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Biomedical subjects

J Hess

Publications and source records attributed to J Hess.

At least 127 records · Page 7Linked to original sources
PubMed1997

Protection against murine listeriosis by an attenuated recombinant Salmonella typhimurium vaccine strain that secretes the naturally somatic antigen superoxide dismutase.

A recombinant (r)-Salmonella typhimurium aroA vaccine strain was constructed which secretes the naturally somatic protein of Listeria monocytogenes, superoxide dismutase (SOD), by the HlyB/HlyD/TolC export machinery. Vaccine efficacy of the SOD-bearing carrier strain was compared with that of the p60-secreting construct, S. typhimurium p60s (J. Hess, I. Gentschev, D. Miko, M. Welzel, C. Ladel, W. Goebel, and S. H. E. Kaufmann, Proc. Natl. Acad. Sci. USA 93:1458-1463, 1996). Vaccination of mice with both constructs induced protection against a lethal challenge with the intracellular pathogen, L. monocytogenes. While the somatic listerial antigen, SOD, is immunologically uncharacterized, the naturally secreted protein of L. monocytogenes, p60, is known to be highly immunogenic. Our data emphasize the high vaccine potential of r-Salmonella constructs secreting antigens of somatic or secreted origin. Moreover, they suggest that the HlyB/HlyD/TolC-based antigen delivery system with attenuated Salmonella spp. as the carrier is capable of potentiating the immune response against foreign proteins independent from their immunogenicity in and display by the natural host.

Animals↗
PubMed1997

Routine prenatal screening for congenital heart disease: what can be expected? A decision-analytic approach.

OBJECTIVES: This study assessed the potential impact of fetal ultrasound screening on the number of newborns affected by cardiac anomalies. METHODS: A decision model was developed that included the prevalence and history of congenital heart disease, characteristics of ultrasound, risk of abortion, and attitude toward pregnancy termination. Probabilities were obtained with a literature survey; sensitivity analysis showed their influence on expected outcomes. RESULTS: Presently, screening programs may prevent the birth of approximately 1300 severely affected newborns per million second-trimester pregnancies. However, over 2000 terminations of pregnancy would be required, 750 of which would have ended in intrauterine death or spontaneous abortion. Further, 9900 false-positive screening results would occur, requiring referral. Only the sensitivity of routine screening and attitude toward termination of pregnancy appeared to influence the yield substantially. CONCLUSIONS: The impact of routine screening for congenital heart disease appeared relatively small. Further data may be required to fully assess the utility of prenatal screening.

Abortion, Spontaneous↗
PubMed1997

The Escherichia coli hemolysin secretion apparatus--a versatile antigen delivery system in attenuated Salmonella.

The E. coli hemolysin (HlyA) secretion apparatus represents a type I secretion system that is fully functional in Salmonella. The system which consists of the two specific membrane proteins HlyB and HlyD and the outer membrane protein TolC, recognizes on HlyA a C-terminally located signal sequence of about 60 amino acids. Fusion proteins to which this signal sequence is covalently linked at the C-terminus are also recognized by this secretion apparatus. The efficiency of secretion is dependent on the rate of folding of the reporter protein. Secretion-competent regions of a given reporter protein that is not secretable as entire protein can be screened by a recently constructed transposon TnhlyAs which allows the insertion of the secretion signal into any region of the reporter protein. The genetic information for antigens of any source ranging in size between 10 and 1000 amino acids can be easily inserted into a recently constructed secretion vector which will allow the secretion of the fused antigen(s) in attenuated Salmonella typhimurium strains and in other attenuated Enterobacteriaceae. By manipulation of the Hly secretion system the antigen can be either completely secreted into the environment, fixed on the outer membrane or arrested in the cytoplasm of the used carrier strain. By the use of appropriate attenuated Salmonella strains the antigen is delivered in isolated compartments or to the cytosolic compartment. The extracellular delivery of such antigens is also possible with the help of appropriate carrier strains. The immunological consequences of the different display of the processed antigen will be discussed in the paper by Hess et al in this volume. With a similar antigen delivery system the easy identification and molecular characterization of unknown antigens recognized by the immune system in an infection is also feasible.

Animals↗
PubMed1996

Development of antigen-delivery systems, based on the Escherichia coli hemolysin secretion pathway.

We describe the development of plasmid vectors carrying the expression sites, an hlyA cassette and the secretion genes of Escherichia coli hemolysin. These allow the synthesis and secretion of heterologous microbial antigens in E. coli and attenuated Salmonella aroA strains. Genes or gene fragments encoding microbial antigens are inserted in-frame into a residual part of the hlyA gene which essentially encodes the HlyA secretion signal (HlyAs). In general, the fused genes, carrying the hlyAs sequence at the 3' terminus, are efficiently expressed, and the synthesized antigens are secreted into the culture supernatant of the producing strain. Attenuated Salmonella strains synthesizing either HlyAs-fused listeriolysin or p60 of Listeria monocytogenes were constructed by this procedure and shown to provide protective immunity against L. monocytogenes in mice. The most effective protection was obtained when these microbial antigens were secreted by the attenuated Salmonella strains. We further present new approaches which may allow the application of this antigen-delivery system to any microbial antigen.

Animals↗
PubMed1996

Echocardiographic and radionuclide pulmonary blood flow patterns after transcatheter closure of patent ductus arteriosus.

BACKGROUND: Transcatheter occlusion of patent ductus arteriosus (PDA) has been associated with protrusion of the occluder device into the left pulmonary artery (LPA). This study was conducted to evaluate the significance of occluder protrusion and its implications for potential obstruction of the LPA and associated decrease of left lung perfusion. METHODS AND RESULTS: Fifty-two patients underwent successful transcatheter PDA occlusion over a period of 5 years. In this study, 49 were reexamined between March and June 1995. In addition to clinical and echocardiographic examination, lung scintigraphy was performed. Protrusion into the LPA was present in 5 of 49 patients (10%). In these patients, maximal flow velocity in the LPA was significantly (P < .01) increased. Decreased left lung perfusion, defined as < 40% of total pulmonary blood flow, was found in 7 of 49 patients (14%). Although mean left pulmonary perfusion was significantly (P = .02) decreased in patients with protrusion, there was considerable overlap with patients without protrusion, and only a weak correlation was found (r = -.35, P = .01) between flow-velocity and left lung perfusion. CONCLUSIONS: Our results demonstrate that protrusion of the device in the LPA is an infrequent finding. If present, it is associated with increased maximal flow velocity in the LPA and diminished left lung perfusion. However, echocardiography and lung scintigraphy are weakly correlated: Increased maximal blood flow velocities in the proximal LPA proved to be a poor indicator or impaired left lung perfusion. Also, decreased perfusion occurs in the absence of echocardiographic evidence of device protrusion.

Blood Flow Velocity↗
PubMed1996

Efficacy of routine fetal ultrasound screening for congenital heart disease in normal pregnancy.

BACKGROUND: Second trimester routine ultrasound evaluation of the fetal heart by means of the four-chamber view has been proposed for prenatal detection of cardiac anomalies. The aim of this study was to evaluate the efficacy of this procedure. METHODS AND RESULTS: A prospective follow-up study on 6922 scanned fetuses was performed. Pregnant women without known risk factors who were scheduled for a routine fetal ultrasound examination between 16 and 24 weeks gestation were invited to participate. Follow-up until 6 months postpartum was available for 5660 subjects (81.8%), of whom 5319 fulfilled all eligibility criteria. by comparing the prenatal diagnosis to the postnatal diagnosis, we obtained sensitivity, specificity, and predictive value (positive and negative). A total of 80 cases of congenital malformations were diagnosed during the study: 44 cases of congenital heart disease, 40 cases of noncardiac malformations, and a combination of the two in 4 cases. The fetal four chamber-view examination was considered abnormal in 7 women who were subsequently referred for extensive fetal ultrasound examination. Two proved to be carrying an affected fetus. Similarly, prenatal referral of 14 women because of suspected noncardiac malformations yielded 12 such cases. The fetal four chamber-view examination had a sensitivity of 4.5% (95% CI, 0.6% to 15%). Sensitivity for noncardiac anomalies was 30% (95% CI, 16.6% to 46.5%). Overall sensitivity of ultrasound examination was 16.3% (95% CI, 2.09% to 48.8%). Specificity and negative predictive value were high (>98%). The positive predictive value was low with wide CIs. CONCLUSIONS: These results suggest that the current mode of routine prenatal ultrasound screening for congenital malformations is inefficient, particularly for cardiac anomalies.

Adolescent↗
PubMed1996

Salmonella typhimurium aroA- infection in gene-targeted immunodeficient mice: major role of CD4+ TCR-alpha beta cells and IFN-gamma in bacterial clearance independent of intracellular location.

Due to the dependency on aromatic precursors, the growth of Salmonella typhimurium aroA- is limited in immunocompetent mice. Here we show that H-21-A beta-/- mice (lacking MHC class II molecules and thus devoid of mature CD4+ TCR-alpha beta cells), TCR-beta-/- mice (devoid of TCR-alpha beta cells), and IFN-gamma R-/- mice (unresponsive to IFN-gamma) are highly susceptible to S. typhimurium aroA- infection compared with heterozygous controls. In contrast, beta 2m-deficient mice (lacking surface MHC class I and thus devoid of conventional CD8+ T cells) or TCR-delta-/- mice (devoid of TCR-gamma delta cells) were equally as resistant to S. typhimurium aroA- infection as their heterozygous littermates. These findings emphasize the vital role of CD4+ TCR-alpha beta cells and IFN-gamma in resistance against S. typhimurium aroA-. Sublethal inocula of S. typhimurium aroA- led to permanent infection in H-21-A beta-/- mice, suggesting that bacterial starvation is insufficient for sterile clearance in immunocompetent mice and that MHC class II-dependent immune mechanisms are required for pathogen eradication. The TCR-beta-/- mice suffered from salmonellosis more severely than the MHC class II-deficient mutants, suggesting an auxiliary function of CD8+ T cells. Recombinant S. typhimurium aroA-, secreting listeriolysin (Hly) of Listeria monocytogenes, are capable of escaping from the phagosome into the cytosol of the host cell. However, the course of infection of these recombinant S. typhimurium SL7207 Hlys and control strains did not differ in beta 2m-/- mutants. This finding argues against direct correlation of cytosolic location of S. typhimurium SL7207 Hlys with CD8+ T cell dependency of protection.

3-Phosphoshikimate 1-Carboxyvinyltransferase↗
PubMed1996

Superior efficacy of secreted over somatic antigen display in recombinant Salmonella vaccine induced protection against listeriosis.

Vaccination provides the most potent measure against infectious disease, and recombinant (r) viable vaccines expressing defined pathogen-derived antigens represent powerful candidates for future vaccination strategies. In a new approach we constructed r-aroA- Salmonella typhimurium displaying p60 or listeriolysin (Hly) antigen of Listeria monocytogenes in secreted or somatic form in the host cell. Vaccination of mice with r-aroA- S. typhimurium induced protection against the intracellular pathogen L. monocytogenes only with secreted and not with somatic antigen. Secreted Hly was slightly more potent in inducing protective immunity than secreted p60. Both r-aroA- S. typhimurium secreting p60 in the endosome and r-aroA- S. typhimurium secreting Hly in the cytosol induced protective CD4+ and CD8+ T-cells suggesting CD8+ T-cell stimulation independent from intracellular residence of r-aroA- S. typhimurium carriers. Hence, not only the type of antigen but also its display by the r-carrier within the host cell critically influences vaccine efficacy.

Amino Acid Sequence↗
PubMed1996

Efficacy of fetal echocardiography and yield by risk category.

OBJECTIVE: To determine the efficacy and yield of tertiary center fetal echocardiography for different high-risk groups. METHODS: Between January 1, 1982, and January 1, 1994, scans for anomalies were performed on 3246 women at increased risk for congenital heart disease in their offspring. Gestational age was 16-25 weeks in 83%. Maternal and gestational age as well as prenatal and postnatal diagnosis were recorded, and follow-up was sought for all pregnancies. By comparing prenatal and postnatal diagnoses, sensitivity, specificity, and predictive values were estimated. Multiple logistic regression was applied to establish the relative yield within the high-risk group. RESULTS: Follow-up was available in 3223 cases (99%). In a separate validation study of 777 women for whom a second set of follow-up data was requested, no additional anomalies were revealed. In total, 20 of 47 cases of cardiac malformations were detected (sensitivity 43%). When taking into account cases that remained undetected because of unfavorable scanning conditions (ie, minute size of the anomaly, awkward fetal position, or severe maternal obesity), the sensitivity for congenital heart disease rose to 51%. Specificity and predictive values were high (above 95%). The relative yield across the high-risk group appeared to be high for parental congenital heart disease and maternal diabetes mellitus, whereas a previous infant or other relatives affected, maternal anti-epileptic drug use, maternal drug abuse, and other reasons for referral each had an estimated yield approximately equal to the prevalence of congenital heart disease in the general population (0.8%). CONCLUSION: Fetal echocardiography for known increased risk appears to be moderately effective. Clear differences in yield are present across currently accepted risk categories.

Adult↗
PubMed1996

Long-term follow-up (10 to 17 years) after Mustard repair for transposition of the great arteries.

BACKGROUND: The management strategies of patients who underwent Mustard repair for transposition (of the great arteries were changed in the 1970s: infants became eligible for direct surgical repair, so Blalock-Hanlon atrioseptostomy could be avoided, and cold cardioplegia was introduced for myocardial preservation. Data are lacking, however, regarding whether these changes have had positive effects on the long-term outcome. We therefore conducted a follow-up study on all 91 patients who underwent a Mustard repair for transposition of the great arteries in our institution between 1973 and 1980 to assess the incidence and clinical importance of sequelae as well as health-related quality of life for these patients. METHODS: Patients who were alive and could be traced through local registrar's offices received an invitation to participate in the follow-up study, which consisted of an interview, physical examination, echocardiography, exercise testing, and standard 12-lead and 24-hour electrocardiography. RESULTS: Patients operated on in the first 4 years had a significantly higher mortality rate and higher incidence of sinus node dysfunction than did patients operated on in the subsequent 4 years (25% vs 2% and 41% vs 3%, respectively). In contrast, the incidence of baffle obstruction necessitating reoperation was significantly higher in the second group. There were no significant differences in echocardiographic findings and exercise capacity between patients operated on in the first 4 years and in the subsequent 4 years. None of the patients had right ventricular failure; a mild degree of baffle leakage or obstruction was seen in 22% of the patients, and the mean exercise capacity was decreased to 84% +/- 16% of normal. CONCLUSION: The changes introduced between 1973 and 1980 have resulted in a considerable reduction of mortality and incidence of sinus node dysfunction but have also resulted in a more frequent need for reoperation.

Adolescent↗
PubMed1996

Protein p60 participates in intestinal host invasion by Listeria monocytogenes.

The role of p60 in intestinal invasion by Listeria monocytogenes was assessed after oral infection of mice with the p60 low-expressing mutant RIII, or with anti-p60 antibody coated wild-type EGD. Invasion by L. monocytogenes RIII bacteria has been unimpaired suggesting that a low density of p60 suffices for entry. Up to 24 h post infection (p.i.), intestinal penetration by L. monocytogenes EGD bacteria was markedly reduced by coating with anti-p60 antibodies. In histological sections, anti-p60 antibody-treated L. monocytogenes EGD, but not uncoated listeriae were still detectable 24 h p.i. at the apical surface of enterocytes in the intestine. We conclude that p60 contributes to host invasion through the natural port of listerial entry, the intestinal epithelium.

Animals↗
PubMed1996

Allograft reconstruction of the right ventricular outflow tract.

OBJECTIVE: Evaluation of allograft reconstruction of the right ventricular outflow tract (RVOT). METHODS: From 1986 to April 1995, 201 allografts (146 pulmonary, 55 aortic) were implanted in 189 patients for conduit reconstruction of the RVOT in congenital heart disease or in the pulmonary autograft procedure. The mean age at allograft implantation was 16 years (range 2 weeks - 54 years). The primary diagnoses of these patients were truncus arterious (n = 19, 10%), transposition of the great arteries (TGA) with ventricular septal defect (VSD) and pulmonary atresia (PA) or stenosis (PS) (n = 14, 7%), PA with VSD (n = 26, 14%), PA or PS with intact septum (n = 7, 4%), tetralogy of Fallot (n = 44, 23%), corrected TGA with PA or PS (n = 11, 6%), tricuspid atresia (n = 9, 5%), aortic valve pathology for pulmonary autograft procedure (n = 55, 29%), and miscellaneous (n = 4, 2%). The allograft implantation was a reoperation in 54 patients (29%). RESULTS: The mean follow-up was 2.5 years (range 4 weeks-9 years). Six patients died in hospital (3.2%). Patient survival at 5 years was 91% (95% CL 86-95%). Freedom from all valve-related events (2 deaths, 17 reoperations, one endocarditis), as determined during reoperation or autopsy at 5 years was 78% (95% CL 65-86%). Freedom from structural allograft failure was 83% (2 deaths, 12 reoperations, 95% CL 70-90%). Allografts implanted for congenital right heart defects failed earlier than allografts used for pulmonary autograft procedures (P = 0.05). Aortic allografts showed structural failure more often than pulmonary allografts (P = 0.05). There were more valve-related events in patients of a younger age at implantation (P = 0.02) and in those allograft valves from younger donors (P = 0.004). CONCLUSIONS: Allograft RVOT reconstruction is an adequate surgical therapy. The allograft should preferably be pulmonary. A younger age at implantation is a risk factor for allograft failure. Donor age may be a thus-far underestimated risk factor for allograft degeneration.

Adolescent↗
PubMed1996

A new PrfA-regulated gene of Listeria monocytogenes encoding a small, secreted protein which belongs to the family of internalins.

A mutant of Listeria monocytogenes EGD was constructed that carries an extended deletion removing the entire PrfA-regulated gene cluster from plcA to plcB and a second deletion inactivating the inlA gene. Upon supplementation of this mutant with multiple gene copies of prfA, a protein of 30 kDa was detected in the supernatant of the mutant strain. The gene encoding this protein was obtained by direct and inverse polymerase chain reaction using oligonucleotide primers that were deduced from partial amino acid sequences of the purified 30 kDa protein. The amino acid sequence of the gene product revealed a protein of 297 amino acids that carried eight repeat units with high homology to those of the two known internalin proteins A and B. This secretory protein, termed internalin C, is much smaller than InlA or InlB and its complete sequence is related to the two known internalins. The gene InlC is transcribed into a monocistronic mRNA from a single promoter which shows a typical consensus sequence for PrfA-binding at the position -40. In contrast to the transcription of the InlAB operon, which is downregulated after shift of an L. monocytogenes EGD culture from brain-heart infusion into minimum essential medium (MEM), transcription of inlC is induced in MEM like most of the other known PrfA-regulated virulence genes. In addition, InlC is strongly transcribed in the cytoplasm of phagocytic J774 cells whereas inlA is poorly transcribed under these conditions, suggesting that internalin C may play a role in a late stage of L. monocytogenes infection rather than in the uptake of L. monocytogenes by non-professional phagocytic cells. An InlC deletion mutant shows reduced virulence when tested in an intravenous mouse model, but intracellular replication of the mutant in Caco-2 and J774 cells appears to be comparable with that of the wild-type strain.

Amino Acid Sequence↗
PubMed1996

CRISP-3, a protein with homology to plant defense proteins, is expressed in mouse B cells under the control of Oct2.

The Oct2 transcription factor is expressed throughout the B-lymphoid lineage and plays an essential role during the terminal phase of B-cell differentiation. Several genes specifically expressed in B lymphocytes have been identified that contain a functional octamer motif in their regulatory elements. However, expression of only a single gene, the murine CD36 gene, has been shown to date to be dependent on Oct2. Here, we present the identification and characterization of a further gene, coding for cysteine-rich secreted protein 3 (CRISP-3), whose expression in B cells is regulated by Oct2. We show that CRISP-3 is expressed in the B-lymphoid lineage specifically at the pre-B-cell stage. By using different experimental strategies, including nuclear run-on experiments, we demonstrate that this gene is transcriptionally activated by Oct2. Furthermore, analysis of CRISP-3 expression in primary B cells derived from either wild-type or Oct2-deficient mice demonstrates the dependence on Oct2. Two variant octamer motifs were identified in the upstream promoter region of the crisp-3 gene, and Oct2 interacts with both of them in vitro. Cotransfection experiments with expression vectors for Oct1 and Oct2 together with a reporter driven by the crisp-3 promoter showed that transcriptional activation of this promoter can only be achieved with Oct2. The C-terminal transactivation domain of Oct2 is required for this activation. Finally, introducing specific mutations in the two variant octamer motifs revealed that both of them are important for full transcriptional activation by Oct2.

3T3 Cells↗
PubMed1995

Functional characterization of the murine homolog of the B cell-specific coactivator BOB.1/OBF.1.

B cell-specific transcriptional promoter activity mediated by the octamer motif requires the Oct1 or Oct2 protein and additional B cell-restricted cofactors. One such cofactor, BOB.1/OBF.1, was recently isolated from human B cells. Here, we describe the isolation and detailed characterization of the murine homolog. Full-length cDNAs and genomic clones were isolated, and the gene structure was determined. Comparison of the deduced amino acids shows 88% sequence identity between mouse and human BOB.1/OBF.1. The NH2-terminal 126 amino acids of BOB.1/OBF.1 are both essential and sufficient for interaction with the POU domains of either Oct1 or Oct2. This protein-protein interaction does not require the simultaneous binding of Oct proteins to DNA, and high resolution footprinting of the Oct-DNA interaction reveals that binding of BOB.1/OBF.1 to Oct1 or Oct2 does not alter the interaction with DNA. BOB.1/OBF.1 can efficiently activate octamer-dependent promoters in fibroblasts; however, it fails to stimulate octamer-dependent enhancer activity. Fusion of subdomains of BOB.1/OBF.1 with the GAL4 DNA binding domain reveals that both NH2- and COOH-terminal domains of BOB.1/OBF.1 contribute to full transactivation function, the COOH-terminal domain is more efficient in this transactivation assay. Consistent with the failure of full-length BOB.1/OBF.1 to stimulate octamer-dependent enhancer elements in non B cells, the GAL4 fusions likewise only stimulate from a promoter-proximal position.

Amino Acid Sequence↗