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Biomedical subjects

C Gu

Publications and source records attributed to C Gu.

89 records · Page 5Linked to original sources
PubMed1993

Synthesis of phosphotyrosine-containing peptides by the solid-phase method. A re-examination of the use of Boc-Tyr(PO3Bzl2)-OH.

A practical and convenient procedure for making phosphotyrosine-containing peptides by the solid-phase method was developed. Phosphotyrosine was incorporated via Boc-Tyr(PO3Bzl2)-OH. The completed peptide was cleaved from the solid support by treatment with 1 M TMSBr-thioanisole-TFA. By gel-phase 31P-NMR spectroscopy we found that one of the benzyl protecting groups on phosphate was completely removed by two consecutive runs of Boc deprotection with 50% TFA-DCM. However, the other benzyl group remained intact throughout the synthesis (35 cycles).

Amino Acid Sequence↗
PubMedDate not supplied

p75 neurotrophin receptor as a modulator of survival and death decisions.

The p75 receptor is the founding member of the TNF receptor superfamily. Members in this receptor family share a common cysteine motif repeated two to six times that serves as the ligand binding domain. In addition, several members contain a cytoplasmic region designated the death domain. The neurotrophins NGF, BDNF, NT-3, and NT-4 each bind to the p75 receptor and also more selectively to members of the Trk family of receptor tyrosine kinases. Although the biological functions of p75 have been elusive, recent experimental evidence supports an involvement of this receptor in apoptosis. This presents a counter-intuitive function for neurotrophins, which are normally required for the survival of neurons during development. The life-and-death decisions by neurotrophins appear to be governed by the level of expression and signaling activities of the p75 and Trk tyrosine kinase receptors and their downstream effector molecules. The generation of the correct number of cells in the nervous system is a highly controlled and coordinated process that is the consequence of cell proliferation and cell death decisions. The appropriate number of neuronal and glial cells formed during development guarantees the establishment of proper innervation and functional synaptic connections. One common mechanism to account for the number of viable cells is the ability to form ligand-receptor complexes that promote cell survival under conditions of limiting concentrations of trophic factors. Another diametrically opposed mechanism is to produce ligand-receptor interactions that can activate programmed cell death directly.

Animals↗
PubMedDate not supplied

Population differences in the pattern of familial aggregation for sex hormone-binding globulin and its response to exercise training: the HERITAGE Family Study.

Familial influences were investigated for baseline sex hormone-binding globulin (SHBG) and its response (post-training minus baseline) to a 20-week endurance exercise training program. One hundred, eighty-four participants from 85 Black families in the HERITAGE Family Study (HERITAGE) were analyzed using a familial correlation model. Baseline SHBG values and the training response were adjusted for the effects of age, baseline BMI, testosterone, estradiol, and fasting insulin levels (plus baseline SHBG values for the training response) within four sex-by-generation groups prior to genetic analysis. Baseline SHBG levels were influenced by appreciable familial effects (maximum heritability h(2) = 54%) with neither spouse resemblance nor sex and generation differences in the correlations. This estimate is only slightly, but not significantly, smaller than the heritability of 64% reported previously in 428 participants from 99 White families in HERITAGE. In contrast to the modest familial effects for the training response in White participants in HERITAGE (h(2) = 25%), there were no evidence of familial resemblance in Blacks in the current study. Furthermore, there was heterogeneity for both baseline SHBG and the training response between Blacks and Whites in the pattern of familial aggregation. In conclusion, baseline SHBG levels are influenced by significant familial effects in both Blacks and Whites, independent of the effects of age, sex, and baseline values of BMI, testosterone, estradiol, and fasting insulin levels. Whereas modest familial effects were detected for the training response in Whites, the lack of similar effects in Blacks may be due to the smaller sample size.

Black People↗
PubMedDate not supplied

Expression of Y box-binding protein-1 correlates with DNA topoisomerase IIalpha and proliferating cell nuclear antigen expression in lung cancer.

Y box-binding protein-1 (YB-1), a member of the DNA binding protein family, interacts with inverted CCAAT boxes (Y-boxes). Y-boxes are located on the promoter of numerous genes, such as DNA topoisomerase IIalpha (Topo IIalpha), proliferating cell nuclear antigen (PCNA) and multidrug resistance 1 (MDR1). In this study, we used immunohistochemical (IHC) staining to detect YB-1 expression in 59 lung cancer tissues and to evaluate whether YB-1 expression was associated with the expression of YB-1 target genes such as Topo IIalpha, PCNA and MDR1 in human lung carcinoma. Twenty-eight out of 59 cases (47.5%) were stained positive for YB-1 in the cytoplasm, while 30 out of 59 cases (50.8%) were positive for PCNA in the nuclei. Topo IIalpha-positive cells were detected in 16 out of 59 cases (27.1%). Eight out of 59 cases (13.6%) had greater than 5% P-gp positive cells expression. There was a significant correlation between the YB-1 and Topo IIalpha expression in small cell lung cancer (SCLC) (p=0.0242). YB-1 expression also correlated with PCNA expression in non-small cell lung cancer (NSCLC) (p=0.0001). Higher levels of YB-1 expression were associated with T3-4 and Stage III-IV tumors in adenocarcinomas (p=0.0072; p=0.0168). In contrast, no relationship was found between YB-1 expression and P-gp expression. Our study suggests that YB-1 expression correlates with Topo IIalpha and PCNA expression in lung cancer.

ATP Binding Cassette Transporter, Subfamily B, Mem↗