Biomedical subjects

Xiaoming Li

Publications and source records attributed to Xiaoming Li.

At least 19 recordsLinked to original sources

PubMed2026

Plasma proteomic profiling characterizes candidate biomarkers of perimesencephalic non-aneurysmal subarachnoid hemorrhage.

OBJECT: This study aims to explore the plasma proteomic profiles of angiographically confirmed pmSAH and aSAH, and to identify candidate protein biomarkers for discriminating these subtypes on a biological level. METHODS: The differentially abundant proteins of plasma samples from patients with pmSAH (n = 30) and aSAH (n = 30) were analyzed by data-independent acquisition proteomics, and candidate biomarkers were screened. RESULTS: 291 candidate biomarkers were obtained that could be used to distinguish pmSAH patients from aSAH patients, among which 76 were upregulated and 215 were downregulated in pmSAH. Subsequently, the 10 candidate biomarkers were validated by enzyme-linked immunosorbent assay in a validation cohort of 72 subjects. ORM1, ORM2, HP and NMNAT1 were specifically down-regulated in the pmSAH group, while ANP32A was specifically up-regulated in the pmSAH group. FGL2 was specifically up-regulated in the aSAH group. The combined model of ORM2, HP and ANP32A had the best discriminative power (AUC = 0.880). CONCLUSIONS: This study identified ORM2, HP, and ANP32A as candidate biomarkers reflecting biological differences between pmSAH and aSAH. SIGNIFICANCE: Although some proteomic studies have analyzed aneurysmal subarachnoid hemorrhage, to date, there have been no reports on the circulating proteomic analysis of pmSAH. Comparative analysis of the circulating proteomic differences between pmSAH and aSAH may not only help understand the causes of pmSAH, but also contribute to a deeper understanding of mechanisms showing how pmSAH differs from the formation and rupture mechanisms of intracranial aneurysms.

Humans↗

PubMed2026

Metagenomic insights into microbial drivers of organic micropollutant removal in wastewater-impacted riverbank filtration.

Organic micropollutants (OMPs) in wastewater treatment plant (WWTP) effluent pose persistent risks to aquatic ecosystems and drinking water sources. Riverbank filtration (RBF) is a nature-based treatment process, yet the compartment-specific roles of riverbed sediment and downstream soil in OMP attenuation remain poorly resolved under wastewater-impacted conditions. Here, we combined targeted chemical analysis, OMP property compilation, shotgun metagenomics, EnviPath-based biotransformation annotation, and exploratory network analysis to investigate OMP attenuation in a laboratory-scale RBF system treating real WWTP effluent for 10 months. Nineteen OMPs were monitored along a sequential sediment-soil filtration pathway. Sediment preferentially attenuated hydrophilic or charged compounds, including lidocaine, amantadine, and sotalol, whereas soil contributed more strongly to the attenuation of naproxen, atenolol, and losartan. Metagenomic profiling revealed distinct microbial communities and functional gene repertoires between sediment and soil after long-term operation. Sediment harbored higher relative abundances of genes associated with oxidative xenobiotic transformation, including cytochrome P450-related enzymes, demethylases, dehydrogenases, oxidases, and aromatic compound degradation pathways. An exploratory Spearman network further identified associations among microbial genera, EnviPath-annotated candidate biotransformation genes, and OMP removal rates, including 17 KO-OMP links supported by both correlation and pathway annotation. These findings indicate that sediment and soil develop complementary microbial functional potentials that may support compound-specific OMP attenuation. This study provides a mechanistic basis for optimizing sediment-soil configurations in wastewater-impacted RBF systems and for improving nature-based barriers against diverse OMP mixtures.

Wastewater↗

PubMed2007

HIV-related risk behaviors and history of sexually transmitted diseases among male migrants who patronize commercial sex in China.

BACKGROUND AND OBJECTIVE: Men who pay for sexual services are at increased risk for HIV/sexually transmitted disease. Data on the sociodemographic and behavioral characteristics of such men in China are limited. STUDY DESIGN: Two cross-sectional surveys, using similar instruments, were completed among Chinese migrants in Beijing, Shanghai, and Nanjing in 2002. A total of 1304 rural-to-urban migrant men from community settings ("community sample") and 465 migrant men attending sexually transmitted disease clinics ("STD clinic sample") were included in the current study. RESULTS: Ten percent of men in the community sample and 32.7% of men in the STD clinic sample reported having ever paid for sex. Nearly 20% of clients from the community sample and 60% of clients from the STD clinic sample reported a history of STDs. For both the community and STD clinic samples, working at industrial or construction sectors, multiple sexual partners, regular sex partner having sex with others, and a history of drug use were associated with being a male client. In addition, perceived peer sexual risk and perceived vulnerability to STD were associated with being a male client in the community sample, and a history of STD and being tested for STD/HIV were associated with being a male client in the STD sample. CONCLUSION: Male migrants who paid for sex in China were vulnerable to HIV/STDs. HIV prevention efforts should target young migrant men who work at factory and construction sectors. STD clinics may be important sites for outreach and intervention efforts among male clients.

Adult↗

PubMed2006

Targeted therapy with a Salmonella typhimurium leucine-arginine auxotroph cures orthotopic human breast tumors in nude mice.

We report here a modified auxotrophic strain of Salmonella typhimurium that can target and cure breast tumors in orthotopic mouse models. We have previously reported development of a genetically modified strain of S. typhimurium, selected for prostate tumor targeting and therapy in vivo. The strain, termed S. typhimurium A1, selectively grew in prostate tumors in xenograft models causing tumor regression. In contrast, normal tissue was cleared of these bacteria even in immunodeficient athymic mice with no apparent side effects. A1 is auxotrophic (leucine-arginine dependent) but apparently receives sufficient nutritional support only from tumor tissue. The ability to grow in viable tumor tissue may account, in part, for the unique antitumor efficacy of the strain. In the present report, to increase tumor-targeting capability of A1, the strain was reisolated after infection of a human colon tumor growing in nude mice. The tumor-isolated strain, termed A1-R, had increased targeting for tumor cells in vivo as well as in vitro compared with A1. Treatment with A1-R resulted in highly effective tumor targeting, including viable tumor tissue and significant tumor shrinkage in mice with s.c. or orthotopic human breast cancer xerographs. Survival of the treated animals was significantly prolonged. Forty percent of treated mice were cured completely and survived as long as non-tumor-bearing mice. These results suggest that amino acid auxotrophic virulent bacteria, which selectively infect and attack viable tumor tissue, are a promising approach to cancer therapy.

Animals↗

PubMed2006

Parental awareness of adolescent risk involvement: implications of overestimates and underestimates.

PURPOSE: To explore: 1) parent-adolescent discrepancies on adolescent risk involvement; 2) factors related to parental overestimates and/or underestimates of specific adolescent risk behaviors; and 3) the association of parental overestimates and/or underestimates at baseline with subsequent adolescent risk involvement. METHODS: 754 African American parent-adolescent dyads were recruited from 35 low-income urban communities in Baltimore, Maryland. Parent-adolescent discordance (overestimates and underestimates) regarding adolescent involvement in risk behaviors in three areas (sex, substance use, and violence) were assessed. Multiple logistic regression models were performed to examine the association of parental overestimates or underestimates with subsequent adolescent risk involvement, and to explore potential factors related to parental overestimates and underestimates of each behavior. RESULTS: Percentage of parental overestimation and underestimation ranged from 3% to 24% and 53% to 86%, respectively, for targeted behaviors. Parents reporting higher levels of parental monitoring and open communication were less likely to overestimate, and more likely to underestimate adolescent risk involvement. Parents of adolescents who perceived themselves as better than average in school performance and who participated in religious services were more likely to underestimate adolescents' substance use and sex. Parents of older adolescents overestimated adolescents' sexual experience. Parental overestimation at baseline generally predicted subsequent increased risk of adolescents engaging in these behaviors. Conversely, parental underestimation was associated with subsequent decreased adolescent risk involvement. CONCLUSIONS: Parental underestimation and overestimation of adolescent risk involvement have implications for subsequent adolescent risk involvement. The protective association of parental underestimation and the adverse association of parental overestimation on subsequent adolescent risk involvement indicate that parenting interventions should advance beyond simply improving parent-adolescent concordance on risk behavior.

Adolescent↗

PubMed2006

Analysis of incomplete longitudinal binary data using multiple imputation.

We propose a propensity score-based multiple imputation (MI) method to tackle incomplete missing data resulting from drop-outs and/or intermittent skipped visits in longitudinal clinical trials with binary responses. The estimation and inferential properties of the proposed method are contrasted via simulation with those of the commonly used complete-case (CC) and generalized estimating equations (GEE) methods. Three key results are noted. First, if data are missing completely at random, MI can be notably more efficient than the CC and GEE methods. Second, with small samples, GEE often fails due to 'convergence problems', but MI is free of that problem. Finally, if the data are missing at random, while the CC and GEE methods yield results with moderate to large bias, MI generally yields results with negligible bias. A numerical example with real data is provided for illustration.

Clinical Trials as Topic↗

PubMed2006

Mutation in TRMU related to transfer RNA modification modulates the phenotypic expression of the deafness-associated mitochondrial 12S ribosomal RNA mutations.

The human mitochondrial 12S ribosomal RNA (rRNA) A1555G mutation has been associated with aminoglycoside-induced and nonsyndromic deafness in many families worldwide. Our previous investigation revealed that the A1555G mutation is a primary factor underlying the development of deafness but is not sufficient to produce a deafness phenotype. However, it has been proposed that nuclear-modifier genes modulate the phenotypic manifestation of the A1555G mutation. Here, we identified the nuclear-modifier gene TRMU, which encodes a highly conserved mitochondrial protein related to transfer RNA (tRNA) modification. Genotyping analysis of TRMU in 613 subjects from 1 Arab-Israeli kindred, 210 European (Italian pedigrees and Spanish pedigrees) families, and 31 Chinese pedigrees carrying the A1555G or the C1494T mutation revealed a missense mutation (G28T) altering an invariant amino acid residue (A10S) in the evolutionarily conserved N-terminal region of the TRMU protein. Interestingly, all 18 Arab-Israeli/Italian-Spanish matrilineal relatives carrying both the TRMU A10S and 12S rRNA A1555G mutations exhibited prelingual profound deafness. Functional analysis showed that this mutation did not affect importation of TRMU precursors into mitochondria. However, the homozygous A10S mutation leads to a marked failure in mitochondrial tRNA metabolisms, specifically reducing the steady-state levels of mitochondrial tRNA. As a consequence, these defects contribute to the impairment of mitochondrial-protein synthesis. Resultant biochemical defects aggravate the mitochondrial dysfunction associated with the A1555G mutation, exceeding the threshold for expressing the deafness phenotype. These findings indicate that the mutated TRMU, acting as a modifier factor, modulates the phenotypic manifestation of the deafness-associated 12S rRNA mutations.

Amino Acid Sequence↗

PubMed2006

Chemical characteristics and cytocompatibility of collagen-based scaffold reinforced by chitin fibers for bone tissue engineering.

Chitin is a kind of seemly material to match PLLA for a scaffold, which may create an appropriate environment for the regeneration of tissues. In this study, we prepared and evaluated a new nano-hydroxyapatite/collagen/PLLA (nHACP) scaffold reinforced by chitin fibers for bone-tissue engineering. The chitin fibers were crosslinked with PLLA by dicyclohexylcarbodimide (DCC). The chemical characteristics were evaluated by Fourier transformed infrared (FTIR) spectroscopy and X-ray photoelectron spectroscopy (XPS). The mechanical strength was measured by compressive tests. The fibers, crosslinked with PLLA, could enhance the compressive strength of the scaffold about four times. Human marrow mesenchymal stem cells (MSCs) culture showed that the reinforced nHACP scaffolds were more cytocompatible than that without reinforcement. The crosslinks hardly affected the cytocompatibility of the reinforced scaffolds. The results suggested that the reinforced scaffolds (DCC crosslinked) might be a promising candidate for bone-tissue engineering.

Animals↗

PubMed2006

Rural-to-urban migrants and the HIV epidemic in China.

China is the next probable frontier for the global HIV epidemic. Central to this anticipated growth of the epidemic is the nation's new and growing population of rural-to-urban migrants. Although there are an estimated 120 million migrants, little information is available about their social and cultural context of their lives in urban areas and their HIV-related perceptions and behaviors. On the basis of the in-depth individual interviews conducted among 90 rural-to-urban migrants in 2 major Chinese cities, Beijing and Nanjing, this qualitative study was designed to explore these issues with a particular focus on their relevance to sexual transmission of HIV. The findings suggest an urgent need for HIV/STI prevention programs that address the cultural, social, and economic constraints facing the migrant population in China.

Adult↗

PubMed2006

Early reversible ischemia of femoral head epiphysis in piglets on gadolinium-enhanced MRI: an experimental study.

The purpose of this study is to demonstrate if Gadolinium-enhanced MRI can detect early reversible ischemia of the femoral head epiphysis caused by hip hyper-abduction in piglets. Between 3 and 6 h consistent hyper-abduction, gadolinium-enhanced MRI was performed in 20 femoral heads of 10 piglets. After completion of MRI scan, the piglets were allowed to ambulate freely for 1 or 7 days and re-imaged. The enhanced-MRI results of epiphyseal and physeal cartilage and the secondary center of ossification were observed. MRI appearances and histological findings were compared. On Gadolinium-enhanced MRI, decreased or absent enhancement was seen in 14 cartilaginous epiphyses of all 20 femoral heads. Reperfusion was completed in 10 of 14 femoral heads after one day of ambulation and in the rest 4 after 7 days of ambulation. Gadolinium-enhanced MRI can identify early ischemia and its reversal of the capital femoral epiphysis induced by hip hyper-abduction.

Animals↗

PubMed2006

Trial of an urban adolescent sexual risk-reduction intervention for rural youth: a promising but imperfect fit.

PURPOSE: The purpose of this study was to assess the effectiveness of Focus on Kids (FOK), a sexual risk reduction intervention, shown to be effective among urban, African-American adolescents living in communities with high rates of sexually transmitted diseases, in reducing sexual risk behaviors among rural, white adolescents living in communities with low rates of sexually transmitted diseases. The subjects were 1,131 youth ages 12 to 16 years from 12 rural counties in West Virginia. METHOD: The study was a randomized, controlled, longitudinal trial of a theory-based prevention intervention. Outcomes included self-reported sexual behaviors and perceptions assessed at baseline and at 3, 6, and 9 months after intervention. RESULTS: At baseline, 21% of youth were sexually experienced; 80% reported using a condom at last episode of intercourse. Rates of behaviors did not differ based on intervention assignment (FOK vs control group) after adjusting for baseline differences at any follow-up period among the full cohort or among the subset of youth who completed the intervention curriculum to which they were assigned. Perceptions of risk and protective behaviors were positively influenced by FOK at 3, 6, and 9 months in a fashion consistent with the guiding model of behavioral change and the FOK curriculum. CONCLUSIONS: Consistent with previous studies of FOK in high-risk urban areas, some perceptions were positively altered by FOK in these rural areas, although many of these changes did not persist through 9 months of follow-up. In contrast to previous studies, self-reported sexual risk behaviors did not decrease among FOK youth. FOK was not associated with any increases in sexual risk behaviors.

Adolescent↗

PubMed2006

Perceived smoking norms, socioenvironmental factors, personal attitudes and adolescent smoking in China: a mediation analysis with longitudinal data.

PURPOSE: To gather information on inter-relationships among risk factors affecting adolescent smoking for tobacco control in China, the world's largest tobacco producer and consumer. METHOD: Longitudinal data were collected six months apart in 2003 from 813 students in grades 7, 8, 10, and 11 from two schools in Beijing, China. Linear regression was used to assess both the direct effect from predictor variables (smoking among influential others, pro-tobacco media, and attitudes toward smoking) on cigarette use and the indirect effect mediated through the perceived smoking norms (percentage of smokers among peers). RESULTS: Among the 803 subjects (mean age of 15.5 years, SD = 1.7; 52.1% female), 18.3% of males and 1.7% of females smoked in the past 30 days. Smoking among influential others (best friends, father, mother, male teachers, female teachers, and adults in general) and perceived positive psychological and social rewards from smoking at baseline were associated with number of cigarettes smoked at follow-up, whereas exposure to pro-tobacco media was not significantly associated with smoking. The mediated effect was greater for adult smoking (70% to 90%) than for best friend smoking (11% to 16%). CONCLUSION: Smoking among influential others and attitudes toward smoking influence adolescent smoking both directly and indirectly. The finding of the indirect effect mediated through perceived smoking norms expands our knowledge on smoking etiology. Effective adolescent smoking intervention programs in China need to include a component targeting adult smoking to reduce perceived smoking norms.

Adolescent↗

PubMed2006

Age of sexual initiation and HIV-related behaviours: application of survival analysis.

Previous studies have consistently suggested positive associations between early sexual initiation and subsequent risky sexual behaviours, HIV/STD infection, adolescent pregnancy and substance use. In the present study, survival curves for rural-to-urban migrants in China with and without HIV-related behaviours were analysed to determine (1) the risk of initiating sex at each ageand (2) the association between sexual initiation and HIV-related behaviours.

Adult↗

PubMed2006

Stay away from tobacco: a pilot trial of a school-based adolescent smoking prevention program in Beijing, China.

A quasiexperimental study was conducted to explore the efficacy of the program Stay Away from Tobacco (SAFT). Participants-from 11 classes with 381 students total in grades 7, 8, 10, and 11-were assigned by class to three groups (intervention group T with school teachers delivering the program, intervention group R with researchers delivering the program, and comparison group C). Data were collected at baseline, immediately after the intervention, and 6 months after the intervention. Self-reported smoking was the outcome measure. The 30-day smoking prevalence in group C increased from 4% at baseline to 10% at the 6-month follow-up, whereas this rate declined from 11% to 6% in group T, and from 9% to 1% in group R. For group T, the odds ratio (for 30-day smoking) and the regression coefficient (for indexed number of cigarettes smoked) assessing interactions between intervention and time were 0.20 (p < .001) and -.1605 (p < .05), respectively. The same statistics for group R were 0.09 (p < .001) and -.2406 (p < .01), respectively. The predicted smoking rate declined by 19% from baseline to 6-month follow-up in group T (11.5% vs. 9.3%), and the same rate declined by 26% in group R (11.1% vs. 8.2%). The results from this pilot trial suggest that SAFT can reduce cigarette smoking among middle and high school students through its effect on improving these students' refusal skills and changing their perceived mental and physical values from smoking. A full-scale evaluation is recommended.

Adolescent↗

PubMed2006

Understanding interrelationships among HIV-related stigma, concern about HIV infection, and intent to disclose HIV serostatus: a pretest-posttest study in a rural area of eastern China.

The objective of the study was to examine the interrelationships among HIV-related public and felt stigma, worry of HIV infection, HIV/AIDS knowledge and intention to disclose HIV testing results in a rural area of China, where HIV spread among former commercial blood donors. A one-group pretest-posttest study was conducted among 605 marriage license applicants. The following relationships showed statistical significance in path analysis: (1) HIV/AIDS knowledge --> worry [beta (Standardized coefficient) = -0.39]; (2) worry --> public stigma (beta = 0.27); (3) public stigma --> felt stigma (beta = 0.22); and (4) felt stigma --> intention to disclosure (beta = -0.20). Separate path analyses for males and females generated similar association patterns. HIV counseling reduced perceived worry but exerted little impact on HIV-related stigma and the intention. The pathway from a lack of HIV/AIDS knowledge to increased stigma and to decreased intention to disclose one's serostatus is particularly policy relevant as decreased intention to disclosure may be related to continuing practice of HIV risk behaviors. The findings demonstrate interventions aiming at the reduction of stigma should be targeted at both the individual and community levels.

Adult↗

PubMed2006

Men who have sex with men and human immunodeficiency virus/sexually transmitted disease control in China.

OBJECTIVES: To address the role of men who have sex with men (MSM) in the human immunodeficiency virus (HIV)/sexually transmitted disease (STD) epidemic in China. GOAL: To explore the prevalence of risky sexual behaviors and the existing prevention efforts among men who have sex with men (MSM) in China. STUDY DESIGN: Review of behavioral and STD/HIV prevention studies addressing MSM in China. RESULTS: Sexual risk behaviors including unprotected group sex, anal sex, casual sex, and commercial sex were prevalent among Chinese MSM. Many Chinese MSM also engaged in unprotected sex with both men and women. Most MSM either did not perceive that they were at risk of HIV/AIDS or underestimated their risk of infection. Surveillance and intervention research among these men are still in the preliminary stages. CONCLUSIONS: Chinese MSM are at risk for HIV/STD infection and potential transmission of HIV to the general population. In addition to sexual risk reduction among MSM, reduction of homosexuality- related stigma should be part of effective intervention efforts. Volunteers from the MSM community and health care workers in primary health care system may serve as valuable resources for HIV/STD prevention and control among MSM.

China↗

PubMed2006

A comparison of eight methods for the dual-endpoint evaluation of efficacy in a proof-of-concept HIV vaccine trial.

To support the design of the world's first proof-of-concept (POC) efficacy trial of a cell-mediated immunity-based HIV vaccine, we evaluate eight methods for testing the composite null hypothesis of no-vaccine effect on either the incidence of HIV infection or the viral load set point among those infected, relative to placebo. The first two methods use a single test applied to the actual values or ranks of a burden-of-illness (BOI) outcome that combines the infection and viral load endpoints. The other six methods combine separate tests for the two endpoints using unweighted or weighted versions of the two-part z, Simes', and Fisher's methods. Based on extensive simulations that were used to design the landmark POC trial, the BOI methods are shown to have generally low power for rejecting the composite null hypothesis (and hence advancing the vaccine to a subsequent large-scale efficacy trial). The unweighted Simes' and Fisher's combination methods perform best overall. Importantly, this conclusion holds even after the test for the viral load component is adjusted for bias that can be introduced by conditioning on a postrandomization event (HIV infection). The adjustment is derived using a selection bias model based on the principal stratification framework of causal inference.

AIDS Vaccines↗

PubMed2006

Gadolinium-enhanced MR images of the growing piglet skeleton: ionic versus nonionic contrast agent.

PURPOSE: To determine whether there are differences in the distribution of ionic and nonionic gadolinium-based contrast agents by evaluating contrast enhancement of the physis, epiphyseal cartilage, secondary ossification center, and metaphysis in the knees of normal piglets. MATERIALS AND METHODS: Following approval from the Subcommittee on Research Animal Care, knees of 12 3-week-old piglets were imaged at 3-T magnetic resonance (MR) imaging after intravenous injection of gadoteridol (nonionic contrast agent; n = 6) or gadopentetate dimeglumine (ionic contrast agent; n = 6). Early enhancement evaluation with gradient-echo MR imaging was quantified and compared (Student t test) by means of enhancement ratios. Distribution of contrast material was assessed and compared (Student t test) by means of T1 measurements obtained before and at three 15-minute intervals after contrast agent administration. The relative visibility of the physis, epiphyseal cartilage, secondary ossification center, and metaphysis was qualitatively assessed by two observers and compared (Wilcoxon signed rank test). Differences in matrix content and cellularity that might explain the imaging findings were studied at histologic evaluation. RESULTS: Enhancement ratios were significantly higher for gadoteridol than for gadopentetate dimeglumine in the physis, epiphyseal cartilage, and secondary ossification center (P < .05). After contrast agent administration, T1 values decreased sharply for both agents-but more so for gadoteridol. Additionally, there was less variability in T1 values across structures with this contrast agent. Gadoteridol resulted in greater visibility of the physis, while gadopentetate dimeglumine resulted in greater contrast between the physis and metaphysis (P < .05). CONCLUSION: The results suggest different roles for the two gadolinium-based contrast agents: The nonionic contrast medium is better suited for evaluating perfusion and anatomic definition in the immature skeleton, while the ionic contrast medium is better for evaluating cartilage fixed-charge density.

Animals↗