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Biomedical subjects

R Franz

Publications and source records attributed to R Franz.

At least 37 records · Page 2Linked to original sources

Can right-sided atrioventricular sequential pacing provide benefit for selected patients with severe congestive heart failure?

This study reports on the methods and results of applying right-sided atrioventricular (AV) pacing in 26 patients with advanced cardiomyopathy. Ten of these patients had ischemic cardiomyopathy. Of the 16 patients with nonischemic cardiomyopathy, 10 were idiopathic and 6 were due to secondary causes. The patients had a mean age of 56 +/- 12 years and a left ventricular ejection fraction of 26 +/- 11%. Two transvenous stimulation electrodes were temporarily placed in the high right atrium and right ventricle, respectively. A Swan Ganz catheter was positioned into the pulmonary artery to determine cardiac output by the thermodilution method and to measure the pressure in the pulmonary artery and right atrium. In addition, aortic pressure was measured through a catheter sheath via the right femoral artery. Systemic and pulmonary vascular resistance were calculated. Stimulation was performed in VVI and DDD pacing modes using different AV intervals (40, 80, 125, 150, 175, 200, and 250 msec). No increase of cardiac output was observed for the overall study cohort (p = 0.51). At VVI pacing, stroke volume significantly decreased from 66 +/- 20 mL to 53 +/- 13 mL (p < 0.01). We distinguished between responders who developed an increase of cardiac output of > 1 L/min (n = 12, 46%) and nonresponders (n = 14, 54%). Etiology of either ischemic or nonischemic cardiomyopathy for responders, as well as conduction disturbances (first-degree AV block, LBBB, RBBB), were equally distributed among both groups. Using an AV delay of 150 and 175 msec, responders to DDD pacing derived a significant increase in cardiac output. An AV delay of 150 msec produced both a significant increase of stroke volume and decrease of systemic vascular resistance. In 46% of patients with dilated cardiomyopathy of either ischemic or nonischemic origin, right-sided AV-sequential pacing brought about an improvement of left ventricular function in terms of enhanced cardiac output. We suggest individual testing in all patients with severe left ventricular dysfunction to find responders.

Adult↗

Molecular aspects of fluconazole resistance development in Candida albicans.

Serial Candida albicans isolates from recurrent episodes of oropharyngeal candidosis (OPC) in four AIDS patients which became fluconazole-resistant during therapy were analysed by molecular methods. The CARE-2 fingerprint patterns of the isolates demonstrated that in all four patients fluconazole resistance developed in a previously more susceptible strain. In two cases resistance correlated with enhanced expression of genes encoding multiple drug resistance proteins that mediate active drug efflux. Enhanced mRNA levels of the CDR1/CDR2 genes encoding ABC transporters were observed in fluconazole-resistant isolates from one patient compared with the corresponding susceptible isolates. The fluconazole-resistant isolates from another patient exhibited high mRNA levels of the MDR1 gene encoding a membrane transport protein of the major facilitator superfamily that was not detectably expressed in any of the fluconazole-susceptible isolates. These results demonstrate that in AIDS patients with recurrent OPC the development of fluconazole resistance is usually caused by molecular changes in a previously susceptible C. albicans strain from the same patient.

AIDS-Related Opportunistic Infections↗

Assessment of vascularized fibular graft one year after reconstruction of the wrist after excision of a giant-cell tumour.

We report a patient in whom the distal radius was resected for a giant cell tumour and the bone defect was replaced using a vascularized proximal fibular graft. The graft was viable and hypertrophied and normal callus formed on the distal radius. Due to chronic instability of the wrist the patient underwent revision arthrodesis 1 year after resection. Microscopic studies of the epishyseal region of the fibula showed wide necrosis of the graft with active creeping substitution. Despite the good technical result of the vascularized fibular graft, the vascularization was incomplete in the proximal epiphysis. We discuss possible reasons for this.

Arthrodesis↗

[Ultrasound appendix imaging in mucoviscidosis patients].

PURPOSE: The aim of this study was to determine the presentation of the appendix in patients with cystic fibrosis (CF) compared to a healthy control group and patients with acute appendicitis using high resolution graded compression sonography. METHOD: 59 CF patients (mean age 11 years), 54 healthy children (mean age 9 years) and 322 patients with histologically proven acute appendicitis were evaluated by sonography. A blind ending tubular structure in longitudinal sections and a target-like figure in cross sections without peristalsis was considered as appendix. The maximum distance between the outer echolucent layers was calculated as diameter. RESULTS: In 20%, 67% and 90% of the cases, the appendix was identified in the CF-group, healthy children, and patients with acute appendicitis. The mean diameters were 9.8, 3.9, and 10.9 mm respectively. These differences were statistically significant (p < 0.001 and p < 0.012). CONCLUSION: The appendiceal mucocele in cystic fibrosis is an uncommon but important differential diagnosis of the acute appendicitis.

Acute Disease↗

A study on the equivalence of olive oil and the EU official substitute test media for migration testing at high temperatures.

As a consequence of an increasing awareness and findings about the technical and analytical difficulties related to the employment of triglycerides as fatty food simulants in migration testing, EU Directive 82/711/EEC on the basic rules of migration has been amended for the second time and adapted with the recent Commission Directive 97/48/EC. The major merit of this important amendment is to authorize alternative tests such as extraction tests and to allow substitute tests for the fat test with concrete indication of corresponding test conditions to be applied. As a novelty in food law compliance testing it authorizes a modified polyphenylene oxide (MPPO), well-known as Tenax, a thermostable and highly adsorptive porous polymer, as a 'solid' matrix to substitute fat simulant D at temperatures equal to or higher than 100 degrees C. In the study presented here, comparative migration testing--overall and specific--was carried out between fat simulants olive oil and 14C-labelled HB 307 and the substitute test media iso-octane, 95% ethanol and MPPO using polypropylene materials as examples at test temperatures of 100 degrees C to 120 degrees C and prescribed corresponding substitute test conditions. As a consequence, a number of conclusions were drawn which are relevant for overall and/or specific migration testing under the investigated test conditions. One of the major findings was that MPPO was generally more equivalent to the fat test than the other two substitute test media. The presence of volatile hydrocarbons in the test samples was found to play a crucial role with respect to the equivalence of the iso-octane-based substitute test. At high volatile concentrations in the test sample the iso-octane test underestimated the olive oil benchmark whereas low volatile concentrations led to satisfying equivalence. It is therefore recommended that the procedure is modified and GC-FID screening of the isooctane extract is carried out. As a logical consequence, the possibility of quantitative determination of the overall extract by GC-FID is recommendable and should be investigated in more depth. Concerning the overall migration test procedure in olive oil, the vacuum pre-conditioning at 60 degrees C should be given re-consideration to avoid the possibility of loss of volatile migrants whose determination should be within the scope of the overall migration test method itself. Finally, the specific migration related equivalence between olive oil, MPPO and iso-octane needs further investigations to clarify the net effect of strongly increased diffusion rates at the regular high temperature versus the substitute test solvent accelerated extraction effect at 60 degrees C. Stability aspects of migrants at the different test temperatures deserve further consideration.

Chromatography, Gas↗

A fourth gene from the Candida albicans CDR family of ABC transporters.

Using primers derived from a region of the Candida albicans CDR1 (Candida drug resistance) gene that is conserved in other ABC (ATP-binding cassette) transporters, a DNA fragment from a previously unknown CDR gene was obtained by polymerase chain reaction (PCR). After screening a C. albicans genomic library with this fragment as a probe, the complete CDR4 gene was isolated and sequenced. CDR4 codes for a putative ABC transporter of 1490 amino acids with a high degree of homology to Cdr1p, Cdr2p and Cdr3p from C. albicans (62, 59 and 57% amino acid sequence identity, respectively). Cdr4p has a predicted structure typical for cluster I. 1 of yeast ABC transporters, characterized by two homologous halves, each comprising an N-terminal hydrophilic domain with consensus sequences for ATP binding and a C-terminal hydrophobic domain with six transmembrane helices. In contrast to the CDR1/CDR2 genes, the genetic structure of the CDR4 gene was conserved in 59 C. albicans isolates from six different patients. Northern hybridization analysis showed that the CDR4 gene was expressed in most isolates, but no correlation between CDR4 mRNA levels and the degree of fluconazole resistance of the isolates was found. In addition, a C. albicans mutant in which both copies of the CDR4 gene were disrupted by insertional mutagenesis was not hypersusceptible to fluconazole as compared to the parent strain. Unlike CDR1 and CDR2, CDR4 does not, therefore, seem to be involved in fluconazole resistance in C. albicans.

ATP-Binding Cassette Transporters↗

A systematic study on the stability of selected polymer antioxidants in EU official aqueous and alternative food simulants using HPLC.

Whilst considerable research has been conducted on the stability of plastics additives during processing, there is, on the other hand, a lack of studies on the stability of the same additives in food simulants in the published literature. In the work presented a systematic study has been undertaken on the stability of five selected commercial plastics additives (Irganox 3114, Irganox 1035, Irganox 245, Irganox 1098 and Irgafos P-EPQ) in the three EU-official aqueous food simulants (distilled water, 3% aq. acetic acid and 15% aq. ethanol) and in an alternative fat simulant (95% aq. ethanol) under two different time/temperature exposure conditions (10 days at 40 degrees C and 1 h at 100 degrees C). To enable quantitative analysis of the additives for this investigation, a simple and rapid HPLC method with UV detection was developed. The results obtained showed that the four Irganox-type additives under investigation were practically stable under the applied exposure conditions in all of the employed food simulants. Only Irganox 3114 exhibited a relatively low degree of instability in the ethanolic food simulants. Concerning Irgafos P-EPQ, a mixture of at least seven constituents, a remarkable degradation in ethanol and acetic acid solutions was observed. The developed HPLC method is also considered to be applicable for stability testing of other Irganox-type additives both in aqueous and fatty food simulants.

Acetic Acid↗

Multiple molecular mechanisms contribute to a stepwise development of fluconazole resistance in clinical Candida albicans strains.

From each of two AIDS patients with oropharyngeal candidiasis, five Candida albicans isolates from recurrent episodes of infection which became gradually resistant against fluconazole during antimycotic treatment were analyzed for molecular changes responsible for drug resistance. In both patients, a single C. albicans strain was responsible for the recurrent infections, but the CARE-2 fingerprint pattern of the isolates exhibited minor genetic alterations, indicating that microevolution of the strains took place during fluconazole therapy. In the isolates from patient 1, enhanced mRNA levels of the MDR1 gene, encoding a multiple drug resistance protein from the superfamily of major facilitators, and constitutive high expression of the ERG11 gene, coding for the drug target enzyme sterol 14alpha-demethylase, correlated with a stepwise development of fluconazole resistance. The resistant strains exhibited reduced accumulation of fluconazole and, for the last in the series, a slight increase in drug needed to inhibit sterol 14alpha-demethylation in vitro. In the isolates from patient 2, increased MDR1 mRNA levels and the change from heterozygosity to homozygosity for a mutant form of the ERG11 gene correlated with continuously decreased drug susceptibility. In this series, reduced drug accumulation and increased resistance in the target enzyme activity, sterol 14alpha-demethylase, were observed. These results demonstrate that different molecular mechanisms contribute to a gradual development of fluconazole resistance in C. albicans.

AIDS-Related Opportunistic Infections↗

The application of a predictive migration model for evaluating the compliance of plastic materials with European food regulations.

A model for estimating the migration of organic substances from plastic materials into foodstuffs has been previously developed. The use of this model allows a shift away from expensive and time consuming migration analysis in foods to much simpler and more economic compositional analysis in the material. Starting with toxicologically-based specific migration values, like the over 400 specific migration limit values for organic substances listed in the European Union's Synoptic Document No. 7, the corresponding allowable maximum quantity limits of these substances in the plastic were calculated. The amount of migration that can occur depends on many different factors such as the natures of the plastic, substance and food, contact time and temperature conditions, material thickness and number of uses. These factors can result in a variety of situations which must be taken into account in the estimation of migration. The handling of the migration estimation model is demonstrated for several practical migration scenarios using a series of case studies.

Diffusion↗

[Treatment of Monteggia fracture in children].

Described in this paper is a therapeutic concept by which to cope with Monteggia's fracture in childhood. It is based on experience obtained from 72 cases with injuries of that kind and their evaluation in a group study. Therapeutic approach to the individual case was determined by the following criteria: age of infant, localisation and shape of ulnar fracture, reducibility of capitulum radii, and accompanying injuries requiring treatment on the same arm. The need for surgical stabilisation of ulnar fracture was found to increase along with growing age of the affected child. High-stability anatomic reduction of the ulnar fracture proved to be a prerequisite for safe stabilisation of the radial capitulum. Close reduction has proved to be sufficient in many instances. Open reduction and internal fixation were found to be necessary in cases in which an ulnar fracture was irreducible or instable and/or a radial head was not reducible. Minimal osteosynthesis and plaster cast is considered to be an optional therapy for younger children, whereas ulnar stabilisation by means of plates is preferred for children in somewhat advanced age of childhood. The radial head may be fixed by trans-articular Kirschner's wire (WITT) or primary reconstruction of the annular ligament, using a strip of biceps or triceps tendon, or adaptation around the collum radii and ulna of the proximal radio-ulnar joint by means of a sling of Dexon or Vicryl suture.

Child↗

[Development of atopic disease in early childhood--predisposing factors].

In this study, we attempted to find factors which predispose infants to atopy. 200 unselected newborns were followed up to 3 years of age. Children with elevated cordblood IgE or positive family history developed atopic disease significantly more frequent (p less than 0.05, p less than 0.01). Parental smoking or formula feeding alone did not influence the frequency of subsequent atopic disorders. However, in combination with reduced cordblood CD8-cells atopy was observed significantly more often (p less than 0.05, p less than 0.025). Similar results were found in children with reduced cordblood CD3-cells, whose parents were smokers (p less than 0.01). These results suggest that factors which alone do not influence atopy can enhance each other to predispose atopic disease in early childhood.

Asthma↗