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Biomedical subjects

A Kong

Publications and source records attributed to A Kong.

At least 37 records · Page 2Linked to original sources
PubMed1999

Adrenocortical function in critically ill patients 24 h after a single dose of etomidate.

We compared the effects of single doses of etomidate and thiopentone on adrenocortical function in a randomised controlled clinical trial involving 35 critically ill patients who needed a general anaesthetic. Just before induction of anaesthesia, a baseline blood cortisol sample was taken. Twenty-four hours later we performed a short adrenocorticotrophic hormone stimulation test. No patient had a low cortisol level (< 160 nmol.l-1) at any time during the study. Baseline, pre-ACTH and post-ACTH cortisol levels were similar in the two groups. However, significantly more patients in the etomidate group had an ACTH-stimulated cortisol increment < 200 nmol.l-1. The clinical significance of these findings is not clear, but we conclude that single doses of etomidate may interfere with cortisol synthesis for at least 24 h in the critically ill.

Adolescent↗
PubMed1999

Blocking Gibbs sampling for linkage analysis in large pedigrees with many loops.

We apply the method of "blocking Gibbs" sampling to a problem of great importance and complexity-linkage analysis. Blocking Gibbs sampling combines exact local computations with Gibbs sampling, in a way that complements the strengths of both. The method is able to handle problems with very high complexity, such as linkage analysis in large pedigrees with many loops, a task that no other known method is able to handle. New developments of the method are outlined, and it is applied to a highly complex linkage problem in a human pedigree.

Algorithms↗
PubMed1999

A genome-wide scan reveals a maternal susceptibility locus for pre-eclampsia on chromosome 2p13.

Pre-eclampsia is a common and serious disease and a major cause of maternal and infant mortality. Antenatal care systems world-wide screen for signs of the disease such as hypertension and proteinuria. Unlike most other human disorders it impacts two individuals, the mother and the child, both of whom can be severely affected. The pathophysiology of the disorder is incompletely understood, but familial clustering of the disease is apparent. Here we report the results of a genome-wide screen of Icelandic families representing 343 affected women. Including those patients with non-proteinuric pre-eclampsia (gestational hypertension), proteinuric pre-eclampsia and eclampsia, we detected a significant locus on 2p13 with a lod score of 4.70 (single point P < 3.49 x 10(-6)). This is the first reported locus for pre-eclampsia meeting the criteria for genome-wide significance.

Chromosome Mapping↗
PubMed1999

[A digital simulation study on the effect of change in cardiovascular system parameters on the pulse waveform of the radial artery].

OBJECTIVE: To understand the effect of the change in cardiovascular system parameters on the pressure pulse waveform of the radial artery. METHOD: A previously developed cardiovascular system mathematical model was used in this simulation study. The parameters used were heart rate, ventricular contractility, arterial compliance, peripheral resistance and blood viscosity. RESULT: The change in each parameter would influence the pulse waveform. Most of the influences were in agreement with the results of clinical observations reported in the literature. However, several new phenomena were observed. The effect of change in single parameter on the pulse waveform was different for different combinations of other parameter values. CONCLUSION: It is suggested that the model is useful in studying the relationship between cardiovascular system parameters and pulse waveform of the radial artery.

Aerospace Medicine↗
PubMed1998

[Physical simulation of radial artery displacement].

A previous developed physical cardiovascular simulation is used to investigate the displacement of radial artery during a cardiac cycle. Simulation result shows that the displacement is much greater than the change in the radius of the radial artery. The result is similar to the clinical observation reported before. Based on the simulation result, it is suggested that the displacement of radial artery plays an important part in the Maixiang (pulse condition), which is one of the most important contents of diagnostics in Traditional Chinese Medicine.

Cardiovascular Physiological Phenomena↗
PubMed1997

Mapping of a familial essential tremor gene, FET1, to chromosome 3q13.

Essential tremor (ET), the most common movement disorder in humans, appears to be inherited as an autosomal dominant trait in many families. The familial form is called familial essential tremor (FET), which seems similar to sporadic essential tremor. ET is a cause of substantial disability, particularly in the elderly. The prevalence of Parkinson's disease and dystonia may be increased in families with ET, but other movement disorders are seldom encountered in these families. Here we report the results of a genome-wide scan for FET genes in 16 Icelandic families with 75 affected individuals, in whom FET was apparently inherited as a dominant trait. The scan, which was performed with a 10-cM framework map, revealed one locus on chromosome 3q13 to which FET mapped with a genome-wide significance when the data were analysed either parametrically, assuming an autosomal dominant model (lod score = 3.71), or non-parametrically (NPL Z score = 4.70, p < 6.4 x 10(-6).

Chromosome Mapping↗
PubMed1997

Allele-sharing models: LOD scores and accurate linkage tests.

Starting with a test statistic for linkage analysis based on allele sharing, we propose an associated one-parameter model. Under general missing-data patterns, this model allows exact calculation of likelihood ratios and LOD scores and has been implemented by a simple modification of existing software. Most important, accurate linkage tests can be performed. Using an example, we show that some previously suggested approaches to handling less than perfectly informative data can be unacceptably conservative. Situations in which this model may not perform well are discussed, and an alternative model that requires additional computations is suggested.

Alleles↗
PubMed1997

Linkage mapping in experimental crosses: the robustness of single-gene models.

The robustness of parametric linkage mapping against model misspecification is considered in experimental breeding designs, with a focus on localization of the gene. By examining the expected LOD across the genome, it is shown that single-gene models are quite robust, even for polygenic traits. However, when the marker map is of low resolution, linked polygenes can give rise to an apparent "ghost" gene, mapped to an incorrect interval. The results apply equally well to quantitative traits or qualitative (categorical) traits. The results are derived for backcross populations, with a discussion of extensions to intercross populations and relative-pair mapping in humans.

Crosses, Genetic↗
PubMed1997

Heterogeneity in intensive care units: fact or fiction?

Reports and guidelines concerning intensive care practice have been issued recently. However, the introduction of such centrally issued recommendations may be difficult because of marked heterogeneity between intensive care units. This study examined the facilities (number of beds, consultant sessions, nursing establishment), annual workload (number and types of patients admitted) and outcome (intensive care unit mortality) in the (old) Anglia Region. There were significant differences in the distribution of patients' ages, severities of illness, diagnoses, durations of admission and outcomes. Such heterogeneity may make multicentre trials more difficult to conduct and create problems when uniform measures designed to improve intensive care services are being planned.

APACHE↗
PubMed1997

[Simulation study on the blood volume feedback control].

To describe the relationship between blood volume and the cardiac function mathematically, a computer cardiovascular model, was developed including a systemic circulation, a heart and a pulmonary model and a blood volume feedback control. Simulation results indicate that the chronic heart failure could be compensated by increasing the blood volume to maintain the proper arterial pressure. Deterioration in heart failure causes an increase in blood volume, as well as increases in heart volume and cardiac energy consumption. These results are in agreement with the clinical data and results reported in the literature. The simulation also shows that for a predetermined ventricular contractility, an adequate increase in blood volume will increase the heart volume but decrease the cardiac energy consumption and lead the heart to work in an optimum condition.

Aerospace Medicine↗
PubMed1995

Oculomotor control in calliphorid flies: GABAergic organization in heterolateral inhibitory pathways.

In calliphorid Diptera, motor neurons mediating visually evoked head movements can be excited or inhibited by visual stimuli, depending on the directionality of the stimulus and whether it is in the ipsi- or contralateral visual field. The level at which inhibition occurs is of special interest because binocular activation of homolateral tangential neurons in the lobula plate demonstrates that excitatory interaction must occur between the left and right optic lobes. Recordings and dye fillings demonstrate a variety of motion-sensitive heterolateral pathways between the lobula plates, or between them and contralateral deutocerebral neuropil, which provides descending pathways to neck motor centers. The profiles of heterolateral tangential cells correspond to neurons stained by an antibody against gamma-aminobutyric acid (GABA). Other GABA-immunoreactive interneurons linking each side of the brain correspond to uniquely identified motion-sensitive neurons linking the deutocerebral. Additional inhibitory pathways include heterolateral GABAergic descending and ascending neurons, as well as heterolateral GABAergic neurons in the thoracic ganglia. The functional significance of heterolateral GABAergic pathways was tested surgically by making selective microlesions and monitoring the oculomotor output. The results demonstrate an important new attribute of the insect visual system. Although lesions can initially abolish an excitatory or inhibitory response, this response is reestablished through alternative pathways that provide inhibitory and excitatory information to the same motor neurons.

Animals↗
PubMed1994

Sequential imputation for multilocus linkage analysis.

A Monte Carlo method called sequential imputation is proposed for multilocus likelihood computations. This method is most useful in mapping situations where the data consist of large pedigrees with substantial missing information and it is desirable to perform linkage analysis utilizing data from many polymorphic markers simultaneously. A pedigree example with 155 individuals, 9 loci, and 155,520 haplotypes is used for illustration.

Diabetes Mellitus, Type 2↗
PubMed1994

Asymptotic theory for gene mapping.

In genetic linkage mapping, the precision of the location estimate depends on both the number of individuals and the number of markers. Convergence rates and limit laws are established for several situations in which the number of markers depends on the sample size. Practical implications of the results are discussed.

Chromosome Mapping↗
PubMed1994

Effects of 4-MAPC, a 5 alpha-reductase inhibitor, and cyproterone acetate on regrowth of the rat ventral prostate.

Inhibitors of 5 alpha-reductase activity cause less involution of the rat ventral prostate (VP) than does castration. Studies were conducted in adult Sprague Dawley rats to evaluate the effects of a potent 5 alpha-reductase inhibitor, 4-MAPC, and the antiandrogen, cyproterone acetate (CA), on DNA synthesis and apoptosis. In experiment 1, VP weight fell 33%, 53%, and 83%, and DNA per ventral prostate was reduced 24%, 46%, and 71%, by 4-MAPC, CA, and castration, respectively. In experiment 2, adult rats were castrated, and the VP involuted for 7 days prior to 3 daily injections of testosterone propionate (TP; 1 mg/kg/d) +/- 10 mg/kg/d of 4-MAPC or CA. 3H-thymidine incorporation into VP DNA was increased in castrated animals treated with TP, and 4-MAPC and CA reduced uptake. In experiment 3, animals were treated for 14 days with the same protocol as that used in experiment 2. VP weight was increased in all animals treated with TP when compared with castration, and was reduced by both 4-MAPC and CA. DNA in rats treated with TP was similar to that in intact animals. DNA was not reduced by 4-MAPC, but was reduced by CA. The mRNA for TRPM-2, a marker of apoptosis, was increased only in untreated castrated rats. It appears that CA has a greater inhibitory effect than 4-MAPC on DNA synthesis. A major reason why castration reduces DNA more than either 4-MAPC or CA is that neither of these agents was able to increase programmed cell death to the degree seen with castration.

5-alpha Reductase Inhibitors↗