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Biomedical subjects

R E Miller

Publications and source records attributed to R E Miller.

At least 19 recordsLinked to original sources
PubMed1995

Induction of apoptosis in mature T cells by tumour necrosis factor.

T-cell receptor-induced apoptosis regulates immune responses and can result from interactions between Fas (Apo1/CD95) and Fas ligand (FasL). Mutations in the genes for Fas and FasL cause disorders resembling human autoimmune diseases in lpr and gld mice, respectively. However, peripheral T-cell deletion takes place in lpr mice, and autoimmune syndromes occur in mouse strains without Fas or FasL defects. Here we show that tumour necrosis factor (TNF) can mediate mature T-cell receptor-induced apoptosis through the p75 TNF receptor. Blockage of both TNF and FasL is required to abrogate T-cell death and TNF mediates the death of most CD8+ T cells, whereas FasL mediates the death of most CD4+ T cells. Our results suggest that autoregulatory apoptosis of the mature T cells can occur by two distinct molecular mechanisms.

Animals↗
PubMed1995

Antimalarial activity of new dihydroartemisinin derivatives. 6. alpha-Alkylbenzylic ethers.

A series of diastereomeric dihydroartemisinin alpha-alkylbenzylic ethers was synthesized in search for analogs with higher antimalarial efficacy and longer plasma half-life than the existing artemisinin derivatives. Artelinic acid was used as the model molecule for the design of new analogs. Two approaches were taken in an attempt to (a) increase the lipophilicity of the molecule and (b) decrease the rate of oxidative dealkylation of the target compounds. All compounds in this study showed at least equal or better in vitro antimalarial activity against Plasmodium falciparum than artelinic acid. The most active compounds of this series showed 10-, 20-, and 40-fold better inhibitory activity than artemether, artemisinin, and artelinic acid, respectively. Compounds which have a small methyl group substituted at the alpha-methylene group showed weaker activity than compounds with a larger carbethoxyalkyl substituent, indicating that the lipophilicity and the steric effect of the molecules play important roles in their antimalarial activity. This fact is further substantiated by the significantly weaker antimalarial activity of the carboxylic acids than their corresponding esters. Compounds with electron-withdrawing function (NO2) substantially increase the antimalarial activity. The S-diastereomers, in general, are severalfold more potent than the corresponding R-isomer.

Animals↗
PubMed1995

Inhibition of mature IL-1 beta production in murine macrophages and a murine model of inflammation by WIN 67694, an inhibitor of IL-1 beta converting enzyme.

The proinflammatory cytokine IL-1 beta is synthesized by activated monocytes and macrophages as a 31-kDa, biologically inactive precursor that is proteolytically processed to the biologically active 17-kDa mature molecule by the IL-1 beta converting enzyme (ICE). WIN 67694, Z-Val-Ala-Asp-CH2O(CO)[2,6-(CI2)]Ph, is a potent, selective inhibitor of human ICE. In activated murine peritoneal macrophages, WIN 67694 inhibited the release of mature IL-1 beta with an IC50 of 1.8 microM without any effect on the release of IL-1 alpha, IL-6, or TNF-alpha. The effect was specific to mature IL-1 beta release; the ICE inhibitor did not effect IL-1 beta RNA levels or precursor protein synthesis. In vivo, WIN 67694 was also able to inhibit selectively the release of IL-1 beta in a dose-dependent manner in a subcutaneous tissue chamber implant model of inflammation. IL-1 beta levels in tissue chamber fluid were inhibited 35 and 55% at 10 and 100 mg/kg, respectively. IL-1 alpha, IL-6, and TNF-alpha levels were not affected. The ability to selectively inhibit mature IL-1 beta release in vivo with ICE inhibitors will allow for detailed studies of the role of IL-1 beta and ICE in inflammatory diseases.

Amino Acid Sequence↗
PubMed1995

Management of common bile duct stones in the era of laparoscopic cholecystectomy.

PURPOSE: To assess the safety and efficacy of endoscopic retrograde cholangiopancreatography (ERCP) prior to laparoscopic cholecystectomy. METHODS: In patients suspected of harboring common duct stones, we performed ERCP prior to laparoscopic cholecystectomy (LC). Indications included jaundice, gallstone pancreatitis, elevated liver function tests, and visualizing a common duct stone and/or a dilated common duct on ultrasonography. Data were analyzed retrospectively. RESULTS: Of 217 patients undergoing LC, 37 (17%) had ERCP with or without endoscopic sphincterotomy (ES). Of these 37, common duct stones were noted in 19 patients (51%). Only 1 of 11 (9%) patients with mild gallstone pancreatitis had choledocholithiasis. The only complication following ERCP was pancreatitis in 1 patient who underwent uneventful LC. There were no deaths in the entire series. CONCLUSIONS: ERCP and ES is a safe and effective method of clearing the common duct of stones prior to LC. Patients with mild gallstone pancreatitis do not require ERCP prior to LC.

Adolescent↗
PubMed1995

Description and evaluation of the Res-Q Arrhythmia Control Device.

The Res-Q Arrhythmia Control Device (Intermedics Inc.) is one of the latest entries into the growing implantable cardioverter defibrillator (ICD) market. Dysrhythmias are classified according to their zone of detection, with a bradycardia zone, up to 3 tachycardia zones, and a fibrillation zone. Detection criterion, therapies, and redetection criterion within each zone are independently programmable, tailoring the setup to each individual's needs. In a hierarchical manner, this allows efficacy, urgency, and patient comfort to be appropriately balanced. Tachycardia therapy options include antitachycardia pacing (ATP), low-energy cardioversion, and high-energy shock, while VVI pacing provides bradycardia therapy. ATP programming is extremely flexible. Biphasic waveform and a maximum output of 700 V have yielded a high rate of successful implantation. Unique features include the multiprogrammable sensing autogain, which tracks evoked T waves during pacing, as well as the use of the pulse generator to perform implant testing. Major strengths include programming flexibility and individualized therapy for multiple dysrhythmias. The major shortcoming relates to a lack of stored electrograms. Although long-term follow-up is not yet available, the Res-Q appears to be a capable challenger to a peer group of advanced generation ICDs.

Arrhythmias, Cardiac↗
PubMed1994

Interleukin 7 promotes long-term in vitro growth of antitumor cytotoxic T lymphocytes with immunotherapeutic efficacy in vivo.

A major obstacle to the effective use of adoptive immunotherapeutic treatment of cancer is the difficulty of obtaining tumor-reactive lymphocytes in either sufficient numbers or with appropriate in vivo function to make such an approach feasible. Previous studies have shown that antitumor cytotoxic T lymphocytes (CTL) with in vivo efficacy can be generated in vitro from lymphoid cells obtained from lymph nodes that drain the anatomical site of a tumor. Results presented here demonstrate that inclusion of interleukin 7 (IL-7) into the medium in which such CTL are cultured can support their growth in vitro for prolonged periods of time in the absence of repeated stimulation with either tumor stimulator cells or tumor antigen. More importantly, antitumor CTL propagated in medium containing IL-7 have retained both their antigenic specificity and their ability to reject tumors in vivo subsequent to intravenous injection. Parallel cultures of antitumor CTL similarly cultured in medium containing only IL-2 could only be maintained for 5-6 wk, after which the number and proportion of viable cells that were recoverable from such cultures progressively decreased. Phenotypic analysis of CTL maintained after extended culture (i.e., 22 mo) in medium containing IL-7 demonstrated them to be CD3+4-8+ T cells. These cells were also found to express lymphocyte function associated 1, intercellular adhesion molecule 1, and Mel-14 cell interaction molecules. The data also demonstrate that these CTL do not require the presence of antigen-presenting cell populations to mount a proliferative response to tumor stimulator cells. Cells in these cultures were also demonstrated to produce IL-2 after stimulation with irradiated tumor cells, thereby indicating that these CTL have become independent of the requirement for CD4+ helper cells to survive and function either in vitro or in vivo. Collectively, the findings that IL-7 can beneficially augment the generation, and propagate the long-term growth, of antitumor CTL from lymph nodes draining a tumor site may have profound implications for promoting the immunotherapeutic treatment of cancer in humans.

Animals↗
PubMed1994

gld/gld mice are unable to express a functional ligand for Fas.

Mice homozygous for either the lpr or gld genes develop phenotypically identical autoimmune disorders. The gene responsible for the pathology in lpr/lpr mice encodes the Fas antigen, a protein associated with the induction of programmed cell death. To determine if the defect associated with gld represents a mutation in the ligand for Fas, we have assessed the ability of lymphoid cells from homozygous gld/gld mice to lyse target cells in a Fas-dependent manner. Using an antagonistic antibody to Fas, we demonstrate that activated T cells from normal and lpr mice are capable of inducing Fas-mediated lysis of tumor target cells. In contrast, activated T cells from gld/gld mice fail to induce lysis of tumor targets, although cells from gld mice are able to lyse specific allogeneic targets following mixed lymphocyte culture. In addition, activated T cells from gld/gld homozygous animals are not capable of binding to a Fas.Fc fusion protein at high levels, whereas activated T cells from normal and lpr/lpr animals bind Fas.Fc efficiently. These data indicate that mice homozygous for gld are unable to express a functional ligand for Fas.

Animals↗
PubMed1994

The mouse Fas-ligand gene is mutated in gld mice and is part of a TNF family gene cluster.

The gene for the mouse Fas ligand was cloned and its chromosomal position determined. Fasl was tightly linked to gld (no crossovers in 567 meiotic events) on mouse chromosome 1 and closely linked with a novel member of the same TNF family of ligands, the Ox40 ligand (Ox40l, 1 crossover in 567 meiotic events). Southern blot analysis did not reveal any difference between the Fasl gene from gld and wild-type mice and levels of Fasl mRNA transcripts were similar in PMA and ionomycin induced wild-type and coisogenic gld T cells. Sequence analysis of the gld gene indicated a single amino acid change (Phe Leu) in the COOH terminal portion of this type II transmembrane protein, and COS cells transfected with Fasl cDNA from gld mice failed to induce apoptosis of Fas-expressing target cells. Thus, the data demonstrate that the gld phenotype is the result of a point mutation in the Fasl gene and that Fasl is part of a complex of ligands structurally related to TNF mapping within a small region of mouse chromosome 1.

Amino Acid Sequence↗
PubMed1994

Differential ability of Th1 and Th2 T cells to express Fas ligand and to undergo activation-induced cell death.

Stimulation of previously activated T cells through the antigen receptor can result in the apoptotic death of the responding cell, a process referred to as activation-induced cell death (AICD). This process appears to involve Fas (CD95) and its ligand (Fas-L). The distribution of Fas and Fas-L on various T cell subsets has not been extensively characterized. We have therefore analyzed cells committed to a Th1- or Th2-type differentiation pattern for the expression and function of Fas-L. Using both a sensitive bioassay and flow cytometry, we demonstrate that cloned Th1 cells express high levels of Fas-L, whereas cloned Th2 cells express only low levels. The expression of Fas-L by Th1 and Th2 cells correlates with the relative abilities of these two cell types to undergo AICD. Whereas AICD is readily observed in cultures of cloned Th1, but not Th2 cells, Th2 cells are capable of undergoing apoptosis in the presence of Th1 cells expressing Fas-L. The ability of T cells to undergo AICD appears to be unrelated to the presence of various cytokines. Thus, the Fas/Fas-L pathway appears to be critical for the induction of AICD and this pathway is differentially regulated in cells committed to either Th1 or Th2 differentiation.

Animals↗
PubMed1994

Regulation of apoptosis and T cell activation by Fas-specific mAb.

Fas was initially described as a molecule expressed on the surface of certain cell lines that could mediate programmed cell death (apoptosis) subsequent to ligation by specific mAb. To determine whether mAb to other epitopes on the Fas molecule might mediate other functions, we generated a panel of mAb to the extracellular portion of human Fas. Significant lysis of Fas-expressing target cells was only observed when the new mAb were first bound to a solid-phase support and not when the mAb were added in solution. However, several of these mAb inhibited the killing of target cells induced by the prototypic Fas-specific mAb, CH-11. Those mAb that inhibited apoptosis of target cells mediated by the CH-11 mAb also blocked lysis of target cells mediated by cells expressing Fas ligand. Finally, some of the Fas-specific mAb were found to co-stimulate proliferation of peripheral blood T cells in the presence of immobilized CD3 mAb. Thus, the data indicate the existence of a complex set of interactions mediated by Fas in both normal and transformed lymphoid cells that may have important implications regarding the role(s) of this molecule in regulation of immune responses.

Animals↗
PubMed1994

Preparation and evaluation of peptidic aspartyl hemiacetals as reversible inhibitors of interleukin-1 beta converting enzyme (ICE).

Aspartyl aldehyde, Ac-Tyr-Val-Ala-Asp-H 1 (L-709,049), has been reported to be a potent, reversible inhibitor of interleukin-1 beta converting enzyme (ICE) [Thornberry, N.A. et al. (1992) Nature (London) 356, 768-774]. In the context of our own work, we have developed a general synthetic approach to peptidic aspartyl aldehydes. Semicarbazone derivative, H-Asp(Ot-Bu)-Sc 4, was identified as a stable, masked aspartyl aldehyde equivalent. We have used 4 to synthesize a series of mono-, di- and tripeptide aldehydes, and multigram quantities of Ac-Tyr-Val-Ala-Asp-H 1, Ac-Tyr-Val-Lys-Asp-Sc 21 and Ac-Tyr-Val-Lys-Asp-H 2. Biological evaluation of these aspartyl aldehydes and derivatives suggests that the tripeptide scaffold, Z-Val-Ala-Asp, is a peptide scaffold that retains good potency and selectivity for ICE.

Aldehydes↗
PubMed1994

Molecular cloning of mouse insulin-like growth factor binding protein 4 (IGFBP4) cDNA and expression of a fusion protein with IGF-binding activity.

The TC-1 bone marrow stromal cell line expresses a 2.3 kb IGFBP-4 mRNA transcript. Reverse transcription/polymerase chain reaction was used to amplify the complete open reading frame of the insulin-like growth factor binding protein-4 (IGFBP-4) from poly(A)+ of a murine bone marrow stromal cell line (TC-1). Sequence analysis reveals that the murine IGFBP-4 is highly homologous to the rat IGFBP-4 and less so to the human IGFBP-4. The inferred amino acid sequence has a molecular weight of 25.7 kD. An IGFBP-4/maltose binding protein fusion peptide expression in the pMal-p2 vector produced a fusion protein exhibiting both IGFBP immunoreactivity and IGF-I binding activity with specificity characteristic of IGFBPs.

Amino Acid Sequence↗
PubMed1993

The prevalence of hepatitis A, B and C infection among different ethnic groups in Belize.

Little is known about the prevalence of infection with hepatitis viruses in Belize, Central America. We conducted a serologic survey among members of the Belize Defence Force (BDF), which is composed of the five major ethnic groups in Belize, to estimate prevalence rates of hepatitis A, B, and C among military-aged men and women in Belize. Of approximately 600 men and women in the BDF, 492 (82%) completed a questionnaire and blood collection. Antibody to hepatitis A was found in 94%, with similar rates by age, sex, rank, and ethnicity. Antibody to hepatitis B core antigen (anti-HBc) was found in 31%. Rates of anti-HBc varied significantly among the ethnic groups with the lowest rates in Mestizo (5%) and Mayan Indians (9%), and significantly higher rates among Creoles (30%) and Garifuna (56%). Rates increased with increasing age from 28% in those 18-24 years old to 35% in those > or = 35 years old (P = 0.07, by chi-square test for trend). Hepatitis B surface antigen was found in 21 (4%) overall. Antibody to hepatitis C was found in two (0.4%). In this young healthy population, exposure to hepatitis A before the age of 18 is almost universal, while exposure to hepatitis B is related to age and ethnic origin.

Adult↗