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Biomedical subjects

B Graf

Publications and source records attributed to B Graf.

At least 19 recordsLinked to original sources
PubMed2003

[The Ross procedure (pulmonary autograft) as an alternative for aortic valve replacement].

BACKGROUND AND OBJECTIVE: The Ross procedure (pulmonary autograft) has since the 1980s attracted growing interest as an alternative to the widely practised insertion of a prosthetic aortic valve. The 12-year experience of a consecutive series from one centre are reported here. PATIENTS AND METHODS: Between February 1990 and January 2002 a Ross procedure, predominantly with the subcoronary technique, was performed in 244 consecutive patients with aortic valve disease (244 men, 54 women, mean age 46 +/- 13.5 years). Annual follow-up clinical examinations (mean postoperative period 32.9 +/- 29.5 months in 99 % of the cohort) were performed. RESULTS: Perioperative mortality was 0.8 % (n=2), and there were two late deaths unrelated to the aortic valve disease. Seven patients had to be re-operated for failure of the homograft (n=4) or autograft (n=4). According to clinical criteria, 99 % of the followed-up patients were in New York Heart Association (NYHA) functional class I or II, only two patients, with pulmonary comorbidity, were in class III. Echocardiography demonstrated autografts with nearly normal transvalvular gradient (mean maximal pressure gradient 6.5 +/- 3.3 mmHg), while nine patients had second-degree aortic regurgitation. The mean maximal gradient across the homograft valve in the pulmonary position was 12.0 +/- 6.9 mmHg, while ten patients had second-degree and one had third-degree pulmonary regurgitation. CONCLUSION: The technically demanding Ross procedure produced excellent clinical and hemodynamic mid-term results. It is thus an appealing alternative to the widely used replacement by a prosthetic valve. Definitive assessment awaits further long-term follow-up.

Adult↗
PubMed2001

Inhibition of glucose transport by cyclic GMP in cardiomyocytes.

Recent evidence points to a potential role of cyclic GMP (cGMP) in the control of cardiac glucose utilization. The present work examines whether the glucose transport system of cardiac myocyte is a site of this cGMP-dependent regulation. Treatment of isolated rat cardiomyocytes (for 10 min) with the membrane-permeant cGMP analogue 8-(4-chlorophenylthio)-cGMP (8-p-CPT-cGMP, 200 microM) caused a decrease in glucose transport in non-stimulated (basal) myocytes, as well as in cells stimulated with insulin or with the mitochondrial inhibitor oligomycin B by up to 40%. An inhibitory effect was also observed with another cGMP analogue (8-bromo-cGMP), and in cells stimulated by hydrogen peroxide or anoxia. In contrast, 8-p-CPT-cAMP (200 microM), or the beta-adrenergic agonist isoprenaline (which increases cAMP levels) did not depress glucose transport, and even potentiated the effect of insulin. Blockade of endogenous cGMP formation with the guanylate cyclase inhibitor 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one (ODQ, 10 microM) significantly increased basal and insulin-dependent glucose transport (by 25%), whereas addition of the guanylate cyclase activator 3-(5'-hydroxymethyl-2'furyl)-1-benzylindazol (YC-1, 30 microM) produced a depression of glucose transport (by 20%). Confocal laser scanning microscopic studies revealed that cGMP partially prevents the insulin-induced redistribution of the glucose transporter GLUT4 from intracellular stores to the cell surface. These observations suggest that the glucose transport system of cardiomyocytes represents a metabolic target of inhibition by cGMP, and that this regulation occurs at the level of the trafficking of glucose transporters.

Animals↗
PubMed2001

Study status consistency and duplicate-read protection in a distributed architecture.

UNLABELLED: This presentation will discuss the benefits and pitfalls of implementing a study status and duplicate-read protection mechanism within a distributed picture archiving and communication system (PACS) architecture. There are many advantages to a distributed PACS network in which image studies are proactively pushed to reading stations before they are required by a radiologist. The absence of a central server, which serves on demand, makes managing study status and protecting against duplicate reads challenging. The system to manage study status and read access must be efficient, robust, and easy to administer. A system is presented that accomplishes these goals while maintaining the advantages of a distributed architecture. METHODS: The basic workflow of the system is that image studies acquired at a modality device are automatically sent to an archive server. Using a set of advanced routing rules, the archive automatically routes studies to diagnostic workstations where studies are candidates for diagnostic read. The workstations display a list of all local studies available for reading. A monitor application running on the workstations coordinates access to studies for diagnostic read. Once the status of a study has been changed, the workstations on the networks and the archive are notified, which causes the study to be automatically removed from any list on a workstation where it might be a read candidate. RESULTS: Implementation of this system provides a balanced workflow throughout the system while minimizing the need for costly high-speed network hardware. Additionally studies are read as soon as they are available by the next available radiologist. This workflow is enabled without the need for specific interaction by any of the radiologists on the network. By having the images available at the workstation in an organized worklist, this methodology increases the efficiency of the radiologist. CONCLUSION: The implementation of this system enables a radiology department, or even a specialty group within a department, to gain the benefit of a distributed system as well as the benefits provided by a central-server architecture. This can be done very cost effectively with minimal configuration overhead and hardware requirements.

Computer Systems↗
PubMed2001

Hemodynamics of semilunar valves at rest and exercise at an average of more than two years after the Ross procedure.

BACKGROUND AND AIM OF THE STUDY: Rest, and especially exercise, hemodynamics are valuable determinants to assess outcome of the Ross procedure. In this study, the degree of insufficiency and pressure gradients at rest across the autograft and homograft, as well as the pressure gradients at exercise, were measured. METHODS: Among 115 patients operated on between February 1990 and February 1999, 67 were evaluated echocardiographically at rest and moderate exercise. The mean patient age at subcoronary implantation was 52 +/- 13 years. The mean interval between surgery and investigation was 27.3 +/- 17.4 months. The exercise level was 100 W (n = 47), 75 W (n = 14) or 50 W (n = 6). RESULTS: Fifty-two patients had no or trace aortic insufficiency, 23 were grade I/IV, and two were grade II/IV. Pulmonary insufficiency was graded as none (n = 45), mild (n = 21), and moderate (n = 1). Heart rate increased from 70 +/- 12 beats/min at rest to 108 +/- 19 beats/min at exercise. The maximal pressure gradient across the autograft increased from 6.1 +/- 2.3 mmHg at rest to 8.7 +/- 4.1 mmHg at exercise. The maximal pressure gradient across the homograft increased from 11.8 +/- 5.3 mmHg at rest to 17.7 +/- 8.2 mmHg at exercise. A pressure gradient across the homograft >25 mmHg was measured in 13 patients. CONCLUSION: In most patients, hemodynamics at rest and moderate exercise at an average of more than two years after the Ross procedure were excellent. Some homografts developed pressure gradients at exercise; this finding will form the target of future surgical and scientific investigations.

Adult↗
PubMed2001

Mucormycoses.

Over recent years the clinical importance of mucormycosis has significantly increased. Most frequently mucormycosis occurs in neutropenic patients with haematological diseases. It is caused by fungi of the order Mucorales. The clinical patterns of the disease produced by different genera or species of Mucorales are virtually identical. Rhizopus, Absidia, Rhizomucor and Mucor are the organisms most commonly isolated from patients who suffer from mucormycosis. Diagnosis of mucormycosis is difficult as it is based on culture methods or microscopy of clinical specimens. The diagnosis is often only made after a delay or even post-mortem. Therapy includes surgical intervention if possible and is based on systemic amphotericin B (conventional or liposomal).

Amphotericin B↗
PubMed2000

[Intermediate term clinical results after endoaneurysmorrhaphy in left ventricular aneurysm].

Endoaneurysmorrhaphy (EAR) in postinfarct ventricular aneurysms leads to excellent short-term results. However, the temporal response of EAR is widely unknown. Thus, the indication for surgical treatment of patients with ventricular aneurysms is not well defined. EAR was performed in 157 patients (6/1993-6/1999) with symptomatic ventricular aneurysms (median NYHA III). Factors influencing cardiac mortality and morbidity during follow-up were determined by univariate and multivariate analysis. Perioperative mortality was low: 5%. Mortality during follow-up was 3.3% per year, resulting in a 5-year survival rate of 78%. NYHA classification ameliorated significantly from the preoperative status compared to the follow-up period (median NYHA II; p < 0.001). Multivariate analysis identified preexisting arterial occlusive disease and advanced age (> 70 years) as significant factors influencing medium-term mortality. Implantation of the left internal mammary artery was associated with a better survival rate. Endoaneurysmorrhaphy can be performed with low perioperative mortality, will result in a significant amelioration of the cardiac clinical status and offers low medium-term mortality. Our data indicate that EAR seems to be the procedure of choice for patients with symptomatic ventricular aneurysms.

Aged↗
PubMed2000

Functional role for the class IX myosin myr5 in epithelial cell infection by Shigella flexneri.

Efficient control of Shigella-induced, rho-dependent cytoskeletal rearrangements seems to be required to shape the delicate cellular structures associated with bacterial invasion of epithelial cells. We therefore studied a class IX myosin and rho antagonist, the GTPase-activating protein (GAP) myr5, for a potential role in the bacterial entry process. We show that myr5 is recruited into bacterial entry spots. The recruitment pattern resembled that of rhoC or ezrin, but not rhoA, rac or CDC42, while in vitro GAP activity of myr5 was similar for rhoA, B or C. Analysis of myr5 mutants suggested that GTPase- or ATP-binding activites are not required for Shigella-induced recruitment of this atypical myosin to the bacterial entry site. Functional studies revealed a potential dual role of the myosin functions and the GAP module of myr5 for bacterial internalization.

Cytoskeletal Proteins↗
PubMed2000

Evaluation of the VITEK 2 system for rapid identification of yeasts and yeast-like organisms.

The new VITEK 2 system is a fully automated system dedicated to the identification and susceptibility testing of microorganisms. In conjunction with the VITEK ID-YST card the VITEK 2 system allows the identification of clinically important yeasts and yeast-like organisms in 15 h due to a sensitive fluorescence-based technology. The ID-YST card consists of 47 biochemical reactions. The database comprises 51 taxa, including newly described species. In this study we evaluated the reliability of the VITEK ID-YST card for the identification of yeasts and yeast-like organisms encountered in a clinical microbiology laboratory. A total of 241 strains representing 21 species were studied. The strains were isolated from clinical samples within a period of 60 days prior to the identification. The tests were performed using 24-h to 55-h subcultures on Sabouraud-gentamicin-chloramphenicol agar. Each strain was tested in parallel using the ID 32C strip as a comparison method combined with microscopic morphology and an agglutination test for C. krusei. Overall, 222 strains (92.1%) were unequivocally identified including 11 isolates (4.6%) identified with low discrimination resolved by simple additional tests. Ten strains (4. 1%) for which results were given with low discrimination could not be unequivocally identified with supplemental tests, 4 strains (1. 7%) were misidentified and 5 strains (2.1%) could not be identified. In conclusion, we found that the VITEK 2 system is a rapid and accurate method for the identification of medically important yeasts and yeast-like organisms.

Automation↗
PubMed2000

PCR-derived ssDNA probes for fluorescent in situ hybridization to HIV-1 RNA.

We developed a simple and rapid technique to synthesize single-stranded DNA (ssDNA) probes for fluorescent in situ hybridization (ISH) to human immunodeficiency virus 1 (HIV-1) RNA. The target HIV-1 regions were amplified by the polymerase chain reaction (PCR) and were simultaneously labeled with dUTP. This product served as template for an optimized asymmetric PCR (one-primer PCR) that incorporated digoxigenin (dig)-labeled dUTP. The input DNA was subsequently digested by uracil DNA glycosylase, leaving intact, single-stranded, digoxigenin-labeled DNA probe. A cocktail of ssDNA probes representing 55% of the HIV-1 genome was hybridized to HIV-1-infected 8E5 T-cells and uninfected H9 T-cells. For comparison, parallel hybridizations were done with a plasmid-derived RNA probe mix covering 85% of the genome and a PCR-derived RNA probe mix covering 63% of the genome. All three probe types produced bright signals, but the best signal-to-noise ratios and the highest sensitivities were obtained with the ssDNA probe. In addition, the ssDNA probe syntheses generated large amounts of probe (0.5 to 1 microg ssDNA probe per synthesis) and were easier to perform than the RNA probe syntheses. These results suggest that ssDNA probes may be preferable to RNA probes for fluorescent ISH. (J Histochem Cytochem 48:285-293, 2000)

Cell Line↗
PubMed2000

1K versus 2K monitor: a clinical alternative free-response receiver operating characteristic study of observer performance using pulmonary nodules.

OBJECTIVE: The aim of this study was to investigate whether and how observer performance in detecting pulmonary nodules is influenced by the use of 1K and 2K monitors with and without voluntary postprocessing. MATERIALS AND METHODS: The study was conducted with clinical digital chest radiographs of 48 patients. CT images of the same patient group served as the gold standard. Data on four different monitor conditions (1K overview, 2K overview, 1K with postprocessing, and 2K with postprocessing) were collected using a 6-point confidence-rating scale and interpreted with an alternative free-response receiver operating characteristic. RESULTS: When magnification and window settings were applied on the 1K monitor at the expense of an increased interpretation time, observer performance with the 1K monitor was not significantly different from that with the 2K monitor. A significant difference only occurred between the 1K monitor postprocessing condition and the 1K monitor overview condition. CONCLUSION: Considering diagnostic accuracy, the 1K monitor is sufficient for the detection of pulmonary nodules, provided that postprocessing options--especially magnification--are applied. Further comparative monitor studies on the detectability of other abnormalities (e.g., fine interstitial structures) need to be performed.

Adult↗
PubMed1999

Dimerization of the Agrobacterium tumefaciens VirB4 ATPase and the effect of ATP-binding cassette mutations on the assembly and function of the T-DNA transporter.

The Agrobacterium tumefaciens VirB4 ATPase functions with other VirB proteins to export T-DNA to susceptible plant cells and other DNA substrates to a variety of prokaryotic and eukaryotic cells. Previous studies have demonstrated that VirB4 mutants with defects in the Walker A nucleotide-binding motif are non-functional and exert a dominant negative phenotype when synthesized in wild-type cells. This study characterized the oligomeric structure of VirB4 and examined the effects of Walker A sequence mutations on complex formation and transporter activity. VirB4 directed dimer formation when fused to the amino-terminal portion of cI repressor protein, as shown by immunity of Escherichia coli cells to lambda phage infection. VirB4 also dimerized in Agrobacterium tumefaciens, as demonstrated by the recovery of a detergent-resistant complex of native protein and a functional, histidine-tagged derivative by precipitation with anti-His6 antibodies and by Co2+ affinity chromatography. Walker A sequence mutants directed repressor dimerization in E. coli and interacted with His-VirB4 in A. tumefaciens, indicating that ATP binding is not required for self-association. A dimerization domain was localized to a proposed N-terminal membrane-spanning region of VirB4, as shown by the dominance of an allele coding for the N-terminal 312 residues and phage immunity of host cells expressing cI repressor fusions to alleles for the first 237 or 312 residues. A recent study reported that the synthesis of a subset of VirB proteins, including VirB4, in agrobacterial recipients has a pronounced stimulatory effect on the virB-dependent conjugal transfer of plasmid RSF1010 by agrobacterial donors. VirB4'312 suppressed the stimulatory effect of VirB proteins for DNA uptake when synthesized in recipient cells. In striking contrast, Walker A sequence mutants contributed to the stimulatory effect of VirB proteins to the same extent as native VirB4. These findings indicate that the oligomeric structure of VirB4, but not its capacity to bind ATP, is important for the assembly of VirB proteins as a DNA uptake system. The results of these studies support a model in which VirB4 dimers or homomultimers contribute structural information for the assembly of a transenvelope channel competent for bidirectional DNA transfer, whereas an ATP-dependent activity is required for configuring this channel as a dedicated export machine.

Adenosine Triphosphatases↗
PubMed1999

Proposed entry criteria for postoperative cardiac extracorporeal membrane oxygenation after pediatric open heart surgery.

While extracorporeal membrane oxygenation (ECMO) is being used increasingly after pediatric cardiac surgery, criteria are lacking for initiating ECMO after bypass weaning. To develop clinically useful ECMO entry criteria based on parameters readily available, children were examined at postoperative pediatric intensive care unit (PICU) admission. Using hospital mortality as the primary outcome, univariate and multiple logistic regressions were performed to estimate the predictive value of clinical (age, weight, and diagnosis) and laboratory (arterial blood pressure, pH, lactate, creatine kinase, and arterial and central venous oxygen saturation [ScvO2]) variables. Data from 218 children over a 2 year period were analyzed retrospectively. Univariate regression demonstrated that age, weight, diagnosis, blood pressure, venous and arterial saturation, and lactate were significantly associated with postoperative mortality (p < 0.05). In multiple regression, ScvO2 and lactate level were found to be independent predictors and were used in a predictive model (ScvO2 odds ratio: 2.03-828.6, p = 0.016) (lactate odds ratio: 1.58 -4.20, p = 0.0002) (R2 = 0.70). Applying an 80% risk of mortality to establish entry criteria as in neonatal ECMO, PICU admission values of lactate > 70 mg/dl if ScvO2 < 60% or lactate >163 mg/dl if ScvO2 > 60% are proposed to serve as postoperative ECMO entry criteria if bypass weaning has been possible but is followed by low cardiac output.

Adolescent↗
PubMed1998

CD40 engagement up-regulates cyclooxygenase-2 expression and prostaglandin E2 production in human lung fibroblasts.

A newly emerging view of fibroblasts is that they are vital for initiating inflammation and respond to and direct the activities of leukocytes. Human fibroblasts can express CD40, an activation Ag the ligand of which is displayed by activated leukocytes. We demonstrate here that CD40 engagement on human lung fibroblasts dramatically increases proinflammatory PGE2 synthesis. This up-regulation is mediated through an induction of cyclooxygenase-2 (Cox-2) since Cox-2-selective inhibitors block the up-regulation. Western and Northern blot analyses demonstrated that Cox-2 protein and mRNA are dramatically increased in fibroblasts following CD40 engagement. We conclude that CD40 is a major pathway in human fibroblasts for the induction of Cox-2. There is intense interest in devising strategies for disruption of the CD40-CD40 ligand system to blunt inflammation. Such an intervention would be expected to attenuate the up-regulation of fibroblast Cox-2 and PGE2 production at the site of tissue injury.

CD40 Antigens↗
PubMed1998

Is early kinetic positioning beneficial for pulmonary function in multiple trauma patients?

Body positioning (kinetic therapy) is known to improve oxygenation in patients with impaired pulmonary function and ARDS. We have used body positioning prophylactically in trauma patients whose injury and pattern predispose to ARDS. This retrospective study reports the effects of early prophylactic (group P) versus late (group L) axial rotation on pulmonary function and the incidence of ARDS. Both groups were comparable in age, injury severity and the degree of thoracic injury. Systemic oxygenation was significantly better and the incidence of ARDS significantly lower in group P (group P: 34.3 per cent, group T: 74.1 per cent, P < 0.05). There was a tendency towards a lower incidence of pneumonia and a better survival in group P, which did not reach statistical significance. The duration of kinetic therapy and of ventilation was comparable in both groups. In this retrospective evaluation early prophylactic kinetic therapy was associated with a significantly lower incidence of ARDS compared with that instigated later.

Adult↗
PubMed1998

Oro-palatal dysplasia Bettex-Graf--a new syndrome.

Four cases of an until now undescribed syndrome have been observed in Berne in the last 40 years. All four cases are members of the same family and have occurred in three consecutive generations. They present with a U-shaped palatal cleft, microstomia, hypoplasia of the mandibula and a partial anodontia. An autosomal dominant heredity was demonstrated. Karyograms have been made in three of the patients and in all patients showed an anomaly in the form of a "fragile site" in one chromosome (16 fra 16 [q22]). Surgical and orthopedic treatments were difficult.

Abnormalities, Multiple↗
PubMed1998

[Qualitative and quantitative studies of autofluorescence in fungi].

Fluorescence microscopy is an important method in mycology. It is a common procedure used in immunology or histology and more recently in modern techniques of molecular biology like in-situ hybridization. Since several molds and yeasts show autofluorescence, an interference of this phenomenon with the detection method cannot be excluded. Therefore, we studied autofluorescence in fungi in more detail, in particular with respect to the dependence of this phenomenon from growth conditions, fixing method or mounting medium used. Here we show that moulds cultivated in a liquid medium are strongly autofluorescent which could be considerably reduced by repetitive washing. In moulds, we did not find important differences in autofluorescence levels with the three fixing methods under study. However, this finding cannot be generalized. Thus, in the yeast Candida albicans we found the autofluorescence pattern being largely dependent from the fixing method and the excitation wave length, respectively. In particular, with green excitation we could show that aceton fixation resulted in strong fluorescence of individual cells within a vast population of cells showing little or no autofluorescence. In addition, we could demonstrate that mounting media are able to strongly modify autofluorescence in fungi. Using digital image acquisition with a cooled CCD camera we were able to quantify the influence of different mounting media on fluorescence intensities of Aspergillus fumigatus.

Aspergillus fumigatus↗