Search PubMed⌕ Search

Biomedical subjects

C Gu

Publications and source records attributed to C Gu.

At least 73 records · Page 4Linked to original sources
PubMed1996

Combining extremely concordant sibpairs with extremely discordant sibpairs provides a cost effective way to linkage analysis of quantitative trait loci.

Extremely discordant (ED) sibpairs have been shown to be very powerful for linkage analysis of human quantitative traits [Risch and Zhang (1995) Science 268: 1584-1589]. In many cases, the extremely concordant (EC) sibpairs collected in the process of screening for ED sibpairs carry valuable information for linkage. Therefore, it seems justifiable to investigate the advantages of genotyping and to include them with the ED sibpairs for linkage analysis. Herein we explore the distributions of EC as well as ED sibpairs under various genetic models and provide a basis for combining both types of sibpairs. A simple statistic testing means of genes shared identical by descent (IBD) in applied to combine both types of EC sibpairs (high-high and low-low) with the ED pairs. We show that when a decent number of EC pairs is added to the ED sample for analysis, the power is much enhanced, making it especially desirable when the number of available ED pairs is small. We show at the same time that combining EC pairs with ED pairs is more cost effective than pursuing ED sibpairs alone.

Costs and Cost Analysis↗
PubMed1996

[Surgical treatment of ventricular septal defect complicated by pulmonary hypertension: analysis of 24 cases].

Until now the most important factor affecting the surgical treatment of ventricular septal defect (VSD) is pulmonary hypertention. 307 patients with ventricular septal defect (VSD) were treated surgically from May 1989 to May 1995 with a mortality rate of 2.9%. Among the 307 patients, 24 were complicated by severe pulmonary hypertension (Pp/Ps > or = 80%) and the mortality rate was 20.8%. Perioperative therapy and operative indications were discussed. Catheterization data, physical examination, chest X-ray and electrocardiographic findings were also analysed by comparision with operative outcome.

Cardiac Surgical Procedures↗
PubMed1996

[Feedback regulation of acetylcholine (ACh) on ion channel activity in snake motor nerve terminals].

In the vertebrate motor nerve terminals, the fact that the ACh release was affected by various activators and blockers of ACh receptors suggests the existence of several types of feedback regulation. The regulatory effect of ACh on the various ion channels in the snake motor nerve terminals was investigated by using subendothelial recording technique. (1) Suppression of IK(Ca). Similar to that of 3 mmol/L TEA, IK(Ca) could also be reversibly suppressed by 2 mmol/L ACh. (2) Regulatory effect on ICa. The time course of ICa in the presence of 30 mmol/L TEA was decreased by perfusion of 2 mmol/L ACh, an effect being more clear in high [Ca2+]o (7 mmol/L). The Ca2+ plateau, revealed by further addition of 3,4-DAP (300 mumol/L) to block all K+ channels, was also inhibited. These inhibitory effects could be reversed by 2 mmol/L atropine. It is likely that the inhibition of IK,f and IK(Ca) by ACh is to improve ACh release in normal condition, suggesting the presence of a positive feedback mechanism, while under circumstances in which ICa is increased, ACh may inhibit ICa so as to suppress the release itself as a result of negative feedback mechanism.

Acetylcholine↗
PubMed1995

TDT with covariates and genomic screens with mod scores: their behavior on simulated data.

We describe an extension to the TDT (transmission/disequilibrium test) which allows for more than two marker alleles and for covariates measured on the parent or offspring. We also describe a systematic genomic search where the mod score (maximized lod score) is computed for each marker under constraints on the population prevalence or penetrances of a single locus.

Computer Simulation↗
PubMed1995

A chromosome-based method to infer IBD scores for missing and ambiguous markers.

We propose a probability model to impute missing identical-by-descent (IBD) vectors for linkage analysis, when adjacent marker loci are typed and interference is estimable. A chromosome-based IBD distribution, conditioned on available marker data, is computed using a fast algorithm to estimate the joint probability of genes IBD at several equally spaced linked loci. Weighted IBD vectors are then used in various test statistics for linkage analysis. As an example, we analyzed the 18 affected sib pairs in the GAW9 Problem 1 data set using Risch's lod-score test.

Algorithms↗
PubMed1995

[Reversible elimination of K+ and Na+ currents at motor nerve terminals by SM486, a derivative of artemisinin].

Some derivatives of Artemisinin have been used as malariacides. Artemisinin derivative SM486 is water-soluble and has been shown also to have local anesthesia action. Here we report the effect of SM486 on Na+ and K+ channels at motor nerve terminals. Experiments were performed on mouse triangularis sterni nerve-muscle preparations. Presynaptic currents were picked up with a microelectrode inserted into the subendothelial space of the superficial nerve bundle under visual control using a x400 magnification water immersion objective. The results showed: (1) Both IK and INa were depressed in a dose-dependent manner, although the minimal effective concentration of SM486 for IK was lower than that for INa; (2) The depression was reversible as shown by the fact that the nearly completely blocked INa and IK currents could be restored to the control by simply washing away the perfusate SM486. (3) The decrease of IK was progressive, while the change of INa always began after IK proceeded to decrease rapidly. The effects of procaine on INa and IK are similar to SM486 but the effective concentration was higher.

Anesthetics, Local↗
PubMed1995

[Two case of androgen-secreting ovary tumor].

Two cases of androgen-secreting ovary tumor were reported. patients' chief complaints were menoxemia and hirsutism; clitorism was found by physical examination. Their serum testosterone (T) were high (10.2-6.7nmol/L) and could not be suppressed to normal range by middle-dose dexamethasone inhibiting test. ACTH stimulating test could not stimulate the high serum T to raise futher, but HCG stimulating test could increase serum T to higher level. Pelvic examination, type B ultrasonic and CT scan confirmed a mass on one of the ovaries. Sertoli-Leydig cell tumor and gynandroblastoma were proved respectively by pathology. After removing the tumor, their serum T were returned to normal level.

Adult↗