PubMed Health⌕ Search

Biomedical subjects

K Y Liu

Publications and source records attributed to K Y Liu.

At least 19 recordsLinked to original sources
PubMed2005

Towards automated cellular image segmentation for RNAi genome-wide screening.

The Rho family of small GTPases is essential for morphological changes during normal cell development and migration, as well as during disease states such as cancer. Our goal is to identify novel effectors of Rho proteins using a cell-based assay for Rho activity to perform genome-wide functional screens using double stranded RNA (dsRNAs) interference. We aim to discover genes could cause the cell phenotype changed dramatically. Biologists currently attempt to perform the genome-wide RNAi screening to identify various image phenotypes. RNAi genome-wide screening, however, could easily generate more than a million of images per study, manual analysis is thus prohibitive. Image analysis becomes a bottleneck in realizing high content imaging screens. We propose a two-step segmentation approach to solve this problem. First, we determine the center of a cell using the information in the DNA-channel by segmenting the DNA nuclei and the dissimilarity function is employed to attenuate the over-segmentation problem, then we estimate a rough boundary for each cell using a polygon. Second, we apply fuzzy c-means based multi-threshold segmentation and sharpening technology; for isolation of touching spots, marker-controlled watershed is employed to remove touching cells. Furthermore, Voronoi diagrams are employed to correct the segmentation errors caused by overlapping cells. Image features are extracted for each cell. K-nearest neighbor classifier (KNN) is employed to perform cell phenotype classification. Experimental results indicate that the proposed approach can be used to identify cell phenotypes of RNAi genome-wide screens.

Algorithms↗
PubMed2004

Suicidality among high school students in Hong Kong, SAR.

Suicide is the leading cause of death in Hong Kong SAR for the youth aged 15-24. This study examined the prevalence of suicidality among secondary school students in Hong Kong using a representative, territory-wide sample of 2,586 students. Suicidal behaviors can be conceptualized as a spectrum of self-destructive behaviors. Cumulative logit model analysis indicated that a range of factors, such as unhappy family life, were associated with increasing levels of suicidality. Use of illicit drugs, inhalants, and tobacco differentiated attempters from ideators. The implications of the research findings are discussed.

Adolescent↗
PubMed2001

Exploiting linkage disequilibrium in population isolates.

A comparison of haplotype frequencies between unrelated cases and controls from population isolates identifies a strong signal for the presence/absence of the discrete phenotype in an interval on chromosome 6 bounded by markers 34 and 35. We define a dissimilarity index, D, which is sensitive to differences in allele distributions and differences in the patterns of linkage disequilibrium between cases and controls. We describe two statistical methods to utilize D: a method appropriate for a single moderately sized sample and a sequential approach appropriate for multiple small independent samples.

Alleles↗
PubMed2001

A clustering approach for localizing disease susceptibility loci.

Latent class (LCA) and cluster analysis (CLA) were utilized to identify trait loci for the Genetic Analysis Workshop 12 simulated disease. These techniques create non-overlapping subsets of concordant and discordant affected relative pairs based upon identity-by-descent (IBD) allele sharing at sequences of markers. Subgroups with a large proportion of affected pairs are used to identify markers in proximity to disease susceptibility loci. Both methods are model-free and make use of information from affected and unaffected subjects. In analyses performed without knowledge of the true disease model, LCA and CLA identified regions containing five of the seven trait loci.

Alleles↗
PubMed2001

Direct measurement of microkeratome gap width by electron microscopy.

PURPOSE: To perform an accurate direct measurement of the microkeratome gap width using scanning electron microscopy (SEM). SETTING: Electron Microscope Unit, University of Hong Kong, Hong Kong, China. METHODS: The Cambridge Stereoscan S440 scanning electron microscope was used to measure the gap width of 4 SCMD microkeratomes with high accuracy (+/-1.5 microm). RESULTS: The manufacturer's gap specification for the 4 microkeratomes was 150.0 microm. The gap width measurements using SEM were 164.7 microm, 190.0 microm, 200.6 microm, and 145.9 microm and the respective errors, 9.8%, 26.7%, 33.7%, and 2.7%. Two of the 4 microkeratomes had more than a 25% error in gap width from the specification. CONCLUSIONS: The great variation in gap width from the manufacturer's specification for the 4 SCMD microkeratomes was beyond the standard of tolerance normally accepted in laser in situ keratomileusis (LASIK). Many unexpected LASIK-related keratectasia and corneal perforations may be related to substandard microkeratome manufacturing and calibration. All new microkeratomes and blades should be validated before use to avoid keratectasia and other flap problems in LASIK.

Calibration↗
PubMed2001

History of Chinese stereotactic and functional neurosurgery.

Chinese stereotactic and functional neurosurgery started in 1963. Dr. Jian-Ping Xu did stereotactic surgery for Parkinson's disease with a small Cartesian coordinate stereotactic device which he designed. In 1983, the first Chinese Institute of Stereotactic and Functional Neurosurgery was established by Dr. Jian-Ping Xu and Dr. Ye-Han Wang in the Anhui Provincial Hospital in the city of Hefei. Since then, the Institute has hosted an annual National Workshop on Stereotactic and Functional Neurosurgery, where more than 80% of the functional neurosurgeons now practicing in China have been trained. In 1986, the Chinese Society of Stereotactic and Functional Neurosurgery was established, and the first issue of the Chinese Journal of Stereotactic and Functional Neurosurgery was published. With more than 35 years of development, stereotactic and functional neurosurgery has become a very important branch of surgery in China. More than 5,000 functional neurosurgery procedures and more than 8,000 stereotactic radiosurgery procedures are now performed annually.

China↗
PubMed2001

[A home telemedicine system suitable for China].

The telemedicine developments in china and overseas are introduced in this article. The developmental direction of china home telemedicine, is also discussed, and then a home telemedicine system suitable for china is put forward, and its composition, principle, key components: the home tele-monitor and the remote computer center processing system are introduced in detail.

China↗
PubMed2000

Linkage of a gene for familial hypobetalipoproteinemia to chromosome 3p21.1-22.

Familial hypobetalipoproteinemia (FHBL) is an apparently autosomal dominant disorder of lipid metabolism characterized by less than fifth percentile age- and sex-specific levels of apolipoprotein beta (apobeta) and low-density lipoprotein-cholesterol. In a minority of cases, FHBL is due to truncation-producing mutations in the apobeta gene on chromosome 2p23-24. Previously, we reported on a four-generation FHBL kindred in which we had ruled out linkage of the trait to the apobeta gene. To locate other loci containing genes for low apobeta levels in the kindred, a genomewide search was conducted. Regions on 3p21.1-22 with two-point LOD scores >1.5 were identified. Additional markers were typed in the region of these signals. Two-point LOD scores in the region of D3S2407 increased to 3.35 at O = 0. GENEHUNTER confirmed this finding with an nonparametric multipoint LOD score of 7.5 (P=.0004). Additional model-free analyses were conducted with the square root of the apobeta level as the phenotype. Results from the Loki and SOLAR programs further confirmed linkage of FHBL to 3p21.1-22. Weaker linkage to a region near D19S916 was also indicated by Loki and SOLAR. Thus, a heretofore unidentified genetic susceptibility locus for FHBL may reside on chromosome 3.

Adolescent↗
PubMed2000

Splenic abscess--a changing trend in treatment.

Fifteen patients with splenic abscesses were evaluated between 1985 and 1995. The most common predisposing factors were remote infection, diabetes mellitus and heart disease. Common clinical presentations included leucocytosis, fever, left upper quadrant abdominal pain and left pleural effusion. Four patients with splenic abscesses smaller than 4 cm in diameter were treated with antibiotics alone, and 1 in this treatment group died. Among the 10 patients with splenic abscesses larger than 4 cm in diameter receiving percutaneous drainage, 9 (90%) were successfully cured, including 8 with unilocular abscesses and 1 with multilocular abscesses. Two patients underwent splenectomy. In conclusion, percutaneous drainage using ultrasound or computed tomography guidance may be recommended as the treatment of choice for splenic abscess larger than 4 cm in diameter. Antibiotics alone may sometimes be considered for splenic abscesses smaller than 4 cm in diameter. Splenectomy is reserved for those cases where medical treatment has failed.

Abscess↗
PubMed1999

Genetic dissection of a complex trait.

A number of genetic and statistical tools were applied to various partitions of the simulated data to identify susceptibility loci, relevant environmental factors, and their interaction(s). The distribution of genotypes at D1G24 among affected children in the first population was found to differ significantly from Hardy-Weinberg expectation. Two transmission/disequilibrium tests identified the preferential transmission of allele 1 as the source of the disequilibrium. Simple contingency table analysis revealed a positive association between exposure to environmental factor E1 and disease phenotype. Multipoint linkage analyses on various subsets of the data identified three "signal" regions (in addition to the aforementioned D1G24) localized at D1G9-10, D3G45, and D5G38. The even numbered chromosomes appeared to be devoid of susceptibility loci. Further analyses of subsamples of affected sib pairs, selected according to their disease phenotype and their exposure to E1, clarified some linkage relationships, particularly for D3G45, thereby suggesting the presence of a specific gene x environment interaction. Logistic analysis designed to clarify the relationship between disease phenotype and two risk factors (E1 exposure and the presence of allele 1 at D1G24) in the first population, revealed a significantly negative interaction which, upon learning the details of the generating model, we now attribute to the presence of heterogeneity.

Environment↗
PubMed1999

Covariates in linkage analysis.

We apply a novel technique to detect significant covariates in linkage analysis using a logistic regression approach. An overall test of linkage is first performed to determine whether there is significant perturbation from the expected 50% sharing under the hypothesis of no linkage; if the overall test is significant, the importance of the individual covariate is assessed. In addition, association analyses were performed. These methods were applied to simulated data from multiple populations, and detected correct marker linkages and associations. No population heterogeneity was detected. These methods have the advantages of using all sib pairs and of providing a formal test for heterogeneity across populations.

Genetic Linkage↗
PubMed1999

Primary iliac muscle abscess due to Staphylococcus aureus.

A 55-year-old man presented with a 3-day history of lower back pain and right thigh pain. A diagnosis of discogenic pain had been made at two other hospitals. He had been admitted to a medical center for acute hepatitis 5 months prior to this admission. Large doses of parenteral hydrocortisone were used for 13 days to treat acute hepatitis. At the present admission, he was unable to stand and refused to move his right leg. There was mild tenderness in the right lower abdomen on deep palpation. Passive flexion and rotation of the right hip produced mild pain, while passive extension of the right hip produced severe pain and resistance. The Patrick test was positive and the psoas sign was present on the right side. The erythrocyte sedimentation rate (ESR) was 66/hr. The C-reactive protein (CRP) level was 0.161 g/L. Abdominal sonography showed a lobulated mass in the right iliac fossa. Magnetic resonance imaging showed severe swelling of the right iliac muscle with a central heterogeneous mass. Debridement, drainage of the abscess, and application of a septopal chain were performed via an anterior retroperitoneal approach, and parenteral cephazolin and gentamicin were administered. A culture of the abscess grew Staphylococcus aureus. The ESR and CRP concentrations decreased to within the normal ranges 3 weeks later. Awareness of this disease entity, careful physical examination, and appropriate imaging studies such as ultrasonography and magnetic resonance imaging are key to making a correct diagnosis.

Abscess↗
PubMed1995

Identification of malaria-infected dried mosquitoes by biotinylated DNA probe.

Dot-blot hybridization with cloned genomic DNA labeled with photobiotin as a probe is used to detect Plasmodium falciparum sporozoites in dried mosquitoes. The assay is sensitive enough to detect 2 pg Plasmodium parasite DNA, or one infected mosquito in a pool of 40 insects using DNA extraction samples, or one infected mosquito in a pool of 25 insects without DNA extraction. A single mosquito squashed directly on a nitrocellulose filter for the determination of parasites provides a simple method for the detection of sporozoites. The mosquitoes triturated in reduction buffer were efficient for the screening of malaria infection of mosquitoes in a large number of samples. The species specificity, sensitivity, and ease of performance of this assay as well as the stability of the reagents may make it a useful epidemiological tool.

Animals↗
PubMed1995

[Clinical observation on treatment of 45 angina pectoris patients of coronary heart disease with taponin].

Forty-five patients suffering from angina pectoris of coronary heart disease (CHD) were successfully treated with Taponin. The effect of the treatment was compared with that of nifedipine. The clinical practice showed that the group treated with Taponin yielded better results. After medication, the patients were markedly relieved from angina pectoris of CHD. Meanwhile the improvement of electrocardiogram (EKG) and impedance cardiogram were also observed. The effective rate of EKG improvement was 83.7%. The treatment of angina pectoris of CHD with Taponin was significantly more effective in comparing with control group (P < 0.05).

Adult↗
PubMed1993

Kinetics of circulating haematopoietic progenitors during chemotherapy-induced mobilization with or without granulocyte colony-stimulating factor.

Kinetics of circulating haematopoietic progenitors was analysed during chemotherapy- or chemotherapy plus granulocyte colony-stimulating factor (G-CSF)-induced mobilization of peripheral blood stem cells. Circulating progenitors including colony-forming unit granulocyte/macrophage (CFU-GM), burst forming-unit erythroid (BFU-E) and multilineage colony forming unit (CFU-Mix) were studied serially on alternate days during a recovery phase from chemotherapy for consolidation of complete remission. In 18 patients with acute leukaemia, 27 courses of consolidation chemotherapy were performed with a combination of an intermediate-dose cytosine arabinoside with etoposide (Ara-C/Etop) or mitoxantron (Ara-C/Mit). G-CSF (5 micrograms/kg) was administered during the recovery phase in 6/14 courses with Ara-C/Etop and in 4/13 courses with Ara-C/Mit. G-CSF induced a significant and synchronized increase of circulating CFU-GM, BFU-E and CFU-Mix by more than 4-fold at their peaks. The peak of CFU-GM was significantly correlated with that of both BFU-E and CFU-Mix, irrespective of additional G-CSF mobilization. G-CSF also produced a significant increase of monocytes in a synchronized fashion with an increase of circulating CFU-GM. Interestingly, peripheral blood monocytes spontaneously produced high concentrations of IL-6; a significant correlation was observed between absolute monocyte counts and plasma levels of IL-6 or peak levels of CFU-GM. These observations indicate that the addition of G-CSF to chemotherapy-induced mobilization can facilitate further expansion of a blood progenitor pool during the haematopoietic recovery, probably through the stimulation of monocytes to proliferate and to induce their monokine production such as IL-6. The data also suggest that absolute monocyte counts may be a useful indicator to predict the peak of circulating progenitors for collecting autologous blood stem cells.

Adolescent↗
PubMed1993

[The establishment of genomic DNA libraries for the human malaria parasite Plasmodium falciparum].

The DNA of Plasmodium falciparum has been purified and fragmented with restriction endonuclease BamHI. The fragments have been incorporated in vitro into derivatives of bacteriophage lambda EMBL4 digested with BamHI and Sal I. The recombinant mixture has been ligated and packaged in vitro. The recombinant phages have been identified in E. coli L95 host cell and the libraries have been established in which most of the parasite DNA is represented. The ligation proportion of vector to insert is 3:1. The recombinant phages of 4 x 10(5) have been obtained. By plaque hybridization, we have been able to recover from these libraries specific clones containing repetitive DNA sequences.

Animals↗
PubMed1993

The second dorsal metacarpal flap with vascular pedicle composed of the second dorsal metacarpal artery and the dorsal carpal branch of radial artery.

A pedicle second dorsal metacarpal flap, comprising the second dorsal metacarpal artery, the partial carpal arterial arch of the dorsal hand, and the dorsal carpal branch of radial artery, was designed. The flap may be rotated through two axes of rotation, one at the entry of carpal branch of radial artery into the first dorsal interosseous muscle and one at the entry of the recurrent cutaneous branch arising from the second dorsal metacarpal artery into the skin. The method introduced can increase as much as possible the length of the vascular pedicle of the second dorsal metacarpal flap. Thus, it can cover a small defect at a more distant area. If the width of this flap is not more than 3 cm, the donor site can be closed directly. The flap had been used in five cases with no necrosis of the flap or complication of the donor site. In further investigation of the postoperative patients, no stiffness and tightness have been observed through a short period of rehabilitation of the hand. The results are satisfactory. The anatomy, the operative technique, and three selective cases are described here.

Adult↗