Biomedical subjects

C To

Publications and source records attributed to C To.

6 recordsLinked to original sources

PubMed2002

High-throughput array production using precision glass syringes.

The advantages of using 1, 96, or 384 precision glass syringes in automated high-throughput microdispensers in creating highly uniform and reproducible DNA, protein, and organic compound array filters and slides are described. Using the Hydra Microdispenser and Tango Liquid Handling system, 0.1-5 ng (in 50-300 nL) PCR-amplified, human cancer-related genes and housekeeping genes were spotted onto nylon membranes and coated slides. Protein solutions of 50 microg/mL to 1 mg/mL were spotted onto coated slides or onto MaxiSorp 96-well plates. Up to 6144 spots/membrane and up to 1000 spots/slide were printed. The size of the spots created by glass syringes was uniform and reproducible (precision variation of less than 5%) from spot to spot and membrane to membrane. Using a Tango 384 system, a total of ten 6144-spot filters can be produced in approximately 25 min, translating into a spotting speed of 2.5 min/membrane.

Oligonucleotide Array Sequence Analysis↗

PubMed2000

Tear proteins of normal young Hong Kong Chinese.

BACKGROUND: Analysis of tear proteins is of diagnostic value for abnormal ocular conditions such as dry eye syndrome. Many studies of tear proteins have been performed on Caucasian subjects. However, little is known about these proteins in Chinese eyes. METHODS: The total tear protein concentrations of 30 normal young Hong Kong Chinese were determined by the Bradford method and the modified Lowry method. Bovine serum albumin (BSA) and bovine immunoglobulin G (IgG) were both used as standards for each method. The tear protein patterns were determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), and the concentrations of major tear proteins were quantified by scanning densitometry after SDS-PAGE. RESULTS: The mean +/- SD total tear protein concentrations determined by the Bradford method, using BSA and IgG as standards, were 6.05 +/- 1.58 mg/ml and 11.48 +/- 2.32 mg/ml respectively. The values determined by the modified Lowry method, using the same two standards, were 9.66 +/- 2.03 mg/ml and 7.53 +/- 1.80 mg/ml respectively. The mean +/- SD concentrations of major tear proteins were 2.73 +/- 0.82 mg/ml for lactoferrin, 0.021 +/- 0.028 mg/ml for human serum albumin, 2.89 +/- 0.88 mg/ml for tear-specific prealbumin and 2.46 +/- 0.44 mg/ml for lysozyme. CONCLUSION: The results of total tear protein concentrations indicated that values obtained from different methods and different standards were not comparable. The tear protein patterns of our subjects were qualitatively similar to those reported for Caucasian subjects. However, the concentrations of the major proteins of our subjects were not in accordance with those reported previously. The main reason may be the large variability of method used.

Adolescent↗

PubMed2000

Molecular mechanism(s) of insulin action on the expression of the angiotensinogen gene in kidney proximal tubular cells.

To investigate the molecular mechanism(s) of insulin action on the expression of the angiotensinogen (ANG) gene in kidney proximal tubular cells, we constructed a fusion gene, pOGH (hANG N-1064/+27), containing the 5'-flanking regulatory sequence of the human ANG gene fused with the human growth hormone (hGH) gene as a reporter and stably integrated the fusion gene into the opossum kidney (OK) cell genomes. The level of expression of pOGH (hANG N-1064/+27) was quantified by the amount of immunoreactive hGH secreted into the medium. The addition of a high level of D(+)-glucose (25 mM) or phorbol 12-myristate 13-acetate (PMA, 10(-7) M) stimulated the expression of the fusion gene in OK cells. The stimulatory effect of glucose (25 mM) was blocked by insulin and tolrestat (an inhibitor of aldose reductase). Tolrestat also inhibited the increase of cellular DAG and PKC activity stimulated by 25 mM glucose. While insulin did not affect the cellular DAG and PKC activity, it did block the stimulatory effect of high glucose (25 mM) and PMA on the expression of the fusion gene. Finally, PD98059 (an inhibitor of mitogen-activated protein kinase kinase (MEK)) enhanced the stimulatory effect of high levels of glucose and blocked the inhibitory effect of insulin on the expression of the fusion gene as well as on the phosphorylation of MEK and mitogen-activated protein kinase (MAPK). In contrast, Wortmannin (an inhibitor of phosphatidylinositol-3-kinase) did not block the inhibitory effect of insulin on the ANG gene expression. These studies demonstrate that the action of insulin, blocking the stimulatory effect of a high level of D(+)-glucose (25 mM) on the ANG gene expression is mediated, at least in part, via the 5'-flanking region of the ANG gene and MAPK signal transduction pathway.

Androstadienes↗

PubMed1998

Differential expression of Met/hepatocyte growth factor receptor in subtypes of non-small cell lung cancers.

Hepatocyte growth factor (HGF)/scatter factor (SF) is a multifunctional factor that stimulates epithelial cell motility, invasion and morphogenesis. Its receptor is a transmembrane tyrosine kinase encoded by the Met proto-oncogene. Several studies have suggested a possible role for HGF/Met in tumor development and progression. To investigate the potential roles of Met in human lung cancer biology, we have studied the mRNA and protein expression of Met in normal lung tissue, primary non-small cell lung carcinoma (NSCLC), and NSCLC cell lines. The results indicated a differential pattern of Met expression among various subtypes of NSCLC. The majority of squamous cell carcinoma (SQCC), either in vivo or in vitro, expressed Met mRNA and its protein product at levels much lower than or similar to normal lung tissue or bronchial epithelium. Moreover, SQCC characteristically over-expressed a variant Met mRNA which corresponds to a 5' partially deleted transcript produced by alternative splicing. In contrast, the expression of Met mRNA and its protein product in adenocarcinoma (ADC) and large cell undifferentiated carcinoma were more heterogeneous. Overexpression was demonstrated in approximately 35% and 20% of these subtypes of NSCLC, respectively. Among ADC, intermediate to high levels of Met immunoreactivity correlated with greater degree of tumor differentiation. Furthermore, an accentuation of Met immunoreactivity was often noted in cancer cells at the advancing edge of tumors. These findings support a role for Met in lung cancer cell invasion and differentiation in vivo, but its expression and functions may be modified by the differentiation phenotype of the tumor cells.

Adenocarcinoma↗

PubMed1998

Thirty-day monitoring of insulin-like growth factors and their binding proteins in intensive care unit patients.

This study investigates the regulation of the insulin-like growth factors (IGFs) and their regulatory proteins in 14 critically ill patients during the 30-day period following admission to an intensive care unit (ICU). Levels of IGF-I, IGF-II, IGF binding protein-3 (IGFBP-3) and acid-labile subunit (ALS) were low on admission, and in the 8 patients whose serum IGF-I levels failed to increase over 30 days, levels of the other proteins also remained low, while IGFBP-3 proteolytic activity increased. Of these proteins, ALS correlated best with serum levels of nutritional indicators, particularly prealbumin. IGFBP-2 and IGFBP-6 levels tended to be high in critically ill patients, but showed little change over the 30-day period. In contrast, IGFBP-1 levels were high on admission, correlated with early changes in nitrogen balance, and fell rapidly during the first week. By demonstrating that the IGF-I response in ICU patients is related to changes in the IGF regulatory proteins, this study may be of value in planning therapeutic intervention using growth hormone or IGF-I.

Adult↗

PubMedDate not supplied

Effect of renin-angiotensin system blockade on the expression of the angiotensinogen gene and induction of hypertrophy in rat kidney proximal tubular cells.

Studies have shown that high levels of glucose and angiotensin II (Ang II) stimulate hypertrophy and the expression of matrix protein genes in mouse proximal tubular cells in vitro. The present study tested the hypothesis that blockade of the renin-angiotensin system (RAS) inhibits the stimulatory effect of high levels of glucose on the expression of the renal angiotensinogen (ANG) gene and the formation of Ang II and subsequently attenuates the induction of hypertrophy in kidney proximal tubular cells. Immortalized rat proximal tubular cells (IRPTC) were cultured in monolayer. The levels of expression of rat ANG and ANG mRNA in the IRPTC were quantified by specific radioimmunoassays for rat ANG (RIA-rANG) and by a reverse-transcription polymerase chain reaction (RT-PCR) assay, respectively. Hypertrophy of IRPTC was analyzed by flow cytometry (FACScan) and cellular protein assay. Our studies showed that losartan (an Ang II (AT(1))-receptor blocker), perindopril and captopril (inhibitors of angiotensin-converting enzyme) blocked the stimulatory effect of a high level of glucose (i.e. 25 mM) on the expression of the rat ANG gene and hypertrophy in IRPTC but not by the Ang II (AT(2))-receptor blocker. Our studies indicate that the blockade of RAS is effective in inhibiting the stimulatory effect of hyperglycemia on the expression of the ANG gene and hypertrophy in IRPTC, supporting the notion that the local formation of intrarenal Ang II may play a role in the development of renal hypertrophy during early diabetes.

Angiotensin II↗