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Biomedical subjects

Fang Qian

Publications and source records attributed to Fang Qian.

31 records · Page 2Linked to original sources
PubMed2004

Abutment tooth loss in patients with overdentures.

BACKGROUND: Since the 1960s, the use of natural teeth as overdenture abutments has become part of accepted clinical practice. Several longitudinal studies have been conducted, but tooth loss has not been reported to be a significant problem. The aim of this study was to identify the incidence and causes of tooth loss in a prospective cohort study of subjects wearing overdentures. METHODS: The study, conducted between 1973 and 1994, evaluated 273 subjects (62.3 percent male) with a mean age of 59.6 years. RESULTS: Of the 273 subjects with 666 abutments, 74 lost 133 abutments. The most common cause of tooth loss was periodontal disease (29.3 percent) followed by periapical lesions (18.8 percent) and caries (16.5 percent). Through logistic regression, the authors found that subjects who lost teeth were more likely to have medical problems that could cause soft-tissue lesions of the oral mucosa, were less likely to use fluoride daily and were less likely to return for yearly recall visits. The authors found 22 vertical fractures in 17 subjects. Chi2 analysis revealed that overdenture teeth in the maxillary arch that were opposed by natural teeth were more likely to experience vertical fractures. CONCLUSIONS: In a study that followed up some patients for as long as 22 years, the rate of tooth loss was 20.0 percent. Many of these failures could have been prevented if patients had practiced better oral hygiene. CLINICAL IMPLICATIONS: The findings suggest that if a dentist recommends overdenture therapy, the patient needs to be examined regularly to reduce the risk of experiencing caries and periodontal disease. Also, if the abutments are in the maxilla and are opposed by natural teeth, the dentist should consider using thimble crowns to reduce the risk of vertical fractures.

Aged↗
PubMed2003

Evaluation and characteristics of "dropouts" in a longitudinal clinical study.

This paper attempts to identify characteristics of a longitudinal clinical study's "dropout" population (1974-1996) of patients using overdentures. This study included 395 subjects. Dropouts were identified as persons who did not respond to letters or telephone calls after participating in the study for up to 2 years, could not be located, or did not wish to return to the study. Participants (N=273) and Dropouts (N=84) were compared by evaluating a series of factors: sociodemographic, medical, health, and some oral health behaviors. The population was divided into two very similar cohorts for analysis based on years of recruitment: Group I (1974-1984) and Group II (1985-1993). Significant differences were found between them, including vision problems and risk of oral soft tissue problems related to medical diagnosis. Dropouts were significantly younger than Participants, had fewer hearing and vision problems, tended to brush their teeth more often and were more likely to use daily topical fluoride in their overdentures. The differences between the Dropouts and the Participants may be that younger persons are more mobile and have fewer vision and hearing problems, but this does not help predict their commitment to a study. Health behaviors such as brushing overdenture abutments or fluoride use may be more predictable but are harder to assess until persons have been study participants for some time.

Adolescent↗
PubMed2003

Comparison of soluble decoy IgG fusion proteins of BAFF-R and BCMA as antagonists for BAFF.

BAFF is considered a therapeutic target because dysregulated production of BAFF can induce systemic lupus erythematosus-like phenotype in mice, and elevated levels of BAFF are associated with disease severity in systemic lupus erythematosus and rheumatoid arthritis patients. Fc fusion decoy receptors, BCMA-Fc and BAFF-R-Fc, are therapeutic candidates for blocking BAFF. While studying their interactions with BAFF, we found that BAFF-R-Fc is more effective than BCMA-Fc for blocking BAFF binding to its receptors. We also found that a trimeric BAFF can bind more than one BAFF-R-Fc but only one BCMA-Fc. Moreover, we show that, in contrast to monovalent BAFF-R-Fc, monovalent BCMA does not form stable complexes with BAFF. Differences in their interaction with BAFF predict BAFF-R-Fc would be a better inhibitor. Indeed, we show BAFF-R-Fc is 10-fold more efficacious than BCMA-Fc for blocking BAFF-induced B cell proliferation in vitro and for blocking BAFF-mediated survival of mouse splenic B lymphocytes in vivo.

Animals↗
PubMed2003

Endocrine and metabolic responses to long-term monotherapy with the antiepileptic drug valproate in the normally cycling rhesus monkey.

An association between epilepsy and reproductive disturbances with an apparent increase in a polycystic ovarian syndrome (PCOS) has been reported. Whether this association can be attributed to epilepsy itself or is related to antiepileptic drug therapy, in particular valproate (VPA), remains controversial. We studied effects of a long-term VPA treatment on cycling monkeys, postulating that, if VPA monotherapy were to promote abnormal endocrine and metabolic parameters that are characteristic of PCOS, changes in cyclicity would be readily demonstrated. After a 2-month control, a 12- to 15-month VPA monotherapy was initiated in 7 regularly cycling rhesus monkeys. Overall mean levels of VPA were 88.7 +/- 4.0 (SE) microg/ml. Mean body weight increased progressively during VPA treatment from 8.5 +/- 0.5 kg before treatment to 9.6 +/- 0.7 kg in the last week of treatment (P < 0.05). Monkeys continued to have regular ovulatory menstrual cycles throughout VPA monotherapy. Length of the cycles was 28 +/- 0.58 d in control and 28.4 +/- 1.18 d in the last 3 months of VPA treatment. Follicular and luteal lengths and peak preovulatory estradiol and integrated luteal progesterone levels did not differ between control and treatment. Ovaries from VPA-treated monkeys showed histological evidence of ovulation, and none had characteristic features of PCOS. Endocrine PCOS markers, such as increased early follicular LH/FSH ratio and androgen levels were not different in control and VPA treatment cycles. LH and 17-hydroxyprogesterone responses to GnRH agonist challenges and the insulin response to glucose tolerance tests were similar in control and VPA groups. Lipid profiles were not affected by VPA treatment. The data indicate that a 12- to 15-month therapeutic exposure to VPA does not induce cyclic hormonal or morphological ovarian abnormalities or characteristics of the PCOS when administered to nonepileptic normally cycling nonhuman primates.

Animals↗
PubMed2002

Catalytic oxidative carbonylation of primary and secondary diamines to cyclic ureas. Optimization and substituent studies.

W(CO)(6)-catalyzed oxidative carbonylation of 1,3-propanediamine to the corresponding urea has been examined under a variety of conditions. Following optimization, the Thorpe-Ingold effect on ring closure was studied using 2,2-dialkyl-1,3-propanediamines. For the 2,2-dimethyl- and 2,2-dibutyl-1,3-propanediamines, the yields were increased significantly as compared to that of the unsubstituted case. The eight-membered cyclic urea 5-butyl-5-ethyl-1,3-diazepan-2-one (5f) was formed in 38% yield, while only trace amounts of the cyclic urea were produced from the parent 1,5-pentanediamine. In a study of secondary diamines, yields from the carbonylation of N,N'-dialkyl-2,2-dimethyl-1,3-propanediamines were lower than those obtained from the primary diamines. The main byproducts from secondary diamines were tetrahydropyrimidine derivatives formed from a competitive reaction of the substrate with the oxidant and base.

Journal Article↗
PubMed2002

Crystal structure of extracellular human BAFF, a TNF family member that stimulates B lymphocytes.

B cell activating factor (BAFF), a ligand belonging to the tumor necrosis factor (TNF) family, plays a critical role in regulating survival and activation of peripheral B cell populations and has been associated with autoimmune disease. BAFF is known to interact with three receptors, BCMA, TACI and BAFF-R, that have distant similarities with other receptors of the TNF family. We have determined the crystal structure of the TNF-homologous domain of BAFF at 2.8 A resolution. The structure reveals significant differences when compared to other TNF family members, including an unusually long D-E loop that participates in the formation of a deep, concave and negatively charged region in the putative receptor binding site. The BAFF structure was further used to generate a homology model of APRIL, a closely related TNF family ligand that also binds to BCMA and TACI, but not BAFF-R. Analysis of the putative receptor binding sites of BAFF and APRIL suggests that differences in the D-E loop structure and electrostatic surface potentials may be important for determining binding specificities for BCMA, TACI and BAFF-R.

Amino Acid Sequence↗
PubMed2002

Completely aborted uterine leiomyosarcoma in the puerperium.

A patient passed a large tissue mass at home on postpartum day 1. Pathologic examination demonstrated leiomyosarcoma. A total abdominal hysterectomy was performed, which demonstrated residual disease. All tissue passed in the puerperium should be evaluated to ensure that significant pathologic conditions are not overlooked. Conservative management of leiomyosarcomas is controversial.

Adult↗
PubMed2002

Phosphorylation of the receptor for PTH and PTHrP is required for internalization and regulates receptor signaling.

We have previously shown that agonist-dependent phosphorylation of the PTH/PTHrP receptor occurs on its carboxyl-terminal tail. Using site-directed mutagenesis, phosphopeptide mapping, and direct sequencing of cyanogen bromide-cleaved fragments of phosphoreceptors, we report here that PTH-dependent phosphorylation occurs on the serine residues at positions 491, 492, 493, 495, 501, and 504, and that the serine residue at position 489 is required for phosphorylation. When these seven sites were mutated to alanine residues, the mutant receptor was no longer phosphorylated after PTH stimulation. The phosphorylation-deficient receptor, stably expressed in LLCPK-1 cells, was impaired in PTH-dependent internalization and showed an increased sensitivity to PTH stimulation; the EC(50) for PTH-stimulated cAMP accumulation was decreased by 7-fold. Furthermore, PTH stimulation of the phosphorylation-deficient PTH/PTHrP receptor caused a sustained elevation in intracellular cAMP levels. These data indicate that agonist-dependent phosphorylation of the PTH/PTHrP receptor plays an important role in receptor function.

Amino Acid Sequence↗
PubMedDate not supplied

Relationship between nanoleakage and microtensile bond strength at the resin-dentin interface.

To evaluate the correlation between microtensile dentin bond strength (microTBS) and silver ion penetration, two total-etch 3-step and one self-etch 2-step system were investigated. OptiBond FL adhesive was applied to flat occlusal dentin on six non-carious human molars, and a resin composite "crown" was formed in 2 mm increments. After 24-hour water storage, the teeth were sectioned with a low-speed diamond saw to obtain four-square sticks (approximately 2 mm X 2 mm) per tooth. Cylindrical tensile test specimens were formed with an 0.5 mm2 cross-sectional area. Nail varnish was applied to the dentin within 0.5-1.0 mm of the interface before immersing in 50% silver nitrate for 15 minutes. Following silver fixation, tensile testing was performed in a Zwick UTM at 1 mm/minute using a passive gripping fixture to obtain 72-hour microTBS [23.9 MPa]. The percentage area of silver penetration was measured on debonded specimens using light microscopy and Image-Pro Plus Software [89%]. The procedures were repeated using Scotchbond Multi-Purpose Plus [microTBS = 27.8 MPa; nanoleakage = 67%] and Clearfil SE bond [microTBS = 36 MPa; nanoleakage = 55%]. No significant correlation between microtensile bond strength and nanoleakage was found for all systems. A weak-to-moderate negative relationship was found between microTBS and nanoleakage for OptiBond FL (Spearman r = -0.3844). No correlation was found for the remaining adhesive systems. The correlation between these two common laboratory measurements appears to be adhesive-system dependent.

Acid Etching, Dental↗
PubMedDate not supplied

The effect of chronic methylphenidate administration on tooth maturation in a sample of Caucasian children.

PURPOSE: Over the past 3 decades, methylphenidate hydrochloride (MH; brand names are Concerta, Metadate, Ritalin) has been increasingly prescribed for children and adolescents diagnosed with attention deficit hyperactivity disorder (ADHD). Previous studies have demonstrated growth suppression with chronic MH administration in children and adolescents and an association of delayed dental maturation with delayed growth. It was hypothesized that, perhaps with MH use, there is a concurrent retardation in dental development. Although there has been an abundance of research done on its effect on skeletal development, no one has examined MH's possible effects on the oral cavity-particularly dental development. The purpose of this study was to evaluate dental maturation in children who had taken MH chronically. METHODS: Forty-two Caucasian children between the ages of 7 and 15.9 years who had taken MH for a minimum of 2 years were enrolled. Their dental development was compared to that of a contemporary age- and gender-matched control sample using the Demirjian method to assess dental age. RESULTS: It was found that this study's population of children, who ingested an average dose of 30 mg of MH daily for a mean duration of 54 months, showed no delay in dental maturation. CONCLUSIONS: It is concluded that, for these amounts of MH exposure, there is no effect on dental maturation.

Adolescent↗
PubMedDate not supplied

Survey of Iowa general dentists regarding the age 1 dental visit.

PURPOSE: The purpose of this study was to assess Iowa general dentists regarding the age 1 dental visit. METHODS: A 15-item survey was mailed to 1,521 licensed dentists to address their knowledge, attitudes, and behavior regarding the age 1 dental visit. Chi-square statistics and logistic regression models were used to analyze data. RESULTS: Seven hundred fifteen (47%) useable surveys were returned from 2 mailings. Five hundred forty (76%) general dentists were familiar with the American Academy of Pediatric Dentistry (AAPD) age 1 dental visit recommendation. Most reported obtaining this information through continuing education (37%). Eleven percent believed the first dental visit should occur between 0 and 11 months of age, and 66% reported seeing children younger than 2. "Prefer to refer infants to a pediatric dentist" (20%) was the most common reason for not seeing children 0 to 23 months old. Bivariate and multivariate logistic regression analyses indicated that dentists who believed children should have their first dental visit at 0 to 23 months and those willing to see children at age 0 to 23 months were younger, more recent graduates, more likely to be female, aware of the AAPD recommendations, and were already seeing children 0 to 23 months. CONCLUSIONS: The majority of Iowa general dentists are aware of the AAPD age 1 dental visit recommendation.

Adult↗
PubMedDate not supplied

Child temperament and risk factors for early childhood caries.

PURPOSE: The purpose of this study was to determine if a relationship existed between a mother's perception of her child's temperament and the child's risk factors for early childhood caries (ECC). METHODS: Data was collected from 629 records of children ages 0 to 4 who were patients of the University of Iowa's Infant Oral Health Program. Data included: (1) maternal report of child's temperament; (2) knowledge of ECC; (3) dietary and oral hygiene habits; and (4) clinical evidence of cavitated and noncavitated lesions and visible plaque on maxillary incisors. Chi-square tests and logistic regression models were used to analyze the data. RESULTS: Bivariate analyses showed that children reported as "easy" were more likely to: (1) be younger (P=.001); (2) be breast-fed to sleep (P=.046); (3) be breast-fed throughout the night (P=.012); and (4) have their teeth brushed twice daily (P=.006). Children reported as "difficult" were more likely to: (1) be bottle-fed to sleep (P=.002); and (2) have noncavitated lesions (P=.044). Final logistic regression analysis indicated that children perceived as "easy" were more likely to breast-fed throughout the night (odds ratio [OR]= 1.77; P=.016), while those perceived as "difficult" were more likely to be bottle-fed to sleep (OR=1.74; P=.016). CONCLUSIONS: Maternal reported child temperament may be related to important early childhood caries risk factors.

Age Factors↗