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Biomedical subjects

V Liu

Publications and source records attributed to V Liu.

At least 19 recordsLinked to original sources
PubMed2003

Mycophenolate in dermatology.

Originally used to treat psoriasis nearly three decades ago, mycophenolic acid, reformulated as mycophenolate mofetil (MMF), has been rediscovered by the world of dermatology. As a relatively well-tolerated immunosuppressive used in organ transplant recipients, MMF has recently been reported to show promise for several dermatologic conditions, including psoriasis, pemphigus vulgaris, pyoderma gangrenosum, bullous lichen planus, and even connective tissue diseases such as lupus erythematosus and dermatomyositis. Although not intended to be exhaustive, this review discusses MMF with regard to its basic pharmacology, its side effects, and its reported efficacy in a variety of dermatologic indications. Relevant literature was retrieved by a Medline search combining the terms "mycophenolate" or "mycophenolic acid" and "skin" or "skin disease" or a number of specific conditions ("psoriasis", "dermatitis", "eczema", "pemphigoid", "pemphigus", "vasculitis", "pyoderma gangrenosum", "Crohn's disease", "graft-versus-host disease", "lichen planus"). As MMF has only been recently re-introduced for dermatologic application, the nature of much of the literature is admittedly that of case reports or case series. Nevertheless, the results are sufficiently promising to warrant further larger, control studies.

Dose-Response Relationship, Drug↗
PubMed2000

Role of the conserved WHXL motif in the C terminus of synaptotagmin in synaptic vesicle docking.

Synaptotagmin (Syt) I, an abundant synaptic vesicle protein, consists of one transmembrane region, two C2 domains, and a short C terminus. This protein is essential for both synaptic vesicle exocytosis and endocytosis via its C2 domains. Although the short C terminus is highly conserved among the Syt family and across species, little is known about the exact role of the conserved C terminus of Syt I. In this paper, we report a function of the Syt I C terminus in synaptic vesicle docking at the active zones. Presynaptic injection of a peptide corresponding to the C-terminal 21 amino acids of Syt I (named Syt-C) into the squid giant synapse blocked synaptic transmission without affecting the presynaptic action potential or the presynaptic Ca(2+) currents. The same procedure repeated with a mutant C-terminal peptide (Syt-CM) had no effect on synaptic transmission. Repetitive presynaptic stimulation with Syt-C produced a rapid decrease in the amplitude of the postsynaptic potentials as the synaptic block progressed, indicating that the peptide interferes with the docking step rather than the fusion step of synaptic vesicles. Electron microscopy of the synapses injected with the Syt-C peptide showed a marked decrease in the number of docked synaptic vesicles at the active zones, as compared with controls. These results indicate that Syt I is a multifunctional protein that is involved in at least three steps of synaptic vesicle cycle: docking, fusion, and reuptake of synaptic vesicles.

Action Potentials↗
PubMed2000

Parotid oncocytoma in the Birt-Hogg-Dubé syndrome.

Birt-Hogg-Dubé syndrome consists of fibrofolliculomas, trichodiscomas, and acrochordons and has been associated with several noncutaneous tumors. We report the first case of Birt-Hogg-Dubé syndrome in association with a parotid oncocytoma, a rare salivary gland tumor.

Adenoma, Oxyphilic↗
PubMed1998

Development of an immunoassay for urinary galactosylhydroxylysine.

Galactosylhydroxylysine (GHL) is released during bone resorption and has been shown to be elevated in subjects with metabolic bone loss. GHL is relatively specific for bone, it is not recycled or significantly metabolized during collagen turnover, and the levels are not influenced by diet. Previous measurements of GHL levels in urine have been performed using reverse-phase high performance liquid chromatography following pre-column derivatization. We produced polyclonal antibodies to GHL using GHL purified from sea sponges and developed an immunoassay that can recognize GHL in urine. The antibodies have minimal cross-reactivity with a physiological mixture of amino acids (< 1%), galactose (< 0.2%), lactose (< 0.3%), and glucosylgalactosylhydroxylysine (< 1%). This competitive immunoassay requires no dilution or pretreatment of the samples and provides a rapid and easy method for the evaluation of GHL in urine. Analysis of clinical samples from normal individuals, post-menopausal women, osteoporotic patients and individuals with Paget's disease show that the assay can discriminate between groups with differing levels of bone resorption as well as deoxypyridinoline (Dpd).

Adult↗
PubMed1997

Safety studies of the intraperitoneal injection of E1A--liposome complex in mice.

The HER-2/neu (also called c-erbB-2) proto-oncogene is overexpressed in many human cancer cells, including those of breast cancer and ovarian cancer. We have previously shown that adenovirus 5 E1A inhibits HER-2/neu transcription and functions as a tumor suppressor gene in HER-2/neu-overexpressing cancer cells. Liposome-mediated E1A gene transfer suppresses tumor development and prolongs survival of tumor-bearing mice. In support of a phase I clinical trial of an E1A-liposome complex administered to patients with HER-2/neu-overexpressing breast of ovarian cancer, we conducted a series of studies to evaluate the safety of intraperitoneal injection of E1A in normal mice. The cumulative doses used were from five to 40 times the DNA-lipid starting dose proposed for the phase I clinical trial. In this dosing range, the administration of the E1A-liposome complex had no adverse effects on renal, hepatic and hematological parameters studied. No major organ pathologic changes were observed. We concluded that intraperitoneal administration of E1A-liposome complex at the proposed dose would not be expected to produce significant toxicity. The E1A-liposome clinical trial was recently approved by the Recombinant DNA Advisory Committee and Food and Drug Administration for a phase I trial in patients with HER-2/neu-overexpressing breast and ovarian cancer.

Adenoviridae↗
PubMed1995

Selective actions of certain neuroactive pregnanediols at the gamma-aminobutyric acid type A receptor complex in rat brain.

Certain endogenous pregnanediols (5 alpha-pregnan-3 alpha,20 alpha-diol and 5 beta-pregnan-3 alpha,20 beta-diol) were observed to have limited efficacy as allosteric modulators of t-[35S]butylbicyclophosphorothionate ([35S]TBPS) and [3H]flunitrazepam binding to sites on the gamma-aminobutyric acid (GABA)A receptor complex in rat brain. In contrast, 3 alpha-hydroxy-5 alpha-pregnan-20-one (3 alpha,5 alpha-P) and 3 alpha-hydroxy-5 beta-pregnan-20-one (3 alpha,5 beta-P) have full efficacy. Moreover, 3 alpha,5 beta-P but not 3 alpha,5 alpha-P recognizes high (nanomolar) and low (micromolar) affinity neuroactive steroid sites in these allosteric modulatory assays. The concentration-response curve for 3 alpha,5 alpha-P modulation of [35S]TBPS binding was shifted rightward in the presence of these pregnanediols and GABA. The maximum shift produced by these pregnanediols never exceeded the concentration-response curve obtained with 3 alpha,5 alpha-P alone in the absence of GABA. Additionally, neither 5 alpha-pregnan-3 alpha,20 alpha-diol nor 5 beta-pregnan-3 alpha,20 beta-diol had any effect on the site recognized by 3 alpha,5 alpha-P in the absence of GABA. The difference in the affinities of the two apparent sites (29 nM versus 152 nM in the presence and absence of GABA, respectively) recognized by 3 alpha,5 alpha-P is only approximately 5-fold. In contrast, the difference between the high (30 nM) and low (7 microM) affinity sites discriminated by 3 alpha,5 beta-P is > 200-fold. Thus, the selective interaction between the high affinity site recognized by 3 alpha,5 beta-P and these pregnanediols can be clearly observed. A saturating concentration of 5 beta-pregnan-3 alpha,20 beta-diol selectively eliminated the high affinity component recognized by 3 alpha,5 beta-P, whereas 5 alpha-pregnan-3 alpha,20 alpha-diol did not completely abolish the high affinity site. 5 alpha-Pregnan-3 alpha,20 alpha-diol recognized only a portion of the high affinity sites discriminated by 3 alpha,5 beta-P, relative to 5 beta-pregnan-3 alpha,20 beta-diol, whereas the two pregnanediols recognized a similar population of sites mediating 3 alpha,5 alpha-P inhibition of [35S]TBPS binding. Collectively, these studies provide evidence that the limited efficacy of certain pregnanediols as allosteric modulators of [35S]TBPS binding may be explained in part by selectivity for the high affinity site recognized by 3 alpha,5 beta-P.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1993

Adoptive immunotherapy of hormone-refractory, stage D2 prostate cancer using ex vivo activated autologous T cells (autolymphocyte therapy): results from a pilot study.

There is no effective therapy available for stage D2 prostate cancer once patients become refractory to hormonal therapy. In a pilot study, we treated 17 patients with hormone-refractory stage D2 prostate cancer using autolymphocyte therapy, an outpatient form of adoptive immunotherapy in which patients are treated with autologous T cells that have been activated ex vivo. Feasibility and safety were documented. Transient PSA reductions up to 66% were noted, suggesting biological activity. Further studies to test the safety and efficacy of autolymphocyte therapy in the treatment of prostate cancer are warranted.

Aged↗
PubMed1992

Hepatitis C viremia in patients with hepatitis C virus infection.

Sera from 103 patients were tested for hepatitis C virus RNA by nested polymerase chain reaction assay. Using primers from the highly conserved 5'-untranslated region, we detected hepatitis C virus RNA in 67 (88.2%) of 76 patients positive for antibody to hepatitis C virus by both second-generation and neutralization enzyme immunoassays. Hepatitis C virus RNA was detected in 93% of patients who had been infected for 10 yr or less and in 89% of those who had been infected for longer than 10 yr. Hepatitis C virus RNA was detected in all patients with chronic hepatitis, active cirrhosis or hepatocellular carcinoma and in 50% of those with nonspecific reactive hepatitis or inactive cirrhosis. Hepatitis C virus RNA was not detected in sera from 22 patients negative for antibody to hepatitis C virus or in 5 patients positive for antibody to hepatitis C virus by second-generation but not by neutralization enzyme immunoassay. Using primers from the less conserved nonstructural region 4, we detected hepatitis C virus RNA at a lower frequency, in 66% of patients who were positive for antibody to hepatitis C virus by both second-generation and neutralization enzyme immunoassays. The detection rate was higher in patients with frequent parenteral exposure. Our study showed that hepatitis C viremia can be detected in most patients with hepatitis C virus infection, including those with long-standing infection or advanced liver disease.

Base Sequence↗
PubMed1992

Hepatitis D virus superinfection remains a rare occurrence in non-drug abusers in Hong Kong.

Recent studies from Taiwan reported an increased prevalence of hepatitis D virus (HDV) superinfection as well as a spread of HDV infection to non-drug abusers. We examined the current prevalence of HDV superinfection in Hong Kong by testing sera from a large cohort of patients with acute and chronic hepatitis B virus (HBV) infection, collected between January 1988 and December 1990, for IgG antibody to HDV (anti-HDV). Anti-HDV was detected in 13 (93%) of 14 parenteral drug abusers who had HBV-related chronic liver disease. However, anti-HDV was detected in only one (0.15%) of 664 non-drug abusers who had chronic HBV infection and none of 31% patients with acute hepatitis B. We concluded that HDV superinfection remains a rare occurrence in non-drug abusers in Hong Kong.

Cohort Studies↗
PubMed1992

FLP-mediated intermolecular recombination in the cytoplasm of Drosophila embryos.

We show that when a heat-shock-driven gene that encodes the yeast FLP recombinase is injected into preblastoderm Drosophila embryos, it promotes intermolecular recombination between two coinjected plasmids that bear the specific recombination target sequence, FRT. Minimal, 34-bp FRT sites in the two plasmids are sufficient for their cointegration. The reaction is efficient enough to produce detectable recombinants when one of the plasmids is present in as little as 1000 molecules per embryo. This is comparable to the concentration of unique chromosomal sites, raising the possibility that integration of injected plasmid DNA into FRT-bearing fly chromosomes may also be achievable. Since integrants might be stabilized against the reverse excision reaction if the recombinase could be provided in a sharp pulse, it is encouraging that efficient plasmid cointegration is also achieved when in vitro synthesized FLP RNA rather than DNA is injected into the embryos.

Animals↗