Biomedical subjects

Qianlong Zhu

Publications and source records attributed to Qianlong Zhu.

5 recordsLinked to original sources

PubMed2005

Ethanol-induced alterations in Rab proteins: possible implications for pituitary dysfunction.

Chronic exposure of pubertal male rats to ethanol results in a decline in serum testosterone, increased gonadotropins, pituitary luteinizing hormone (LH) and follicle stimulating hormone (FSH) content, and decreased or inappropriately normal serum LH and FSH levels, suggesting impaired secretory release of gonadotropins. The molecular mechanisms behind this disorder are undefined, but a disruption of vesicle-mediated secretory processes is possible because intracellular protein trafficking pathways are involved in secretion of glycoproteins such as FSH and LH. Because small GTP-binding proteins of Rab family have been implicated as key regulators of membrane and protein trafficking in mammalian cells, this study was designed to test if ethanol-impaired pituitary FSH and LH secretion is associated with changes in Rab proteins, particularly Rab1B, Rab3B, Rab6, and Rab11. Male Sprague-Dawley rats 35 days old were pair-fed a Lieber-DeCarli diet with ethanol or without ethanol for 5 to 60 days. After ethanol exposure, serum testosterone levels decreased while LH and FSH were inappropriately unchanged. Immunohistochemical staining showed decreased Rab1B, Rab3B, and Rab11 protein levels in ethanol-treated pituitaries. Immunoblotting showed that ethanol induced a transient reduction in Rab6 after 5 days of ethanol exposure, whereas Rab3B decreased after 20 days, Rab11 after 30 days, and Rab1B after 60 days. Despite these changes in Rab proteins, mRNA levels were unaffected by ethanol exposure. We concluded that reductions in key Rab proteins may lead to altered vesicle trafficking and may play a role in disruption of pituitary FSH and LH secretion caused by ethanol.

Animals↗

PubMed2005

Exposure to ethanol induces oxidative damage in the pituitary gland.

Chronic exposure of pubertal male rats to ethanol results in a decline in serum testosterone and decreased or inappropriately normal serum luteinizing hormone (LH) and follicle stimulating hormone (FSH) levels suggesting a functional defect in the pituitary. The molecular mechanisms behind this disorder are undefined. A role for ethanol-induced oxidative damage in the pathophysiology is supported by studies in liver, muscle, and heart of experimental animals, but there is limited evidence in the pituitary. We examined markers of oxidative damage to lipids and proteins in pituitaries from rats consuming ethanol for 5, 10, 20, 30, and 60 days in addition to markers of damage to nucleic acids in pituitaries after 60 days of ethanol exposure. There were increases in 8-oxo-deoxyguanosine immunoreactivity, a marker of oxidative damage to nucleic acids, and an overall increase in malondialdehyde and 4-hydroxynonenal, markers of lipid peroxidation. Protein carbonylation and protein nitrotyrosination, markers of protein oxidation, were significantly increased after 30 days and 60 days of ethanol consumption, respectively. After 60 days of ethanol exposure, TUNEL assay revealed that cell death in the ethanol-treated pituitaries was not significantly different from that in the pair-fed controls at the time of examination. We also measured serum testosterone, FSH, and LH after ethanol consumption for 5, 10, 20, 30, and 60 days. Through 5 to 60 days of ethanol exposure, testosterone levels were consistently lower whereas LH and FSH were inappropriately unchanged, suggesting pituitary malfunction. These results provide evidence for ethanol-induced oxidative damage at the pituitary level, which may contribute to pituitary dysfunction.

Aldehydes↗

PubMed2004

Calponin is expressed by Sertoli cells within rat testes and is associated with actin-enriched cytoskeleton.

Within seminiferous tubules, Sertoli cells form three types of actin-filament-containing cell junctions, viz., tight junctions, ectoplasmic specializations, and tubulobulbar complexes. These Sertoli cell junctions are involved in the formation of the blood-testis barrier, germ cell translocation, and the release of spermatozoa. Actin and actin-binding proteins are important for these functions. In the present study, a monoclonal antibody against human smooth-muscle-cell calponin detected a 38-kDa protein in a total protein extract of rat testis. The protein has a molecular weight identical to that of aorta calponin and binds calmodulin. Calponin mRNA was detected in the testis and cultured rat Sertoli cells by the reverse transcription/polymerase chain reaction method. Thus, the 38-kDa protein present in the testes is a basic isoform of calponin. In adult rats (70 days of age or older), calponin was detected within seminiferous tubules at sites of Sertoli cell junctions. Cultured Sertoli cells express calponin, whereas cultured spermatogonia do not. When rat testicular tissue was fractionated into cytosol, membrane, and cytoskeleton fractions, calponin was detected in all three fractions. Calcium, potassium, and okadaic acid reduced the amount of calponin associated with the cytoskeleton. These data suggest that Sertoli cells express calponin. The function of calponin within the testis is as yet unknown.

Actins↗

PubMed2003

Antiphospholipid antibodies before and after liver transplantation.

OBJECTIVE: The aim of this study was to determine whether liver transplantation of patients with antiphospholipid antibodies (APA) is 1) adversely affected with vascular thrombosis and 2) whether such antibodies persist post transplantation. METHODS: Twelve patients with APA awaiting transplant were identified and characterized biochemically and immunologically. Each had the level of APA determined using commercially available enzyme-linked immunoassay kits before, during, and after liver transplantation. RESULTS: No patient in this series experienced a transplant-related vascular thrombosis. The titer of APA fell to levels at or below those present in normals and remained low in two of 12 or undetectable in 10 of 12 patients 1 yr after liver transplantation. CONCLUSIONS: We reached the following conclusions: 1) Antiphospholipid positivity does not identify patients at high risk for post-transplant vascular thrombosis. 2) The levels of antiphospholipid present in sera pretransplant fell during transplantation and remained low or undetectable 1 month and 1 yr post transplantation.

Aged↗

PubMed2002

Effects of soybean extract on morphology and survival of Caco-2, SW620, and HT-29 cells.

Soybean consumption may be beneficial to prevention of certain human cancers. Low incidence of colon cancer in Asian countries is associated with consumption of soybean products. A limited number of human and animal studies suggested that soybean consumption might prevent colon cancer; other studies did not support this conclusion. Therefore, it is important to understand the biological effects of soybeans on colon cells. In the present study, cultures of Caco-2, SW620, and HT-29 cells were treated with soybean extract, the soluble fraction of a soybean product. The crude extract contains proteins and many soluble components of soybeans. After incubation with soybean extract (1-6%, vol/vol) for 24 h, most Caco-2 cells were found to contain numerous vacuoles within the cytoplasm and to become very flat. Exposure to > 6% soybean extract resulted in cell death and giant vacuoles. Soybean extract (0.25-2%) induced small vacuoles within the cytoplasm of SW620 cells. SW620 cells detached from culture dishes at > 2% soybean extract. Exposure to 0.5-2% soybean extract produced vacuoles within HT-29 cells similar to those observed in SW620 cells. Soybean extract significantly reduced density of Caco-2, SW620, and HT-29 cells. Reducing protein content of soybean extract reduced but did not abolish its effects on colon cells. Purified genistein (12.5 micrograms/ml) was capable of producing morphological changes similar to those observed after treatment of colon cells with soybean extract. Assays using annexin V-propidium iodide demonstrated that treatment of Caco-2 and SW620 cells with soybean extract increased cell death. Membranes of vacuoles in soybean-treated Caco-2 and SW620 cells were labeled with Texas red-conjugated wheat germ agglutinin, a cytological marker for the Golgi apparatus. Exposure to soybean extract enhanced protein levels of Rab6, a small GTP-binding protein that is involved in regulation of membrane traffic of the Golgi apparatus. Data from this study suggest that exposure to soybean extract or isoflavones affects morphology and survival of colon cancer cells and that the response to soybean extract varies depending on the cell lines examined.

Caco-2 Cells↗