Biomedical subjects

Fei Xue

Publications and source records attributed to Fei Xue.

8 recordsLinked to original sources

PubMed2006

Role of birthweight in the etiology of breast cancer.

Breast cancer may originate in utero. We reviewed the available evidence on the association between birthweight and the risk of breast cancer. To date, 26 research papers addressing this issue have been published. The majority of studies identified a positive link between birthweight and premenopausal, but not postmenopausal, breast cancer. The relative risk estimate for breast cancer comparing women with high birthweight to women with low birthweight combining all studies including both pre- and postmenopausal breast cancer was 1.23 (95% confidence interval 1.13-1.34). The mechanisms underlying this association likely include elevated levels of growth factors that may increase the number of susceptible stem cells in the mammary gland or initiate tumors through DNA mutations. Loss of imprinting (LOI) of growth hormone genes relevant for intrauterine growth, such as insulin-like growth factor 2 (IGF2), leads to abnormally high levels of these hormones evidenced by high birthweight. LOI of IGF2 has also been found in mammary tumor tissue. The role of environmental factors that stimulate such epigenetic regulation of gene expression remains to be elucidated.

Birth Weight↗

PubMed2006

Longitudinal study of birthweight and the incidence of breast cancer in adulthood.

A high birthweight has been associated with an increased risk of breast cancer later in life. The role of adult variables, possible effect modifiers and cancer characteristics has been little studied. We explored these in two large prospective cohort studies of women, the Nurses' Health Study (NHS) and the Nurses' Health Study II (NHS II). We collected information on birthweight from 152,608 female nurses participating in NHS and NHS II. During 10 years and 1.3 million person-years of follow-up, invasive breast cancer was newly diagnosed among 828 premenopausal and 2312 postmenopausal women. Data were analyzed using a Cox proportional hazards model. Premenopausal women with a birthweight of <5.5 lbs had a covariate-adjusted hazard ratio (HR) for breast cancer of 0.66 [95% confidence interval (CI) 0.47-0.93] compared with women born at 8.5 lbs or above. Adult height was the only factor explaining some of the association between birthweight and breast cancer incidence; after adjustment for height the HR was 0.73 (95% CI 0.51-1.03). The association between birthweight and the incidence of breast cancer was stronger among women with estrogen-receptor positive and progesterone-receptor positive breast cancer. Among postmenopausal women, no important association between the birthweight and the incidence of breast cancer was detected (HR comparing women with a birthweight of 5.5 lbs or less with women with a birthweight>8.5 lbs: 0.97; 95% CI 0.80-1.16). In these two large prospective cohorts, a low birthweight was associated with a decreased incidence of breast cancer among premenopausal women. This association was independent of other factors operating later in life, except for adult height.

Adult↗

PubMed2006

XIST repression in the absence of DNMT1 and DNMT3B.

X chromosome inactivation (XCI) in human and mice involves XIST/Xist gene expression from the inactive X (Xi) and repression from the active X (Xa). Repression of the XIST/Xist gene on the Xa has been associated with methylation of its 5' region. In mice, Dnmt1 has been shown to be involved in the methylation and transcriptional repression of Xist on Xa. We examined maintenance of XIST gene repression on Xa in HCT116 cell lines knockout for either DNMT1 or DNMT3B and for DNMT1 and DNMT3B simultaneously. Methylation of the XIST promoter and XIST transcriptional repression is sustained in DNMT1-, DNMT3B- and DNMT1/DNMT3B knockout cells. Despite global DNA demethylation, the double knockout cells present only partial demethylation of the XIST promoter, which is not sufficient for gene reactivation. In contrast, global DNA demethylation with 5-aza-2'-deoxycytidine leads to XIST expression. Therefore, in these human cells maintenance of XIST methylation is controlled differently than global genomic methylation and in the absence of both DNMT1 and DNMT3B.

Cell Line↗

PubMed2006

Enteral feeding of glycyl-glutamine dipeptide improves the structure and absorptive function of the small intestine after allogenetic liver transplantation in rats.

BACKGROUND: Recipients of liver transplantation could have postoperative structural injury and declined absorptive function in the gastrointestinal tract. Glutamine (Gln) is a special nutrient of small intestinal mucosa and of various kinds of cells proliferating rapidly. But Gln could form a kind of poisonous pyroglutamic acid in water solution, which is the limitation of Gln in clinical practice. Glycyl-glutamine (Gly-Gln) is highly soluble and can be hydrolyzed to release glutamine. This study was undertaken to observe the effect of Gly-Gln dipeptide by enteral feeding on the intestinal structure and absorptive function after allogenetic liver transplantation in rats. METHODS: Twelve male inbred Lewis rats were selected randomly as donors, and 24 male inbred BN rats as recipients of allogenetic liver transplantation. The recipients were also randomly divided into two groups: control group (ALA group, n=12) and experimental group (GLN group, n=12). In each group, 6 normal BN rats were sampled as the normal parameter on the 3rd preoperative day. The 6 recipients in the control group received alanine 0.6 g/kg daily for 3 days before operation and 7 days after operation by gastric perfusion, and the 6 recipients in the experimental group were given Gly-Gln 0.6 g/kg daily the same way. The 12 BN recipients underwent 3-day fasting (free access to water with 0.23% sodium chloride) and orthotopic liver transplantation in aseptic conditions and were given subcutaneous injection of CsA 2 mg/kg daily after the operation. The 12 BN recipients were sampled on the 8th postoperative day. All of the 24 BN rats were subjected to examination of mucosal structure, activities of Na+-K+-ATP and disaccharidase, and D-xylose absorption test. RESULTS: The 12 BN recipients were alive after liver transplantation. On the 3rd preoperative day, mucosal structure, activities of Na+-K+-ATP and disaccharidase and D-xylose absorption in the two groups were not significantly different. On the 8th postoperative day, the parameters of the two groups were markedly changed compared with those on the 3rd preoperative day. However, the parameters of GLN group were remarkably higher than those of ALA group. CONCLUSION: Enteral feeding of Gly-Gln could improve the structure and absorptive function of the small intestine after liver transplantation in rats.

Animals↗

PubMed2006

[Study on the myoelectric activity of dilatation muscles of upper airway in patients with obstructive sleep apnea-hypopnea syndrome under asleep condition].

OBJECTIVE: To observe the changes of the electromyography(EMG) of the dilatation muscles of upper airway in patients with obstructive sleep apnea-hypopnea syndrome (OSAHS) under asleep condition and to explore their functions and significance. METHOD: The myoelectronic activity of levator palatini muscle, tensor palatini muscle, genioglossus muscle was measured by ENG in patients with moderate to serious OSAHS before and after induction of sleep and was compared with normal control. RESULT: (1) The myoelectronic activity of dilation muscles of the upper airway in OSAHS patients were higher than that in control under awake condition (P < 0.01). (2) When the patients were asleep, the myoelectronic activity of these muscles dropped significantly (P < 0.01). (3) The decrease of myoelectronic activity of dilatation muscles of upper airway was more dramatic in patients with OSAHS than that in control when turned from awake condition to asleep condition (P < 0.01). CONCLUSION: The compensative raise of myoelectronic activity of dilatation muscles of upper airway under awake condition and the decompensation when asleep in patients with OSAHS were important in the pathogenesis.

Adult↗

PubMed2004

Hyperparathyroidism and subsequent incidence of breast cancer.

Preliminary data are available on the coexistence of primary hyperparathyroidism and breast carcinoma. To further understand the association between hyperparathyroidism and breast cancer, we conducted a record-linkage study in Sweden using the Swedish Cancer Registry from 1958-1997. A total of 9,835 women who underwent surgery for primary parathyroid adenoma were followed to evaluate the hypothesis that a history of primary hyperparathyroidism increases the risk of subsequent breast cancer. During 99,929 person-years of follow-up, 331 cases of newly diagnosed breast cancer were reported. The number of expected breast cancers in this population was 260.0. This resulted in a standardized incidence ratio of 1.27 (95% confidence interval [CI] = 1.14-1.41). The relation persisted over time after the surgical removal of the parathyroid adenoma. Possible explanations for the observed association are a shared etiology including genetic and environmental factors such as early life radiation, and hypercalcemia after the overproduction of parathyroid hormone, which may increase breast cancer incidence.

Adenoma↗

PubMed2002

Aberrant patterns of X chromosome inactivation in bovine clones.

In mammals, epigenetic marks on the X chromosomes are involved in dosage compensation. Specifically, they are required for X chromosome inactivation (XCI), the random transcriptional silencing of one of the two X chromosomes in female cells during late blastocyst development. During natural reproduction, both X chromosomes are active in the female zygote. In somatic-cell cloning, however, the cloned embryos receive one active (Xa) and one inactive (Xi) X chromosome from the donor cells. Patterns of XCIhave been reported normal in cloned mice, but have yet to be investigated in other species. We examined allele-specific expression of the X-linked monoamine oxidase type A (MAOA) gene and the expression of nine additional X-linked genes in nine cloned XX calves. We found aberrant expression patterns in nine of ten X-linked genes and hypomethylation of Xist in organs of deceased clones. Analysis of MAOA expression in bovine placentae from natural reproduction revealed imprinted XCI with preferential inactivation of the paternal X chromosome. In contrast, we found random XCI in placentae of the deceased clones but completely skewed XCI in that of live clones. Thus, incomplete nuclear reprogramming may generate abnormal epigenetic marks on the X chromosomes of cloned cattle, affecting both random and imprinted XCI.

Animals↗

PubMed2002

[Auditory neuropathy].

OBJECTIVE: To explore the clinical and auditory functional feature of auditory neuropathy(AN). METHOD: The clinic signs, audiometric test and electrophysiology were analyzed on 54 cases of AN. RESULT: 70 ears had low frequency pure tone hearing loss. 24 ears had cover basic hearing threshold. 6 ears had flat hearing threshold. 4 ears showed high frequency hearing loss. The average low-frequency, median-frequency and high-frequency hearing threshold were 67.63 +/- 15.30, 43.61 +/- 16.28 and 32.25 +/- 14.80 dB HL respectively. The tympanograms are normal. 77 ears lost acoustic reflex. 31 ears increased acoustic reflex threshold. All of them induced no ABR and had normal DPOAE with 26 cases' contralateral acoustic suppression uninfluenced. 16 cases had controversial pure tone threshold compared with speech discrimination. 23 had normal temporal bone CT image or MRI. 10 cases accompanied with peripheral neuropathy. CONCLUSION: Abnormal ABR, normal DPOAE, unparallel pure tone threshold to speech audiometry, loss of stapedial acoustic reflex and OAE contralateral acoustic suppression, loss of the pure tone threshold primarily in low-frequency SNHL are the important features of AN, which shows that the lesioned site may lie at the intracochlear acoustic nerve. It is necessary to differentiate it from the common SNHL and central nerve hearing loss.

Acoustic Impedance Tests↗