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Biomedical subjects

H Xu

Publications and source records attributed to H Xu.

At least 613 records · Page 34Linked to original sources
PubMed1995

Vitamin E stimulates trabecular bone formation and alters epiphyseal cartilage morphometry.

The effects of dietary vitamin E (VIT E) and lipids on tissue peroxidation and fatty acid composition, epiphyseal growth plate cartilage development, and trabecular bone formation were evaluated in chicks. A 2 x 2 factorial design was followed using two levels (30 and 90 IU/kg of diet) of dl-alpha-tocopheryl acetate and two different dietary lipids. The basal semipurified diet contained one of the following lipid treatments: anhydrous butter oil (40 g/kg) + soybean oil (60 g/kg), [BSO], or soybean oil (100 g/kg), [SBO]. After 14 days of feeding, the level of alpha tocopheryl in plasma was higher and thiobarbituric acid reactive substances (TBARS) were less in plasma and liver of chicks supplemented with 90 IU of VIT E compared with those given 30 IU of VIT E. Body weights and tibiotarsal bone lengths were not affected by the dietary treatments. Saturated fatty acids (14:0, 15:0, 16:0, 17:0, and 18:0) were increased in the tibiotarsal bone of chicks fed the BSO diet. In contrast, total polyunsaturated fatty acids and the ratio unsaturated fatty acids/saturated fatty acids were higher is plasma of chicks fed SBO compared with the values from chicks fed BSO. The thickness of the entire growth plate cartilage and the lower hypertrophic chondrocyte zone was significantly greater in chicks fed 90 IU/kg of VIT E. Kinetic parameters on bone histomorphometry indicated that mineral apposition rate was higher in chicks fed 90 IU of VIT E. The interaction effect between the VIT E and BSO treatments led to the highest trabecular bone formation rate among the groups. These data suggest that VIT E protects against cellular lipid peroxidation in cartilage to sustain normal bone growth and modeling.

Animals↗
PubMed1995

The mechanism for the effect of selenium supplementation on immunity.

Lipid peroxide (LPO) in lymphocytes from mice was evaluated by measuring substances reactive to thiobarbituric acid (TBA). The product resulting from the reaction of TBA with lymphocytes was extracted with n-butyl and fluorescence intensity was determined. The degree of lipid peroxidation, expressed as fluorescence intensity f547, was assessed for stimulation of lymphocytes with concanavalin A (Con A), and was related to lymphocyte proliferation in response to Con A if Se was administered. The lymphocyte proliferation was determined by [3H]thymidine incorporation, expressed as cpm. The effect of superoxide dismutase (SOD), added to cell culture on lymphocyte proliferation was also evaluated. It was found that LPO in lymphocytes before Con A stimulation was significantly less than that after stimulation (p < 0.001), and that SOD promoted lymphocyte proliferation dose dependently. The addition of Na2Seo3 to lymphocyte culture or supplementation in drinking water to mice decreased the produced LPO in lymphocyte in response to Con A. In the presence of Se, there is an inverse correlation between the levels of LPO in lymphocyte and the stimulated proliferation (r = -0.8902, r = -0.9439). In conclusion, active oxygen species scavenging was proposed as one of the mechanisms for Se to promote immunity.

Animals↗
PubMed1995

Effect of selenium in recovery of immunity damaged by H2O2 and 60Co radiation.

Con A stimulated lymphocytes proliferation was measured as [3H]thymidine incorporation and IgG was quantified by single radial immunodiffusion to study recovering or protecting effect of selenium (Se) on immunity attacked by exogenous active oxygen species, H2O2 and 60Co-radiation, respectively. Lipid peroxidation was also determined to observe the relation between antioxidation ability and protecting ability of Se. It was found that H2O2 injured lymphocytes immunocompetence deeply and 60Co-radiation decreased immune response capacity greatly, but that administration of Se counteracts this damage. The antioxidative ability of Se was correlated with its protecting ability.

Animals↗
PubMed1995

Does "incessant" ovulation increase risk for early menopause?

OBJECTIVE: We attempted to determine whether gynecologic histories differ in women who have and have not experienced an early menopause. STUDY DESIGN: A group of 344 "case" women whose average age at menopause was 42.2 years and an age-matched group of 344 "control" women still menstruating or menopausal after age 46 were selected from a survey of 10,606 women aged 45 to 54 years for interviews about their reproductive history. RESULTS: Case women were more likely to have had menarche at or before age 11, had shorter cycle lengths, had fewer pregnancies with live births, and had more frequent pelvic operations including unilateral oophorectomy and multiple cesarean sections. Case women had a greater number of presumed ovulatory cycles, as estimated from age at menarche, average cycle length, and years of anovulation associated with pregnancies or oral contraceptive use. In a multivariate model including smoking status and body mass index, ovulatory cycles were a significant predictor of early menopause, especially after an estimated 300 ovulations. CONCLUSION: The reproductive histories of women who experienced an early menopause suggest a pattern of more rapid oocyte loss ("incessant" ovulation).

Case-Control Studies↗
PubMed1995

Newborn baboon immunity: lessons in cross-species transplantation.

BACKGROUND: The critical shortage of organ donors has greatly limited the number of heart transplantations performed each year. This is particularly true of the newborn patient, for whom xenotransplantation may provide an alternative therapeutic option to allotransplantation. The role of newborn immunity in xenotransplantation is not clearly understood. METHODS: We examined the humoral immune responses of 9 nonimmunosuppressed newborn baboons (900 to 1200 g) aged 28 to 44 days undergoing heterotopic pig heart transplantation. Grafts were explanted between 1 and 87 hours after transplantation. RESULTS: Despite the degree of species, disparity, hyperacute rejection was not observed in any of the nine transplanted grafts. Whole-cell enzyme-linked immunosorbent assay demonstrated newborn baboon serum to contain very low binding levels of anti-pig natural immunoglobulin M xenoantibody when compared with adult baboon serum. Newborn serum, like adult serum, contained anti-pig natural immunoglobulin G xenoantibody. However, newborn baboon serum was not cytotoxic to pig endothelial cells, suggesting that immunoglobulin M and not immunoglobulin G is the primary xenoreactive antibody. CONCLUSIONS: The low binding levels of anti-pig immunoglobulin M xenoantibody, the absence of cytotoxicity to pig endothelial cells, and the avoidance of hyperacute rejection after heart transplantation suggest that newborn primates may have an immunologic advantage as the recipients of hearts transplanted across species barriers. Whether this advantage can be extended to the human condition is currently being explored in our laboratory.

Animals↗
PubMed1995

Opioid peptide receptor studies. 1. Identification of a novel delta-opioid receptor binding site in rat brain membranes.

Our laboratory was among the first to propose the existence of delta receptor subtypes: a delta site thought to be associated with a mu-delta-opioid receptor complex termed the delta cx binding site and delta site not associated with the mu-delta-opioid receptor complex, termed the delta ncx site. In previous studies, we assayed the delta cx site with [3H][D-Ala2,D-Leu5]enkephalin using rat brain membranes depleted of delta ncx sites by pretreatment with the site-directed acylating agent, (+)-trans-SUPERFIT. In the present study, we investigated, using (+)-trans-SUPERFIT-pretreated membranes, the possibility of heterogeneity of the delta cx binding site. Two sites were resolved: the delta cx-1 site at which mu ligands are potent noncompetitive inhibitors and delta ligands are weak competitive inhibitors, and the delta cx-2 site where delta ligands are potent and mu ligands are weak, mixed competitive-noncompetitive inhibitors. Although the delta cx-2 site has a delta-like ligand-selectivity profile, several experiments distinguished it from the delta ncx site. Two lines of evidence suggest that the delta ncx site corresponds to the cloned delta receptor. One, the delta receptor was cloned from the NG108-15 cell line, and this receptor, like the delta ncx binding site, irreversibly binds SUPERFIT and (+)-trans-SUPERFIT. Secondly, administration of delta-antisense DNA selectively decreases delta ncx binding. Viewed collectively, the major finding of this study is the discovery of a novel SUPERFIT-insensitive and delta-antisense-insensitive delta cx-2 binding site.

Analgesics↗
PubMed1995

Opioid peptide receptor studies. 3. Interaction of opioid peptides and other drugs with four subtypes of the kappa 2 receptor in guinea pig brain.

Using guinea pig, rat, and human brain membranes depleted of mu and delta receptors by pretreatment with the site-directed acylating agents BIT (mu selective) and FIT (delta selective), previous studies from our laboratory resolved two subtypes of the kappa 2 binding site, termed kappa 2a and kappa 2b. In more recent studies, we used 6 beta-[125Iodo]-3,14-dihydroxy-17-cyclopropylmethyl-4,5 alpha-epoxymorphinan ([125I]IOXY) to characterize multiple kappa 2 binding sites in rat brain. The results indicated that [125I]IOXY, like [3H]bremazocine, selectively labels kappa 2 binding sites in rat brain membranes pretreated with BIT and FIT. In the rat brain, using 100 nM [D-Ala2-MePhe4,Gly-ol5]enkephalin to block [125I]IOXY binding to the kappa 2b site, we resolved two subtypes of the kappa 2a binding site. In the present study we examined the binding of [125I]IOXY to the kappa 2 receptors of guinea pig brain. As observed in rat brain, [125I]IOXY, under appropriate assay conditions, selectively labels kappa 2 binding sites. Quantitative binding studies readily demonstrated the presence of kappa 2a and kappa 2b binding sites. The kappa 2a binding sites were selectively assayed using 5 microM [Leu5]enkephalin to block [125I]IOXY binding to the kappa 2b sites, and kappa 2b sites were selectively assayed using 5 microM (-)-(1S,2S)-U50,488 to block [125I]IOXY binding to the kappa 2a sites. Under these conditions, two subtypes of the kappa 2a site were resolved with high (kappa 2a-1) and low (kappa 2a-2) affinity for nor-BNI (Ki values = 0.88 and 476 nM) and CI977 (Ki values = 17.5 and 95,098 nM). Similarly, two subtypes of the kappa 2b site were observed with high (kappa 2b-1) and low (kappa 2b-2) affinity for [D-Ala2-MePhe4,Gly-ol5]enkephalin (DAMGO) (Ki values = 97 and 12,321 nM) and alpha-neoendorphin (Ki values = 33 and 5308 nM). Two-site models were also resolved in the presence of 100 microM 5'-guanylyimidodiphosphate (GppNHp). We carried out detailed ligand selectivity analysis of the multiple kappa 2 binding sites. Most test agents were either nonselective or selective for the kappa 2a-1 site. Nalbuphine was moderately selective for the kappa 2a-2 site. Similarly, although most test agents were either nonselective or selective for the kappa 2b-1 site, butorphanol, and the delta antagonists naltrindole, naltriben, and 7-benzylidene-7-dehydronaltrexone were moderately selective for the kappa 2b-2 site.(ABSTRACT TRUNCATED AT 400 WORDS)

Amino Acid Sequence↗
PubMed1995

Cross-sectional and case-controlled analyses of the association between smoking and early menopause.

To examine potential confounders and dose-response data for the association between smoking and menopause, we used both a cross-sectional and case-controlled approach. In total, 10,606 middle-aged women residing in eastern Massachusetts were surveyed about their age at menopause and smoking history; 344 women (cases) with natural menopause prior to age 47 and 344 age-matched women (controls) who were still menstruating or who had a menopause after age 46 were selected for further study. Risk for menopause was assessed by Kaplan-Meier, Cox proportional hazards, or logistic regression models. From cross-sectional data on 8657 women aged 45-54, the hazards odds ratio for a natural menopause among women who ever smoked compared to non-smokers was 1.31 (95% C.L. 1.21-1.42) and among women who had accumulated 30 or more pack-years was 1.87 (95% C.L. 1.67-2.04) after adjustment for parity and weight. An additional potential confounder from the case-controlled study was lower educational attainment, and after adjustment for this variable, significant trends persisted for risk of early menopause associated with age began smoking (P = 0.03), years of smoking (P = 0.01) and pack-years of smoking (P = 0.03). This study demonstrates an association between smoking and early menopause in both cross-sectional and case-controlled data that is not confounded by parity, weight, socio-economic status, or nutritional variables.

Adult↗
PubMed1995

Low concentrations of serum tyrosine in neuroleptic-free schizophrenics with an early onset.

The concentrations of serum tyrosine, phenylalanine and tryptophan have been determined in 23 male neuroleptic-free patients with schizophrenia and 28 male healthy control subjects. Tyrosine was significantly lower in neuroleptic-free patients with an early onset (starting before adulthood) than in healthy control subjects (p < 0.05), and the ratio of tyrosine to phenylalanine was significantly lower in neuroleptic-free patients with an early onset than in those with a late onset (starting at adulthood). No significant differences in these three amino acids were found between the patients with a late onset and healthy control subjects. The present findings suggest that there may be a disturbance of balance between tyrosine and phenylalanine in early-onset patients with schizophrenia.

Adult↗
PubMed1995

Epidemiologic evidence for uterine growth factors in the pathogenesis of ovarian cancer.

To examine the association between ovarian cancer and prior hysterectomy or tubal ligation in light of various interpretations, we combined data from two previously conducted case-control studies of ovarian cancer. This included 450 women with histologically verified epithelial ovarian cancer and 454 age-matched women from the general population for whom data on prior pelvic surgery were available to estimate exposure odds ratios. Overall there was a nonsignificant deficit of case patients who had had a hysterectomy or tubal ligation (odds ratio (OR) = 0.9; 95% confidence interval (CI), 0.6 to 1.3). A protective effect of prior hysterectomy or tubal ligation was more apparent among women who had the surgery 20 or more years previously (OR = 0.6; 95% Ci, 0.3 to 1.1), women who had not used talc in their hygiene (OR = 0.6; 95% CI, 0.4 to 1.0), and women with mucinous tumors of the ovary (OR = 0.3; 95% CI, 0.1 to 1.0). Although these data do not clearly establish the validity of or mechanisms for an association between prior pelvic surgery and ovarian cancer, we speculate that such an association exists and may be mediated through absent or reduced uterine growth factors that reach the ovaries through the uteroovarian circulation, with mucinous tumors most dependent on such factors.

Adenocarcinoma, Mucinous↗
PubMed1995

Effects of previous use of oral contraceptives on early follicular phase follicle-stimulating hormone.

OBJECTIVE: To determine if previous oral contraceptive (OC) use is associated with changes in early follicular phase FSH, LH or E2. DESIGN: A cross-sectional study examining determinants of early follicular phase hormone levels. SUBJECTS: Subjects included 106 premenopausal women with a family history of ovarian cancer and 116 premenopausal women without this history who were not taking OCs currently. All subjects completed a structured interview and gave an early follicular phase blood sample. SETTING: Gynecologic Epidemiology Center and Familial Ovarian Cancer Research Center. MAIN OUTCOME MEASURES: Follicle-stimulating hormone, LH, and E2 were measured in early follicular phase plasma samples. RESULTS: Recency or length of prior OC use did not affect early follicular phase LH or E2 levels. Length of OC use did not affect FSH levels in all subjects; but lower levels of FSH were observed in women over age 45 who had used OCs for > 5 years. Early follicular phase FSH is lower in women with OC use within the past 5 years compared with women with more remote use or who never used OCs, after adjustment for age, smoking, and family history status. CONCLUSIONS: Past use of OCs may have a residual effect on basal FSH levels in women not using them currently that depends on recency of use and to a lesser extent duration of prior use.

Adult↗
PubMed1995

Family history as a predictor of early menopause.

OBJECTIVE: To determine the relative importance of family history as a predictor of early menopause. DESIGN: Case-control study. From a population-based survey of 10,606 women between 45 and 54 years of age, we selected 344 cases with early menopause (average age 42.2 years) and 344 age-matched controls who were still menstruating or who had a menopause after age 46 years. Subjects were interviewed about their medical and family history and blood was drawn for identification of women who were carriers for the classic or Duarte variant of galactosemia, a potential hereditary factor for early menopause. Logistic regression analysis was used to estimate the risk of an early menopause in women with and without a family history of early menopause. RESULTS: Overall 129 (37.5%) of the early menopause cases reported a family history of menopause before age 46 years in a mother, sister, aunt, or grandmother compared to 31 (9.0%) of controls yielding an odds ratio (OR) of 6.1 (95% confidence interval [CI] of 3.9 to 9.4) after adjustment for smoking history, education, parity, and body mass index. Risk for early menopause associated with family history of same was greatest: for family history in a sister, OR = 9.1 (95% CI 3.1 to 26.5); multiple relatives, OR = 12.4 (95% CI 4.4 to 34.2); and cases menopausal before age 40 years, OR = 8.4 (95% CI 2.5 to 31.2). Cases with a family history of early menopause were not more likely to have errors of galactose metabolism compared with cases without a family history or to all controls, nor did they possess Turner's stigmata such as short stature, but they were less likely to have brothers in their sibships. CONCLUSIONS: Although preferential recall of family history by women with early menopause could contribute to the association between family history and early menopause observed in this study, a genetic factor is also plausible including partial deletions of the X chromosome compatible with the deficiency of male siblings in cases with family history of early menopause.

Adult↗
PubMed1995

Age-related development of human anti-pig xenoantibody.

Human cytotoxic natural xenoantibodies are believed to be of the immunoglobulin M class in nature. However, a thorough understanding of the development of these natural antixenodonor xenoantibodies remains incomplete. In this study, serum samples were obtained from newborn, infant, and adult human beings. An enzyme-linked immunosorbent assay was used to determine the binding of human natural immunoglobulin M xenoantibodies to pig aortic endothelial cells and pig lymphocytes. A complement-mediated cytotoxicity assay was used to measure the cytotoxicity of newborn, infant, and adult serum to cultured pig aortic endothelial cells and pig lymphocytes. Adult human serum contained both natural immunoglobulin M and immunoglobulin G xenoantibodies to pig endothelial cells and lymphocytes, whereas newborn infant serum contained only immunoglobulin G xenoantibodies. Only adult human serum was cytotoxic to pig endothelial cells and lymphocytes. Human immunoglobulin M xenoantibodies became detectable by age 1 month. By age 2 months these natural anti-pig xenoantibodies reached serum levels equivalent to those in the human adult and resulted in similar cytotoxicity to that of adult human serum. These findings indicate that (1) natural anti-pig immunoglobulin M xenoantibodies are absent from newborn infant human serum, (2) newborn human serum is not cytotoxic to pig endothelial cells and lymphocytes despite the presence of immunoglobulin G xenoantibodies that bind to pig endothelial cells and lymphocytes, and (3) natural anti-pig immunoglobulin M xenoantibodies begin to develop as early as age 1 month and by age 2 months attain a circulating level comparable to that found in the adult.

Adult↗
PubMed1995

cDNA selection from 10 Mb of chromosome 21 DNA: efficiency in transcriptional mapping and reflections of genome organization.

The technique of cDNA hybridization selection has been applied individually to 16 YAC clones mapping to various regions of the long arm of human chromosome 21. YACs represented approximately 10 Mb of non-overlapping DNA, and cDNA sources included fetal brain, whole fetus, and adult testes, thymus, liver and spleen. Sequencing, Northern analysis, RT-PCR and cDNA library screenings have been used to identify and partially characterize a non-redundant set of novel genes. A preliminary analysis strategy of the selected cDNAs has proven rapid and effective for isolation of the more highly represented genes and is suitable for survey transcriptional mapping efforts. By scaling up to screen > 1000 cDNA fragments per 100 kb of YAC DNA, more rare transcripts are identified and lead to comprehensive gene maps. Strong regional variations in transcriptional activity were observed, with gene densities ranging from < 1/2000 kb to > 1/15 kb. This effort has produced a large number of new genes of potential relevance to Down Syndrome.

Adult↗
PubMed1995

Transient expression of calcium-independent nitric oxide synthase in blood vessels during brain development.

The calcium-independent nitric oxide synthase, known as NOS-II or inducible NOS, is only present in adult brain during pathologies that involve inflammatory events. We sought to establish whether NOS-II was also expressed in the course of normal brain development. NOS-II mRNA, measured by quantitative polymerase chain reaction, appeared during the perinatal period in different brain areas. It was detected on embryonic day 14, the earliest time analyzed, and then levels decayed until the first postnatal week when a second, more robust phase of expression arose to peak around postnatal day 7. Expression then declined to negligible levels in adulthood. Immunohistology revealed translation of the NOS-II protein in both embryonic and postnatal animals, localized to parenchymal blood vessels, whereas no vessel staining was detected in adults. Furthermore, NOS-II mRNA and enzymatic activities were present in isolated brain microvessels from developing animals but not from adults, and P7 vessels contained a 125 kDa protein band detected with a monoclonal antibody raised against rat NOS-II protein. These results indicate that the calcium-independent NOS mRNA and functional protein are transiently expressed in vessels throughout the brain in the course of normal development.

Animals↗
PubMed1995

Differentiated macrophages synthesize a heparan sulfate proteoglycan and an oversulfated chondroitin sulfate proteoglycan that bind lipoprotein lipase.

Lipoprotein lipase (LpL), which facilitates lipoprotein uptake by macrophages, associates with the cell surface by binding to proteoglycans (PGs). Studies were designed to identify and characterize specific PGs that serve as receptors for LpL and to examine effects of cell differentiation on LpL binding. PG synthesis was examined by radiolabeling THP-1 monocytes and macrophages (a cell line originally derived from a patient with acute monocytic leukemia) with [35S]sodium sulfate and [3H]serine or [3H]glucosamine. Radiolabeled PGs isolated from the cell surface were purified by chromatography and identified as chondroitin-4-sulfate (CS) PG and heparan sulfate (HS) PG. A sixfold increase in CSPG and an 11-fold increase in HSPG accompanied cell differentiation. Whereas HS glycosaminoglycan chains from both monocytes and macrophages were 7.5 kD in size, CS chains increased in size from 17 kD to 36 kD with cell differentiation, and contained hexuronyl N-acetylgalactosamine-4,6-di-O sulfate disaccharides. LpL binding was sevenfold higher to differentiated cells, and affinity chromatography demonstrated that two cell surface PGs bound to LpL: HSPG and the oversulfated CSPG produced only by differentiated cells. We conclude that differentiation-associated changes in cell surface PG of human macrophages have functional consequences that could increase the atherogenic potential of the cells.

Cell Differentiation↗
PubMed1995

[Study on the relationship between uterine bleeding with intrauterine device and viral infection].

OBJECTIVE: To study the relationship between uterine bleeding with intrauterine device (IUD) and virus infection. METHODS: Virus isolation from endometrium samples both with IUD and without IUD was performed with rabbit kidney cell. The cell pathogen effect (CPE) directed the positive isolation. All isolated viruses were further identified by polymerase chain reaction (PCR) for human cytomegalovirus (HCMV) and by neutralizing test for herpes simplex virus type II (HSV-II). RESULTS: The endometrial samples were obtained from four groups: 113 patients with uterine bleeding with IUD; 109 healthy women, without uterine bleeding with IUD; 24 healthy women without IUD and 11 patients with uterine bleeding without IUD. The rates of virus isolation in four groups mentioned above were 59.29%, 19.27%, 16.67% and 63.64% respectively. The positive rates for HCMV and HSV-II in the four groups were 38.81%, 19.05%, 1/4, 3/7 and 23.88%, 23.87%, 1/4, 0.00% respectively. The unidentified viruses were 37.31%, 57.14%, 2/4 and 4/7 respectively. CONCLUSIONS: These results showed that some endometrial samples from both the bleeding groups and the controls were infected by HCMV and HSV-II. The incidence of virus infection in women with uterine bleeding with IUD was much higher than that of the controls, but similar to that is the patients with uterine bleeding without IUD. The results suggested that IUD could activate latent viruses (HCMV, HSV-II) infection and induce bleeding in certain conditions.

Adult↗