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Biomedical subjects

C D Liu

Publications and source records attributed to C D Liu.

24 records · Page 2Linked to original sources
PubMed1994

Peptide YY immunoneutralization inhibits meal-induced absorption in vivo.

BACKGROUND: Plasma peptide YY (PYY) levels rise after a meal and have recently been shown to increase small bowel-absorption. The purpose of this study was to determine whether immunoneutralization of PYY would block postprandial absorption in vivo. METHODS: Exteriorized, neurovascularly intact jejunal and ileal segments (25 cm) were created in six mongrel dogs. After a 2-week recovery luminal perfusion with an isotonic buffer, containing [14C]-polyethylene glycol as a volume marker, was used to analyze water and sodium flux after an oral meal. Each meal was accompanied by either intravenous anti-PYY (0.5 mg.kg-1.h-1) or nonspecific immunoglobulin IG (control). PYY antibody binding was determined by radioimmunoassay. RESULTS: Displacement studies showed complete PYY neutralization. In control experiments feeding increased absorption of sodium and water in both segments. PYY immunoneutralization had no effect on jejunal absorption but significantly diminished ileal absorption (p < 0.05). CONCLUSIONS: These results suggest that PYY acts selectively in the ileum to increase postprandial fluid and electrolyte absorption after a meal. Agents directed at PYY-stimulated absorption may prove to be of therapeutic benefit in patients with malabsorptive conditions.

Animals↗
PubMed1991

[Association of HLA antigens with thyrotoxic periodic paralysis].

Periodic paralysis is a rare and peculiar complication of thyrotoxicosis, especially in Chinese and Japanese patients. The susceptibility to autoimmune thyroid disease has recently been reported to be strongly linked with certain immunogenetic factors. The objective of this study was to seek a genetic marker by HLA typing in Chinese patients with thyrotoxic periodic paralysis (TPP). The distribution of HLA-A, B, C, DR and DQ antigens in 20 thyrotoxic patients with periodic paralysis and 51 thyrotoxic patients without periodic paralysis was compared with that in 100 controls. The results showed that among the patients with TPP, these was a highly significantly increase of HLA-B51 frequency and B51 appeared to be linked with Cw3 in a state of dysequilibrium.

Adult↗
PubMed1990

[Etiological and influential factors of involutional osteoporosis in old Chinese].

A comprehensive analysis is reported in 376 healthy middle and old-age persons, including measurements of bone mineral content (BMC) of the mid-radias, pituitary sex hormones (RIA), serum calcium, phosphate, albumin, alkaline phosphatase, urinary calcium, phosphate, hydroxyproline (BCA), daily intake of protein and calcium, physical exercise and activity, body weight, amenorrhea etc. Results showed that the preponderance of bone resorption over bone formation is the essential pathophysiological change of involutional osteoporosis. For females, bone loss is regulated mainly by estrogen in presenile group, co-regulated by estrogen and androgen in senile group. For males, urinary hydroxyproline excretion is also regulated by estrogen A remarkable correlation was observed between BMC and the following factors: serum calcium, urinary calcium, hydroxyproline, body weight, physical exercise, amenorrhea, intake of protein and calcium. Our data indicated that the intake of calcium daily in old chinese should not be lower than 700 mg (male) and 900 mg (female), protein should not be lower than 60-70 g. The age of onset, prevalence rate and BMC average reduction rate of osteoporosis in chinese were also observed in the studies.

Aged↗
PubMedDate not supplied

Synthetic peptide YY analog binds to a cell membrane receptor and delivers fluorescent dye to pancreatic cancer cells.

Pancreatic cancer continues to have a dismal prognosis despite multimodality treatment plans. Peptide YY (PYY) is a gut hormone that suppresses pancreatic exocrine and endocrine function. Previous experiments have shown that shortened synthetic PYY(22-36) analog decreases pancreatic cancer cell growth while also decreasing intracellular cyclic adenosine monophosphate. Our purpose was to construct an optimal synthetic PYY analog that binds to pancreatic cancer cells that may be used for imaging and therapy. Biotinylated PYY analogs with lengths ranging from PYY(1-36), PYY(9-36), PYY(14-36), PYY(22-36), and PYY(27-36) were tested with flow cytometry and receptor cross-linking studies to measure cell membrane binding. Growth inhibition studies were also performed using monotetrazolium tests to determine potency of various PYY analogs. Quantitative flow cytometry reveals the highest specific binding of PYY(14-36) to pancreatic cancer cells. Cross-linking studies reveal a receptor on the cell membrane of human pancreatic ductal adenocarcinoma cells. Growth inhibition studies reveal that PYY (14-36) has the highest potency against PANC-1 and MiaPaCa-2 cells. A novel synthetic PYY analog binds to the cell surface of pancreatic cancer cells and has the ability to deliver fluorescent dyes. The strategy of using biotinylated peptides to deliver avidin-dye complexes to cancer cells will allow imaging of pancreatic tumors and delivery of therapeutic agents.

Biotinylation↗