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S Lutz

Publications and source records attributed to S Lutz.

At least 19 recordsLinked to original sources
PubMed2003

Dominance for vestibular cortical function in the non-dominant hemisphere.

The aim of this (15)O-labelled H(2)O bolus positron emission tomography (PET) study was to analyse the hemispheric dominance of the vestibular cortical system. Therefore, the differential effects of caloric vestibular stimulation (right or left ear irrigation with warm water at 44 degrees C) on cortical and subcortical activation were studied in 12 right-handed and 12 left-handed healthy volunteers. Caloric irrigation induces a direction-specific sensation of rotation and nystagmus. Significant regional cerebral blood flow increases were found in a network within both hemispheres, including the superior frontal gyrus/sulcus, the precentral gyrus and the inferior parietal lobule with the supramarginal gyrus. These areas correspond best to the cortical ocular motor centres, namely the prefrontal cortex, the frontal eye field and the parietal eye field, known to be involved in the processing of caloric nystagmus. Furthermore, distinct temporo-parietal activations could be separated in the posterior part of the insula with the adjacent superior temporal gyrus, the inferior parietal lobule and precuneus. These areas fit best to the human homologues of multisensory vestibular cortex areas identified in the monkey and correspond to the parieto-insular vestibular cortex (PIVC), the visual temporal sylvian area (VTS) and areas 7 and 6. Further cortical activations were seen in the anterior insula, the inferior frontal gyrus and anterior cingulum. The subcortical activation pattern in the putamen, thalamus and midbrain is consistent with the organization of efferent ocular motor pathways. Cortical and subcortical activation of the described areas was bilateral during monaural stimulation, but predominant in the hemisphere ipsilateral to the stimulated ear and exhibited a significant right hemispheric dominance for vestibular and ocular motor structures in right-handed volunteers. Similarly, a significant left hemispheric dominance was found in the 12 left-handed volunteers. Thus, this PET study showed for the first time that cortical and subcortical activation by vestibular caloric stimulation depends (i) on the handedness of the subjects and (ii) on the side of the stimulated ear. Maximum activation was therefore found when the non-dominant hemisphere was ipsilateral to the stimulated ear, i.e. in the right hemisphere of right-handed subjects during caloric irrigation of the right ear and in the left hemisphere of left-handed subjects during caloric irrigation of the left ear. The localization of handedness and vestibular dominance in opposite hemispheres might conceivably indicate that the vestibular system and its hemispheric dominance, which matures earlier during ontogenesis, determine right- or left-handedness.

Adult↗
PubMed2001

Creating multiple-crossover DNA libraries independent of sequence identity.

We have developed, experimentally implemented, and modeled in silico a methodology named SCRATCHY that enables the combinatorial engineering of target proteins, independent of sequence identity. The approach combines two methods for recombining genes: incremental truncation for the creation of hybrid enzymes and DNA shuffling. First, incremental truncation for the creation of hybrid enzymes is used to create a comprehensive set of fusions between fragments of genes in a DNA homology-independent fashion. This artificial family is then subjected to a DNA-shuffling step to augment the number of crossovers. SCRATCHY libraries were created from the glycinamide-ribonucleotide formyltransferase (GART) genes from Escherichia coli (purN) and human (hGART). The developed modeling framework eSCRATCHY provides insight into the effect of sequence identity and fragmentation length on crossover statistics and draws contrast with DNA shuffling. Sequence analysis of the naive shuffled library identified members with up to three crossovers, and modeling predictions are in good agreement with the experimental findings. Subsequent in vivo selection in an auxotrophic E. coli host yielded functional hybrid enzymes containing multiple crossovers.

Algorithms↗
PubMed2001

Predicting crossover generation in DNA shuffling.

We introduce a quantitative framework for assessing the generation of crossovers in DNA shuffling experiments. The approach uses free energy calculations and complete sequence information to model the annealing process. Statistics obtained for the annealing events then are combined with a reassembly algorithm to infer crossover allocation in the reassembled sequences. The fraction of reassembled sequences containing zero, one, two, or more crossovers and the probability that a given nucleotide position in a reassembled sequence is the site of a crossover event are estimated. Comparisons of the predictions against experimental data for five example systems demonstrate good agreement despite the fact that no adjustable parameters are used. An in silico case study of a set of 12 subtilases examines the effect of fragmentation length, annealing temperature, sequence identity and number of shuffled sequences on the number, type, and distribution of crossovers. A computational verification of crossover aggregation in regions of near-perfect sequence identity and the presence of synergistic reassembly in family DNA shuffling is obtained.

Algorithms↗
PubMed2001

Transfer of biological traces in cases of hanging and ligature strangulation.

In hanging and ligature strangulation, the noose mostly causes a mark or groove which is formed partly by compression of the skin and partly by abrasion with loss of the upper epidermal layers. The horny scales abraded from the neck may be transferred to the strangulation device or to the interposed textiles where they are sometimes visible at stereomicroscopic examination or even to the naked eye as silver-grey particles. The morphologic features of the epidermal transfer due to hanging and ligature strangulation is demonstrated by 14 case examples. The biological traces may be sufficient for comparative DNA typing by means of PCR-based methods. In 9 out of the 14 cases, genomic DNA typing was successful. Analysis of mtDNA succeeded in another two cases, although genomic DNA could not be detected. Beside the accumulation of solid epidermic particles the paper describes deposition of serous and fatty tissue fluid at the ligature (mainly adjacent to skin ridges).

Adult↗
PubMed2001

Rapid generation of incremental truncation libraries for protein engineering using alpha-phosphothioate nucleotides.

Incremental truncation for the creation of hybrid enzymes (ITCHY) is a novel tool for the generation of combinatorial libraries of hybrid proteins independent of DNA sequence homology. We herein report a fundamentally different methodology for creating incremental truncation libraries using nucleotide triphosphate analogs. Central to the method is the polymerase catalyzed, low frequency, random incorporation of alpha-phosphothioate dNTPs into the region of DNA targeted for truncation. The resulting phosphothioate internucleotide linkages are resistant to 3'-->5' exonuclease hydrolysis, rendering the target DNA resistant to degradation in a subsequent exonuclease III treatment. From an experimental perspective the protocol reported here to create incremental truncation libraries is simpler and less time consuming than previous approaches by combining the two gene fragments in a single vector and eliminating additional purification steps. As proof of principle, an incremental truncation library of fusions between the N-terminal fragment of Escherichia coli glycinamide ribonucleotide formyltransferase (PurN) and the C-terminal fragment of human glycinamide ribonucleotide formyltransferase (hGART) was prepared and successfully tested for functional hybrids in an auxotrophic E.coli host strain. Multiple active hybrid enzymes were identified, including ones fused in regions of low sequence homology.

Amino Acid Sequence↗
PubMed2001

An explicit no response instead of time-out in automated visual-field testing.

BACKGROUND: To evaluate the effect of response-acquisition technique on psychometric performance in visual-field testing, the conventional one-button yes/time-out method was compared with a two-button yes/no method for responding whether or not the stimulus was detected. There are a number of situations in which the single-button technique leads to ambiguous results. In this study, we thus expected the yes/no method to reduce tendencies towards habituation and automatic responding. Our hypothesis was that the two-button technique could reduce the rate of erroneous responses. METHODS: Luminance-difference sensitivity for bright stimuli (32') on a photopic background was evaluated at 26 locations within the central visual field (30 degrees) using a specially equalised video display unit and a modified 4/2-dB staircase strategy (six reversals, maximum-likelihood threshold estimation). Sixty-one ophthalmologically normal subjects (aged 20-30 years) were examined twice with each method. RESULTS: Mean sensitivities with the two-button yes/no method were found to be, on average, 0.13 dB above those measured with the one-button yes/time-out technique--a difference without clinical relevance. Within-subject variability did not differ between the two methods. However, the less intuitive two-button yes/no method had a slightly higher number of false responses in catch trials. CONCLUSION: Compared to the conventional one-button yes/time-out method, the two-button yes/no method in normal young subjects thus showed little difference in mean sensitivities and equivalent within-subject variabilities. Concerning our initial hypothesis, the yes/no method is of somewhat higher complexity and is not able to reduce the rate of erroneous responses. The one-button yes/time-out method fared a little better in error rate. In summary, the yes/no method is an alternative and additional possibility of response acquisition in visual-field testing, which is worthy of being tested in a clinical study with elderly subjects.

Adult↗
PubMed2001

Nutrition socialization experiences of children in the Head Start program.

Some preschoolers may be at risk for overweight and obesity. To gain greater insight into children's early nutrition socialization experiences, the association of adult nutrition attitudes and mealtime behaviors to young children's eating behaviors and weight-for-height was investigated. Forty-six parent-child pairs and 8 Head Start teachers participated. Children were weighed and measured; parents completed measures of child eating behaviors, nutrition attitudes, and family mealtimes; teachers reported their own nutrition attitudes and were observed during mealtimes. Correlational findings indicated that parents' negative mealtime practices were associated with higher child weight-for-height and that parents' positive nutrition-attitudes were related to more pleasant family mealtimes, fewer negative mealtime practices, and less troublesome child eating behaviors. The Head Start mealtime environment was developmentally appropriate and predictable for children. Although teachers engaged in some nutrition teaching during meals, a number of opportunities were missed for promoting children's nutrition socialization. In sum, these results identified potential opportunities for improving children's early nutrition socialization experiences.

Adult↗
PubMed2001

Increased activity of membrane-associated nucleoside diphosphate kinase and inhibition of cAMP synthesis in failing human myocardium.

OBJECTIVE: Chronic heart failure is associated with a decreased responsiveness of the heart to beta-adrenergic receptor agonists. We recently demonstrated a receptor-independent activation of G proteins and modulation of cardiac adenylyl cyclase activity by sarcolemmal membrane-associated nucleoside diphosphate kinase. We wondered whether changes in the activity of nucleoside diphosphate kinase occur in heart failure and contribute to or compensate for the impairment in myocardial receptor-mediated cAMP generation. METHODS: Sarcolemmal membranes were purified from non-failing and failing human left ventricular myocardium. The protein level and activity of nucleoside diphosphate kinase were quantified. The influence of nucleoside diphosphate kinase on adenylyl cyclase activity was determined by measuring the effect of GDP on adenylyl cyclase activity in the absence and presence of nucleoside diphosphate kinase inhibitors. RESULTS: The amount and activity of nucleoside diphosphate kinase in sarcolemmal membranes from failing hearts (n=13) were increased 3- to 4-fold compared to levels in membranes from non-failing myocardium (n=5). This increase in sarcolemmal nucleoside diphosphate kinase activity resulted in a 50% inhibition of adenylyl cyclase activity over a range of GDP and ATP concentrations. CONCLUSION: The amount and activity of nucleoside diphosphate kinase are increased in sarcolemmal membranes of failing human myocardium, resulting in a substantial receptor-independent inhibition of adenylyl cyclase activity.

5'-Nucleotidase↗
PubMed2001

Symptom frequency and severity in patients with metastatic or locally recurrent lung cancer: a prospective study using the Lung Cancer Symptom Scale in a community hospital.

PURPOSE: To define symptoms and therapeutic requirements for patients with metastatic or locally recurrent lung cancer. METHODS AND MATERIALS: Data were collected from 69 consecutive patients with locally advanced lung cancer seen in consultation at a radiation oncology facility serving a community hospital in Virginia. The Lung Cancer Symptom Scale, a validated quality of life instrument, measured the incidence of symptoms in this group. RESULTS: Average survival for the entire group was 7 months. Fifty-seven patients received 81 courses of radiation therapy, 33 directed at thoracic disease and 48 delivered to sites of metastasis. Thirty-three percent of those who received radiation therapy required treatment to more than one anatomic site. Every patient was symptomatic at the time of consultation, with the number (p = 0.001) and severity (p = 0.001) of symptoms they suffered worse in the patient group seen 0 to 3 months prior to death rather than 4 to 6 months prior to death. With the exception of cough, symptoms were marked in their severity. CONCLUSIONS: Patients with advanced lung cancer suffer frequent and severe symptoms that worsen in the final months of life. The appropriate timing and combination of radiotherapy and chemotherapy are yet to be resolved. Future studies will require use of validated quality of life instruments to better catalogue palliation and treatment toxicity.

Aged↗
PubMed2000

DNA typing of human remains found in damp environments.

DNA typing is often used to determine identity from human remains. The environment to which the material has been exposed, however, is crucial for the success of the investigation. Damp conditions in particular can cause a rapid degradation of DNA, even in bone and teeth, and thus reduce the chances of successful typing. Here, we present the results of investigations performed on four skulls that had been lying in a damp environment for periods ranging from almost 1 year to about 45 years. In none of these cases was DNA typing successful on bone or, where present, on teeth. Where remnants of brain tissue were used, however, complete STR typing was possible in one case, partial STR typing in another, and mtDNA sequencing could be carried out in three cases. These findings suggest that brain tissue is relatively resistant to putrefaction in damp environments and, unlike bone, appears to exhibit a certain degree of protection against DNA degradation.

Aged↗
PubMed2000

Is it possible to differentiate mtDNA by means of HVIII in samples that cannot be distinguished by sequencing the HVI and HVII regions?

The mitochondrial control region includes three so-called hypervariable (HV) regions, in which the polymorphic positions show a particularly high frequency. According to a population study of 200 unrelated individuals from Germany, HVI (positions 16,024-16,365, according to Anderson) showed 88 variable positions in a total length of 342 bp (26%) and HVII (positions 73-340) displayed 65 mutable sites in 268 bp (24%). HVIII (positions 438-574) exhibited a slightly lower variability, with 25 polymorphic sites within 137 bp (18%), but contrasted clearly with the background, which showed variability rates of only 7% (positions 16,366-16,569, 1-72) and 3% (positions 341-437), respectively. At present, the displacement (D)-loop database in Magdeburg comprises 904 sequences of the mitochondrial HVI region and HVII region from Germans, Austrians and Swiss. By means of this material, the extent to which the mtDNA sequences that do not differ in the HVI and HVII regions can be differentiated by additionally sequencing HVIII was investigated.

Austria↗
PubMed2000

Mitochondrial DNA in the Central European population. Human identification with the help of the forensic mt-DNA D-loop-base database.

Sequencing of mtDNA is an advanced method for the individualisation of traces. Disadvantages of this method are expensive and time-consuming analysis and evaluation procedures as well as the necessary stock of population-genetic data which is still insufficient. Central European institutes of forensic medicine from Germany, Austria, and Switzerland have been working together since the beginning of 1998 to establish a mtDNA database. The aim is to build up a large stock of forensically established data and provide population-genetic data for frequency investigations, which will serve as a basis for expert opinions and scientific research. Good data quality is ensured by using original sequences only. Ring tests, which have been conducted to enhance analytical reliability, revealed a high correspondence rate of the analytical results obtained by the individual member institutes. Today 1410 sequences are available for comparison, of which 1285 sequences in the HV1 and HV2 regions cover the full ranges from 16051 to 16365 and from 73 to 340 (according to Anderson). The major part is formed by Central European sequences comprising 1256 data sets from Germany, Austria, and Switzerland. Today the database contains sequences from a total of 12 European, six African and three Asian countries including 100 sequences from Japan. This paper is aimed at discussing the individualisation potentials of mtDNA as well as the possibilities and limits of ethnic differentiation by means of pairwise sequence differences on the basis of the data stock available.

Austria↗
PubMed2000

Mitochondrial heteroplasmy among maternally related individuals.

The second hypervariable segment of the human mtDNA control region contains a homopolymeric tract of cytidines between nucleotides (nt) 303 and 315, interrupted by a thymidine at position 310, according to the Cambridge reference sequence. By direct sequencing, some individuals show blurred sequence chromatograms in this region which are not caused by a sequencing artefact but by high levels of length heteroplasmy. With respect to this length heteroplasmy ten maternally related individuals and two unrelated probands were examined. The relative proportions of length variants in the homopolymeric tract in selected individuals were determined by cloning and sequencing of multiple independent clones. All ten family members examined were heteroplasmic while the proportions of each genotype varied widely in different individuals. The size of a possible mitochondrial bottleneck during embryonic development of the offspring is discussed with respect to the changes in mitochondrial haplotypes within mother-offspring pairs. Our data are consistent with both slow and rapid segregation of mtDNAs between the generations, which would implicate a tight as well as a wide bottleneck. Therefore, a common bottleneck size in all individuals from this lineage seems to be very unlikely.

Chromosome Segregation↗
PubMed2000

Homology-independent protein engineering.

Is structure, rather than sequence, the key to the successful generation of truly novel proteins? While protein evolution by homologous recombination has become an established tool to explore confined regions in sequence space, the generation of functional hybrid proteins by homology-independent methods further expands the scope of protein engineering.

Combinatorial Chemistry Techniques↗
PubMed2000

e-business means survival for health care organizations in 2010.

Within the next five years, most health care organizations will communicate with suppliers, other providers, payers, regulators, and patients through the Internet. The Internet will recalibrate expectations of speed and service for patients and providers, but it also will increase accountability in which digitalized information is tracked and analyzed. The rate at which health care organizations are developing Web-based solutions is neck-snapping in the United States. As individual product lines, departments, and subsidiaries grow their own e-health businesses, organizations must decide which initiatives they must fund, which are essential to survival, and which could be financial black holes.

Commerce↗
PubMed1999

Blockade of dopamine D2, but not of D1 receptors in the rat globus pallidus induced Fos-like immunoreactivity in the caudate-putamen, substantia nigra and entopeduncular nucleus.

In the present study, we investigated Fos-like immunoreactivity (FLI) evoked by pallidal dopamine (DA) D1 and D2 receptor blockade in the caudate-putamen (CPu), substantia nigra (SN) and entopeduncular nucleus (EP), i.e. major target areas of pallidal efferents. Results demonstrate that infusion of the selective D1 antagonist SCH23390 (1 and 4 microg/0.5 microl) into the globus pallidus (GP) did not induce FLI in the CPu, SN and EP. In contrast, intrapallidal infusion of a low dose of the selective D2 antagonist S(-)-sulpiride (15 microg/0.5 microl) induced FLI restricted to the CPu. A higher dose of intrapallidal S(-)-sulpiride (25 microg/0.5 microl) induced FLI in the CPu as well as in the SN and EP. These findings add further evidence to notion that the GP plays a central role in the basal ganglia circuitry and demonstrate an involvement of extrastriatal DA via D2 receptors.

Animals↗
PubMed1999

An in vitro screening technique for DNA polymerases that can incorporate modified nucleotides. Pseudo-thymidine as a substrate for thermostable polymerases.

DNA polymerases are desired that incorporate modified nucleotides into DNA with diminished pausing, premature termination and infidelity. Reported here is a simple in vitro assay to screen for DNA polymerases that accept modified nucleotides based on a set of primer extension reactions. In combination with the scintillation proximity assay (SPA[trade]), this allows rapid and simple screening of enzymes for their ability to elongate oligonucleotides in the presence of unnatural nucleotides. A proof of the concept is obtained using pseudo-thymidine (psiT), the C-nucleoside analog of thymidine, as the unnatural substrate. The conformational properties of psiT arising from the carbon-carbon bond between the sugar and the base make it an interesting probe for the importance of conformational restraints in the active site of polymerases during primer elongation. From a pool of commercially available thermostable polymerases, the assay identified Taq DNA polymerase as the most suitable enzyme for the PCR amplification of oligonucleotides containing psiT. Subsequent experiments analyzing PCR performance and fidelity of Taq DNA polymerase acting on psiT are presented. This is the first time that PCR has been performed with a C-nucleoside.

Animals↗