12 months in the MMT program in Hunan province were similar to the national data. Dose, type of drug abuse, age and HIV status were related to the period of retention.


Assuntos
Metadona/administração & dosagem , Cooperação do Paciente/estatística & dados numéricos , Transtornos Relacionados ao Uso de Substâncias/reabilitação , Fatores Etários , China , Seguimentos , Soronegatividade para HIV , Soropositividade para HIV/complicações , Humanos , Uso Comum de Agulhas e Seringas/estatística & dados numéricos , Transtornos Relacionados ao Uso de Substâncias/complicações , Fatores de Tempo
11.
Zhong Nan Da Xue Xue Bao Yi Xue Ban ; 33(1): 21-5, 2008 Jan.
Artigo em Chinês | MEDLINE | ID: mdl-18245899

RESUMO

OBJECTIVE: To explore the effect of health service and its influential factors in flood disaster areas. METHODS: Fifty-five towns were sampled randomly from Dongting Lake area suffering from flood in 1998. The health service level, effect, and its influence factors were investigated retrospectively. RESULTS: The incidence rate of notifiable infectious diseases was 11.7 per thousand, prevalence rate of chronic disease was 51.2 per thousand, infant mortality rate was 43.1 per thousand, neonatal mortality rate was 10.2 per thousand, and the total mortality rate was 554.3/100,000 in Dongting Lake area. The health investment level was significantly associated with the incidence rate of notifiable infectious diseases, the infant mortality rate, and total mortality rate. Duration of flood and income per capita were important factors for the effect of health investment. CONCLUSION: Increasing health investment and residents' income in the flood disaster area, shortening the duration of flood would play positive role in residents' health in the flood disaster area.


Assuntos
Doença Crônica/epidemiologia , Doenças Transmissíveis/epidemiologia , Inundações , Serviços de Saúde/provisão & distribuição , China/epidemiologia , Humanos , Incidência , Prevalência
12.
Zhonghua Liu Xing Bing Xue Za Zhi ; 28(5): 499-502, 2007 May.
Artigo em Chinês | MEDLINE | ID: mdl-17877184

RESUMO

OBJECTIVE: To probe into the application value of the height shortening value as the self-examination index of the middle-aged and aged group's osteoporosis or reduced bone mineral density in communities. METHODS: Four communities were selected by cluster sampling at random in Changsha city to be the objects of study, among which women were 45 years old or older and men were 60 years old. Difference and the percentage proportion of the height shortening between the height of the research objects which was measured at their youth and the height measured at this study, were calculated. Mineral density of the anteroposterior lumber spine L2-L4, the left femur neck of each object of study with the DPX-IQ dual energy X-ray (DEXA) were both examined. Results examined by DEXA were recognized as "Golden Standards" and different absolute and relative height shortening values were taken as positive cutoff points. Sensitivity, specificity and Youden's index were calculated to draw the receiver operator characteristic curve in order to get the positive cutoff which was most suitable to both sensitivity and specificity, and to calculate the predicative values of that self-examination method among different groups. RESULTS: 3 cm of height shortened seemed to be the positive cutoff of the self-examination of osteoporosis, and its sensitivity, specificity and Youden's index were 75.4%, 76.7% and 0.521 respectively. 2 cm of height shortened was suggested as the positive cutoff of the self-examination method of reduced bone mineral density, while its sensitivity, specificity and Youden's index were 81.7%, 75.6% and 0.573 respectively. In this self-examination method, positive predicative value was the highest (76.4%; 88.7%) among the women group aged over 65. CONCLUSION: Certain height-shortening value could be used as the rough index of screening osteoporosis of reduced bone mineral density, which set a simple and easy way of self-examination for the middle-aged and elderly population.


Assuntos
Estatura/fisiologia , Osteoporose/epidemiologia , Absorciometria de Fóton , Idoso , Idoso de 80 Anos ou mais , Densidade Óssea , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Osteoporose/fisiopatologia
13.
J Oral Maxillofac Surg ; 65(6): 1109-16, 2007 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-17517293

RESUMO

PURPOSE: This study used a biomechanical model to examine fundamental questions about rigid plate fixation treatment for maxillary Le Fort I fractures. Specifically, we sought to elucidate the principal strain patterns generated in miniplates and bite force transducers secondary to all masticatory forces, as well as the amount of permanent deformations incurred due to these loading forces. MATERIALS AND METHODS: Forty polyurethane synthetic maxillary and mandibular replicas were used to simulate the mandible and maxilla. Ten replicas were controls (group A). The other 30 were divided into 3 groups (10 each), according to the fixation techniques of 3, 2, and 1 miniplates each side (groups B-D), that were osteotomized in the Le Fort I fracture line on the maxilla. Different forces of masseter medial pterygoid, temporalis, and lateral pterygoid muscles were loaded onto the replicas to simulate different functional conditions (anterior incisor, premolar, and molar clenching). Rosette strain gauges were attached at predefined points on the plates and the bite force transducer to compare the stability and bite force of the different fixation methods for maxillary Le Fort I fractures. RESULTS: Statistically significant differences were found for the deformation of the plates among fixation techniques. The order of stability for each technique was: group B greater than group C greater than group D. In regard to bite force, no difference was found between those found with group A and group B (P > .05), whereas the bite forces of groups C and D were less than those of group A (P < .05). CONCLUSIONS: The fixation of 3 miniplates on each side provides sufficient stability and restores the bite force to the level of the intact maxilla. "The ideal fixation" with 2 miniplates on each side restores 90% of the bite force, and there were more deformations of the miniplates with the "ideal fixation" compared to those found with group B. Group D fixation produced the worst effects for the treatment of maxillary Le Fort I fractures with a weak bite force and insufficient stability.


Assuntos
Placas Ósseas , Fixação Interna de Fraturas/instrumentação , Fraturas Maxilares/fisiopatologia , Dente Pré-Molar/fisiopatologia , Fenômenos Biomecânicos , Força de Mordida , Desenho de Equipamento , Humanos , Incisivo/fisiopatologia , Músculo Masseter/fisiopatologia , Fraturas Maxilares/classificação , Modelos Anatômicos , Dente Molar/fisiopatologia , Contração Muscular/fisiologia , Poliuretanos , Músculos Pterigoides/fisiopatologia , Estresse Mecânico , Propriedades de Superfície , Músculo Temporal/fisiopatologia , Transdutores
14.
Hua Xi Kou Qiang Yi Xue Za Zhi ; 24(3): 254-6, 2006 Jun.
Artigo em Chinês | MEDLINE | ID: mdl-16845964

RESUMO

OBJECTIVE: To measure the permeability of human temporomandibular joint (TMJ) disc and cartilage to provide basic parameter for oral biomechanics and tissue engineering, and analyze its mechanisms of pathology and load-release. METHODS: Confined compression method was used to measure the permeability (k value) of four cadavers' TMJs, which were sampled into three parts: disc, condyle and glenoid fossa with different diameters (2 mm, 3 mm and 4 mm). All 128 samples were tested with correspond diameter indenter. RESULTS: Larger the sample diameter was, higher the k value became. The highest k value appeared in the disc while the lowest appeared in glenoid fossa. CONCLUSION: In normal condition, TMJ can suffer huge load by decreasing its permeability. Disc is weakest for the higher permeability, it's easy-damaged region is an initiated factor of TMJ disease.


Assuntos
Cartilagem , Disco da Articulação Temporomandibular , Humanos , Permeabilidade , Engenharia Tecidual
15.
Hua Xi Kou Qiang Yi Xue Za Zhi ; 24(5): 393-6, 2006 Oct.
Artigo em Chinês | MEDLINE | ID: mdl-17315643

RESUMO

OBJECTIVE: To develop a functional biomechanical mandibular model, and to observe the stress distribution of angle-fractured mandible under different rigid internal fixation (RIF) methods. METHODS: A biomechanical model of mandible was built which include the simulative temporal-mandibular joint (TMJ) and was under mechanical loads of masseter, temporalis, medial pterygoid and lateral pterygoid. The different stress pattern was measured by strain gauges. Under the standard mandibular angle fracture, bilateral molar biting and four pairs of muscles loading, the strains were compared to evaluate the stability of one-or two-miniplate fixation. RESULTS: The fixation of miniplate in the lateral oblique line can recover the main stress on the non-fracture side, but it was broken in the fracture side. The tension increased in the lower border of mandibular angle. CONCLUSION: Through the biomechanical study based on the functional mandibular model, only one miniplate fixation in lateral oblique line for mandible angle fracture was insufficient buttressing of the segments, while the additional miniplate in the lower margin can recover the stress pattern and provide more stability.


Assuntos
Fixação Interna de Fraturas , Fraturas Mandibulares , Fenômenos Biomecânicos , Placas Ósseas , Humanos , Mandíbula , Músculo Masseter , Dente Molar
16.
Sichuan Da Xue Xue Bao Yi Xue Ban ; 35(4): 516-9, 2004 Jul.
Artigo em Chinês | MEDLINE | ID: mdl-15291115

RESUMO

OBJECTIVE: To study the stress distribution of intact mandible, especially that of the mandibular angle under different muscle loading and biting condition. METHODS: Develop a more accurate, more objective mandibular model, measure the different stress patterns on the outer surface of the mandible by strain gauges due to different biting sites (INC and ICP) and different loading methods (masseter, temporalis and four pairs of muscles). RESULTS: It was found that the strain in the zone of mandibular angle is more markedly under masseter loading; that the strain in the zone of anterior mandibular ramus is more markedly under temporalis loading; and that the stress in the zone of mentum becomes a tension because of the medial pterygoid under the load of four pairs of muscles. During anterior teeth biting, the stress of mandible angle is larger than that of the bilateral molar biting. When an occlusal load is on the ipsilateral molars, there is a reversal result of the stress direction in the upper line of the mandibular angle. CONCLUSION: Different muscular loading and biting condition can change the stress distribution of the mandible. It is important to develop a functional model of human mandible to study its complex biomechanics behavior.


Assuntos
Força de Mordida , Mandíbula/fisiologia , Músculos da Mastigação/fisiologia , Adulto , Fenômenos Biomecânicos , Oclusão Dentária , Análise do Estresse Dentário , Humanos , Arcada Edêntula , Modelos Biológicos , Estresse Mecânico , Suporte de Carga/fisiologia
17.
Hua Xi Kou Qiang Yi Xue Za Zhi ; 22(3): 252-4, 2004 Jun.
Artigo em Chinês | MEDLINE | ID: mdl-15293479

RESUMO

OBJECTIVE: To introduce cryotreat technique into prosthetic dentistry by testing the tensile properties of CW-H Co-Cr-Mo cast alloy before and after cryotreat and to observe the image changes by SEM to study the mechanism that changes the tensile properties of the alloy. METHODS: 15 CW-H cast alloy were divided into 3 groups, i.e. control group (G1), cryotreated group (G2) and cryotreated plus post-cryogenic treated group (G3). The gauge test technique was employed to test the modulus of elasticity. Then the strength and percentage elongation (PE) were tested. SEM images were used to analyze the mechanism that improved the tension properties of the alloy. RESULTS: For CW-H alloy the strength and the modulus of elasticity of both G2 and G3 were effectively increased but PE effectively decreased than G1. There was no effectively difference between G2 and G3, but G3 was larger than G2. SEM images of G2 and G3 showed that secondary-carbonide separated out all over the alloy. CONCLUSION: The results obtained above suggest that cryotreat is an effective method in enhancing tensile properties of CW-H Co-Cr-Mo cast alloy.


Assuntos
Ligas Dentárias/química , Vitálio/química , Técnica de Fundição Odontológica , Elasticidade , Dureza , Temperatura , Resistência à Tração
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