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Biomedical subjects

J Boyer

Publications and source records attributed to J Boyer.

At least 109 records · Page 6Linked to original sources
PubMed1994

Bioactive Arg-Gly-Asp conformations in anti-integrin GPIIb-IIIa antibodies.

Antibodies can mimic the biological function of physiological ligands, yet few examples indicate the structural similarity between antibodies and the ligands that they mimic. Originally, the competition of antibodies for ligand binding sites was conjectured to be through similar three-dimensional conformations, which represent the "internal image" of the given ligand. Here we show that residues in a complementary determining region (CDR) can adopt the same bioactive structures observed in ligands. Structure-function studies of three anti-GPIIb-IIIa murine monoclonal antibodies, PAC-1, LJ-CP3, and OP-G2, indicate that the RYD sequence in their H-CDR3 domain occupies the same conformational space as RGD in conformationally constrained, bioactive, GPIIb-IIIa cell-surface adhesion ligands. The relative location of the guanidinium and carboxylate groups in the RXD regions is identified as an important recognition feature, and the conformational space occupied by this region in the antibodies is only slightly larger than that in the most bioactive peptides. Additionally, we show that antibodies can unveil other potential bioactive sequences, which may impart specificity. Thus antibodies are an exquisite probe for identifying motifs of short adhesion stretches, thereby revealing amino acid sequences and restricted geometries that might be used as lead compounds in drug design.

Amino Acid Sequence↗
PubMed1994

DNA inoculation induces protective in vivo immune responses against cellular challenge with HIV-1 antigen-expressing cells.

Direct DNA inoculation induces immune responses through the delivery of nonreplicating transcription units that drive the synthesis of specific foreign proteins within the inoculated host. These proteins are processed within host cells and through association with relevant MHC antigens that can become the subject of immune surveillance and elicit immune responses against pathogens. Direct introduction of DNA into mice has been reported to be antigenic as demonstrated by the use of this technique to develop immune responses against human growth hormone, influenza proteins, as well as HIV-1 proteins. Most recently the demonstration of the use of this technology to produce anti-HIV-1 immune responses has been reported in nonhuman primates. Accordingly a more detailed analysis of this technology could generate important insight into the generality of this approach for immune therapy or vaccine design. In this article we further our investigation of direct DNA inoculation as a tool for induction of relevant immune responses against HIV-1 in vivo. We demonstrate expression of HIV-1 antigens in the inoculated muscle of animals. Inoculated animals demonstrate significant cytotoxic T cell responses against HIV-1 antigen-expressing targets. Furthermore, using a novel challenge system, we demonstrate that the majority of immunized animals can reject lethal, HIV-1 antigen-expressing cell challenge in an antigen-specific manner. This technology has relevance for the development of immunization strategies against HIV as it provides for specific antigen production in vivo without the use of infectious agents.

AIDS Vaccines↗
PubMed1993

Gene inoculation generates immune responses against human immunodeficiency virus type 1.

Recently, immunization techniques in which DNA constructs are introduced directly into mammalian tissue in vivo have been developed. In theory, gene inoculation should result in the production of antigenic proteins in a natural form in the immunized host. Here we present the use of such a technique for the inoculation of mice with a human immunodeficiency virus type 1 (HIV-1) envelope DNA construct (pM160). Mice were injected intramuscularly with pM160 and were subsequently analyzed for their anti-HIV envelope immune responses. Antisera collected from inoculated animals reacted with the recombinant HIV-1 envelope in ELISA and immunoprecipitation assays. The antisera also contained antibodies that were able to neutralize HIV-1 infection and inhibit HIV-1-mediated syncytium formation in vitro. Furthermore, splenic lymphocytes derived from pM160-inoculated animals demonstrated HIV-envelope-specific proliferative responses. The gene inoculation technique mimics features of vaccination with live attenuated viruses and, therefore, may ultimately prove useful in the rapid development of safe and efficacious vaccines as it provides for production of relevant antigen in vivo without the use of infectious agents.

Amino Acid Sequence↗
PubMed1993

Sequence of a 7.8 kb segment on the left arm of yeast chromosome XI reveals four open reading frames, including the CAP1 gene, an intron-containing gene and a gene encoding a homolog to the mammalian UOG-1 gene.

We report here the DNA sequence of a segment of chromosome XI of Saccharomyces cerevisiae extending over 7.8 kb. The segment contains four long open reading frames, YKL150, YKL153, YKL155 and YKL156, YKL155 corresponds to the CAP1 gene. YKL153 contains an intron and shows an extremely biased codon usage suggestive of a highly expressed protein. YKL156 is a homolog to UOG-1, an open reading frame associated with the cDNA clone of the mammalian growth/differentiation factor 1. YKL150 reveals common motifs to both the RNA polymerase II elongation factor of Drosophila melanogaster and to the yeast PPR2 gene product.

Actin Capping Proteins↗
PubMed1993

Norethindrone alters apolipoprotein E concentration and isoform expression in rat plasma high-density lipoproteins.

The administration of norethindrone, a synthetic progestin, to female rats caused marked decreases in the cholesterol and protein contents of high-density lipoproteins (HDL). A 84% decrease in the total apolipoprotein (apo) E of HDL was associated with a 80% decrease in the proportions of apoE isoforms E1 and E2, whereas E3 and E4 were unchanged. This appears to be the first demonstration of hormonally-induced modification of the apoE phenotype.

Animals↗
PubMed1993

Limited disease small cell lung cancer: alternating combination of doxorubicin, etoposide, ifosfamide and hyperfractionated radiotherapy. Final results of a multicentric pilot study for the Groupe Lyonnias d'Oncologie Thoracique (GLOT).

In order to evaluate the effect on prolonging survival of alternating chemotherapy and radiotherapy schedules in patients with limited disease small cell lung cancer, 89 patients were included in a multi-institutional pilot study between January 1986 and May 1989. Treatment consisted of induction chemotherapy using the combination of doxorubicin, etoposide and ifosfamide (AVI) for four consecutive courses, followed by two cycles of the VI chemotherapy alternating with three hyperfractionated radiotherapy courses and then followed by two additional courses of AVI. Objective response to the four cycles of AVI combination was observed in 65 patients (75%). Thirteen out of 30 patients (44%) who were in partial response (PR) after induction chemotherapy were converted into complete response (CR) after the three alternating courses of chemotherapy and radiotherapy. The principal side effect related to combined modality treatment was acute radiation pneumonitis (21.5% cases) reversible except one which resulted in toxic death, and a second with chronic lung fibrosis with permanent WHO Grade 2 dyspnea (14%). Local relapse was observed in 47% of the patients who were considered in CR at the end of the treatment program and cerebral metastases were the first site of detectable relapse in 25% cases. The 3-year actuarial disease-free survival of the 89 patients is 5%, and the median actuarial survival is 14 months. This study shows that the promising survival rates seen in our previously published interim analysis were not maintained. Reasons for this might include the choice of a non cisplatinum containing induction chemotherapy, the late introduction of thoracic irradiation and/or to the use of non-restrictive criteria for selecting patients.

Adult↗
PubMed1993

DNA inoculation induces neutralizing immune responses against human immunodeficiency virus type 1 in mice and nonhuman primates.

DNA, or genetic, inoculation mimics aspects of attenuated vaccines in that synthesis of specific foreign proteins is accomplished in the host. These proteins can be processed and presented on the relevant major histocompatibility complex (MHC) antigens and ultimately become the subject of immune surveillance. Very recently, we have described the use of the new technology to generate immune responses in mice against the human immunodeficiency virus type 1 (HIV-1) envelope using a gp160 DNA construct. Further analysis of this technology specifically in regard to HIV vaccine design is clearly important. In this report, we describe the analysis of additional HIV constructs as immunogens in both mice and report the use of this genetic immunization technology in nonhuman primates. In these studies, successful seroconversion occurs in more than 70% of the mice following the second immunization with 100 micrograms of construct DNA; three and four immunizations result in routinely 100% seroconversion of the mice. Furthermore, the same strategy has successfully seroconverted primates following their second inoculation, resulting in the generation of both antiviral and neutralizing antibodies in this animal species. These studies are the first report of which we are aware that demonstrate successful immunization of nonhuman primates through genetic vaccination technology and the first to describe genetic immunization of primates against HIV antigens. This technology has relevance for the development of safe and efficacious immunization strategies against HIV because it provides for relevant antigen production in vivo without the use of infectious agents.

AIDS Vaccines↗
PubMed1993

Inhibition of cholinesterases by histamine 2 receptor antagonist drugs.

Many studies have demonstrated that histamine 2 receptor antagonists (H2RA) have in vitro anticholinesterase effects, but discrepancies about type and potency of this inhibitory effect exist among published results. Moreover, cholinesterase inhibition has not been shown in patients receiving H2RA. These discrepancies led us to study the in vitro antibutyryl- and in vitro antiacetylcholinesterase activities of ranitidine, cimetidine, nizatidine comparatively to pyridostigmines. Plasma cholinesterase activity (PCEA), erythrocyte cholinesterase activity (ECEA) and plasma ranitidine levels were measured in six patients before and during continuous IV infusion (150 or 200 mg/d) of ranitidine. Our in vitro results confirm the weak anticholinesterase activity of H2RA. Ranitidine is the most potent inhibitor of butyrylcholinesterase (Ki = 61 microM). Ranitidine and nizatidine are the most potent inhibitors of acetylcholinesterase (Ki' = 2.1 microM, Ki' = 5.1 microM, respectively) but one thousand times less effective than pyridostigmine (Ki = 0.003 microM). The results in patients show no statistically significant difference between PCEA and ECEA measured before and during ranitidine infusion (plasma ranitidine levels between 0.31 and 1.25 microM).

Acetylcholinesterase↗
PubMed1993

[Laser therapy of villous rectocolonic tumors. Evaluation of results by multivariate analysis].

One hundred and twenty-four patients (mean age: 70 years) with a villous tumour of the rectum (n = 98) or the colon (n = 26) were treated by laser therapy from 1985 to 1991. Initial complete eradication was obtained in 93.5% of cases with a median time of 16 months. Using multivariate analysis, the tumor size (> 4 cm) only was predictive of eradication (P < 0.001). At 6 and 12 months, the actuarial eradication rates were 91 and 98% for small tumours versus 45 and 74% for larger tumours respectively. The actuarial recurrence rates were 10.5, 23, and 37% at 6, 12 and 24 months, and no longer increased after 3 years. No predictive factor of recurrence was isolated by multivariate analysis. Seven complications (5.6%) and 4 malignant transformations (3.4%) occurred. This study confirms the efficiency and low morbidity of laser therapy, especially in patients with small tumors, less than 4 cm in size.

Adenoma, Villous↗
PubMed1993

Terlipressin plus transdermal nitroglycerin vs. octreotide in the control of acute bleeding from esophageal varices: a multicenter randomized trial.

We undertook a multicenter randomized trial to compare the efficacy of terlipressin combined with transdermal nitroglycerin and that of octreotide in the emergency control of acute variceal hemorrhage in cirrhosis. Over 16 mo, 87 patients with endoscopically proved active bleeding from esophageal or cardiac varices were enrolled in five centers in France and randomly assigned to receive intravenous terlipressin (2 mg and then 1 mg/4 hr over 24 hr) and transdermal nitroglycerin (10 mg/12 hr over 24 hr) (group 1) or octreotide (continuous intravenous infusion of 25 micrograms/hr over 12 hr and then 100 micrograms at hr 12 and hr 18 subcutaneously) (group 2). Initial control of bleeding was assessed at the end of 12 hr of treatment on the basis of stability of blood pressure and hematocrit level with no further transfusion requirements. At 12 hr, bleeding was controlled in 59% (24 of 41) in group 1 and 78% (36/46) of group 2 patients (Fisher's exact test, p = 0.064). Mean transfusion requirements over this 12-hr period were significantly greater in group 1 (three blood units; range = 0 to 13) than in group 2 (one blood unit; range = 0 to 5) (p = 0.002). After the first 12 hr, 20% of patients (5 of 24) had repeat bleeding in group 1 compared with 27% (10 of 36) in group 2. During the first 48-hr period, five patients (12%) died in group 1, compared with 3 (6%) in group 2. Few side effects were noted in either group. However, in group 1 two patients experienced severe bradycardia; it resulted in death in one patient.(ABSTRACT TRUNCATED AT 250 WORDS)

Administration, Cutaneous↗