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Biomedical subjects

N Huang

Publications and source records attributed to N Huang.

114 records · Page 7Linked to original sources
PubMed1988

Alpha-tocopherol, a potent modulator of endothelial cell function.

The effect of alpha-tocopherol on various endothelial cell functions was evaluated in vitro using cultures of human umbilical vein endothelial cells. Prostacyclin synthesis, plasminogen activator activity and von Willebrand factor activity were evaluated in control and alpha-tocopherol supplemented cultures. Alpha-tocopherol produced stimulation of prostacyclin production which peaked at or near 0.5 mM. Plasminogen activator activity was markedly reduced by the addition of alpha-tocopherol. Von Willebrand factor activity showed a significant decrease of processed and cellular forms that was dose-dependent. The incorporation of alpha-tocopherol into endothelial cells could be demonstrated by measuring intracellular levels of the vitamin in washed endothelial cells. Our results show that alpha-tocopherol has a profound effect on multiple endothelial cell functions which are intimately involved in hemostasis.

Cells, Cultured↗
PubMed1980

Effect of cimetidine and pancreatic enzymes on serum and fecal bile acids and fat absorption in cystic fibrosis.

Steatorrhea persists in most cystic fibrosis patients with exocrine pancreatic insufficiency despite enzyme replacement, perhaps because gastric acid inactivates oral enzymes. Bile acid malabsorption may parallel steatorrhea. We studied the effect of adding cimetidine (300 mg a.c.) to pancreatic enzyme therapy in 8 patients with cystic fibrosis and steatorrhea. Fecal bile acid, weight and fat, and postprandial serum bile acids were measured with and without cimetidine. D-Xylose absorption was normal in all patients. On constant diets, 72-hr stools were collected during enzyme therapy and during a 5-day course of enzymes plus cimetidine. Addition of cimetidine to enzyme decreased fecal weight (257 +/- 32.6 to 198.6 +/- 32.5 g/day), increased the percent of dietary fat absorbed (75.0 +/- 4.9 to 80.1 +/- 4.1%, P less than 0.05), but had no effect on fecal bile acids (4.7 +/- 0.9 to 4.2 +/- 1.0 mmol/m2/day). Compared with no therapy, enzymes increased postprandial serum bile acid at 60 min (9.56 +/- 1.0 to 14.0 +/- 1.3 muM/liter, P less than 0.05) and at 120 min (9.4 +/- 1.2 to 12.4 +/- 1.6 muM/liter, P less than 0.02). The addition of cimetidine to enzymes abolished this postpranidial bile acid rise. In conclusion, addition of cimetidine to oral pancreatic enzyme therapy decreases stool weight and fat but perhaps not stool bile acids in cystic fibrosis. However, correction of fat absorption is incomplete. Enzyme therapy increases postprandial serum bile acids, and this increase is abolished with oral cimetidine. In view of the incomplete correction of steatorrhea and the alterations in serum bile acids induced by cimetidine, further research with this new medication is needed before it can be recommended for routine clinical use in patients with cystic fibrosis.

Adolescent↗
PubMedDate not supplied

Expression and purification of functional human alpha-1-Antitrypsin from cultured plant cells.

Human alpha-1-antitrypsin (AAT), the most abundant protease inhibitor found in the blood, was expressed in rice embryonic tissue suspension cell culture. This was accomplished by cloning the codon-optimized AAT gene into a vector containing the rice RAmy3D promoter and its signal sequence. The synthetic gene incorporates codons synonymous with those found in highly expressed rice genes. Approximately 1000 stable transformed calli were produced by particle bombardment mediated transformation and were screened for high AAT expression using a porcine elastase inhibitory activity assay. The band shift assay also confirmed that rice-derived AAT is functional regarding its binding capability to the elastase substrate. Time course studies were conducted to determine the optimum, postinduction expression levels from cell culture. AAT expression equivalent to 20% of the total secreted proteins was achieved, and a purification scheme was developed that yielded active AAT with purity greater than 95%. The potential applications of purified plant-derived AAT for treatments of various AAT-deficient diseases are discussed.

Animals↗
PubMedDate not supplied

Association of TP53 mutation, p53 overexpression, and p53 codon 72 polymorphism with susceptibility to apoptosis in adult patients with diffuse astrocytomas.

Clarification of TP53 alterations is important to understand the mechanisms underlying the development of diffuse astrocytomas. It has been suggested that the alleles of TP53 at codon 72 differ in their ability to induce apoptosis in human cancers. The aim of this study was to analyze the possible association of TP53 mutation, p53 overexpression, and p53 codon 72 polymorphism with susceptibility to apoptosis in adult Brazilian patients with diffuse astrocytomas. We analyzed 56 surgical specimens of diffuse astrocytomas for alterations of TP53, using polymerase chain reaction single-strand conformation polymorphism (PCR-SSCP) direct sequencing. p53 and cleaved caspase 3 protein expression were assessed by immunohistochemistry. We found TP53 mutations in 19.6% (11 out of 56) of tumors tested, with the lowest mutation rate found in the cases of glioblastomas (8.8%) (p = 0.03). Only 16.1% of tumors tested showed cleaved caspase 3-positive staining, demonstrating that apoptosis is very inhibited in these tumors. All tumors having TP53 mutation and p53 accumulation had no expression of cleaved caspase 3. Additionally, no association was observed in tumors having proline and arginine alleles and expression of cleaved caspase 3. We concluded that clarification of the TP53 alterations allows a better understanding of the mechanisms involved in the progression of diffuse astrocytomas, and the allele status at codon 72 was not associated with apoptosis in these tumors.

Adult↗
PubMedDate not supplied

Incidence of dementia in a community-dwelling Brazilian population.

The authors report the incidence of dementia in a community-dwelling Brazilian population. In 1997, 1656 individuals aged 65 years or more, the majority being of very low educational level, were screened at their homes in Catanduva, Brazil, and dementia was diagnosed in 118 cases. The remaining 1538 individuals were rescreened 3.25 years later applying a health questionnaire, the Mini-Mental State Examination (MMSE) and the Pfeffer Functional Activities Questionnaire (PFAQ). According to PFAQ and MMSE scores, selected subjects were submitted to clinical, neurologic, and cognitive evaluations. The subjects diagnosed with dementia underwent laboratory tests and brain computed tomography. A total of 1119 individuals were rescreened and 50 incident cases of dementia (28 with Alzheimer disease [AD]) were identified. The incidence rate of dementia was 13.8 and of AD was 7.7 per 1000 person-years for individuals aged 65 years or older. The incidence rates of dementia almost doubled with every 5 years of age. There was no difference according to gender, but women had a higher incidence of dementia, predominantly AD, in very old age. There was a trend for higher incidence of dementia in illiterates (p = 0.07), but multivariate analysis disclosed significant association only between age and higher incidence of dementia. The incidence rates of dementia in this Brazilian community are comparable to those reported in Western and Asian studies.

Age Distribution↗