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A Brandes

Publications and source records attributed to A Brandes.

At least 37 records · Page 2Linked to original sources
PubMed1997

[Atrial sensing and atrioventricular synchrony in single lead VDD pacemakers. Can the appearance of atrial undersensing be predicted?].

Single-lead VDD-pacing is an alternative to DDD-systems in patients with AV-block and normal sinus node function. Atrial sensing plays a central role in these pacemakers. AV-synchrony, incidence of atrial arrhythmias and the occurrence of sinus node disease were investigated in 108 patients with VDD-pacemakers followed over a mean period of 24.8 months after implantation. Determinants influencing the occurrence of atrial undersensing were especially focused on. Mean atrial potential and sensing threshold were reduced within the first 2 weeks after implantation (p < 0.01). Intermittent atrial undersensing occurred in 25.9% of patients and was observed in 82.1% of these patients within the first 2 weeks after implantation. Positioning the atrial dipole in the low right atrium showed a significantly higher incidence of atrial undersensing (42% in comparison to 24% in the other positions). In a multivariate analysis including intra- and postoperative measurements as well as characteristics of the pacemakers and leads, it was the only parameter significantly (p < 0.02) correlated to the occurrence of atrial undersensing. Atrial fibrillation was observed in 4.6% of patients, a sinus node disease became evident in 2.7% of patients; 92.6% of patients remained in the AV-synchronous mode. Intermittent atrial undersensing is common in single-lead VDD-pacemakers and difficult to provide during implantation. The atrial dipole should not be positioned in the low right atrium and highest atrial sensitivity should generally be programmed. Nevertheless, VDD-pacing achieves an AV-synchrony comparable to DDD-pacemakers.

Aged↗
PubMed1997

Comparative analysis of the chromosomal and genomic organization of Ty1-copia-like retrotransposons in pteridophytes, gymnosperms and angiosperms.

We have investigated the physical distribution of the reverse transcriptase genes of Ty1-copia-like retrotransposable elements from 12 plant species belonging to different subdivisions by hybridization in situ on chromosome preparations. Ty1-copia-like elements showed different and non-random hybridization patterns. A dispersed distribution throughout most of the chromosomes with reduced hybridization at some regions or with some weak clustering at other regions was found in Allium cepa, Beta vulgaris, Brassica campestris, Brassica oleracea, Pennisetum glaucum, Pinus elliottii, Selaginella apoda, Vicia faba and Vicia narbonensis. Reduced hybridization occurred mainly at centromeric regions, nucleolus-organizing regions and regions known to be mainly composed of tandemly repeated sequences. In the fern Pteris cretica the retroelements showed a dispersed genomic organization with clustering at some chromosomal regions and whole chromosomes showing little signal. In Arabidopsis thaliana and Cicer arietinum Ty1-copia-like elements were found in clusters at the paracentromeric heterochromatin, a novel organization for a repetitive element in A. thaliana. New retroelement families were isolated from A. thaliana and from Beta vulgaris. Alignment of the deduced peptide sequences with Ty1-copia-like elements from other plants showed considerable divergence which was used to calculate their relationships, indicating the value of reverse transcriptase gene analysis in phylogenetic and biodiversity studies.

Amino Acid Sequence↗
PubMed1997

Multiple repetitive DNA sequences in the paracentromeric regions of Arabidopsis thaliana L.

Nine repetitive DNA sequences, present in the haploid Arabidopsis thaliana genome in 7-300 copies, were hybridized in situ to metaphase and interphase chromosomes. Every sequence was detected on all five chromosome pairs, but was not evenly dispersed over the genome. Clusters of signals were found in particular regions of the centromeric heterochromatin, and each sequence showed a characteristic distribution pattern. Some sequences hybridized more strongly on different chromosomes, reflecting chromosome-specific amplification or the presence of homologous sequences. No hybridization signals could be detected on euchromatic regions. In situ hybridization on extended chromatin fibres showed that the pAL1 repeats are interrupted by another repetitive DNA sequence. A cosmid subclone (74A) contained a (GA)38 microsatellite motif, and hybridization with a (GA) oligonucleotide revealed that most of the hybridization sites of 74A correspond to the distribution of this microsatellite motif. The results show that the paracentromeric heterochromatin of A. thaliana chromosomes is composed not only of the tandemly arranged 180-bp repeat family pAL1/pAtMr, but also of some other repetitive sequences, thus giving a better understanding of the organization of sequences at the centromeres of A. thaliana.

Arabidopsis↗
PubMed1997

The chromosomal distributions of Ty1-copia group retrotransposable elements in higher plants and their implications for genome evolution.

Retrotransposons make up a major fraction--sometimes more than 40%--of all plant genomes investigated so far. We have isolated the reverse transcriptase domains of the Ty1-copia group elements from several species, ranging in genome size from some 100 Mbp to 23,000 Mbp, and determined the distribution patterns of these retrotransposons on metaphase chromosomes and within interphase nuclei by DNA:DNA in situ hybridization. With some exceptions, the reverse transcriptase domains were distributed over the length of the chromosomes. Exclusion from rDNA sites and some centromeres (e.g., slash pine, 23,000 Mbp, or barley, 5500 Mbp) is frequent, whereas many species exclude retrotransposons from other sites of heterochromatin (e.g., intercalary and centromeric sites in broad bean). In contrast, in the plant Arabidopsis thaliana, widely used for plant molecular genetic studies because of its small genome (c. 100 Mbp), the Ty1-copia group reverse transcriptase gene domains are concentrated in the centromeric regions, colocalizing with the 180 bp satellite sequence pAL1. Unlike the pAL1 sequence, however, the Ty1-copia signal is also detectable as weaker, diffuse hybridization along the lengths of the chromosomes. Possible mechanisms for evolution of the contrasting distributions are discussed. Understanding the physical distribution of retrotransposons and comparisons of the distribution between species is critical to understanding their evolution and the significance for generation of the new patterns of variability and in speciation.

Chromosome Mapping↗
PubMed1996

A novel repetitive sequence associated with the centromeric regions of Arabidopsis thaliana chromosomes.

The middle repetitive fraction of the Arabidopsis genome has been relatively poorly characterized. We describe here a novel repetitive sequence cloned in the plasmid mi167, and present in approximately 90 copies in the genome of Arabidopsis thaliana ecotype Columbia. Hybridization analysis to physically mapped YAC clones representing Arabidopsis chromosome 4 revealed four mi167-hybridizing loci, all clustered near the centromere. No other loci were detected on YAC clones covering chromosome 4. In situ hybridisation experiments to Arabidopsis chromosome spreads showed that mi167-hybridizing sequences are clustered at the centromeric heterochromatin of all five chromosomes; on two chromosomes the hybridization appeared to be localised on one arm. Additional mi167-hybridizing loci were detected, one of which was adjacent to a non-centromeric, heterochromatic region. This work supports the idea that the majority of middle repetitive DNA in the Arabidopsis genome is clustered. It also adds to our understanding of the organization of the centromere of Arabidopsis chromosome 4.

Arabidopsis↗
PubMed1996

Chromosome 'painting' in plants - a feasible technique?

It is shown that chromosome painting is as yet not possible for plants with very complex genomes, neither intra- nor interspecific. The reasons are inefficient blocking of dispersed repetitive sequences and insufficient signal intensity of short unique sequences. Future perspective are indicated.

Biotin↗
PubMed1996

Electrophysiological characteristics of bipolar membrane carbon leads with and without steroid elution compared with a conventional carbon and a steroid-eluting platinum lead.

In a controlled study, the following four bipolar leads with passive fixation were implanted in 46 patients with the Siemens-Multilog-VVI or Sensolog-VVIR-pacemakers: membrane covered activated porous carbon with steroid elution (Siemens 1402 T, 11 patients) and without (Siemens 1403 T, 15 patients); activated carbon (Siemens 1010 T, 10 patients); and platinum with steroid elution (Medtronic Cap-Sure 5026, 10 patients). Stimulation threshold (STH) (assessed by a vario-test), impedance (IMP), and the intracardial R wave potential (IRW) (both gauged by a telemetric method) were measured 1, 5, and 10 days as well as 3 and 6 months after implantation during unipolar and bipolar stimulation, chronaxie rheobase product (CRP) and energy consumption (EC) were systematically determined. Differing insignificantly at the first day after implantation, STH is significantly lower for the 1402 T and CapSure 5026 leads at the tenth day. However, the 1402 T lead shows a significant increase of STH in the follow-up, in contrast to the other leads. The lowest chronic STH was found in the CapSure 5026 lead (CRP is significantly lower in all other leads, too). IMP is significantly lower in the CapSure 5026 lead compared to 1010 T lead. EC does not differ significantly during chronic stimulation in spite of the best possible programming of pulse amplitude and duration. No significant changes of IRW were observed. Unipolar versus bipolar stimulation shows significantly lower STH, CRP, and IMP, differences of EC and IRW were insignificant. In conclusion, the addition of steroid in membrane covered carbon leads protracts the increase of STH, but does not prevent it. The CapSure 5026 lead shows advantageous stimulation characteristics, but energy consumption is not significantly reduced because of low impedance and impossibility of programming an appropriate low output in Multilog pacemakers.

Aged↗
PubMed1996

[Transient pacemaker dysfunction and spontaneous arrhythmias in symptomatic and asymptomatic patients with ventricular demand pacemakers].

This prospective cross-sectional study include 100 consecutive patients (56 males, 44 females, 29 to 86 (mean = 67.5 +/- 12.2) years) with ventricular inhibited demand pacemakers 0.1 to 94.7 (mean 23.3 +/- 25.4) months after pacemaker implantation. Fifty-two patients were free of symptoms, whereas 48 patients were still complaining of syncope, dizziness, or palpitations. After history, physical examination, and 12-lead standard ECG all patients underwent 24-h Holter monitoring. A computer-aided analysis of spontaneous arrhythmias was done first. In a second run computed-aided analysis of transient pacemaker dysfunctions was performed with a specially designed pacemaker module. There were no significant differences between asymptomatic and symptomatic patients with regard to the incidence of transient pacemaker dysfunctions, with regard to defined types of pacemaker dysfunctions, spontaneous ventricular arrhythmias, and with regard to supraventricular tachycardias. A significant difference between asymptomatic and symptomatic patients was found, however, regarding the Lown classification of ventricular arrhythmias, because asymptomatic patients showed class 0 and I/II arrhythmias more frequently (p < 0.025). In the 100 patients a total of 6609 pacemaker dysfunctions were observed, 5104 failures to sense and 1505 inappropriate inhibitions. Most patients showed up to 240 pacemaker dysfunctions per 24 h. There were no failures to capture. Different types of pacemaker dysfunctions were found with different clinical implications. Due to the Holter findings in nine patients pacemakers were reprogrammed or replaced. After pacemaker implantation the number of patients with severe symptoms significantly decreased compared to the number of patients before pacemaker implantation. Nonetheless, there was a number of patients still complaining of symptoms after pacemaker implantation. In only a few patients did pacemaker implantation worsen symptoms . Our data show that with use of long-term ECG transient pacemaker dysfunctions and spontaneous arrhythmias are more frequent than patients' history and common standard techniques in the pacemaker clinic may suggest Holter monitoring, therefore, is a useful diagnostic tool, not only in symptomatic, but also in asymptomatic pacemaker patients. It allows to obtain a reliable survey of the real amount of transient pacemaker dysfunctions in the individual patient, which is the base for further therapeutic decisions.

Adult↗
PubMed1995

Barley telomeres are associated with two different types of satellite DNA sequences.

The genomic organization of two different types of satellite DNA sequences was analysed by means of fluorescence in situ hybridization (FISH) and pulsed-field gel electrophoresis (PFGE) in barley. Satellite HvT01 was detected at all chromosome ends except the long arms of chromosomes 2 and 7. The unrelated satellite pAS1 was found at all chromosome ends except the long arm of chromosome 7 and at two interstitial sites, both located on the long arm of chromosome 4 on the standard karyotype. Southern and in situ hybridization further indicate that pAS1 also occurs interspersed in the barley genome. For most chromosome ends, the linear order of HvT01 and pAS1 could not be determined by in situ hybridization except at the short arms of chromosomes 2 and 6, where HvT01 is more distal than pAS1. This is confirmed by PFGE analysis, HvT01 being frequently associated with the telomeric repeat but not pAS1. Furthermore, we found that HvT01 occurred in clusters up to 1000 kb in size, whereas the pAS1 cluster had a maximum size of 500 kb. Sequence comparison revealed that both satellites are completely unrelated and differ considerably in their G + C contents.

Base Sequence↗
PubMed1995

[Calcinosis of the meniscus. Morphologic and roentgenographic findings for zonal classification].

Primary and secondary meniscal chondrocalcinoses lead to typical changes in X-ray pictures of isolated menisci. Combined X-ray, light and electron microscopic examination of the four menisci in 70 autopsy cases showed calcifications in 13 cases (18.6%). Three types of calcification could be discriminated with the help of topographical and morphological criteria: Type 1 A: disseminated calcification. All four menisci were affected equally. Crystals of calcium pyrophosphate dihydrate (CPPD) were found on light and electron microscopy. Energy-dispersive X-ray analysis (EDX) showed the crystal deposits to consist of 46.5% calcium and 53.5% phosphorus. Type 1 B: Calcification occurring in limited areas. A calcification was found which did affected neither a whole meniscus nor all four menisci of any "quartet" observed. Crystals were found next to areas of stronger meniscal degeneration. EDX showed the same results described for type 1 A. Type 2: Confluent calcification. A cloud-like diffuse calcification was discerned on the X-ray pictures. Light and electron microscopically pseudocystic structures appeared which contained a fine granular amorphous material. No crystals were found. The structures appeared in the neighbourhood of necrotic fibres. EDX showed 44% calcium, 51.2% phosphorus, 2.8% sulphur, 0.74% magnesium and 0.6% potassium. The findings lead to the conclusion that calcification type 1 A represents primary chondrocalcinosis, whereas type 1 B corresponds to secondary chondrocalcinosis. Type 2 was identified as postnecrotic, dystrophic calcification. Careful analysis of X-ray pictures of isolated menisci can yield useful information concerning pathogenetic factors of meniscal calcification.

Calcium Pyrophosphate↗
PubMed1995

[Wound management after wisdom tooth osteotomy].

Closure and dressing techniques in wound treatment after surgical removal of the mandibular third molars were compared. Large abscesses were found after third molar removal in 8 percent. An extraoral incision was made in 58 percent of these cases. On the other side, in a group of 1189 third molar removals treated by a gauze strip no abscess was observed. In a further investigation the subjective disturbance of patients treated with a dressed gauze were the slightest. Also, the dressing technique in the treatment after third molar removal could decrease the number of postoperative infections.

Bandages↗
PubMed1994

[The reliability of computer-assisted long-term ECG analysis of pacemaker malfunction in patients with ventricular demand pacemakers].

The importance of the pacemaker follow-up clinic has markedly increased in the face of the currently available multiprogrammable pacemakers. In contrast to the common standard techniques in assessing pacemaker dysfunctions, Holter monitoring allows the detection of transient pace-maker dysfunctions during a long period of time. Especially computer-aided analysis provides a considerable progress, because different pacemaker dysfunctions can be detected during prolonged time periods, and--in contrast to visual analysis--a reliable survey of the real extent of transient pacemaker dysfunctions in the individual patient is assessed. The reliability of computer-aided analysis by a specially designed module was prospectively investigated in 100 consecutive patients with permanent ventricular inhibited demand pacemakers. It could be demonstrated that the positive predictive accuracy of this analysis was limited to 60.2% in detecting failures to sense and 63.2% in detecting inappropriate inhibitions, respectively. All detected failures to capture were false positive events. The positive predictive accuracy, therefore, was not calculated for this category of event. The overall positive predictive accuracy was 59.9%. In contrast, the sensitivity of computer-aided analysis was remarkably high. Possible causes of false positive and false negative findings are described. The reliability of pacemaker pulse detection was also investigated. Out of 100 analyzed Holter recordings five showed a temporary total loss of pacemaker pulses. Loss of single pacemaker pulses was found in 30 patients. False positive pacemaker pulses were seen in three patients. These results show that visual control and validation by an experienced physician are mandatory.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1993

Oxidative modification of low density lipoproteins by human polymorphonuclear leukocytes.

Oxidatively modified low density lipoproteins are thought to play an important role in the generation of macrophage-derived foam cells in early atherosclerotic lesions. Cultured endothelial cells, monocytes, macrophages and smooth muscle cells can modify low density lipoproteins, either by a free radical mechanism or by the action of lipoxygenases. Previous studies demonstrated that activated human polymorphonuclear leukocytes can oxidize low density lipoprotein lipids. Stimulation of the cells with phorbol 12-myristate 13-acetate resulted in an increase both in superoxide anion production and in low density lipoprotein oxidation. The present results show that the oxidative modification of low density lipoproteins by human polymorphonuclear leukocytes can be inhibited by superoxide dismutase but not by the lipoxygenase inhibitor, (5,8,11,14)-eicosatetraynoic acid. The low density lipoproteins oxidized by polymorphonuclear leukocytes were recognized by the scavenger receptor of macrophages (P 388 cell line). It is proposed that the superoxide anion is an important factor in the oxidative modification of low density lipoproteins induced by polymorphonuclear leukocytes, and that under conditions of increased oxidative metabolism in vivo, polymorphonuclear leukocytes can contribute to foam cell formation by a scavenger receptor-dependent process at lesion sites.

5,8,11,14-Eicosatetraynoic Acid↗
PubMed1992

DNA markers closely linked to nematode resistance genes in sugar beet (Beta vulgaris L.) mapped using chromosome additions and translocations originating from wild beets of the Procumbentes section.

Genes conferring resistance to the beet cyst nematode (Heterodera schachtii Schm.) have been transferred to sugar beet (Beta vulgaris L.) from three wild species of the Procumbentes section using monosomic addition and translocation lines, because no meiotic recombination occurs between chromosomes of cultured and wild species. In the course of a project to isolate the nematode resistance genes by strategies of reverse genetics, probes were cloned from DNA of a fragmented B. procumbens chromosome carrying a resistance gene, which had been isolated by pulsed-field gel electrophoresis. One probe (pRK643) hybridized with a short dispersed repetitive DNA element, which was found only in wild beets, and thus may be used as a molecular marker for nematode resistance to progeneis of monosomic addition lines segregating resistant and susceptible individuals. Additional probes for the resistance gene region were obtained with a polymerase chain reaction (PCR)-based strategy using repetitive primers to amplify DNA located between repetitive elements. One of these probes established the existence of at least six different chromosomes from wild beet species, each conferring resistance independently of the others. A strict correlation between the length of the wild beet chromatin introduced in fragment addition and translocation lines and the repeat copy number has been used physically to map the region conferring resistance to a chromosome segment of 0.5-3 Mb.

Animals↗
PubMed1992

Urinary caffeine metabolites in man. Age-dependent changes and pattern in various clinical situations.

In an exploratory study the 24-h urinary excretion pattern of caffeine and 14 of its major metabolites was studied in 32 volunteers (adults, adolescents and children), 14 patients either with end stage renal disease or liver cirrhosis, 7 heavy smokers and 27 patients on therapy with cimetidine, allopurinol, theophylline or phenytoin. Caffeine and its metabolites were quantified by UV-absorption after liquid/liquid-extraction and HPLC-separation, which ensured proper analysis of 1-methyluric acid. In adults the renal excretion of caffeine derivatives corresponded to an intake of 509 mg caffeine/day, with 1-methyluric acid as the predominant metabolite. About 69% of caffeine was degraded by the paraxanthine pathway, and theobromine- (19%) and the theophylline pathway (14%) were less important. The ratio of paraxanthine formation to urinary caffeine concentration (= clearance equivalent) was about 2.2 ml.min-1.kg-1 in adults, and the corresponding ratios for theophylline and theobromine were 0.43 ml.min-1.kg-1 and 0.59 ml.min-1.kg-1, respectively. As expected, caffeine degradation was impaired in patients with cirrhosis and was increased in persons who smoked heavily or who were on phenytoin therapy. The results document the possibility of noninvasively investigating gross differences in caffeine disposition by analysis of the urinary pattern of its metabolites.

Adolescent↗
PubMed1992

Tissue polypeptide antigen in breast cancer cytosol: a new effective prognostic indicator.

Since 1982 we have been evaluating oestrogen and progesterone receptors (PgR), cathepsin D and the cytosolic levels of the tumour marker, tissue polypeptide antigen (TPA), in 257 patients radically resected for breast cancer (follow-up 24-81 months). TPA was measured by an immunoradiometric assay previously validated for cytosol. No significant associations were found between cytosolic TPA and age, tumour size, lymph-node status, receptor status and cathepsin D. TPA+ cases showed a significantly longer disease-free survival (DFS) and overall survival (OS) than TPA-patients (log-rank P < 0.0001). The prognostic value of cytosolic TPA was also demonstrated after stratification by nodal status, PgR and cathepsin D. The prognostic value of TPA was independent of the other prognostic indicators, being the most powerful among the evaluated indices (Cox multivariate analysis: chi 2 15.5 for DFS, 11.4 for OS). We conclude that cytosolic TPA is a powerful additional prognostic factor in primary breast cancer. Its prognostic role should therefore be extensively evaluated.

Antigens, Neoplasm↗
PubMed1992

Carboplatin plus 5-fluorouracil and leucovorin in previously treated patients with metastatic breast cancer.

The commonly reported second-line chemotherapy regimens administered for metastatic breast cancer usually induce few responses, which last no more than 4 to 8 months. We used carboplatin 50 mg/m2 on days 2, 3, and 4 of each course, leucovorin 500 mg/m2 on days 1 through 5 in 30-minute infusions, and 5-fluorouracil (5-FU) 375 mg/m2 intravenous bolus 1 hour after each leucovorin dose to treat 32 patients with metastatic breast cancer. Six patients had previously received treatment with only one cytotoxic chemotherapy regimen, usually CMF (cyclophosphamide/methotrexate/5-FU). Twenty-six patients had received treatment with two or more regimens of chemotherapy previously, and most of them also had received radiotherapy and endocrine manipulations. Fifteen patients had visceral deposits. In cases of excessive or persistent toxicity, single daily doses were not reduced, but the start of the next course was delayed or its duration reduced. Of 26 heavily pretreated patients, 12 responded, primarily those with disease in lymph nodes, skin, breast, and pleura. One patient with liver deposits had a complete remission confirmed at laparoscopy and echogram. Survival was probably prolonged, with a median duration of response of 5 months (range, 3 to 22+), and moderate side effects that did not compromise quality of life during treatment. The probability of response was not related to the type of pretreatment (with or without 5-FU) nor to response to previous treatments.

Adult↗