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Biomedical subjects

G Frankel

Publications and source records attributed to G Frankel.

At least 91 records · Page 5Linked to original sources
PubMed1996

Comparison of numerous delivery systems for the induction of cytotoxic T lymphocytes by immunization.

A variety of vaccine delivery systems including peptides with various adjuvants, recombinant particles, live recombinant viruses and bacteria and plasmid DNA were tested for their ability to induce CD8+ cytotoxic T lymphocytes (CTL) against a well-defined epitope (amino acids 252-260) from the circumsporozoite (CS) protein of Plasmodium berghei. We compared routes of immunization that would be applicable for the administration of a malaria vaccine in humans. The majority of these vaccines did not induce high CTL responses in the spleens of immunized mice. However, both a yeast-derived Ty virus-like particle expressing the optimal nine-amino acid epitope SYIPSAEKI from the CS protein (CSP-VLP) and a lipid-tailed peptide of this same sequence induced high levels of the major histocompatibility complex (MHC) class I-restricted CTL with one and three subcutaneous immunizations, respectively. Moreover, these CTL were able to recognize naturally processed antigen expressed by a recombinant vaccinia virus. The levels of CTL induced by CSP-VLP could be augmented by co-immunization with certain cytokines. Target cells pulsed with CSP-VLP were recognized and lysed, showing that the particles were effectively processed and presented through MHC class I presentation pathway. The levels of CTL induced using CSP-VLP and lipopeptides are comparable to those observed after immunization with multiple doses of irradiated sporozoites.

Amino Acid Sequence↗
PubMed1996

Detection of proviral human T-cell lymphotrophic virus type I DNA in mouthwash samples of HAM/TSP patients and HTLV-I carriers.

Human T-cell lymphotrophic virus type I (HTLV-I), is a member of the oncogenic retroviruses family endemic in several parts of the world and also recently identified in the Jewish Mashhadi population who immigrated from Iran to Israel. The virus is the causative agent of adult T-cell leukemia (ATL) and a chronic myelopathy known both as tropical spastic paraparesis (TSP) or HTLV-I associated myelopathy (HAM). The known modes of HTLV-I transmission are by sexual intercourse, from mother to child in breast milk, via blood transfusion, and by sharing of needles by parenteral drug users. In the present study we examined the presence of HTLV-I provirus genomic DNA by nested polymerase chain reaction (PCR) and by DNA hybridization in mouthwash samples obtained from 13 Mashhadi-born Iranian Jews with spastic paraparesis associated with HTLV-I, 4 Mashhadi-born Iranian Jews asymptomatic carriers for HTLV-I and 21 healthy controls. Proviral HTLV-I DNA was detected by mouthwash PCR in 12 of 17 HTLV-I infected subjects (71%) but in none of 21 controls. Proviral DNA was also detected in mouthwash samples using HTLV-I probe by dot blot hybridization assay. The presence of HTLV-I proviral DNA in whole saliva may suggest a possible transmission of the virus via saliva and explain the increased rate of infection in elderly Mashhadi-Jewish population.

Base Sequence↗
PubMed1996

Intimin from enteropathogenic Escherichia coli restores murine virulence to a Citrobacter rodentium eaeA mutant: induction of an immunoglobulin A response to intimin and EspB.

The formation of attaching and effacing (A/E) lesions is central to the pathogenesis of enteropathogenic Escherichia coli (EPEC)-mediated disease in humans and Citrobacter rodentium (formerly C. freundii biotype 4280)-mediated transmissible colonic hyperplasia in mice. Closely related outer membrane proteins, known as intimins, are required for formation of the A/E lesion by both EPEC (Int(EPEC)) and C. rodentium (Int(CR)). A secreted protein, EspB (formally EaeB), is also necessary for A/E-lesion formation. Here we report that expression of a cloned Int(EPEC), encoded by plasmid pCVD438, restores murine virulence to an intimin-deficient mutant of C. rodentium DBS255. Replacement of Cys937 with Ala abolished the ability of the cloned EPEC intimin to complement the deletion mutation in DBS255. Ultrastructural examination of tissues from wild-type C. rodentium and DBS255(pCVD438)-infected mice revealed multiple A/E lesion on infected cells and loss of contact between enterocytes and basement membrane. Histological investigation showed that although both wild-type C. rodentium and DBS255(pCVD438) colonized the descending colon and induced colonic hyperplasia in orally infected 21-day-old mice, the latter strain adhered to epithelial cells located deeper within crypts. Nonetheless, infection with the wild-type strain was consistently more virulent, as indicated by a higher mortality rate. All the surviving mice, challenged with either wild-type C. rodentium or DBS255(pCVD438), developed a mucosal immunoglobulin A response to intimin and EspB. These results show that C. rodentium infection provides a relevant, simple, and economic model to investigate the role of EPEC proteins in the formation of A/E lesions in vivo and in intestinal disease.

Adhesins, Bacterial↗
PubMed1995

Expression of LacZ from the htrA, nirB and groE promoters in a Salmonella vaccine strain: influence of growth in mammalian cells.

Attenuated Salmonella strains are currently being evaluated as live vectors for the delivery of heterologous antigens to the mammalian mucosal and systemic immune systems. An approach to improving the stability of heterologous antigen expression during vaccination is to drive expression of the foreign protein from promoters, e.g. nirB, that become activated when Salmonella enter the host. Salmonella strains were constructed that harboured similar multicopy plasmids encoding the lacZ gene. In each strain, lacZ expression was driven from either the nirB, htrA or groE promoters. Expression of LacZ increased in all vaccine strains as they were shifted from conditions of low to high temperature. In addition, expression of lacZ driven from the htrA and nirB promoters significantly increased when the Salmonella entered eukaryotic cells, including macrophages. Expression of lacZ from the groE promoter was significantly elevated in macrophages but not in cells derived from epithelia. These promoters may be useful for optimising heterologous antigen expression within immune cells of the host.

Antigens↗
PubMed1995

Effect of deoxymannojirimycin and Brefeldin A on Yersinia pseudotuberculosis invasin--eukaryotic cell interaction.

The cell surface receptors of the Yersinia pseudotuberculosis invasin protein are the alpha 3-6 beta 1 integrins. Invasin and the extracellular matrix protein fibronectin bind to the same or closely located sites on alpha 5 beta 1 integrin, although invasin bind with a much greater affinity. Invasin-integrin interaction promotes bacterial penetration into eukaryotic cells. Binding of fibronectin to its integrin receptor seems to be dependent on terminal oligosaccharides processing. In this paper, we have examined the effect of 1-deoxymannojirimycin (dMNJ), an inhibitor of Golgi alpha-mannosidases involved in processing of N-glycan precursors, and of Brefeldin A (BFA), a natural product of fungi which has profound effects on the structure and function of the Golgi apparatus, on invasin-cell interaction. We found that unlike fibronectin, the interaction of invasin with cells was resistance to dMNJ. However, preincubating cells with BFA caused a dose dependent inhibition of invasin-mediated cell entry, while cell invasion by Salmonella typhimurium was not affected.

1-Deoxynojirimycin↗
PubMed1995

Sixteen-month experience with video-assisted extraperitoneal laparoscopic bladder neck suspension.

After an extensive favorable experience with the Lapides-Ball open retropubic bladder neck suspension, we chose to perform this operation laparoscopically. We describe video-assisted extraperitoneal laparoscopic bladder neck suspension (VELBNS), in which we employ a single laparoscopic cannula and a laparoscopic bladder suspension set for suturing and simultaneously use video-assisted cystoscopy and laparoscopy for precise suture placement. Over 16 months, we operated on 70 patients with stress urinary incontinence secondary to hypermobility of the urethra. We describe the patient evaluation and selection and the surgical principles and techniques. Five procedures were converted to open operations because of bladder lacerations (two cases) or inability to dissect the space of Retzius because of scar tissue (three cases). At 3 months, 4 patients had unresponsive de novo urgency incontinence, and 61 patients were dry and without protection. One patient had a recurrence at 6 months that was corrected by open surgery. All 12 patients seen at 1 year were dry. We intend to survey our patients annually to obtain long-term results.

Adult↗
PubMed1995

Molecular characterization of a carboxy-terminal eukaryotic-cell-binding domain of intimin from enteropathogenic Escherichia coli.

A eukaryotic cell-binding domain from the intimin (Int) polypeptide of enteropathogenic Escherichia coli O127 (EPEC) was investigated. Derivatives of the carboxy-terminal 280-amino-acid domains of Int (Int-EPEC280) and the Int homolog invasin (Inv) from Yersinia pseudotuberculosis (InvYP280) were fused to the E. coli maltose-binding protein (MBP), expressed, and purified. The smallest MBP-IntEPEC fusion protein that efficiently mediated binding to HEp-2 cells, monitored by using purified fusion proteins in fluorescence activated cell sorter analysis or by using fluorescent Covaspheres coated with purified fusions, contained the carboxy-terminal 150 amino acids of Int. Replacement of Cys-937 with Ser (IntEPEC280CS) destroyed the cell-binding activity of IntEPEC280. Covaspheres coated with MBP-IntEPEC280 were associated with HEp-2 cell microvilli but failed to induce actin accumulation underneath bound particles or cell spreading on coated plastic surfaces. MBP-IntEPEC280, but not MBP, MBP-IntEPEC280CS, or MBP-InvYP280, inhibited EPEC entry into HEp-2 cells.

Adhesins, Bacterial↗
PubMed1994

Characterization of the C-terminal domains of intimin-like proteins of enteropathogenic and enterohemorrhagic Escherichia coli, Citrobacter freundii, and Hafnia alvei.

Surface proteins called intimins (Int), which are homologous to the invasin protein (Inv) of Yersinia spp., play a role in inducing brush border damage, termed attachment and effacement, which follows infection by enteropathogenic and enterohemorrhagic Escherichia coli, Citrobacter freundii biotype 4280, and Hafnia alvei. Maltose-binding protein (MBP) fusions containing the C-terminal 280 amino acids of Int-like proteins of strains of enteropathogenic E. coli, enterohemorrhagic E. coli, H. alvei, and C. freundii biotype 4280 and of Yersinia pseudotuberculosis Inv were constructed and purified. The 3' end of the gene for the H. alvei Int-like protein was sequenced and showed homology to corresponding regions of other Int-encoding genes. Binding of MBP-Int-like and MBP-Inv fusion proteins to HEp-2 cells was demonstrated by immunofluorescence microscopy and by fluorescence-activated cell sorting. MBP-Inv induced attachment and spreading of HEp-2 cells to plastic-coated wells, but MBP-Int-like fusion proteins did not. Preincubation of HEp-2 cells with MBP-Inv, but not with MBP-Int-like fusion proteins, inhibited MBP-Inv-induced cell attachment. Fixed staphylococci and fluorescent polymer microspheres coated with both MBP-Int-like and MBP-Inv fusion proteins showed enhanced adhesion to HEp-2 cells. These fusion proteins will facilitate studies of the role of intimin in the pathogenesis of diarrhea associated with members of the family Enterobacteriaeceae that induce attachment and effacement.

ATP-Binding Cassette Transporters↗
PubMed1993

Cloning and sequencing of two new fli genes, the products of which are essential for Salmonella flagellar biosynthesis.

We have identified two new open reading frames downstream from fliC, which appear to encode 19- and 20-kDa proteins that are essential for flagellar formation. The nucleotide and the predicted amino acid sequences of the genes are presented. Both genes, termed fliU and fliV, are preceded by the flagellar-specific -10 consensus promoter DNA sequence, suggesting their expression in the earlier stages of flagellar-component biosynthesis.

Amino Acid Sequence↗
PubMed1993

Spastic paraparesis associated with human T-lymphotropic virus type I: a clinical, serological, and genomic study in Iranian-born Mashhadi Jews.

The Mashhadi-Jewish community originating in Iran is a closed and ethnically segregated population with a unique history and a high rate of intrafamilial marriage among its members. A high risk of infection by human T-lymphotropic virus type I (HTLV-I) and of adult T-cell leukemia associated with such infection was found in this population. HTLV-I is also associated with a syndrome of progressive spastic paraparesis. We therefore evaluated the occurrence of HTLV-I infection and spastic paraparesis in Mashhadi-born Iranian Jews who immigrated to Israel. We examined 83 Mashhadi-born subjects (52 women, 31 men; mean age, 61 +/- 15.5 years) and 73 age-matched non-Mashhadi Iranian-born Jews. Blood samples were tested for HTLV-I antibodies by particle agglutination test. The polymerase chain reaction (PCR) was used to detect HTLV-I proviral DNA sequences from peripheral blood mononuclear cells. Fifteen Mashhadi-born Jews (18%) were both seropositive and PCR-positive for HTLV-I. Four HTLV-I-seronegative subjects were found to be positive for HTLV-I proviral DNA by PCR. Of the 19 HTLV-I-infected subjects (11 women, 8 men; mean age, 59 +/- 16 years), 13 (68%) had spastic paraparesis of varying severity. There were no signs of myelopathy in the Mashhadi-born subjects who were negative for HTLV-I proviral DNA by PCR. None of the non-Mashhadi Iranian Jews was seropositive or PCR-positive for HTLV-I proviral DNA, or had clinical signs of spastic paraparesis.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1993

Phase and antigenic variation--the impact on strategies for bacterial vaccine design.

Many pathogens have the ability to vary the antigenic composition of surface-associated antigens. Often, this variation is mediated by the regulation of gene expression. By varying its antigenicity, the pathogen is able to avoid host immune responses more efficiently; however, this makes the design of vaccines against pathogens that exhibit antigenic variation difficult. In this review, we use the pathogenic Neisseria as an example of antigenically variable bacteria and discuss some attempts to overcome the problems of vaccine design posed by such organisms.

Antigenic Variation↗