Biomedical subjects

Y K Fu

Publications and source records attributed to Y K Fu.

16 recordsLinked to original sources

PubMed1997

Diagnostic criteria for pseudomalignant osteoblastoma.

AIMS: Osteoblastoma is a rare bone tumour and differentiation from osteosarcoma is occasionally a diagnostic problem. The difficulty is further compounded when such a lesion microscopically shows cytological or architectural atypia. METHODS AND RESULTS: A case of pseudomalignant osteoblastoma occurring in the left iliac crest of a 34-year-old Chinese woman is presented. Radiographic findings were non-diagnostic, but favoured a benign yet locally aggressive lesion. Histologically the diagnosis was based on the findings of classical osteoblastoma areas harbouring pseudomalignant osteoblasts in the absence of mitoses, but there were co-existing atypical architectural features also. CONCLUSION: The significance and pathogenesis of the 'permeative pattern' are discussed. Difficulties in differentiating borderline lesions are emphasized.

Adult↗

PubMed1996

Accuracy and efficiency of X-ray requests initiated by triage nurses in an accident and emergency department.

A study was carried out from 1 March 1995 to 31 March 1995 in the Accident & Emergency department, Pamela Youde Nethersole Eastern Hospital, Hong Kong. The aim was to assess the feasibility of requesting X-rays by triage nurses based on a pre-set protocol prior to patients being seen by a doctor. Judgement of the attending physician was used as the gold standard by which to judge the need for radiographs requested by the triage nurse. In addition, the senior medical officer or consultant would judge whether the triage nurse had applied the protocol correctly. A total of 934 patients were included in the study and 883 (94.54%) patients had X-rays requested by the triage nurse. Only 5.44% of the radiographs requested by nurses were considered to haven been unnecessary by the doctor. There was no statistically significant difference in agreement for the child and adult groups. In 917 (98%) of cases, nurses had adhered to the protocol. A saving of an average of 18.59 minutes of total service time was obtained during the study. Requesting of X-ray by triage nurse was feasible

Adult↗

PubMed1994

Reduction in superoxide anion secretion and bactericidal activity of neutrophils from aged rats: reversal by the combination of gamma interferon and growth hormone.

Polymorphonuclear neutrophils (PMN) from bone marrow of 24-month-old rats kill Escherichia coli less efficiently than PMN from 3-month-old rats. Secretion of O2- and killing of E. coli by PMN from both young and old rats can be significantly augmented by preincubation with either 250 U of gamma interferon (IFN-gamma) or 250 ng of growth hormone (GH) per ml. This priming is specific, because neutralizing monoclonal antibodies against either IFN-gamma or GH completely abrogate the enhanced O2- secretion by PMN from young rats. However, in contrast to PMN from young rats, PMN from aged rats are not primed to kill E. coli by 10-fold-lower concentrations of either IFN-gamma (25 U/ml) or GH (25 ng/ml). To explore the mechanism for the reduction in bacterial killing by PMN from old rats, a syngeneic GH-secreting pituitary cell line (GH3) was implanted in vivo. PMN from GH3-treated aged rats, but not control aged rats, could now be primed in vitro for O2- secretion by IFN-gamma (25 U/ml). Although PMN from aged rats do not respond to the lower doses of either IFN-gamma or GH, the combination of both reagents totally restores the ability of PMN to secrete O2- and to kill E. coli. This synergistic priming is observed with PMN from aged rats, but not with those from young rats, and can be detected when both reagents are added simultaneously or when they are added in either sequence. Furthermore, addition of a monoclonal antibody against either IFN-gamma or GH abrogates the synergism of these two molecules. Collectively, these data identify an important alteration in myeloid cells from aged rodents by showing that their PMN are intrinsically unable to respond to low concentrations of IFN-gamma by secreting O2- and killing bacteria. The results also define a previously unrecognized synergism in PMN from aged animals by showing that GH synergizes with IFN-gamma both in vivo and in vitro to restore these suppressed responses.

Aging↗

PubMed1994

[Gas chromatographic method with EC detection to determine isosorbide-5-mononitrate (IS-5-MN) in human serum and its pharmacokinetic parameters].

A simple, sensitive and precise capillary GC-ECD method was developed for the determination of isosorbide-5-mononitrate in human serum. Pharmacokinetic parameters of the drug was obtained from the human serum level-time curve measured. Serum samples were extracted with a mixture of ethyl ether-ethyl acetate (4:1), the upper phase was collected and evaporated to about 100 microliters under a gentle nitrogen stream. Isosorbide dinitrate was used as internal standard. With a human serum sample size of 200 microliters, the detection limit of IS-5-MN was found to be about 5 ng/ml, and the absolute recovery from 74% to 85%. The within-day and between-day relative standard deviation were less than 7% and 9%, respectively. This method was applied to the pharmacokinetic studies of IS-5-MN tablets from two different sources. Two sets of t1/2 (Ke), Tmax and AUC values obtained from 8 volunteers were tested statistically and no significant difference was found.

Chromatography, Gas↗

PubMed1993

Physicochemical dissociation of CD4-mediated syncytium formation and shedding of human immunodeficiency virus type 1 gp120.

The mechanism of CD4-mediated fusion via activated human immunodeficiency virus type 1 (HIV-1) gp41 and the biological significance of soluble CD4 (sCD4)-induced shedding of gp120 are poorly understood. The purpose of these investigations was to determine whether shedding of gp120 led to fusion activation or inactivation. BJAB cells (TF228.1.16) stably expressing HIV-1 envelope glycoproteins (the gp120-gp41 complex) were used to examine the effects of pH and temperature on sCD4-induced shedding of gp120 and on cell-to-cell fusion (syncytium formation) with CD4+ SupT1 cells. sCD4-induced shedding of gp120 was maximal at pH 4.5 to 5.5 and did not occur at pH 8.5. At physiologic pH, sCD4-induced shedding of gp120 occurred at 22, 37, and 40 degrees C but neither at 16 nor 4 degrees C. In contrast, syncytia formed at pH 8.5 (maximally at pH 7.5) but not at pH 4.5 to 5.5. At pH 7.5, syncytia formed at 37 and 40 degrees C but not at 22, 16, or 4 degrees C. Preincubation of cocultures of TF228.1.16 and SupT1 cells at 4, 16, or 22 degrees C before the shift to 37 degrees C resulted in similar, increased, or decreased syncytium formation, respectively, compared with the control. Furthermore, an activated intermediate of CD4-gp120-gp41 ternary complex may form at 16 degrees C; this intermediate rapidly executes fusion upon a shift to 37 degrees C but readily decays upon a shift to the shedding-permissive but fusion-nonpermissive temperature of 22 degrees C. These physicochemical data indicate that shedding of HIV-1 gp120 is not an integral step in the fusion cascade and that CD4 may inactivate the fusion complex in a process analogous to sCD4-induced shedding of gp120.

CD4 Antigens↗

PubMed1992

Growth hormone augments superoxide anion secretion of human neutrophils by binding to the prolactin receptor.

Recombinant human growth hormone (HuGH) and human prolactin (HuPRL), but not GH of bovine or porcine origin, prime human neutrophils for enhanced superoxide anion (O2-) secretion. Since HuGH, but not GH of other species, effectively binds to the HuPRL receptor (HuPRL-R), we used a group of HuGH variants created by site-directed mutagenesis to identify the receptor on human neutrophils responsible for HuGH priming. A monoclonal antibody (MAb) directed against the HuPRL-R completely abrogated O2- secretion by neutrophils incubated with either HuGH or HuPRL, whereas a MAb to the HuGH-R had no effect. The HuGH variant K172A/F176A, which has reduced affinity for both the HuGH-binding protein (BP) and the HuPRL-BP, was unable to prime human neutrophils. This indicates that priming is initiated by a ligand-receptor interaction, the affinity of which is near that defined for receptors for PRL and GH. Another HuGH variant, K168A/E174A, which has relatively low affinity for the HuPRL-BP but slightly increased affinity for the HuGH-BP, had much reduced ability to prime neutrophils. In contrast, HuGH variant E56D/R64M, which has a similar affinity as wild-type HuGH for the HuPRL-BP but a lower affinity for the HuGH-BP, primed neutrophils as effectively as the wild-type HuGH. Finally, binding of HuGH to the HuPRL-BP but not to the HuGH-BP has been shown to be zinc dependent, and priming of neutrophils by HuGH was also responsive to zinc. Collectively, these data directly couple the binding of HuGH to the HuPRL-R with one aspect of functional activation of human target cells.

Adult↗

PubMed1991

A novel role of growth hormone and insulin-like growth factor-I. Priming neutrophils for superoxide anion secretion.

Growth hormone (GH) and the GH-dependent growth promoting peptide, insulin-like growth factor-I (IGF-I), are both potent signals for priming human and porcine polymorphonuclear neutrophils (PMN) to secrete superoxide anion (O2-). PMA, opsonized-zymosan, or FMLP could all be used as triggering stimuli to demonstrate priming by GH or IGF-I. As positive controls, IFN-gamma and LPS also primed both human and porcine PMN for enhanced O2- release. However, only the LPS-mediated enhancement was inhibited by polymyxin B, which demonstrates that the priming induced by GH, IGF-I, or IFN-gamma was not caused by LPS contamination. Furthermore, a specific antibody to GH abrogated priming induced by this molecule. In contrast to IGF-I, the closely related molecule insulin was unable to prime PMN even at pharmacologic levels. Insulin, at pharmacologic levels, antagonized the priming mediated by IGF-I but had no effect on GH priming. A mAb directed against the human IGF-I receptor blocked the enhanced secretion of O2- by human PMN that was caused by IGF-I, but not GH, indicating that neutrophil priming induced by GH was not mediated by inducing extracellular release of IGF-I. However, priming PMN by both GH and IGF-I required de novo protein synthesis, because cycloheximide completely abrogated enhanced O2- secretion that was caused by these growth factors. These data show that a classic pituitary hormone (GH), as well as its widely recognized growth promoting peptide (IGF-I), are involved in regulating an important functional activity of both porcine and human PMN. Inasmuch as GH and IGF-I have recently been demonstrated to be synthesized by leukocytes, these data support the possibility that both of these proteins could act in a paracrine fashion as cytokines to prime PMN for an enhanced respiratory burst.

Adult↗

PubMed1988

Detection of cellulose-binding proteins in electrophoresis gels by filter paper affinity blotting.

Proteins separated in electrophoresis gels were tested for the ability to bind cellulose by a simple blotting procedure. Proteins were blotted onto Whatman No. 1 filter paper by diffusion or by electrophoretic transfer and detected by Coomassie blue staining. Certain proteins released into culture supernatant by Bacteroides succinogenes NR9 (ATCC 43854) adhered strongly to cellulose, but were not found to have carboxymethylcellulose activity. Boiling of samples prior to electrophoresis eliminated the ability of proteins to bind to cellulose. Proteins that did not adhere to filter paper cellulose were detected on a nitrocellulose membrane placed behind the filter paper during electrophoretic transfer. The technique, referred to as filter paper affinity blotting, detects cellulose-binding proteins with great sensitivity.

Bacterial Proteins↗

PubMed1983