Connective tissue growth factor is secreted through the Golgi and is degraded in the endosome.

Connective tissue growth factor (CTGF) is a cysteine-rich heparin-binding polypeptide that promotes proliferation, collagen synthesis, and chemotaxis in mesanchymal cells. When coinjected subcutaneously with transforming growth factor beta (TGFbeta), CTGF promotes sustained fibrosis in rats. However, little is known about the cell biology and structure/functional relationship of CTGF. In particular, no detailed characterization of the subcellular localization of CTGF has occurred, nor have sequences been identified within this protein required for this localization. In this report, using immunofluorescence and Western blot analysis, we show that CTGF is localized to the Golgi apparatus both in dermal fibroblasts and activated hepatic stellate cells. Using these methods, no CTGF was detected in endosomal, plasma membrane, cytosolic or nuclear fractions. Addition of brefeldin A, a drug that disrupts the Golgi, blocks the secretion of CTGF. We further show that the amino-terminal 37 amino acids of CTGF are sufficient to localize a heterologous protein (red fluorescent protein, RFP) to the Golgi. Although within this region of human CTGF is a N-glycosylation site, tunicamycin, which blocks N-linked glycosylation, has no significant effect on CTGF secretion. Surprisingly, mutation of a single amino acid residue, CYS-34, to alanine prevents localization of a CTGF-RFP fusion protein to the Golgi. These results are the first proof that endogenous CTGF is localized to the Golgi apparatus. Furthermore, using exogenously added (125)I-labeled CTGF, we show that CTGF is internalized and rapidly degraded in the endosome. That is, CTGF is quantitatively secreted through the golgi and is degraded in the endosome.

Solid phase extraction of ultra-trace amounts of Ag+ by using octadecyl silica membrane disks modified with a new fulvalen derivative.

A simple method for the rapid extraction and determination of ultra-trace amounts of Ag+ ions using octadecyl-bonded silica membrane disks modified with a recently synthesized fulvalen (tetramethyltetrathiafulvalen) (TMTTF) and graphite furnace atomic absorption spectrometry is presented. The extraction efficiency and influence of the flow rate, pH, nature of the counter ion and type and the least amount of eluent for the stripping of Ag+ from disks and breakthrough volume were evaluated. The maximum capacity of the membrane disks modified by 5 mg of TMTTF used was found to be 482 +/- 6 micrograms Ag+. The detection limit of the proposed method is 1.0 ng/dm3. The method was applied to the recovery of Ag+ ions from different synthetic and water samples.

Solid phase extraction and determination of lead in soil and water samples using octadecyl silica membrane disks modified by bis[1-hydroxy-9,10-anthraquinone-2-methyl]sulfide and flame atomic absorption spectrometry.

A simple, reliable and relatively fast method has been developed to selectively separate and concentrate trace amounts of lead from aqueous samples for the measurement by flame atomic absorption spectrometry. By the passage of aqueous samples through an octadecyl-bonded silica membrane disk modified by a recently synthesized bis(anthraquinone)sulfide, Pb(2+) ions adsorb quantitatively and almost all matrix elements will pass through the disk to drain. The retained lead ions are then stripped from the disk by minimal amount of acetic acid as eluent. The proposed method permitted large enrichment factors of about 300 and higher. The limit of detection of the proposed method is 50 ng Pb(2+) per 1000 ml. The effects of various cationic interferences on the recovery of lead in binary mixtures were studied. The method was successfully applied to the determination of lead in soil and water samples.