PubMed HealthSearch

Biomedical subjects

W M Lee

Publications and source records attributed to W M Lee.

At least 19 recordsLinked to original sources

Regulation of anion secretion by cyclo-oxygenase and prostanoids in cultured epididymal epithelia from the rat.

1. The role of cyclo-oxygenase (COX) in the regulation of anion secretion (measured as short- circuit current, Isc) in cultured epididymal epithelia from immature rats was investigated. 2. COX inhibitors attenuated the increase of anion secretion caused by bradykinin (LBK) but had no effect on that caused by PGE2, suggesting that prostaglandin synthesis mediates the secretory response of the tissues to LBK. 3. The apparent IC50 values for indomethacin, piroxicam and L-745,337 in inhibiting the LBK-induced Isc were 0.14, 1.34 and 15.7 microM, respectively. This order of potency: indomethacin > piroxicam > L-745,337 >> DFU suggests the involvement of the COX-1 isozyme in the mediation of the secretory response to LBK. 4. Among the COX products (prostaglandins, thromboxane and prostacyclins) tested, only PGE2 and, to a much lesser extent, PGF2alpha stimulated anion secretion by cultured rat epididymal epithelia. 5. The effect of PGE2 was mimicked by 11-deoxyl PGE1, a specific prostaglandin E (EP)2/4 receptor agonist, but not by sulprostone, a specific EP1/3 receptor agonist, indicating that cyclic AMP-coupled EP2/4 receptors are involved in the LBK-stimulated anion secretion. 6. A reverse transcriptase-polymerase chain reaction study detected the expression of COX-1 and COX-2 mRNA in intact rat epididymis and in cultured epididymal epithelia. The expression of COX-1 mRNA was reduced by LBK by 44 %. 7. Immunohistochemical studies demonstrated the presence of COX-1 immunoreactivity in the basal cells of the intact rat epididymis. By comparison, COX-2 immunoreactivity was detected in the apical pole of the principal cells. 8. The role of COX in the formation of the epididymal microenvironment and the implication of long term administration of non-steroidal anti-inflammatory drugs (NSAIDs) on male fertility are discussed.

Animals

Etiology and outcome for 295 patients with acute liver failure in the United States.

Little information is available on acute liver failure (ALF) in the United States. We gathered demographic data retrospectively for a 2-year period from July 1994 to June 1996 on all cases of ALF from 13 hospitals (12 liver transplant centers). Data on the patients included age, hepatic coma grade on admission, presumed cause, transplantation, and outcome. Among 295 patients, 74 (25%) survived spontaneously, 121 (41%) underwent transplantation, and 99 (34%) died without undergoing transplantation. Ninety-two of 121 patients (76%) survived 1 year after transplantation. Acetaminophen overdose was the most frequent cause (60 patients; 20%), followed by cryptogenic/non A non B non C (NANBNC; 15%), idiosyncratic drug reactions (12%), hepatitis B (10%), and hepatitis A (7%). Spontaneous survival rates were highest for patients with acetaminophen overdose (57%) and hepatitis A (40%) and lowest for those with Wilson's disease (no survivors of 18 patients). The transplantation rate was highest for Wilson's disease (17 of 18 patients; 94%) and lowest for autoimmune hepatitis (29%) and acetaminophen overdose (12%). Age did not differ between survivors and nonsurvivors, perhaps reflecting a selection bias for patients transferred to liver transplant centers. Coma grade on admission was not a significant determinant of outcome, but showed a trend toward affecting both survival and transplantation rate. These findings on retrospectively studied patients from the United States differ from those previously gathered in the United Kingdom and France, highlighting the need for further study of trends in each country.

Acetaminophen

Interferon alfa-2b alone or in combination with ribavirin as initial treatment for chronic hepatitis C. Hepatitis Interventional Therapy Group.

BACKGROUND: Only 15 to 20 percent of patients with chronic hepatitis C have a sustained virologic response to interferon therapy. We compared the efficacy and safety of recombinant interferon alfa-2b alone with those of a combination of interferon alfa-2b and ribavirin for the initial treatment of patients with chronic hepatitis C. METHODS: We randomly assigned 912 patients with chronic hepatitis C to receive standard-dose interferon alfa-2b alone or in combination with ribavirin (1000 or 1200 mg orally per day, depending on body weight) for 24 or 48 weeks. Efficacy was assessed by measurements of serum hepatitis C virus (HCV) RNA and serum aminotransferases and by liver biopsy. RESULTS: The rate of sustained virologic response (defined as an undetectable serum HCV RNA level 24 weeks after treatment was completed) was higher among patients who received combination therapy for either 24 weeks (70 of 228 patients, 31 percent) or 48 weeks (87 of 228 patients, 38 percent) than among patients who received interferon alone for either 24 weeks (13 of 231 patients, 6 percent) or 48 weeks (29 of 225 patients, 13 percent) (P<0.001 for the comparison of interferon alone with both 24 weeks and 48 weeks of combination treatment). Among patients with HCV genotype 1 infection, the best response occurred in those who were treated for 48 weeks with interferon and ribavirin. Histologic improvement was more common in patients who were treated with combination therapy for either 24 weeks (57 percent) or 48 weeks (61 percent) than in those who were treated with interferon alone for either 24 weeks (44 percent) or 48 weeks (41 percent). The drug doses had to be reduced and treatment discontinued more often in patients who were treated with combination therapy. CONCLUSIONS: In patients with chronic hepatitis C, initial therapy with interferon and ribavirin was more effective than treatment with interferon alone.

Adult

Immune suppression by recombinant interleukin (rIL)-12 involves interferon gamma induction of nitric oxide synthase 2 (iNOS) activity: inhibitors of NO generation reveal the extent of rIL-12 vaccine adjuvant effect.

Recombinant interleukin 12 (IL-12) can profoundly suppress cellular immune responses in mice. To define the underlying mechanism, recombinant murine (rm)IL-12 was given to C57BL/6 mice undergoing alloimmunization and found to transiently but profoundly suppress in vivo and in vitro allogeneic responses and in vitro splenocyte mitogenic responses. Use of neutralizing antibodies and genetically deficient mice showed that IFN-gamma (but not TNF-alpha) mediated rmIL-12-induced immune suppression. Splenocyte fractionation studies revealed that adherent cells from rmIL-12-treated mice suppressed the mitogenic response of normal nonadherent cells to concanavalin A and IL-2. Addition of an inhibitor of nitric oxide synthase (NOS) restored mitogenic responses, and inducible (i)NOS-/- mice were not immunosuppressed by rmIL-12. These results support the view that suppression of T cell responses is due to NO produced by macrophages responding to the high levels of IFN-gamma induced by rmIL-12. When a NOS inhibitor was given with rmIL-12 during vaccination of A/J mice with irradiated SCK tumor cells, immunosuppression was averted and the extent of rmIL-12's ability to enhance induction of protective antitumor immunity was revealed. This demonstrates that rmIL-12 is an effective vaccine adjuvant whose efficacy may be masked by its transient immunosuppressive effect.

Adjuvants, Immunologic

c-myc mRNA is down-regulated during myogenic differentiation by accelerated decay that depends on translation of regulatory coding elements.

Murine C2C12 myoblasts induced to differentiate into multinucleated myotubes decrease their levels of c-myc mRNA 3-10-fold through posttranscriptional mechanisms that recognize regulatory elements contained in protein-coding sequences in exons 2 and 3 of the mRNA. To determine the mechanism by which these elements mediate c-myc mRNA down-regulation, we examined the regulation of mutant MYC and human beta-globin-MYC fusion mRNAs. Regulation of mRNAs containing MYC exon 2 or 3 is abolished by insertion of an upstream termination codon indicating that regulatory function depends on their translation. Exploiting this translation dependence, we show that pharmacologic inhibition of translation with cycloheximide abolishes the down-regulation of regulated MYC and globin-MYC mRNAs and induces their levels in differentiating C2C12 cells. We exclude the possibility that this induction in mRNA levels results from cycloheximide effects on transcription or processing of parts of the RNA other than the regulatory elements, leading to the conclusion that cycloheximide induction results from mRNA stabilization. We show that the magnitude of cycloheximide induction can be used to estimate turnover rates of mRNAs whose decay is translation-dependent. By using cycloheximide inducibility to examine turnover rates of MYC and globin-MYC mRNAs, we show that the MYC exon 2 and exon 3 regulatory elements, but not MYC 3'-untranslated region or chloramphenicol acetyltransferase coding sequences, mediate accelerated mRNA decay in differentiating, but not undifferentiated, C2C12 cells. We show that these regulatory elements must be translated to confer accelerated mRNA decay and that increased turnover occurs in the cytoplasm and not in the nucleus. Finally, using cycloheximide induction to examine mRNA half-lives, we show that mRNA turnover is increased sufficiently by mechanisms targeting the exon 2 and 3 regulatory elements to account for the magnitude of c-myc mRNA down-regulation during differentiation. We conclude from these results that c-myc mRNA down-regulation during myogenic differentiation is due to translation-dependent mechanisms that target mRNAs containing myc exon 2 and 3 regulatory elements for accelerated decay.

Animals

Interleukin-12 and interleukin-18 synergistically induce murine tumor regression which involves inhibition of angiogenesis.

The antitumor effect and mechanisms activated by murine IL-12 and IL-18, cytokines that induce IFN-gamma production, were studied using engineered SCK murine mammary carcinoma cells. In syngeneic A/J mice, SCK cells expressing mIL-12 or mIL-18 were less tumorigenic and formed tumors more slowly than control cells. Neither SCK.12 nor SCK.18 cells protected significantly against tumorigenesis by distant SCK cells. However, inoculation of the two cell types together synergistically protected 70% of mice from concurrently injected distant SCK cells and 30% of mice from SCK cells established 3 d earlier. Antibody neutralization studies revealed that the antitumor effects of secreted mIL-12 and mIL-18 required IFN-gamma. Interestingly, half the survivors of SCK.12 and/or SCK.18 cells developed protective immunity suggesting that anti-SCK immunity is unlikely to be responsible for protection. Instead, angiogenesis inhibition, assayed by Matrigel implants, appeared to be a property of both SCK.12 and SCK.18 cells and the two cell types together produced significantly greater systemic inhibition of angiogenesis. This suggests that inhibition of tumor angiogenesis is an important part of the systemic antitumor effect produced by mIL-12 and mIL-18.

Animals

Recombinant interleukin 12 enhances cellular immune responses to vaccination only after a period of suppression.

Adjuvant use of recombinant murine IL-12 (rmIL-12) was examined in mice vaccinated with irradiated syngeneic tumor or allogeneic cells. rmIL-12 given to A/J mice vaccinated with irradiated SCK tumor cells engineered to secrete granulocyte/macrophage-colony-stimulating factor resulted in significantly better protection from tumor challenges 28 days after vaccination but, unexpectedly, severely compromised host protection 14 days after vaccination. Immune suppression was rmIL-12 dose dependent and manifested as reduced splenic CTL activity, stimulated cytokine release and ability to reject SCK cells. Transient immune suppression was also seen with rmIL-12 given during vaccination of C3H/HeN mice with irradiated K1735 melanoma cells and of C57BL/6 mice with irradiated allogeneic HKB cells. The period of suppression coincided with transiently reduced splenic T-cell mitogenic responses to concanavalin A and IL-2, suggesting that they may be causally related. Suppression appears to be due to impaired immune effector mechanisms rather than impaired host immunization, which is actually enhanced as evidenced by the enhanced reaction to immunogens when hosts are challenged later after rmIL-12 administration. Demonstration that rmIL-12, as it is frequently used, induces a transient period of impaired immune response that can compromise host protection suggests that the unquestioned effectiveness of rmIL-12 against murine tumors is primarily due to activation of mechanisms other than antigen-specific tumor immunity (e.g., antiangiogenic effects) and that use of human IL-12 should be monitored for similar effects.

Animals

Eosinophils bind rhinovirus and activate virus-specific T cells.

Episodes of virus-induced exacerbations of asthma are accompanied by increased eosinophils (EOS) in respiratory secretions and evidence of EOS degranulation. Although rhinoviruses (RV) are the viruses most often implicated in exacerbations of asthma in both children and adults, little is known about the immune response to this group of viruses and, in particular, EOS-RV interactions. To define such interactions, we incubated human rhinovirus type 16 (RV16), a serotype using ICAM-1 as a receptor, with EOS purified from PBMC, and measured EOS-RV binding, EOS-mediated Ag presentation and T cell activation, and EOS cell surface marker expression and superoxide production. Significant RV16 binding occurred to EOS that were pretreated with granulocyte-macrophage CSF, and this binding was inhibited by anti-ICAM-1 mAb. EOS also presented viral Ags to RV16-specific T cells, causing T cell proliferation and secretion of IFN-gamma. RV16 induced a significant shift from CD18dim to CD18bright, but did not affect EOS expression of CD54, CD69, or HLA-DR. Finally, RV16 did not induce superoxide production from peripheral blood EOS. These findings suggest that RV16 also binds to airway EOS, which resemble granulocyte-macrophage CSF-treated blood EOS in terms of high expression of ICAM-1. Furthermore, our findings suggest that EOS could participate in RV-induced immune responses through Ag presentation and T cell activation. By activating RV-specific T cells, EOS may play an important role in the initiation of antiviral T cell responses, and these effects could also contribute to enhanced airway inflammation and increased asthma symptoms in susceptible individuals.

Adult

Early hepatitis C virus-RNA responses predict interferon treatment outcomes in chronic hepatitis C. The Consensus Interferon Study Group.

In previous studies employing interferons (IFNs) in the treatment of chronic hepatitis C, there have been few reliable predictors of sustained responses. We retrospectively evaluated the predictive value of hepatitis C virus (HCV)-RNA measurements in the first few months during consensus interferon (CIFN) treatment using a sensitive reverse-transcriptase polymerase chain reaction assay to determine sustained responses. Data from two large treatment trials, one of IFN-naive patients and one of retreated relapsers and nonresponders, were used, including serum samples at 2-week intervals in the naive study and 8-week intervals in the retreatment study. Patients received initial CIFN (9 microgram) treatment for 6 months and were assessed 6 months after treatment. There were 28 sustained viral responders of 232 CIFN-treated patients. Of the sustained responders, 48% had already cleared HCV RNA from serum (<100 copies/mL) by week 2, 78% by week 4, 81% by week 6, and 96% by week 12. Patients with early HCV-RNA clearance were more likely to have sustained responses than those who responded later. Early clearance of HCV from serum was also associated with greater likelihood of a sustained response to 48 weeks of retreatment with 15 microgram CIFN. Ninety-five percent of the sustained responders were HCV-RNA-negative by week 8 of retreatment. Early assessment of HCV RNA may help in the prediction of sustained responses to IFN and allow the value of continued treatment to be determined early in the course of IFN therapy.

Antiviral Agents

Adenoviral transduction of melanoma cells with B7-1: antitumor immunity and immunosuppressive factors.

Previous studies in experimental models have demonstrated that the transduction of human or murine melanoma cells with the co-stimulatory B7-1 molecule induces effective antitumor immune responses. In order to develop B7-1 gene transfer as a therapeutic tool in the clinical management of melanoma, efficient means of in vivo gene transfer must be used. To this end we evaluated in vitro and in vivo immune responses associated with adenoviral transduction of murine and human melanoma cells with B7-1. Adenovirus-mediated transduction of human and murine melanoma cells with B7-1 leads to high-level transgene expression in vitro and in vivo and does not affect MHC class I and II expression. Adenovirus-delivered B7-1 induced antitumor immune responses, on the basis of observations that human melanoma cells transduced to express human B7-1 were able to co-stimulate allogeneic and autologous T cells to proliferate and that murine melanoma K1735 cells transduced to express murine B7-1 were rejected by syngeneic, immunocompetent mice. By contrast, intratumoral injection of an adenovirus encoding murine B7-1 failed to eliminate established murine melanoma (K1735) despite high-level transgene expression in tumor cells. Potent T cell inhibitory factor(s) secreted by both K1735 cells and select human melanoma cells may contribute to the failure to achieve protection in this setting. Thus, immune inhibitory melanoma-derived factors need to be taken into account when considering the clinical use of B7-1 immunotherapy.

Adenoviridae

Tumor cell responses to IFNgamma affect tumorigenicity and response to IL-12 therapy and antiangiogenesis.

Expression of a dominant negative mutant IFNgammaR1 in murine SCK and K1735 tumor cells rendered them relatively unresponsive to IFNgamma in vitro and more tumorigenic and less responsive to IL-12 therapy in vivo. IL-12 induced histologic evidence of ischemic damage only in IFNgamma-responsive tumors, and in vivo Matrigel vascularization assays revealed that while IFNgamma-responsive and -unresponsive tumor cells induced angiogenesis equally well, IL-12 and its downstream mediator IFNgamma only inhibited angiogenesis induced by the responsive cells. IL-12 induced angiogenesis inhibitory activity in the responsive cells, which may be attributable to production of the chemokine IP-10. Thus, IL-12 and IFNgamma inhibit tumor growth by inducing tumor cells to generate antiangiogenic activity.

Animals

Review article: interferon and hepatitis C--factors predicting therapeutic outcome.

Hepatitis C chronically infects approximately 1.5% of Americans and is the most common clinical problem facing hepatologists. Since the virus was initially described in 1989, development of an effective therapy has been challenging. Although several different therapeutic agents have been used, no therapy has been shown to reliably eradicate the virus. Interferon-alpha, a cytokine with immunostimulatory and anti-viral properties, has become the therapy of choice for patients with chronic hepatitis C infection. Trials assessing the efficacy of interferon-alpha have characterized host and viral factors predictive of responses to treatment. A thorough understanding of these predictive factors is requisite to providing cost-effective therapeutic decisions for the patient with chronic hepatitis C infection.

Antiviral Agents

Relationship between biochemical and virological responses to interferon therapy in chronic hepatitis C infection. Consensus Interferon Study Group.

We have investigated the relationship between serum alanine aminotransferase (ALT) and hepatitis C virus (HCV) RNA in the assessment of responses to interferon (IFN) therapy in chronic HCV infection. Data from 704 patients with HCV infection who were randomized to receive consensus IFN-alpha (CIFN) 3 micrograms (n = 232 patients) or 9 micrograms (n = 232 patients), or IFN-alpha 2b 3 million units (MU) (n = 240 patients), were used for these analyses. All patients were treated three times weekly. Hepatitis C viral RNA (HCV RNA) was determined by quantitative reverse transcriptase-polymerase chain reaction (RT-PCR) with a lower limit of detection of 100 copies ml-1. Of patients with normal serum ALT concentrations, 53% (120/225) had undetectable HCV RNA at the end-of-treatment period and 47% (51/109) had undetectable HCV RNA at the end of the post-treatment observation period. In contrast, of the patients with undetectable HCV RNA, 75% (120/161) and 84% (51/61) had normal serum ALT activities at the end-of-treatment and post-treatment observations periods, respectively. The majority of patients with undetectable HCV RNA had normal ALT values. In contrast, only half of the patients with normal ALT values were negative for HCV. End-of-treatment HCV RNA response also better predicted sustained virological response than did end-of-treatment ALT response.

Adult

Insulin does not promote rat mammary carcinogenesis.

Indirect evidence from both epidemiological studies and animal experiments suggests that insulin may promote breast cancer development. In this study, we directly tested for a promoting effect of insulin on mammary carcinogenesis in Sprague-Dawley rats. Fifty day-old female rats received an i.p. injection of 37.5 mg/kg methylnitrosourea (MNU). Five days later, the animals were randomized into two groups. One group received insulin injections five times/week until the time of death, while the other control group received similar injections of normal saline. Over the course of 26 weeks following MNU treatment, the mammary tumour incidence in the insulin-treated group did not differ significantly from the saline-treated controls. Furthermore, the number of tumours per tumour-bearing rat did not differ between groups. Our results demonstrate that insulin is not a promoter of mammary carcinogenesis in this model.

Animals

Rat testicular extracellular superoxide dismutase: its purification, cellular distribution, and regulation.

Using multiple HPLC steps, we have identified and purified a 68-kDa polypeptide (as estimated by gel permeation HPLC) to apparent homogeneity, from primary Sertoli cell-enriched culture medium, that consisted of two monomers of 35 (alpha chain) and 33 kDa (ss chain) on SDS-polyacrylamide gel running under reducing conditions. Partial N-terminal amino acid sequence analysis of these two monomers revealed sequences of NH2-DXGESGVDLADRL (SODEX-alpha) and NH2-XXDTGESGVDLADXL (SODEX-ss), which are identical to rat extracellular superoxide dismutase (SODEX) with the exceptions that SODEX-alpha and SODEX-ss are missing, respectively, four (Trp-Thr-Met-Ser) and two (Trp-Thr) amino acids from their N-termini, compared to rat SODEX, suggesting that the cleavage sites of the SODEX gene in the testis are different from that of other organs. Studies by sequential use of reverse transcription and polymerase chain reaction (PCR) using two SODEX primers have demonstrated the expression of SODEX in the heart, brain, lung, kidney, epididymis, testis, Sertoli, and germ cells, with low expression in the liver and ovary and no expression in the uterus, spleen, or thymus. Nucleotide sequence analysis of this 447-base pair PCR product from Sertoli cells revealed that its sequence is equivalent to the sequence of previously published rat SODEX. During testicular maturation, the SODEX steady-state mRNA level increased significantly from 20 to 60 days of age and then declined at 90 days of age. Such an increase in the testicular SODEX expression during maturation is not likely a result of an up-regulation by germ cells, since germ cells isolated from either 20- or 60-day-old rats when cocultured with Sertoli cells failed to elicit an increase in SODEX expression in the cocultures. Using primary Sertoli cell cultures in vitro, it was found that Sertoli cell SODEX expression was stimulated by interleukin-1alpha but not by either interferon-gamma or basic fibroblast growth factor. These results illustrate that Sertoli cells as well as germ cells synthesize and/or secrete a testicular variant of SODEX that may provide essential clues to understanding superoxide radical-mediated damage in the gonad.

Animals

WIN 52035-dependent human rhinovirus 16: assembly deficiency caused by mutations near the canyon surface.

Three drug-dependent mutants of human rhinovirus 16 (HRV16) were characterized by sequence analyses of spontaneous mutant isolates and were genetically reconstructed from a parental cDNA plasmid. These mutants formed plaques in the presence but not in the absence of the selecting antiviral drug, WIN 52035, which binds to the capsid of wild-type virus and inhibits its attachment to the host cell. The drug-dependent phenotype of each mutant was caused by a single amino acid substitution in the VP1 coat protein. The three independent mutations conferring drug dependence are M1103T, T1208A, and V1210A. Single-step growth experiments involving rescue of one of the three mutants (V1210A) by delayed drug addition suggested (i) that the drug dependence lesion is at the stage of virus assembly and (ii) that one or more components of the viral assembly pool decay in the absence of drug. RNA accumulation and infectivity were unaffected by the absence of drug in all three mutants, suggesting that the labile assembly component is coat protein.

Antiviral Agents

Antibody-mediated neutralization of human rhinovirus 14 explored by means of cryoelectron microscopy and X-ray crystallography of virus-Fab complexes.

The structures of three different human rhinovirus 14 (HRV14)-Fab complexes have been explored with X-ray crystallography and cryoelectron microscopy procedures. All three antibodies bind to the NIm-IA site of HRV14, which is the beta-B-beta-C loop of the viral capsid protein VP1. Two antibodies, Fab17-IA (Fab17) and Fab12-IA (Fab12), bind bivalently to the virion surface and strongly neutralize viral infectivity whereas Fab1-IA (Fab1) strongly aggregates and weakly neutralizes virions. The structures of the two classes of virion-Fab complexes clearly differ and correlate with observed binding neutralization differences. Fab17 and Fab12 bind in essentially identical, tangential orientations to the viral surface, which favors bidentate binding over icosahedral twofold axes. Fab1 binds in a more radial orientation that makes bidentate binding unlikely. Although the binding orientations of these two antibody groups differ, nearly identical charge interactions occur at all paratope-epitope interfaces. Nucleotide sequence comparisons suggest that Fab17 and Fab12 are from the same progenitor cell and that some of the differing residues contact the south wall of the receptor binding canyon that encircles each of the icosahedral fivefold vertices. All of the antibodies contact a significant proportion of the canyon region and directly overlap much of the receptor (intercellular adhesion molecule 1 [ICAM-1]) binding site. Fab1, however, does not contact the same residues on the upper south wall (the side facing away from fivefold axes) at the receptor binding region as do Fab12 and Fab17. All three antibodies cause some stabilization of HRV14 against pH-induced inactivation; thus, stabilization may be mediated by invariant contacts with the canyon.

Amino Acid Sequence