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Biomedical subjects

A Wagner

Publications and source records attributed to A Wagner.

At least 307 records · Page 17Linked to original sources
PubMed1995

[Collection and long-term preservation of peripheral stem cells].

The methods of collection and storage of peripheral blood stem cells are described, and the harvesting after conditioning with cytokines and/or myelosuppressive therapy is discussed. It could be demonstrated that the combination of cytostatics and cytokines gives the best yield and enables to collect a sufficient amount of peripheral bloodstem cells for a successful engraftment after myeloablative therapy with only few aphereses.

Antineoplastic Agents↗
PubMed1995

Adrenoleukodystrophy. A case report.

PURPOSE: Adrenoleukodystrophy is a hereditary, usually X-linked recessive disorder, characterized by progressive demyelination of cerebral white matter and adrenal insufficiency. MATERIAL AND METHODS AND RESULTS: We report the case of a 14-year-old boy, presenting the typical changes in CT and MR with almost symmetrical changes in the white matter only, with no mass effect and a rim of enhancement. Adrenoleukodystrophy may resemble tumour but shows no mass effect. DISCUSSION AND CONCLUSION: We discuss the differential diagnoses and underline the importance of the characteristic appearance of this disease. Adrenoleukodystrophy is diagnosed by serum analysis.

Adolescent↗
PubMed1995

[Computer-assisted intraoperative visualization of dental implants. Augmented reality in medicine].

In this paper, a recently developed computer-based dental implant positioning system with an image-to-tissue interface is presented. On a computer monitor or in a head-up display, planned implant positions and the implant drill are graphically superimposed on the patient's anatomy. Electromagnetic 3D sensors track all skull and jaw movements; their signal feedback to the workstation induces permanent real-time updating of the virtual graphics' position. An experimental study and a clinical case demonstrates the concept of the augmented reality environment--the physician can see the operating field and superimposed virtual structures, such as dental implants and surgical instruments, without loosing visual control of the operating field. Therefore, the operation system allows visualization of CT planned implantposition and the implementation of important anatomical structures. The presented method for the first time links preoperatively acquired radiologic data, planned implant location and intraoperative navigation assistance for orthotopic positioning of dental implants.

Computer Graphics↗
PubMed1994

[Magnetic resonance imaging compared to myelography and CT. Diagnostic value in patients with suspected medullary spinal compression syndrome].

Comparison between myelography (MY) and magnetic resonance imaging (MRI) was carried out in 36 patients with clinical suspicion of spinal cord or root compression due to metastatic disease in the spinal canal. In three patients metastatic lesions were visualized on MY but not on MRI, while there were no cases with a negative MY and a positive MRI. In 44% of the cases MY alone or combined with postmyelographic CT (pm-CT) showed a larger tumour extension than did MRI, while the opposite occurred in 25%. As for detection of bony metastases and tumour masses localized outside the spine there was no difference between MRI and MY + pm-CT. The results indicate that the choice between MRI and MY + pm-CT still can be based on the availability and quality of the procedure at a given institution.

Evaluation Studies as Topic↗
PubMed1994

Food restriction eliminates preneoplastic cells through apoptosis and antagonizes carcinogenesis in rat liver.

Restriction of dietary calories reduces cancer formation in experimental animals and probably also in humans. This effect is generally attributed to the inhibitory effect of fasting on cell proliferation. Here we studied the effect of fasting on physiological cell death through apoptosis by using rat liver as a model. (i) In normal liver, involution of hyperplasia by apoptosis was reinforced by food withdrawal and suppressed by feeding. Complete food withdrawal for 8 days or food reduction by 40% for 3 months eliminated 20-30% of normal liver cells through apoptosis. (ii) Putative preneoplastic liver foci exhibited severalfold higher rates of DNA replication and apoptosis than unaltered liver. Food restriction lowered DNA replication but increased apoptosis, which reduced the number and volume of putative preneoplastic liver foci by 85% within 3 months. Subsequent return to ad libitum feeding normalized cell replication and apoptosis but clear differences in the volume and number of putative preneoplastic liver foci persisted throughout the following 17 months. Treatment of animals after food restriction with nafenopin, a peroxisome proliferator and potent tumor promoter, produced only half as many hepatocellular adenomas and carcinomas as in animals fed unrestrictedly throughout their lifetime. This indicates that food restriction had actually eliminated a part of the initiated cells. This study demonstrates that food restriction preferentially enhances apoptosis of preneoplastic cells. This effect in combination with lowered cell replication provides protection from carcinogenesis.

Animals↗
PubMed1994

Evolution of gene networks by gene duplications: a mathematical model and its implications on genome organization.

Networks of transcriptional regulators have key roles in metazoan development. Important forces in the evolution of these networks are gene duplications and gene deletions, events that may change the spatiotemporal expression pattern of network genes. A measure for the probability of such changes after gene-duplication events is proposed. This measure is based on a simple mathematical model that describes such networks as dynamical systems and on properties of ensembles of these dynamical systems. It is predicted that this probability depends only on the fraction of genes duplicated in a single event and that it is largest if approximately 40% of the genes in a network are duplicated. This property is robust with respect to variations in model parameters. On these grounds, it is argued that (i) evolution of gene networks should preferentially occur either by duplication of single genes or by duplication of all genes involved in a network, and that (ii) tight linkage ("clustering") or strong dispersal are the two evolutionarily most favorable forms of genomic organization of genes forming such networks.

Animals↗
PubMed1994

Different requirements of ICAM-1/LFA-1 adhesion in allorecognition and self-restricted antigen recognition by class II-specific T cell clones.

We have analyzed the influence of non-antigen-specific interactions between ICAM-1 and LFA-1 in target recognition by allospecific and antigen-specific T cells at the clonal level, using human and mouse fibroblasts transfected with HLA-DR1 or DR2 with or without co-expression of ICAM-1, as antigen-presenting cells. The results show a great heterogeneity in the requirements for ICAM-1/LFA-1 interactions for antigen-specific and alloreactive T cell responses and this requirement may depend on the avidity of any particular interaction. The data also show that for most alloreactive clones, ICAM-1/LFA-1 adhesion is not sufficient to facilitate efficient T cell recognition of its target molecule. HLA class II recognition by a large proportion of the DR1- and DR2-specific alloreactive clones studied was different for class II molecules expressed on murine or human fibroblasts compared to human lymphoid cells, and was independent of ICAM-1 expression on the stimulator cells. The inability of some T cell clones to recognize HLA-class II expressed on non-lymphoid cells suggests the absence of specific epitopes and could be due to the lack of the relevant peptides, either because they are derived from species-specific proteins or to differences in processing of endogenous antigen in the transfected stimulator cells.

Animals↗
PubMed1994

PLT-30: an improvement for platelet collection on the Baxter CS-3000 Plus.

The CS-3000 is a well-established blood cell separator. To increase the efficiency of platelet collection, Baxter developed a new separation chamber, the TNX-6, for the follow-up model of the CS-3000, the CS-3000 Plus. To reduce the occurrence of platelet aggregates and to increase platelet yield and efficiency the collection chamber A-35 has been replaced by a new, volume-reduced chamber called PLT-30. We analyzed on the basis of 201 platelet separation procedures with the CS-3000 Plus fitted with both new chambers the efficiency of platelet collection. The platelet yield per unit (mean +/- SE) was 4.55 x 10(11) +/- 0.07 x 10(11) and the efficiency was 50.79 +/- 0.76%; only 3.98% of the platelet concentrates were below 3 x 10(11). To compare our data with results from the A-35 we enrolled 33 random donors (17 in Innsbruck, 16 in Vienna) in a controlled study. Using both chambers in a randomly selected sequence within a period of 1 month on each chamber, we evaluated platelet yield, efficiency, and the contamination with white blood cells (WBCs). We found a platelet yield per unit (mean +/- SE) of 3.74 x 10(11) +/- 0.11 x 10(11) using the A-35 and of 4.4 x 10(11) +/- 0.21 x 10(11) with the new PLT-30 (P = .0001). The efficiency of the collecting process (mean +/- SE) was higher with the PLT-30 (47.76 +/- 2.11%) than with the A-35 (40.68 +/- 1.29%). The difference is statistically significant (P = .0001).(ABSTRACT TRUNCATED AT 250 WORDS)

Cell Separation↗
PubMed1994

Tail-to-tail orientation of the Atlantic salmon alpha- and beta-globin genes.

We report the cloning of a cDNA and two corresponding beta-globin genes of the Atlantic salmon (Salmo salar L.) as well as two genes for alpha-globins. Nucleotide sequence analysis of the cDNA shows that the predicted beta-globin peptide comprises 148 amino acids with a calculated molecular mass of 16,127 Da and an overall amino acid similarity of 40-50% to higher vertebrates and 60-90% to fish sequences. The study of the genomic organization of alpha- and beta-globin genes shows that, as is the case in Xenopus, the salmon genes are adjacent. Two sets of linked alpha- and beta-globin genes were isolated and restriction-enzyme polymorphisms indicate that they belong to two distinct loci, possibly as a result of the salmon tetraploidy. In each locus the alpha- and beta-globin genes are oriented 3' to 3' relative to each other with the RNA coding sequences located on opposite DNA strands. This is the first evidence for this type of arrangement found for globin genes. Moreover, while the linkage found in salmon and Xenopus supports the hypothesis of an initial tandem duplication of a globin ancestor gene, our results raise the question of the actual original orientation of the duplicated genes.

Amino Acid Sequence↗
PubMed1994

Epistasis can facilitate the evolution of reproductive isolation by peak shifts: a two-locus two-allele model.

The influence of epistasis on the evolution of reproductive isolation by peak shifts is studied in a two-locus two-allele model of a quantitative genetic character under stabilizing selection. Epistasis is introduced by a simple multiplicative term in the function that maps gene effects onto genotypic values. In the model with only additive effects on the trait, the probability of a peak shift and the amount of reproductive isolation are always inversely related, i.e., the higher the peak shift rate, the lower the amount of reproductive isolation caused by the peak shift. With epistatic characters there is no consistent relationship between these two values. Interestingly, there are cases where both transition rates as well as the amount of reproductive isolation are increased relative to the additive model. This effect has two main causes: a shift in the location of the transition point, and the hybrids between the two alternative optimal genotypes have lower average fitness in the epistatic case. A review of the empirical literature shows that the fitness relations resulting in higher peak shift rates and more reproductive isolation are qualitatively the same as those observed for genes causing hybrid inferiority.

Alleles↗
PubMed1994

Comparison of clinical neurological function and CT response during chemotherapy for initial brain metastases from small cell lung cancer.

We compared the clinical neurological and functional response with changes in CT during systemic combination chemotherapy in 20 patients with initial brain metastases from small cell lung cancer (SCLC). Seven patients died within four weeks from start of chemotherapy, leaving 13 patients for evaluation of treatment response. Eight patients improved to or maintained a high neurological score, meaning no or insignificant neurological deficits or disability. Three patients had a stable neurological score, and 2 patients deteriorated. The median duration of the clinical response was 20 weeks. Based on changes in CT four patients had complete remission, six had partial remission, and two showed no change. One patient had a rapid deterioration of her clinical condition and died without CT control. Five patients with late CNS relapse were treated with second-line cranial irradiation inducing clinical improvement in three. Median survival was 11 weeks, and in assessable patients, excluding early deaths, 28 weeks. In conclusion initial brain metastases respond to systemic chemotherapy as readily as extracranial locations of SCLC, and in many patients prolonged neurological and CT remission can be achieved.

Aged↗
PubMed1994

Effect of low dose sedation with diazepam on ventilatory response at moderate altitude.

UNLABELLED: Benzodiazepines are in wide use in out of hospital emergency medicine in at sea level, as well as in alpine rescue services. Ventilatory depression is a common side effect of high dose intravenous benzodiazepines. The objective of our study was to evaluate the effect of low dose benzodiazepines on ventilation at moderate altitude. DESIGN: Randomized, double blind, placebo controlled crossover trial. Blood gas analysis of 8 healthy subjects was performed before and one hour after 5 mg of oral diazepam or placebo at 171 m and at 3,000 m altitude. PaO2 and PaCO2 before and after diazepam or placebo medication at 171 m did not change significantly. At 3,000 m altitude. PaO2 decreased and PaCO2 increased significantly one hour after 5 mg of oral diazepam (PaO2 64.7 +/- 3.4 vs. 60.0 +/- 1.5 mmHg, PaCO2 28.3 +/- 2.3 vs. 33.3 +/- 1.8 mmHg, p < 0.05). Placebo did not influence PaO2 and PaCO2. CONCLUSION: Low dose diazepam inhibits ventilatory adaptation to mild hypoxia at moderate altitude. Caution in benzodiazepine use in moderate altitude is therefore necessary.

Adult↗
PubMed1994

[Multiple organ failure syndrome in protracted tachycardia (based on 4 cases)].

The multiple organ dysfunction syndrome (MODS) is mainly caused by sepsis--community acquired or more frequently by nosocomial infections acquired on the intensive care unit. Further causes are intoxications, burns and multiple trauma. MODS worsens the prognosis of intensive care patients. We report on four cases of MODS developing outside hospital as a result of sustained tachycardia. Severity of MODS was apparently dependent on the duration of tachycardia and was rapidly reversible after termination of the tachycardia. Our observations show that sustained tachycardia may also cause MODS.

Aged↗
PubMed1994

Effects of the renin inhibitor N-[N-(3-(4-amino-1-piperidinyl-carbonyl)-2(R)-benzylpropionyl)-L- histid inyl] -(2S,3R,4S)-1-cyclohexyl-3,4-dihydroxy-6(2-pyridyl)-hexane-2-amide acetate in anesthetized rhesus monkeys.

The renin inhibitory effect of the non-peptide renin inhibitor S 2864 (N-[N-(3-(4-Amino-1-piperidinyl-carbonyl)-2(R)-benzylpropionyl)-L- histidinyl]-(2S,3R,4S)-1-cyclohexyl-3,4-dihydroxy-6(2-pyridyl)-hexane-2- amide acetate, CAS 135683-92-0) was characterized in vitro and in vivo in primates. In vitro, S 2864 inhibited the activity of purified human plasma renin with an IC50 of 3.8 x 10(-10) mol/l and did not affect related human aspartyl proteases like human cathepsin E, cathepsin D or pepsin. In vivo, in anesthetized sodium depleted rhesus monkeys S 2864 decreased mean arterial blood pressure after intraduodenal (i.d.) administration of 2 mg/kg significantly by 27% from 94 +/- 8 to 62 +/- 6 mmHg for 90 min. Heart rate was not changed. Cumulative intravenous (i.v.) administration of S 2864 or remikiren in doses of 1, 10 and 30 micrograms/kg significantly decreased systemic blood pressure, dP/dtmax and cardiac output while heart rate was not changed. Plasma angiotensin II (ANG II) levels as well as renin activity were dose dependently reduced after 10, 30 and 60 min. It is concluded that S 2864 is an effective specific inhibitor of human renin eliciting marked blood pressure lowering activities in primates.

Anesthesia↗
PubMed1994

High resolution image-cytometric differentiation of hormone sensitive and hormone insensitive prostatic carcinomas.

Until the present it was not possible to predict hormone sensitivity of prostatic carcinoma. Based on studies correlating image cytometric results of hormone receptor negative and hormone receptor positive breast carcinomas, the present study aims at separating responders and non-responders to hormone therapy in metastatic prostatic carcinoma. From May-Grünwald-Giemsa stained slides of fine needle aspirates of 23 patients with metastasizing prostatic carcinoma about 100 nuclei per slide were taken by TV camera for image-cytometric processing. One thousand and twenty-two nuclei came from 10 patients who showed tumour regression for at least 36 months and who all survived for more than 5 years. One thousand three hundred and thirty-two nuclei were from prostatic aspirates of patients who showed a continuous tumour progression despite receiving hormone therapy. All patients of the latter group died within 5 years. A correct classification of the patient groups of responders and non-responders was possible in 19-21 of 23 cases by means of high resolution image analysis including nuclear structural features. It was found that even simple planimetric features, like the nuclear perimeter, or densitometric features, such as the total nuclear extinction, differed markedly between the two groups. The data show that nuclei from hormone sensitive prostatic carcinoma are distinct from those of non-sensitive ones in the present series. The interpretation of results must take into account that the very strict criteria for hormone sensitivity leads to a highly selected patient group. The application of the method to an unselected patient group can be presumed to yield a higher rate of false classifications.

Azure Stains↗
PubMed1994

[Prevalence of alcohol drinking in Alpine skiing].

UNLABELLED: Previous investigations showed direct correlation between the degree of alcoholization and the severity of injuries after ski accidents. The aim of our study was to investigate the prevalence of alcohol use on slopes and on ski tours. RESULTS: The examination of breath in 414 probands proved 30% alcohol positive ski tourists. A significantly higher frequency of alcohol positive skiers was found on tours, if an open mountain hut was located on the tour, but the mean degree of alcoholization was significantly higher on slopes.

Adolescent↗