Biomedical subjects

L Y Song

Publications and source records attributed to L Y Song.

At least 19 recordsLinked to original sources

PubMed2006

Symbiosis of Mycoplasma hominis in Trichomonas vaginalis may link metronidazole resistance in vitro.

Fourteen of 28 Trichomonas vaginalis isolates collected from patients in Guangzhou, China from 2003 to 2004 were found to be naturally infected with Mycoplasma hominis, as determined by PCR using specific primers. In vitro metronidazole sensitivity assay of the 28 isolates revealed four displaying low susceptibility [minimum lethal concentration (MLC)= approximately 13-25 microg/ml] and another four displaying high resistance (MLC=50-100 microg/ml). The overwhelming majority of these resistant isolates (7/8) were mycoplasma-infected. The mean of MLCs of mycoplasma-infected isolates is approximately 10-fold higher than the mean of noninfected isolates (p=0.029). Sequence analyses of PCR-amplified small subunit-large subunit rRNA interspacer regions (ITS1/5.8S/ITS2) revealed that 23 of the 28 samples are identical, the remaining five being separable into two groups, each with a single point mutation. These internal transcribed spacer sequence variants are associated neither with mycoplasma infection nor with drug resistance. In contrast, random amplified polymorphic DNA analyses of DNAs using 10 different primers showed that the drug-resistant isolates are clustered together in association with mycoplasma infection, albeit more loosely. Taken together, the results obtained from this study suggest that in vitro metronidazole resistance of T. vaginalis is related to mycoplasma infection of this protozoan.

Animals↗

PubMed2002

Characterization of the inhibitory effect of PEG-lipid conjugates on the intracellular delivery of plasmid and antisense DNA mediated by cationic lipid liposomes.

Poly(ethylene glycol)-lipid (PEG-lipid) conjugates are widely used in the field of liposomal drug delivery to provide a polymer coat that can confer favorable pharmacokinetic characteristics on particles in the circulation. More recently these lipids have been employed as an essential component in the self-assembly of cationic and neutral lipids with polynucleic acids to form small, stable lipid/DNA complexes that exhibit long circulation times in vivo and accumulate at sites of disease. However, the presence of a steric barrier lipid might be expected to inhibit the transfection activity of lipid/DNA complexes by reducing particle-membrane contact. In this study we examine what effect varying the size of the hydrophobic anchor and hydrophilic head group of PEG-lipids has on both gene and antisense delivery into cells in culture. Lipid/DNA complexes were made using unilamellar vesicles composed of 5 mole% PEG-lipids in combination with equimolar dioleoylphosphatidylethanolamine and the cationic lipid dioleyldimethylammonium chloride. Using HeLa and HepG2 cells we show that under the conditions employed PEG-lipids had a minimal effect on the binding and subsequent endocytosis of lipid/DNA complexes but they severely inhibited active gene transfer and the endosomal release of antisense oligodeoxynucleotides into the cytoplasm. Decreasing the size of the hydrophobic anchor or the size of the grafted hydrophilic PEG moiety enhanced DNA transfer by the complexes.

Cell Nucleus↗

PubMed2001

Effect of combination therapy including protease inhibitors on mortality among children and adolescents infected with HIV-1.

BACKGROUND: Combination therapy including protease inhibitors has been shown to be effective in treating adults infected with human immunodeficiency virus type 1 (HIV-1), but there are only limited data regarding the treatment of children and adolescents. METHODS: A cohort of 1028 HIV-1-infected children and adolescents, from birth through 20 years of age, who were enrolled in research clinics in the United States before 1996 was followed prospectively through 1999. We used proportional-hazards regression models to estimate the effect on mortality of combination therapy including protease inhibitors. RESULTS: Seven percent of the subjects were receiving combination therapy including protease inhibitors in 1996; by 1999, 73 percent were receiving such therapy. In univariate analyses, a higher base-line percentage of lymphocytes that were CD4-positive, a higher weight for age, a higher height for age, black race, Hispanic ethnic background, younger age, and perinatally acquired infection were associated with a longer median time to the initiation of this type of therapy (P<0.001). After adjustment for covariates, the differences among racial and ethnic groups in the time to initiation were not statistically significant. Mortality declined from 5.3 percent in 1996 to 2.1 percent in 1997, 0.9 percent in 1998, and 0.7 percent in 1999 (P for trend <0.001). There were reductions in mortality in all subgroups defined according to age, sex, percentage of CD4+ lymphocytes, educational level of the parent or guardian, and race or ethnic background. In adjusted analyses, the initiation of combination therapy including protease inhibitors was independently associated with reduced mortality (hazard ratio for death, 0.33; 95 percent confidence interval, 0.19 to 0.58; P<0.001). CONCLUSIONS: The use of combination therapy including protease inhibitors has markedly reduced mortality among children and adolescents infected with HIV-1.

Adolescent↗

PubMed2001

The social functioning of persons with chronic mental illness: an empirical typology of consumers and correlates of social functioning.

This study examined the typology of consumers and correlates of their social functioning using the Social Functioning Scale (SFS). Data were obtained from 244 outpatients of two psychiatric hospitals and psychiatric ward inpatients in two general hospitals through a structured in-person interview. The typology was generated using Cluster Analysis, and the profile of each group was further examined. The results indicated that there were four distinct groups of consumers. Multiple regression analysis revealed that consumers' sex, age, education, diagnosis, behavioral problems, family caregivers' age, employment status, and overall social support were significantly associated with consumers' social functioning. The implications for previous research findings and psychiatric rehabilitation service are discussed.

Adolescent↗

PubMed1998

Functional binding between Gbeta and the LIM domain of Ste5 is required to activate the MEKK Ste11.

BACKGROUND: In the budding yeast Saccharomyces cerevisiae, the pheromones that induce haploid cells of opposite cell types to mate activate the Gbeta and Ggamma subunits of a heterotrimeric G protein. These subunits signal through the PAK kinase Ste20 to activate a mitogen-activated protein (MAP) kinase cascade comprising the MEKK Ste11, the MEK Ste7 and two MAP kinases, Fus3 and Kss1. The pathway requires Ste5, a scaffold protein that tethers the MAP kinase cascade enzymes into a high molecular weight complex. Ste5 is thought to associate with Gbeta in a pheromone-independent manner, but it is not known if this interaction affects signaling. RESULTS: A ste5C180A mutant - which expresses Ste5 disrupted in the LIM domain, a putative metal-binding motif that has been proposed to be essential for Ste5 oligomerization - could not transmit the pheromone signal from Gbeta through Ste20 to Ste11. The Ste5C180A protein was impaired in binding Gbeta, although it could oligomerize, bind Ste11, Ste7 and Fus3, facilitate the basal activation of Ste11, and relay the Ste11 signal to MAP kinases. Ste5 bound to Gbeta in a pheromone-dependent manner and preferentially associated with a phosphorylated form of Gbeta in wild-type and ste20Delta, but not in ste5C180A, strains. CONCLUSIONS: Pheromone induces binding of Gbeta to Ste5 through its LIM domain. This binding is essential for activation of Ste11 and is distinct from the ability of Ste5 to oligomerize or to serve as a scaffold and relay the signal from Ste11 to the MAP kinases. Pheromone also induces Ste5-dependent phosphorylation of Gbeta.

Adaptor Proteins, Signal Transducing↗

PubMed1998

Violence exposure and emotional trauma as contributors to adolescents' violent behaviors.

OBJECTIVE: To investigate the degree to which violence exposure and symptoms of psychological trauma are related to adolescents' own violent behaviors. DESIGN AND SETTING: Anonymous self-report questionnaire administered to students in 6 public high schools (grades 9-12). PARTICIPANTS: Sixty-eight percent of the students attending the participating schools during the survey participated in the study (N=3735). Ages ranged from 14 to 19 years; 52% were female; and 35% were African American, 33% white, and 23% Hispanic. RESULTS: Multiple regression analysis determined that violence exposure and symptoms of psychological trauma together explained more than 50% of the variance in both male and female self-reported violent behavior. The independent effects of exposure to violence explained about one quarter of the variance in both male and female adolescents' violent behaviors. Anger was found to be the leading trauma symptom. CONCLUSION: Our findings suggest that health clinicians and other professionals who encounter adolescents should routinely screen them for both exposure to violence and symptoms of anger.

Adolescent↗

PubMed1997

Predictors of depressive symptomatology among lower social class caregivers of persons with chronic mental illness.

This study examined the predictors of depressive symptomatology among caregivers of persons with chronic mental illness. Data were collected through in-person interviews with family caregivers of 103 adults with chronic mental illness who were served by mental health case management agencies. The results indicated that insufficiency of overall social support was the most powerful predictor of caregiver depressive symptomatology. In addition, caregiver burden had a significant unique contribution to caregiver depressive symptomatology, with higher levels of burden associated with greater levels of caregiver depressive symptomatology. Higher levels of client behavioral problems and insufficient support from family members and mental health professionals related to the caregiving role were associated with higher levels of caregiver depressive symptomatology through their associations with caregiver burden. Caregiver race was not significantly related to caregiver burden or to caregiver depressive symptomatology after controlling for other variables. Over two-fifth of White caregivers and over one-quarter of Black caregivers were at risk for clinical depression. Implications for practice and research are discussed.

Adult↗

PubMed1995

Adolescents' exposure to violence and associated symptoms of psychological trauma.

OBJECTIVE: To examine the extent to which adolescents are exposed to various types of violence as either victims or witnesses, and the association of such exposure with trauma symptoms; specifically, the hypotheses that exposure to violence will have a positive and significant association with depression, anger, anxiety, dissociation, posttraumatic stress, and total trauma symptoms. DESIGN AND SETTING: The study employed a survey design using an anonymous self-report questionnaire administered to students (grades 9 through 12) in six public high schools during the 1992-1993 school year. PARTICIPANTS: Sixty-eight percent of the students attending the participating schools during the survey participated in the study (N = 3735). Ages ranged from 14 to 19 years; 52% were female; and 35% were African American, 33% white, and 23% Hispanic. RESULTS: All hypotheses were supported. Multiple regression analyses of the total sample revealed that violence exposure variables (and to a lesser extent, demographic variables) explained a significant portion of variance in all trauma symptom scores, including depression (R2 = .31), anger (R2 = .30), dissociation (R2 = .23), posttraumatic stress (R2 = .31), and total trauma (R2 = .37). CONCLUSIONS: A significant and consistent association was demonstrated linking violence exposure to trauma symptoms within a diverse sample of high school students. Our findings give evidence of the need to identify and provide trauma-related services for adolescents who have been exposed to violence.

Adolescent↗

PubMed1995

The psychosocial issues of women serving time in jail.

Two hundred and one randomly selected female inmates incarcerated at a municipal jail were interviewed to establish the needs of this population and to formulate appropriate rehabilitative interventions. Measures of social support for this sample were uniformly low. Scores on the Global Severity Index of the Brief Symptom Inventory showed that 64 percent of the women were in the clinical range for mental health problems. Scores obtained from the Short Drug Abuse Screening Test indicated that 83 percent of the women were in the substance abuse range. When child and adult sexual abuse were combined, 81 percent of the women had been sexually victimized at some time in their lives. The data point to the need for improved programs and conditions within penal settings and for intermediate sanctions for nonviolent female offenders. Such sanctions could include both correctional day treatment and community-based correctional living sites.

Adult↗

PubMed1995

Facilitators and barriers to caregiver support group participation.

This study examined the facilitators and barriers to support group participation among lower socioeconomic status African-American and Caucasian caregivers of persons with chronic mental illness. Data were collected through in-person interviews with family caregivers of 198 adults with chronic mental illness. The results indicated that a substantial numbers of caregivers had little knowledge about support groups. Mental health professionals were cited as important facilitators of support group participation. Barriers to support group participation pertained to accessibility and personal factors including lack of time, lack of need, difficulties sharing feelings, concern for confidentiality, and not knowing anyone who was a group member. There were few differences by caregiver race. Implications for mental health case managers and agencies and for future research are discussed.

Adult↗

PubMed1994

Direct and indirect interactions of cocaine with childbirth outcomes.

OBJECTIVE: To evaluate neonatal sequelae of maternal cocaine use during pregnancy. METHODS: One hundred women positive for cocaine use during pregnancy were compared with 100 matched controls who did not use cocaine. Maternal characteristics and infant neonatal outcomes were compared. We used t tests, chi 2, and multiple regression analyses to evaluate the contributions of cocaine vs other drugs to outcome. RESULTS: Cocaine was the best predictor of increased incidence of abortions, higher maternal gravidity, and poorer prenatal care. Cocaine was also the best predictor of preterm birth and of lower birth weight, after controlling for prematurity. Maternal use of cocaine and alcohol in combination was the best predictor of decreased linear growth, after controlling for prematurity. CONCLUSIONS: Maternal cocaine use predicts negative birth outcomes directly, as well as through obstetric risk factors of abortion history and less prenatal care. Interactive effects of cocaine and alcohol should be considered in future studies of birth outcomes.

Abortion, Spontaneous↗

PubMed1994

Predictors of burden among lower socioeconomic status caregivers of persons with chronic mental illness.

This study uses a stress-coping-support framework to examine the predictors of caregiver burden with a sample of 103 lower social class family caregivers of persons with chronic mental illness. Results of multiple regression analyses show that the greater the frequency of client behavioral symptoms and the lower the amount of perceived support from family members, the higher the level of overall caregiver burden. Examination of the predictors of specific types of burden-family disruption, stigma, strain, and dependency-reveal that different constellations of variables predict different types of burden. The need for mental health agencies to address caregiver and client concerns is addressed. Implications are presented for practice and future research.

Adult↗

PubMed1994

Sexual victimization and substance abuse in psychiatrically hospitalized adolescents.

This article investigates the relationship between substance abuse and sexual abuse in a population of 260 psychiatrically hospitalized adolescents. Seven hypotheses are set forth to test a model that uses parental alcohol abuse, sexual abuse status, and gender as exogenous variables, perceived benefit of alcohol or drugs as an endogenous mediating variable, and substance abuse as the dependent variable. Using these variables, a path model was constructed and revised based on empirical testing. The revised model achieved an adjusted R2 of .38, thus explaining 38 percent of the variance in this sample's abuse of alcohol or drugs. The model suggests that within clinical populations, sexually abused adolescents should be screened for substance abuse, and attention should be given to parental alcohol abuse as well as the degree to which adolescents perceive benefits from their alcohol or drug use.

Adolescent↗

PubMed1993

Divalent cations, phospholipid asymmetry and osmotic swelling in electrically-induced lysis, cell fusion and giant cell formation with human erythrocytes.

We have previously reported that acidic phospholipids are exposed at the surface of human erythrocytes when the cells are subjected to electrical breakdown. It has now been shown that the prothrombinase assay, which was used previously for the determination of acidic phospholipids, is specific for phosphatidylserine under the conditions of our experiments. In the light of this finding, we have investigated and characterised factors that govern cell lysis, cell fusion, and the formation of giant cells induced by electrical breakdown with human erythrocytes in media of low ionic strength. Divalent cations (1.1 mM) protected the cells against haemolysis, in the order Mn2+ > Ca2+ > Ba2+ > Mg2+ >> Zn2+, whereas about 99% of the cells lysed immediately on breakdown in the presence of Na+ or K+ (2.1 mM), or Al3+ (0.95 mM). The lengths of pearl chains of fused erythrocytes formed was similarly greatest with Mn2+ and decreased progressively with Ba2+, Zn2+, Ca2+ and Mg2+. No cell fusion occurred with Na+, K+, or Al3+. It is suggested that interactions with phosphatidylserine, which is exposed at the cell surface by electrical breakdown, may enable Mn2+, Ba2+ and Ca2+ ions to inhibit cell lysis (via membrane resealing) and facilitate cell fusion. Following electrically-induced cell fusion, erythrocytes round-up into giant cells. It has previously been proposed that Ca2+ ions accelerate the rounding-up process. However, data are presented which show that, as with erythrocytes treated with Sendai virus, the formation of rounded, giant cells following cell fusion depends on the osmotic swelling properties of permeabilised erythrocytes. Osmotic swelling may also have induced any hemi-fused cells present to fuse completely. Zn2+ ions anomalously enabled erythrocytes to round-up very rapidly into giant cells following electrical breakdown. This phenomenon may result from an interaction of Zn2+ ions with cysteine groups in membrane proteins, which decreases the immediate loss of ions that occurs when erythrocytes are subjected to electrical breakdown in low-ionic-strength media.

Cadmium↗

PubMed1992

Relationships between the surface exposure of acidic phospholipids and cell fusion in erythrocytes subjected to electrical breakdown.

The procoagulant activity of human erythrocytes, which provides a measure of the translocation of acidic phospholipids from the inner to the outer monolayer of the plasma membrane, has been compared with the percentage cell fusion in experiments on the effects of electrical breakdown pulses under differing experimental conditions. After treatment with breakdown pulses of 20 microseconds or longer (5 kV cm-1), the plasma membranes of erythrocytes in 250 mM sucrose exhibited an almost complete loss of asymmetry with respect to acidic phospholipids. As the breakdown voltage was increased from 2 to 5 kV cm-1 (with breakdown pulses of 99 microseconds), the surface exposure of acidic phospholipids and cell fusion increased approximately in parallel. Furthermore, with 99 microseconds pulses and a voltage of 3 kV cm-1, a decrease in the osmolarity from 250 to 150 mM of the sucrose medium was accompanied by an increase in both the surface exposure of acidic phospholipids and the extent of cell fusion. Breakdown pulses of 2-5 microseconds were sufficient to cause a marked loss of asymmetry, but no cell fusion was observed unless the pulse length was at least 20 microseconds. Kinetic experiments indicated that exposure of the acidic phospholipids at the cell surface was more likely to be due to a direct effect of the electric field pulses on plasma membrane structure than to secondary effects, such as the action of endogenous proteinases on the membrane skeleton. It seems possible that a localised, surface exposure of acidic phospholipids may contribute to the 'long-lived fusogenic state' (Sowers, A.E. (1986) J. Cell Biol. 102, 1358-1362) and the 'transient permeant structures' (Teissié, J. and Rols, M.P. (1986) Biochem. Biophys. Res. Commun. 140, 258-266) that enable cell fusion to occur when contact between cells is established after they have been subjected to field pulses. Our observations also provide circumstantial support for the concept that changes in the phospholipid asymmetry of membranes may be important in physiologically-occurring instances of biomembrane fusion.

Animals↗

PubMed1991

Membrane fusion without cytoplasmic fusion (hemi-fusion) in erythrocytes that are subjected to electrical breakdown.

There are many reports of hemi-fusion in phospholipid vesicles but few published studies on hemi-fusion in cells. We report evidence from both fluorescence microscopy and freeze-fracture electron microscopy for hemi-fusion in the electrofusion of human erythrocytes. We have also characterised the conditions that favour hemi-fusion as opposed to complete fusion, and discuss the possibility that hemi-fusion might precede complete electrically-induced cell fusion. A membrane probe (DiIC16) and a cytoplasmic probe (6-carboxyfluorescein) were used to investigate the behaviour of doubly-labelled human erythrocytes which were aligned in chains by dielectrophoresis and then exposed to high voltage breakdown pulses. Some of the cells were fused by the pulses, as shown by diffusion of both membrane and cytoplasmic probes from labelled to unlabelled cells. With other cells, the membrane probe diffused into unlabelled cells after the breakdown pulses, without the cytoplasmic probe diffusing into unlabelled cells or leaking into the medium. Membrane fusion (hemi-fusion) thus occurred without cytoplasmic fusion in these erythrocytes. Such cells were irreversibly, but fragilely, attached to their neighbours by the breakdown pulses. There was an inverse relationship between conditions that permit complete fusion and those that favour hemi-fusion, with respect to breakdown pulse length, breakdown voltage and, in particular, osmolarity and temperature. The incidence of hemi-fusion in 250 mM erythritol was twice that in 150 mM erythritol, and hemi-fusion was 5-fold greater at 25 degrees C than at 20 degrees C. Hemi-fused erythrocytes occasionally fused completely on heating to 50 degrees C, demonstrating that hemi-fusion can proceed to complete cell fusion. Freeze fracture electron micrographs of preparations of hemi-fused cells revealed long-lived, complementary depressions and protrusions on the E- and P-fracture faces, respectively, of tightly apposed cells that may mediate hemi-fusion. The possibility that the fusion of closely adjacent human erythrocytes by electrical breakdown pulses may involve an intermediate, shared bilayer structure, which is stable in certain conditions but which can be ruptured by osmotic swelling of the permeabilised cells, is discussed.

Cytoplasm↗

PubMed1990

Stress and depression in mothers of failure-to-thrive children.

Compared 30 mothers whose children were hospitalized for failure-to-thrive (FTT) to a normative group on standardized measures of perceived stress and depression. Child and maternal medical and demographic data were also taken. Standardized development and feeding assessments were done. Descriptive statistics, correlational analyses, and t tests were used to describe and examine group differences. FTT children were perceived overall as more stressful, less adaptable, more inconsolable, and more unhappy than were healthy children. Child characteristics associated with higher maternal stress levels were higher birth weight, absence of organic disease or behavioral feeding problems, and higher IQ. Maternal self-report of depression, attachment to her child, sense of competence in parenting, social isolation, and relationship to spouse were not different from the normative sample.

Attitude to Health↗

PubMed1990

[Experimental study of the pathological mechanism of thromboxane A2 in alkaline ocular burn].

The authors investigated the pathological mechanism of thromboxane A2 in alkaline burn of the eye. Thromboxane B2 (metabolic product of thromboxane A2) in aqueous humor of the burned eye significantly increased in 30 minutes after the burn. The pathological change was the formation of thrombosis 2 hours after the alkaline burn, especially in the anterior segment. The role of thromboxane A2 in alkaline burn of the eye was ascertained.

Alkalies↗