Biomedical subjects

J Hess

Publications and source records attributed to J Hess.

At least 145 records · Page 8Linked to original sources

PubMed1995

Contribution of alpha/beta and gamma/delta T lymphocytes to immunity against Mycobacterium bovis bacillus Calmette Guérin: studies with T cell receptor-deficient mutant mice.

Mutant mice with defined T cell deficiencies were infected with Mycobacterium bovis bacillus Calmette Guérin (BCG) and the relative contribution of alpha/beta T cells and gamma/delta T cells to the host immune response was assessed. Recombinase activating gene (RAG-1)-/- mutants as well as T cell receptor (TcR) beta-/-, but not TcR-delta-/-, mutants succumbed to M. bovis BCG infection and failed to develop granulomatous lesions. Antigen-induced IFN-gamma production by spleen cells in vitro was abrogated in RAG-1-/- mutants and markedly diminished in TcR-beta-/- and TcR-delta-/- mice. Reconstitution experiments suggest that both alpha/beta and gamma/delta T cells are essential for antigen-specific IFN-gamma secretion. Our data formally prove the crucial role of alpha/beta T cells and reveal accessory functions of gamma/delta T cells in optimum immunity against M. bovis BCG.

Animals↗

PubMed1995

The efficacy of flecainide versus digoxin in the management of fetal supraventricular tachycardia.

Fetal supraventricular tachycardia (SVT) can be successfully treated transplacentally, but in cases where fetal hydrops develops there is considerable morbidity and mortality. The present study was carried out to establish whether the introduction of flecainide altered obstetric management and fetal outcome. A retrospective analysis took place of 51 singleton pregnancies which were referred to the division of prenatal diagnosis because of fetal tachycardia between 1982 and 1993. SVT was documented in 50 out of 51 fetuses, one of which displayed a combination of extensive rhabdomyomas and severe hydrops and died shortly after referral. In the other fetus ventricular tachycardia was diagnosed. Of the remaining 49 fetuses, 14 did not receive any prenatal treatment, but nine needed postnatal treatment. Transplacental treatment of SVT took place in 35 fetuses, of which 22 presented without hydrops and 13 with hydrops. These subsets differed significantly with respect to restoration of normal sinus rhythm (73% vs. 30%; p < 0.001) and mortality (0% vs. 46%; p < 0.001). Digoxin was effective in restoring sinus rhythm in 55 per cent of the non-hydropic fetuses but in only eight per cent of the hydropic fetuses. Flecainide was effective in restoring sinus rhythm in all non-hydropic fetuses where digoxin treatment failed, and in 43 per cent of hydropic fetuses. Administration of flecainide resulted in a significantly reduced mortality (p < 0.001) compared with digoxin treatment. No adverse effects were seen. Postnatal anti-arrhythmic treatment was necessary in 23 infants. Treatment could be withdrawn within one year in all cases but one.

Anti-Arrhythmia Agents↗

PubMed1995

Substitution of mivacurium for succinylcholine for ECT in elderly patients.

Three cases are reported where pre-existing medical conditions (severe osteoporosis, amyotrophic lateral sclerosis, cardiac arrhythmias) made the administration of succinylcholine during ECT potentially dangerous. Therefore, mivacurium was substituted as the muscle relaxant necessary for safe therapy. Full reversal of the non-depolarizing muscle relaxant was assured by post-reversal use of the peripheral nerve stimulator with full recovery of train-of-four response.

Aged↗

PubMed1995

Prenatal diagnosis of congenital heart disease; prospects and problems.

Routine fetal echocardiography has been submitted as an antenatal screening test for congenital heart disease despite a wide range of efficacy reported. Hence, evaluation of the variable results of prenatal ultrasound screening programs was pursued. As the studies appeared to have a heterogeneous design, the originally reported figures have been corrected for one plausible prevalence of cardiovascular anomalies. Clinical setting (general hospitals vs. teaching hospitals), case ascertainment (retrospective vs. prospective; follow-up on (suspected) cases only vs. routine follow-up) and length of follow-up (< 1 year vs. a longer period) all have similar effects on the reported yield of cases and sensitivity of the proposed screening test. Notably, a relatively low yield of cases causes a seemingly high sensitivity, whereas a higher yield of cases causes a seemingly low sensitivity. Additional factors of study design, e.g. case definition, diagnostic procedures and appliances used, were usually not described in detail, yet may also have affected the results. Evaluating diagnostic tests apparently demands a rigorous study design to overcome biased results. Furthermore, no sufficient evidence could be found meriting current routine prenatal screening for congenital heart disease.

Female↗

PubMed1995

Cardiac status and health-related quality of life in the long term after surgical repair of tetralogy of Fallot in infancy and childhood.

The long-term results of surgical repair of tetralogy of Fallot were assessed by means of extensive cardiologic examination of 77 nonselected patients 14.7 +/- 2.9 years after surgical repair of tetralogy of Fallot in infancy and childhood. Because of the frequent use of a transannular patch (56%) for the relief of right ventricular outflow tract obstruction, the prevalence of elevated right ventricular systolic pressure was low (8%), but the prevalence of substantial right ventricular dilation with severe pulmonary regurgitation was high (58%). The exercise capacity of patients with a substantially dilated right ventricle proved to be significantly decreased (83% +/- 19% of predicted) when compared with that of patients with a near normal sized right ventricle (96% +/- 13%). Eight out of 10 patients who had needed treatment for symptomatic arrhythmia had supraventricular arrhythmia, which makes supraventricular arrhythmia--in numbers--a more important sequela in the long-term survivors than ventricular arrhythmia. Older age at the time of the operation and longer duration of follow-up were not associated with an increase in prevalence or clinical significance of sequelae.

Adolescent↗

PubMed1995

Isolated pulmonary vein stenosis in complex congenital heart disease, simulating cor triatriatum by cardiac catheterization and transoesophageal echocardiography.

A case of localized stenosis of the lower left pulmonary vein, associated with perimembranous ventricular septal defect (VSD) and secundum atrial defect (ASD), a borderline sized mitral valve apparatus and left ventricle, is described. This final diagnosis was made at surgery, as the localized stenosis of the left pulmonary vein was misinterpreted as partial cor triatriatum by cardiac catheterization, cineangiocardiography and extensive echocardiographic studies. Surgical correction of all the defects was successful, but pulmonary vascular resistance was still increased 2 years after surgery.

Cardiac Catheterization↗

PubMed1995

Aspects of the aetiology of congenital heart disease.

A concise overview of current knowledge on the aetiology of congenital heart disease is provided. At present, only 10 to 20% of the cases occurring in neonates can be attributed to known risk factors. Recurrence within relatives, chromosomal anomalies, genetic disorders, maternal disease and teratogen exposure are addressed briefly; contemporary research models and methods, e.g. embryology and genetics and molecular biology, are referred to. A major innovation has been the introduction of the concept of common pathogenetic pathways. Thus, different teratogenic factors or risk-factors may affect normal development at an identical stage and cause similar malformations. Also, the importance of timing of an event is stressed. If the time frame of exposure does not coincide with embryogenesis any teratogenic effect may be missed. Large-scale epidemiological studies on fetuses and neonates with congenital heart disease are introduced as a third mode of research on the aetiology, although this approach is not used efficiently at present; cases of intra-uterine death can be considered a valuable source of information that needs further attention. Combined, the above three lines of research may prove productive, but the design of a comprehensive research project would need to be handled carefully. Possibilities for prevention of the occurrence of cardiovascular malformations are reported. Through lack of knowledge of causality, at present, only secondary prevention may be possible and hence deserves attention. However, there appears to be no provision for thorough pre-natal screening tests for congenital heart disease in an unselected population.

Heart Defects, Congenital↗

PubMed1995

Salmonella strain secreting active listeriolysin changes its intracellular localization.

We describe the construction of an attenuated Salmonella dublin aroA strain which secretes via the Escherichia coli hemolysin secretion machinery an active hybrid cytolysin consisting of listeriolysin from Listeria monocytogenes and the C-terminal secretion signal of E. coli hemolysin. This hemolytic S. dublin strain is partially released into the cytoplasm of the host cell following uptake by J774 macrophage cells, whereas the nonhemolytic control S. dublin aroA strain remains in the phagosome.

Animals↗

PubMed1995

Involvement of bactericidal factors from thrombin-stimulated platelets in clearance of adherent viridans streptococci in experimental infective endocarditis.

Platelets activated with thrombin release bactericidal factors. We studied the role of the susceptibility of viridans streptococci to these bactericidal factors in the development of infective endocarditis (IE). By using the experimental endocarditis rabbit model, the initial adherence and the development of IE were assessed for 10 viridans streptococcal strains differing in their susceptibilities to releasate (material released) from thrombin-activated platelets. Six strains were susceptible and four strains were resistant to these releasates. The numbers of vegetations (VGs) colonized at 5 min and 48 h after intravenous challenge with 10(4) CFU were determined. At 5 min after challenge, significantly more VGs were colonized with bacteria of the six platelet releasate-susceptible strains than with bacteria of the four releasate-resistant strains (P < 0.005). In the releasate-susceptible group of strains, the number of colonized VGs decreased significantly between 5 min and 48 h after intravenous inoculation (P < 0.001). Such a decrease was not observed with the releasate-resistant strains. As a result, the final developments of IE due to releasate-susceptible and -resistant strains were not significantly different. The releasate-susceptible strain 1 and the releasate-resistant strain 2 were selected for more detailed experiments. Rabbits were killed at 5 and 30 min and 2, 4, and 48 h after inoculation. The number of culture-positive VGs as well as the number of adherent bacteria on the individual VGs were determined. The 90% infective dose for each strain was 10(5) CFU. At low inoculum concentrations (10(3) and 10(4) CFU) a larger proportion of the inoculated bacteria of both strains was found to be adherent on VGs than at higher challenge doses. The number of culture-positive VGs as well as the number of adherent bacteria per VG decreased rapidly in the first 30 min after challenge with strain 1 but not after challenge with strain 2. Additional experiments with the platelet releasate-susceptible strain S224 and the platelet releasate-resistant stain S182 confirmed the data obtained with strains 1 and 2 and indicated that releasate-susceptible strains disappeared from the VGs with time, whereas releasate-susceptible strains persisted. In vitro studies with VGs excised 5 min after challenge with stain 1 or 2 showed that clearance of the releasate-susceptible strain 1 was not caused by complement bactericidal activity or surface phagocytosis by polymorphonuclear cells. Bacterial cells of strain 1 adherent on excised VTGs were rapidly cleared by exposure to fresh clotting blood or to releasates from thrombin-stimulated platelet suspension.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗

PubMed1995

Listeria monocytogenes p60 supports host cell invasion by and in vivo survival of attenuated Salmonella typhimurium.

The extracellular protein p60 is a major virulence factor of the intracellular bacterium Listeria monocytogenes. Its roles in pathogen survival in vivo and host cell invasion in vitro were studied. To this end, Salmonella typhimurium SL7207 was used as carrier for secreted p60-HlyA fusion protein by Escherichia coli HlyB and HlyD transport proteins. C57BL/6 mice infected intravenously with this strain suffered from increased bacterial numbers in livers and spleens compared with the p60-nonexpressing control strain, but only transiently. In vitro experiments showed that p60 promotes invasion of recombinant S. typhimurium SL7207 p60 into hepatocytes and resting macrophages independent from complement. Moreover, the uptake of wild-type L. monocytogenes EGD and L. monocytogenes BUG 8, an internalin-deficient strain, into hepatocytes was partially blocked by anti-p60 antibodies. The impaired invasion of dissociated bacterial chains of L. monocytogenes RIII, a p60 expression mutant, into hepatocytes and macrophages was partially restored by addition of p60- or p60-HlyA-enriched bacterial supernatants. These data suggest that the L. monocytogenes surface-associated proteins, p60 and internalin, act in concert to achieve optimal uptake into nonprofessional phagocytes and macrophages. Together, these experiments reveal a substantial impact of p60 on cell invasion and virulence and thus emphasize the importance of the intracellular habitat for survival of L. monocytogenes in the host.

Animals↗

PubMed1995

Restricted replication of Listeria monocytogenes in a gamma interferon-activated murine hepatocyte line.

The intracellular pathogen Listeria monocytogenes replicates mainly in resting macrophages and hepatocytes residing in infected tissues. Both innate and acquired resistance strongly depend on activation of listericidal capacities of macrophages by gamma interferon (IFN-gamma) produced by natural killer cells and T lymphocytes. In contrast to macrophages, hepatocytes have been considered to serve purely as a cellular habitat, prolonging survival of the pathogen in the host. By using an immortalized murine hepatocyte line, the relationship between L. monocytogenes and this cell type has been analyzed in more detail. Our data reveal that hepatocytes are able to eradicate listeriolysin-deficient (avirulent) L. monocytogenes but fail to control growth of listeriolysin-expressing (virulent) L. monocytogenes organisms. Following stimulation with IFN-gamma, hepatocytes gained the capacity to restrict growth of virulent L. monocytogenes, although less efficiently than the highly listericidal IFN-gamma-activated macrophages. Hepatocytes costimulated with a combination of IFN-gamma, interleukin 6 (IL-6), and tumor necrosis factor alpha (TNF-alpha) expressed the highest antilisterial activities. Although IFN-gamma-stimulated hepatocytes produced demonstrable levels of reactive nitrogen intermediates (RNI), the results of inhibition studies do not support a major role for these molecules in antilisterial hepatocyte activities. In contrast, inhibition of RNI produced by macrophages neutralized their antilisterial effects. IFN-gamma-stimulated, L. monocytogenes-infected hepatocytes expressed TNF-alpha mRNA, suggesting that they are a source of this cytokine during listeriosis. These studies suggest a novel function for hepatocytes in listeriosis: first, IFN-gamma-stimulated hepatocytes could contribute to listerial growth restriction in the liver, and second, through secretion of proinflammatory cytokines, they could promote phagocyte influx to the site of listerial growth.

Amino Acid Oxidoreductases↗

PubMed1995

Morphological, haemodynamic, and clinical variables as predictors for management of isolated ventricular septal defect.

OBJECTIVE: To assess the predictive impact of morphological, haemodynamic, and clinical variables in the management of patients with isolated ventricular septal defect. DESIGN: Retrospective analysis of variables by a sophisticated database management system. PATIENTS AND METHODS: 263 consecutive patients with isolated ventricular septal defect diagnosed by echocardiography. The morphological type and haemodynamic character of the ventricular septal defect was characterised in each patient. In addition, variables were introduced to represent the need for diuretics, growth, and potential delay in growth. In 43 patients (16.3%) the ventricular septal defect was closed surgically; 220 patients (83.7%) were managed conservatively and spontaneous closure of the ventricular septal defect occurred in 65 (29.5%). There were no deaths. RESULTS: All patients managed surgically had non-restrictive defects and were operated on during the first year of life. A few patients with non-restrictive defects were managed conservatively. The two groups differed significantly only with respect to mean growth delay (0.65 (0.27) v 0.9 (0.21), P < 0.001). Only the morphology of the ventricular septal defect significantly (P < 0.001) influenced the probability of closure. CONCLUSIONS: Findings imply that early surgical closure of ventricular septal defect is indicated in patients with non-restrictive ventricular septal defect and severe growth delay. Other patients should be managed conservatively. In these patients the morphological type of the defect determines the probability of spontaneous closure and provides an estimate of the period over which decreased in size or closure can be expected.

Child, Preschool↗

PubMed1995

Evaluation of the pulmonary vasculature and dynamics with intravascular ultrasound imaging in children and infants.

The ability to assess the pulmonary vasculature in pulmonary vascular disease by hemodynamic or histologic evaluation is limited. We sought to determine the feasibility of intravascular ultrasound techniques in infants and children and to assess simultaneously the morphology and dynamics of pulmonary arteries. Patients were seen in the Department of Pediatrics, Division of Pediatric Cardiology, Sophia Children's Hospital, Rotterdam, The Netherlands. We performed intravascular ultrasound imaging in 11 pediatric patients with congenital heart disease undergoing cardiac catheterization. Luminal diameter, area, and pulsatility were determined at two to five sites in the pulmonary branches. Pulmonary vascular reaction to 100% oxygen inhalation was studied. Patients weighed 4.1-51.0 kg (21.8 +/- 16.3 kg, mean +/- SD). Luminal diameters, areas, and pulsatilities could be determined reproducibly in arteries with diameters from 1.6 to 9.3 mm. In total 39 sites were studied in 11 patients. Pulsatility was related to vessel size (r = 0.81), although a substantial interindividual variation was present. After 100% oxygen inhalation, pulsatility increased in all arteries (from 20.0 +/- 3.3% to 25.9 +/- 2.9%, p < 0.05), and vasodilatation could be directly visualized, most prominently in the smallest arteries (percentage change in diameter, mean 7.4 +/- 2.8% versus -2.8 +/- 3.1% in the largest arteries, p < 0.001). Measurement of wall thickness was not feasible, but specific changes in the appearance of the wall structure could be recognized in a patient with severely elevated pulmonary vascular resistance. The specific advantages of intravascular ultrasound in assessing pulmonary vascular disease are discussed.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗

PubMed1995

Fuzzy logic in drug delivery.

The first article in this series concentrated on the definition of terms and the methods that are applied in fuzzy logic. This article discusses the advantages of fuzzy logic in drug-delivery applications. The derivation of membership functions, linguistic variables, and drug-delivery control rules are shown for various delivery devices. A specific solution is discussed, which uses fuzzy logic decision-support methods for optimized treatment through respiratory drug delivery.

Administration, Inhalation↗

PubMed1995

Fuzzy logic and medical device technology.

This article introduces the concept of fuzzy logic and discusses its application in analytical processes. Terms such as fuzzy sets and membership functions, which can be used to describe the process states and conditions of a system, are defined. An example is given of how this reasoning technique could be applied to an actual device.

Biomedical Engineering↗

PubMed1995

Improved experimental cancer therapy by radioantibody dose intensification as a result of syngeneic bone marrow transplantation.

Myelosuppressive toxicity is dose-limiting for radioimmunotherapy. We have reported on the use of cytokine intervention (rhIL-1 and rmGM-CSF) to stimulate differentiation of progenitor cells and reduce radioantibody-induced leukopenia and thrombocytopenia (J. Natl. Cancer Inst. 84:399, 1992; Cancer 73:1073, 1994). As an alternative to the use of cytokines, we investigated the effect of syngeneic bone marrow transplantation on the ability to dose-escalate radioantibody. Injection of 10(7) bone marrow cells from a donor mouse 6 to 8 days after a 340- to 360-microCi dose of radioantibody (LD100/28)--a 25 to 30% increase above the maximal tolerated dose--resulted in 100% survival. This observation is associated with a recovery in neutrophil and thrombocyte counts within 21 days of therapy (normal recovery after 275 microCi takes 42 days). None of the mice survived when BMT was done at either 4 or 11 days after radioantibody. Marrow from normal donor mice was more effective than that from cytokine-primed mice whose marrow cells were actively cycling after a 5-day course of IL-1/GM-CSF. The combination of the two myeloprotective approaches, BMT plus a 14-day schedule of IL-1 (2 x 10(3) U/d) and GM-CSF (1 microgram/d) intervention, provided a greater stimulation of peripheral WBC counts than either approach alone; however, further dose escalation under these conditions was not feasible. The 30% intensification in radioantibody dose offers a therapeutic advantage for both bulky disease (GW-39 subcutaneous nude mouse model) and micrometastatic disease (GW-39 intrapulmonary model). In the bulky tumor model, the increase in administered dose resulting from BMT extends the 8-week growth delay observed at 275 microCi 131I-MN-14 IgG by an additional 7 weeks. In the metastatic model, dose intensification increased median animal survival from 15 to 23 weeks. Therefore, by optimizing the use of BMT, a greater therapeutic benefit can be derived from radioantibody therapy in a solid tumor model. This study represents a proof of principle, that BMT can be effective for low-dose-rate therapy as it has been for short-duration intense chemotherapy and radiation therapy. It also highlights several important issues to consider when attempting to apply the method in the clinic.

Animals↗

PubMed1995

Pulmonary homograft insertion after repair of pulmonary stenosis.

Although the results of intracardiac repair for pulmonary stenosis or atresia are generally good, some patients develop symptoms due to to pulmonary regurgitation and right ventricular dilatation. Implantation of a pulmonary homograft may have a beneficial effect on these symptoms. Twenty-seven patients with symptoms due to pulmonary regurgitation and right ventricular dilatation were reoperated. The indication for surgery was dyspnea in 19, arrhythmia in five and both symptoms in three patients. The arrhythmia was supra-ventricular in four, ventricular in two and both supra-ventricular and ventricular in another two patients. A cryopreserved pulmonary homograft was implanted in the right ventricular outflow tract. Mean interval between intracardiac repair and homograft implantation was 15.6 years. Mean age at homograft implantation was 23.0 years. Concomitant procedures were performed in 18 patients. There were two early deaths (7%). Replacement of the homograft was necessary in one patient, 21 months after insertion. This patient had residual pulmonary stenosis immediately after surgery. On mid-term follow up (mean 36 months) all patients with dyspnea as indication for operation improved, except one with right and left ventricular dysfunction. Only two of eight patients with arrhythmia improved. On echocardiography, pulmonary regurgitation decreased in all patients. Right ventricular dilatation decreased in only 14 patients (52%). We conclude that pulmonary regurgitation after transannular patching can be treated with implantation of a cryopreserved pulmonary homograft with acceptable mortality and low morbidity. Clinical improvement results from reduction of the right ventricular volume overload rather than from decline in right ventricular dilatation. Arrhythmia as the only indication for operation is controversial.

Adolescent↗

PubMed1995

SmaCS: smart classification system for the design, maintenance and use of complex terminologies. Application in pediatric cardiology.

The development of a generic Smart Classification System (SmaCS) for the design, construction, maintenance, and use of complex controlled terminologies is described. The ability of SmaCS to create and maintain terminologies that are combinations of structured terms and domain-specific knowledge is an important aspect of its design. SmaCS can therefore be used both for both controlled data-collection, using integrity rules included in the terminology, and intelligent data-retrieval. The design and implementation of SmaCS and application in the domain of pediatric cardiology are described.

Cardiology↗