Frequency-specific plasticity of the auditory cortex elicited by thalamic stimulation in the rat.

In a process known as frequency-specific plasticity, electrical stimulation of the ventral division of the medial geniculate body (MGBv) in the thalamus evokes a shift in the frequency-tuning curves of auditory cortical (AC) neurons toward the best frequency (BF) of stimulated MGBv neurons. However, the underlying synaptic mechanisms of this process are uncharacterized. To investigate whether this dynamic change depends on thalamocortical (TC) synaptic plasticity, we studied frequency-specific changes in synaptic transmission efficacy in TC pathways evoked by thalamic stimulation. Specifically, we induced cortical plasticity by repetitive focal electrical stimulation of the MGBv in rats and measured receptive field shifts and local field potentials in AC neurons. Our data show that focal electrical stimulation of the MGBv induced receptive field shifts as well as long-term potentiation or depression of the local field potentials in AC neurons. The evoked potentiation and depression depended on the frequency of the electrical stimulation of the MGBv synchronized with the BF of MGBv and AC neurons. Receptive field shifts were produced by inhibition of responses at the BF of the recorded AC neurons and facilitation of responses at the BF of the stimulated MGBv neurons. These results suggest that MGBv neurons play a decisive role in the expression of AC synaptic plasticity and that activation of different frequency-specific TC pathways may be the synaptic mechanism underlying this plasticity.

[Status and influencing factors of the duration of breast feeding in Shihezi].

OBJECTIVE: To report the duration of breastfeeding among a population of Shihezi women and to identify factors that are associated with the duration of any breastfeeding. METHODS: A cohort study was performed among 399 infants and mothers randomly recruited both in the People's Hospital and the Maternal and Child Health Institute in 2003 in Shihezi City to investigate the feeding practices and feeding duration by month. Cox's proportional hazards model was used to identify factors that were associated with the risk for termination of breastfeeding before 24 months. RESULTS: The median of breastfeeding duration was 6 months (25% quartile was 5 months and 75% quartile was 11 months). A majority of infants were weaned in the sixth month. By 12 months, only 21.8% of infants were still receiving breastfeeding and 0.5% by 24 months. Breastfeeding duration was associated with mother's return to work. CONCLUSIONS: The duration of breastfeeding in Shihezi City was short.

[Peripheral blood CD34+-positive mononuclear cells participate in neovasculogenesis of human ovarian epithelial carcinoma].

OBJECTIVE: To observe whether endothelial cell (EC) progenitors (CD(34)(+)-positive mononuclear cells) participated in neovasculogenesis of ovarian epithelial carcinoma through in vitro and in vivo experiments, and to explore the mechanism of tumor neovasculogenesis. METHODS: CD(34)(+)-positive mononuclear cells were isolated from peripheral blood of ovarian epithelial carcinoma patients by means of magnetic beads coated with antibody to CD(34)(+), plated on culture dishes coated with human fibronectin in endothelium medium, and examined by using RT-PCR, fluorescence-activated cell sorting (FACS) and nitric oxide (NO) assay kit for the expression of EC lineage-markers. EC-like cells were labeled with DiI ex vivo, and injected into immunodeficiency mice model with transplanted hypodermic SKOV3 by caudal vein. After 4 - 6 weeks, the tumor was resected and examined by confocal microscopy, and immunohistochemistry. RESULTS: In vitro, CD(34)(+)-positive mononuclear cells differentiated into ECs. In animal models of SKOV3, EC progenitors (CD(34)(+)-positive mononuclear cells) incorporated into sites of neovasculogenesis in tumor, 4 - 6 weeks later DiI-labeled cells incorporated into capillaries and small arteries. CONCLUSIONS: The neovasculogenesis in human ovarian epithelial carcinoma involves angiogenesis and vasculogenesis.

[Expression and significance about VEGF, KDR, MMP-1, and transcription factor Ets-1 in human cervical carcinoma].

OBJECTIVE: To study the expression of VEGF, KDR, MMP-1, and its transcription factor Ets-1 on the interstitial neovasculogenesis in human cervical carcinoma on molecular level, which may provide further theoretic bases on judgement of prognosis and explain interregularity between neovasculagenetic factors. METHODS: VEGF, KDR, MMP-1, and Ets-1 were detected in 87 cervical carcinomas by in situ hybridization and immunohistochemistry. The survival curves for patients with detected tumors were compared with the curves for those without tumors. Multivariate analyses were performed with Pearson analysis. RESULTS: VEGF mRNA and its protein were mainly expressed in cytoplasms of tumor cells, positive rate was 78.6% (68/87) and 70.4% (61/87) respectively. KDR mRNA and its protein were mainly expressed in vascular endothelial cells, as correlation coefficient between KDR and VEGF was 0.892. Over expression of MMP-1 was seen in both endothelial cells and tumor cells, especially in hyperplasia of endothelial cells. Ets-1 was mainly expressed in both endothelial cells and tumor cells, correlation coefficient between Ets-1 and KDR, MMP-1, was 0.900 and 0.873, respectively. Four factors of above were highly related with tumor differentiation, lymph nodes metastasis as well as 5 years survival rate. CONCLUSIONS: VEGF, KDR, MMP-1, and Ets-1 are important factors on neovasculogenesis in cervical carcinoma, which may be considered to be reference indicator for determining biology behavior of cervical carcinoma, and may provide further theoretic bases on antineovasculagenetic therapy.