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Biomedical subjects

K Cheung

Publications and source records attributed to K Cheung.

84 records · Page 5Linked to original sources
PubMed1983

The origin of chemiluminescence produced by neutrophils stimulated by opsonized zymosan.

The luminol-dependent chemiluminescence (CL) of neutrophils phagocytosing zymosan is inhibited by superoxide dismutase (SOD), catalase, sodium benzoate, and 2,5-dimethyl furan. In the present report it is shown that inhibition by SOD and 2,5-dimethyl furan is diminished and removed, respectively, by the omission of glucose from the incubation medium. Zymosan-induced CL is also inhibited by inhibitors of arachidonic acid (AA) metabolism, including 5,8,11,14-eicosatetraynoic acid, nordihydroguaiaretic acid, quinacrine, indomethacin, and aspirin, by prostaglandins E1 and E2, theophylline, and dibutyryl cyclic AMP (cAMP), and by the addition of AA, sodium fluoride, and xanthine oxidase plus xanthine to the cell suspension. These findings lead us to postulate that the metabolism of AA via the lipoxygenase (and cyclooxygenase) pathway(s) is the source of CL observed in neutrophils after phagocytosis. Reactive oxygen species produced as a result of activation of NAD(P)H oxidase provide oxidizing agents for the oxidation of AA along these pathways. It is also suggested that elevated levels of cAMP induced by prostaglandins synthesized via the cyclooxygenase pathway may play a role in the regulation of the zymosan-induced CL response.

Arachidonic Acids↗
PubMed1982

Combined neutrophil and T-cell deficiency: initial report of a kindred with features of the hyper-IgE syndrome and chronic granulomatous disease.

A six year old female presented with a recent history of pyoderma gangrenosum involving her legs and arms associated with an episode of Mycoplasma-like pneumonia. This was followed by Aspergillus osteomyelitis involving her left ulna and right femur. Both the skin lesions and the osteomyelitis responded to prolonged treatment with antifungal and antibiotic agents. Investigation of this patient revealed (1) an elevated serum IgE (4,800 units/ml), (2) defect in neutrophil chemotaxis that appeared to be due to immune complexes, (3) an abnormal nitroblue tetrazolium (NBT) result (0 percent stimulated and unstimulated), and (4) depressed mitogen responses to concanavalin A, phytohemagglutinin, and pokeweed mitogen, negative results of intradermal skin tests, and negative dinitrochlorobenzene (DNCB) sensitization. The patient's clinically unaffected sibling had similar findings except for a positive DNCB response. In both children, intracellular bacterial killing of catalase-positive and negative organisms was normal. Kindred studies revealed widespread T-cell abnormalities consistent with autosomal dominant inheritance. Tissue typing studies showed that affected siblings shared the A1, B8, DR3 haplotype. This kindred is unique in that both the proband and the sibling have abnormalities of both the hyper-IgE syndrome and chronic granulomatous disease.

Child↗
PubMed1982

Measurement of circulating immune complexes in human sera by enzyme immunoassay.

Two methods, based on enzyme immunoassay, are described for the detection and quantitation of circulating immune complexes (CIC) in human sera. Aggregated human gamma globulin (AHG) or immune complexes in human sera are bound to complement receptors on Raji cells or to Clq adsorbed on to the plastic surface of microtitre plates. The bound complexes are subsequently detected using peroxidase-conjugated anti-human immunoglobulin antisera. The assays offer a benefit over previously described assays in that they use cheap, commercially available antisera and enable the detection of immune complexes composed of varying immunoglobulin classes.

Animals↗
PubMed1982

Immunopharmacology of Chinese medicine 1, ginseng induced immunosuppression in virus-infected mice.

Total saponins extracted from Panax ginseng, when injected into mice at a dose of approximately 10 mg/kg body weight, have no significant effect on the generation of cytotoxic T cell activity, induction of natural killer cell activity and humoral antibody production in mice infected subsequently with A/WSN influenza virus. The saponins, however, selectively suppressed the delayed-type hypersensitivity responses to the virus when administered to the animals before but not after virus sensitization. Thus, ginseng pretreatment can induce immunological unresponsiveness in one arm of the immune system. Such selective immunosuppression effect of the total saponins of ginseng may be related to their steroid-like structure.

Animals↗
PubMedDate not supplied

Fetal umbilical and internal carotid artery blood flow velocity waveforms during maternal fenoterol administration.

Blood flow velocity waveforms in the fetal umbilical and internal carotid artery were studied during maternal fenoterol treatment in 25 pregnant patients admitted for premature labour between 27 and 35 weeks of gestation. The pulsatility index (PI) from the umbilical artery was significantly reduced (p = 0.02), the PI being situated below the -2 SD limit of the normal reference curve in 28%. There was no statistically significant difference in PI from the umbilical artery when distinguishing between ruptured and unruptured membranes. The reduced pulsatility index of the umbilical artery suggests a decrease in vascular resistance, hence improved utero-placental perfusion. The pulsatility index of the fetal internal carotid artery followed the normal distribution.

Adolescent↗
PubMedDate not supplied

The influence of organizational factors on occupational low back injuries.

The unique home care environment puts nurses at risk of low back injuries. Protecting nurses may mean the difference between delivering cost-effective quality care and no care at all. This study, conducted in Alberta, Canada, disclosed a lack of organizational resources and use of occupational health services in home care providers. Involving frontline staff as management partners may provide a solution for the development of an effective injury prevention program in home care.

Adult↗
PubMedDate not supplied

Internet-based support for bioscience research: a collaborative genome center for human chromosome 12.

This paper describes an approach that provides Internet-based support for a genome center to map human chromosome 12, as a collaboration between laboratories at the Albert Einstein College of Medicine in Bronx, New York, and the Yale University School of Medicine in New Haven, Connecticut. Informatics is well established as an important enabling technology within the genome mapping community. The goal of this paper is to use the chromosome 12 project as a case study to introduce a medical informatics audience to certain issues involved in genome informatics and in the Internet-based support of collaborative bioscience research. Central to the approach described is a shared database (DB/12) with Macintosh clients in the participating laboratories running the 4th Dimension database program as a user-friendly front end, and a Sun SPARCstation-2 server running Sybase. The central component of the database stores information about yeast artificial chromosomes (YACs), each containing a segment of human DNA from chromosome 12 to which genome markers have been mapped, such that an overlapping set of YACs (called a "contig") can be identified, along with an ordering of the markers. The approach also includes 1) a map assembly tool developed to help biologists interpret their data, proposing a ranked set of candidate maps, 2) the integration of DB/12 with external databases and tools, and 3) the dissemination of the results. This paper discusses several of the lessons learned that apply to many other areas of bioscience, and the potential role for the field of medical informatics in helping to provide such support.

Chromosome Mapping↗
PubMedDate not supplied

Screening parameters for ThinPrep and conventional gynecologic cytology via automated monitoring.

OBJECTIVE: To compare diagnostic discrepancies and screening parameters between conventional (CP) and ThinPrep (TP) (Cytyc Corporation, Boxborough, Massachusetts, U.S.A.) cervicovaginal samples using Pathfinder (Neopath, Redmond, Washington, U.S.A.). STUDY DESIGN: Pathfinder tracked average screening time, percent slide coverage and percent overlap of viewing fields for CP and TP. False negative rate (FNR) was determined by rescreening 10% of random and high-risk negative cases. CP and TP FNR with Pathfinder were compared to control groups without Pathfinder. RESULTS: A total of 46,393 Pathfinder cases were evaluated (43,354 CP, 3,039 TP) as compared to 62,981 without Pathfinder (60,307 CP, 2,674 TP). FNR was calculated for 12,983 negatives. Using Pathfinder resulted in a significant reduction in FNR for CP atypical squamous cells of undetermined significance and atypical glandular cells of undetermined significance cases. No decrease in FNR was observed for CP squamous intraepithelial lesions or for TP cases. TP slides were screened 66 seconds faster on average than CP. With electronic feedback, mean percent slide coverage and percent overlap were similar between CP and TP cases. Without feedback, coverage dropped and overlap increased slightly for both CP and TP. Technologists screened faster with feedback, saving an average of 50 seconds on CP and 41 seconds on TP. CONCLUSION: Pathfinder significantly reduced FNR for CP but not TP. Technologists screened TP significantly faster than CP while maintaining similar coverage and overlap. Pathfinder feedback itself may decrease screening time.

Cervix Uteri↗
PubMedDate not supplied

Evaluation of sexual abuse in the pediatric patient.

Evaluating a patient for suspected child sexual abuse can be daunting for many pediatric primary care practitioners. The consequences of misdiagnosis can be devastating. Knowledge of common clinical presentations, both physical signs and symptoms and behavioral changes, is paramount. Sexual abuse allegations must be reported and investigated by child protection agencies or law enforcement. Practitioners must be aware of when and how to report suspected child sexual abuse, in addition to having a basic understanding of the medical examination and findings. With a caring, knowledgeable, and sensitive approach to allegations of sexual abuse, the practitioner can assist the child and his or her family through this very difficult process.

Child↗