PubMed Health⌕ Search

Biomedical subjects

F H Kong

Publications and source records attributed to F H Kong.

10 recordsLinked to original sources
PubMed2000

Optimal sampling times in bioequivalence tests.

In bioequivalence studies, drug formulations are compared in terms of bioavailability parameters such as the area under the concentration-time curve (AUC), the maximum concentration (Cmax), and the time to maximum concentration (t(max)). Accuracy in measuring these parameters directly affects the accuracy of bioequivalence tests. Because the number of blood draws per patient is limited, the blood collection times must be spaced so that concentration-time curve measurements can produce accurate bioavailability parameter estimates. This paper describes an optimization approach for calculating optimal time designs for one-compartment models, but is sufficiently general for other compartmental models. Simulation indicates that the optimal design improves the accuracy of AUC estimation.

Area Under Curve↗
PubMed1998

A stochastic approximation algorithm with Markov chain Monte-carlo method for incomplete data estimation problems.

We propose a general procedure for solving incomplete data estimation problems. The procedure can be used to find the maximum likelihood estimate or to solve estimating equations in difficult cases such as estimation with the censored or truncated regression model, the nonlinear structural measurement error model, and the random effects model. The procedure is based on the general principle of stochastic approximation and the Markov chain Monte-Carlo method. Applying the theory on adaptive algorithms, we derive conditions under which the proposed procedure converges. Simulation studies also indicate that the proposed procedure consistently converges to the maximum likelihood estimate for the structural measurement error logistic regression model.

Journal Article↗
PubMed1996

[The diversity of human hematopoietic stem/progenitor cells. I. Two-color flow cytometric analysis of the different functional subpopulations of CD 34+ hematopoietic stem/progenitor cells riched from human bone marrow].

In hematopoiesis; the human CD 34 protein is a strict developmental stage-specific antigen that marks hematopoietic stem/progenitor cells, suggesting that it plays an essential role in hematopoiesis. More recently, it has been demonstrated that hematopoietic cells expressing the CD 34 antigen constitute various heterogeneous cell populations in which each CD 34+ subset was associated with commitment to a particular lineage, and differed from other's in reconstituting hematopoiesis. In this report, we have assessed the different functional subpopulation of CD 34+ hematopoietic stem/progenitor enriched from human bone marrow using Isolex TM 50 system according to the strategy on immunomagnetic separation of positive selection. CD 34+ cell population of high purity (> 90% CD 34+) was analyzed by means of double staining procedure of flurorescein conjugated monoclonal antibodies on the two-color FACAcan or FACS 440. Eight cell subsets of at least of bone marrow CD 34 hematopoietic stem/progenitor cells have been defined by undertaking a comparative coexpressing of CD 71, CD45, CD 33 and HLA-DR antigens on CD 34 hematopoietic stem/progenitor cells. The frequencies of various subsets in two illustrative are as following: 1). CD 34+/CD 71- and CD 34+/CD 71+ (23.43%-56.6% versus 33.4%-66.6%): 2). CD 34+/CD45- and CD 34+/CD45+ (80.8%-82.5% versus 8.1%-11.2%): 3). CD 34+/CD 33- and CD 34+/CD 33+ (20.4%-80.6% versus 14.6%-64.8%): 4). CD 34+/DR- and CD 34+/DR+ (6.3%-11.0% verus 82.8%-85.5%). Immunological double color staining of IGSS-APAAP was also used to further analyse the CD 34+ cell subsets as above-mentioned, the results were very similar to those obtained by FACScan. Our data indicate that CD 34+ hematopoietic cell fraction is far from being a uniform cell population, and many works regarding biological properties and regulation mechanism of different subsets of CD 34+ hematopoietic stem/progenitor cells are being carried out.

Antigens, CD↗
PubMed1991

The pharmacophore of debromoaplysiatoxin responsible for protein kinase C activation.

Protein kinase C is physiologically activated by 1,2-diacyl-sn-glycerol in the S configuration. The enzyme is also powerfully activated by structurally diverse tumor promotors. A model has been developed that demonstrates how the various tumor promotors and diacylglycerols can all be accommodated by the same binding site of the kinase. One prediction of this model concerns the structural nature of the pharmacophore in the tumor promotor debromoaplysiatoxin. This prediction is realized by synthesizing the analogs with the deduced pharmacophore and demonstrating that they are potent activators of protein kinase C. These findings provide strong experimental support for our structural model of protein kinase C activation.

Animals↗
PubMed1990

Human leukocyte antigens -A, -B, -C, and -DR and nasopharyngeal carcinoma in northern China.

We observed HLA associations in patients with nasopharyngeal carcinoma from northern China. There was an increased risk of nasopharyngeal carcinoma associated with HLA-B35 and a difference in the HLA association between patients with early- and late-onset disease. The frequency of B35 was significantly higher in patients than in control subjects, especially in early-onset patients (less than 30 years old). Late-onset patients had a higher frequency of DR2 as compared with normal subjects.

Adult↗