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Biomedical subjects

R Wimmer

Publications and source records attributed to R Wimmer.

At least 19 recordsLinked to original sources
PubMed2006

A family case of fertile human 45,X,psu dic(15;Y) males.

We report on a familial case including four male probands from three generations with a 45,X,psu dic(15;Y)(p11.2;q12) karyotype. 45,X is usually associated with a female phenotype and only rarely with maleness, due to translocation of small Y chromosomal fragments to autosomes. These male patients are commonly infertile because of missing azoospermia factor regions from the Y long arm. In our familial case we found a pseudodicentric translocation chromosome, that contains almost the entire chromosomes 15 and Y. The translocation took place in an unknown male ancestor of our probands and has no apparent effect on fertility and phenotype of the carrier. FISH analysis demonstrated the deletion of the pseudoautosomal region 2 (PAR2) from the Y chromosome and the loss of the nucleolus organizing region (NOR) from chromosome 15. The formation of the psu dic(15;Y) chromosome is a reciprocal event to the formation of the satellited Y chromosome (Yqs). Statistically, the formation of 45,X,psu dic(15;Y) (p11.2;q12) is as likely as the formation of Yqs. Nevertheless, it has not been described yet. This can be explained by the dicentricity of this translocation chromosome that usually leads to mitotic instability and meiotic imbalances. A second event, a stable inactivation of one of the two centromeres is obligatory to enable the transmission of the translocation chromosome and thus a stably reduced chromosome number from father to every son in this family.

Chromosome Aberrations↗
PubMed2005

Evolutionary breakpoint analysis on Y chromosomes of higher primates provides insight into human Y evolution.

Comparative FISH mapping of PAC clones covering almost 3 Mb of the human AZFa region in Yq11.21 to metaphases of human and great apes unravels breakpoints that were involved in species-specific Y chromosome evolution. An astonishing clustering of evolutionary breakpoints was detected in the very proximal region on the long arm of the human Y chromosome in Yq11.21. These breakpoints were involved in deletions, one specific for the human and another for the orang-utan Y chromosome, in a duplicative translocation/transposition specific for bonobo and chimpanzee Y chromosomes and in a pericentric inversion specific for the gorilla Y chromosome. In addition, our comparative results allow the deduction of a model for the human Y chromosome evolution.

Animals↗
PubMed2005

The evolution of the azoospermia factor region AZFa in higher primates.

Clones of a PAC contig encompassing the human AZFa region in Yq11.21 were comparatively FISH mapped to great ape Y chromosomes. While the orthologous AZFa locus in the chimpanzee, the bonobo and the gorilla maps to the long arm of their Y chromosomes in Yq12.1-->q12.2, Yq13.1-->q13.2 and Yq11.2, respectively, it is found on the short arm of the orang-utan subspecies of Borneo and Sumatra, in Yp12.3 and Yp13.2, respectively. Regarding the order of PAC clones and genes within the AZFa region, no differences could be detected between apes and man, indicating a strong evolutionary stability of this non-recombining region.

Animals↗
PubMed2003

Association of parental history of stroke with clinical parameters in patients with ischemic stroke or transient ischemic attack.

BACKGROUND AND PURPOSE: Data regarding hereditary influences on stroke remain controversial. We investigated possible associations of a family history of stroke with clinical parameters in a large cohort of well-documented patients with ischemic cerebrovascular events, with special reference to sex-specific differences. METHODS: We analyzed the association between a maternal and/or paternal history of stroke and clinical parameters in 1564 patients with known maternal and paternal history of stroke and suffering from ischemic stroke or transient ischemic attack within the Vienna Stroke Registry. RESULTS: Patients with a maternal history of stroke were significantly more often female (54%) than those without (44%; P=0.003). Hypertension was more prevalent in female patients with than in those without a maternal history of stroke (87% versus 74%; P=0.001). These associations remained significant after multivariate adjustment (adjusted odds ratio, 1.9; 95% CI, 1.1 to 3.5; P=0.024). Of those female patients with an echocardiogram (n=225), those with a maternal history of stroke more often had left ventricular hypertrophy (48%) than those without (20%) (adjusted odds ratio, 3.6; 95% CI, 1.5 to 8.2; P=0.003). In contrast, hypertension was equally prevalent in male patients with or without a maternal history of stroke (75% versus 74%; P=0.754). We found no significant associations of clinical parameters with a paternal history of stroke. CONCLUSIONS: Our results indicate a sex-specific relationship between a maternal history of stroke and the prevalence of hypertension and left ventricular hypertrophy in female patients with ischemic cerebrovascular events.

Aged↗
PubMed2003

Chromosome painting shows that the proboscis monkey (Nasalis larvatus) has a derived karyotype and is phylogenetically nested within Asian Colobines.

The exceptional diploid number (2n=48) of the proboscis monkey (Nasalis larvatus) has played a pivotal role in phylogenies that view the proboscis monkey as the most primitive colobine, and a long-isolated genus of the group. In this report we used molecular cytogenetic methods to map the chromosomal homology of the proboscis monkey in order to test these hypotheses. Our results reveal that the N. larvatus karyotype is derived and is not primitive in respect to other colobines (2n=44) and most other Old World monkeys. The diploid number of 2n=48 can be best explained by derived fissions of a segment of human chromosomes 14 and 6. The fragmentation and association of human chromosomes 1 and 19 as seen in other Asian colobines, but not in African colobines, is best explained as a derived reciprocal translocation linking all Asian colobines. The alternating hybridization pattern between four segments homologous to human chromosomes 1 and 19 on N. larvatus chromosome 6 is the result of the reciprocal translocation followed by a pericentric inversion. N. larvatus shares this pericentric inversion with Trachypithecus, but not with Pygathrix. This inversion apparently links Nasalis and Trachypithecus after the divergence of Pygathrix. The karyological data support the view that Asian colobines, including N. larvatus, are monophyletic. They share many linking karyological features separating them from the African colobines. The hybridization pattern also suggests that Nasalis is nested within Asian Colobines and shares a period of common descent with other Asian colobines after the divergence of Pygathrix.

Animals↗
PubMed2003

Impregnation of softwood cell walls with melamine-formaldehyde resin.

Melamine-formaldehyde (MF) resin impregnation has shown considerable potential to improve a number of wood properties, such as surface hardness and weathering resistance. In this study, selected factors influencing the uptake of MF resin into the cell wall of softwood were studied. Using UV-microspectroscopy, it could be shown that water soluble MF diffused well into the secondary cell wall and the middle lamella. Concentrations as high as 24% (v/v) were achieved after an impregnation of 20 h. High cell wall moisture content, high water content of the resin used for impregnation, and low extractive content are factors which are favourable for MF resin uptake into the cell wall. For dry cell walls, solvent exchange drying improved resin uptake to a similar extent, as was the case when cell walls were soaked in water.

Construction Materials↗
PubMed2003

Structural background of cyclodextrin-protein interactions.

Cyclodextrins are cyclic oligosaccharides with the shape of a hollow truncated cone. Their exterior is hydrophilic and their cavity is hydrophobic, which gives cyclodextrins the ability to accommodate hydrophobic molecules/moieties in the cavity. This special molecular arrangement accounts for the variety of beneficial effects cyclodextrins have on proteins, which is widely used in pharmacological applications. We have studied the interaction between beta-cyclodextrin and four non-carbohydrate-binding model proteins: ubiquitin, chymotrypsin inhibitor 2 (CI2), S6 and insulin SerB9Asp by NMR spectroscopy at varying structural detail. We demonstrate that the interaction of beta-cyclodextrin and our model proteins takes place at specific sites on the protein surface, and that solvent accessibility of those sites is a necessary but not compelling condition for the occurrence of an interaction. If this behaviour can be generalized, it might explain the wide range of different effects of cyclodextrins on different proteins: aggregation suppression (if residues responsible for aggregation are highly solvent accessible), protection against degradation (if point of attack of a protease is sterically 'masked' by cyclodextrin), alteration of function (if residues involved in function are 'masked' by cyclodextrin). The exact effect of cyclodextrins on a given protein will always be related to the particular structure of this protein.

Cyclodextrins↗
PubMed2003

Cytogenetic mapping and orientation of the rhesus macaque MHC.

Applying fluorescence in situ hybridisation (FISH), six cosmid clones of rhesus macaque origin containing the genes SACM2L, RING1, BAT1 and MIC2, MIC3, MICD, and MOG of the major histocompatibility complex (MHC) were localised to the long arm of the rhesus macaque chromosome 6 in 6q24, the orthologous region to human 6p21.3. Furthermore, centromere to telomere orientation of the rhesus macaque MHC as well as the internal order of the MHC genes tested are the same as in human. Fiber-FISH allows a rough estimate of distances between these MHC genes in the rhesus macaque, and, as in the human, the rhesus macaque MHC comprises about 3 to 4 Mb.

Animals↗
PubMed2002

Temporal variation of microfibril angle in Eucalyptus nitens grown in different irrigation regimes.

In 1990, a 2-ha plantation of Eucalyptus nitens (Deane and Maiden) Maiden was established in southeastern Tasmania and subjected to different irrigation regimes. Point dendrometers were installed in March 1995 to monitor radial stem movement every 15 min over several growing seasons. In this study, data from two growing seasons (1996-1998) were considered. From these measurements, daily increments of stem radius were determined. At the end of the second growing season, we extracted 12-mm cores and measured microfibril angles (MFA) of the wood at high resolution. Microfibril angles were rescaled on a time axis and mapped to daily and distance-based elements. Among treatments, irrigated trees in particular formed higher MFA early in the growing season (September-November) and lower MFA later in the growing season. Trees subjected to cyclic droughts showed clear relationships between MFA and soil water deficits, with MFA increasing in response to water stress release. Increases in MFA were preceded by accelerations in daily increment of stem radius. Among treatments, trees subjected to severe drought had the smallest MFA and generally low fluctuations in MFA. Irrigated trees were susceptible to changes in climate, whereas growth of the trees in the other treatments was limited by water availability. Use of path-analysis showed that temperature had an effect on stem radius increment but not on MFA; wind speed was the only factor that influenced MFA directly. Microfibril angle was correlated with stem shrinking and expansion phases; growth period length and growth rates were positively related to MFA.

Eucalyptus↗
PubMed2002

Comparative mapping of CDY and DAZ in higher primates.

The human male specific expressed gene families CDY and DAZ are known to be repetitively clustered in the Y-specific region of the human Y chromosome. Comparative FISH-mapping of DNA clones specific for CDY and DAZ resulted in a Y-specific but diverse signal pattern within the non-recombining region of the Y-chromosomes of human and great apes. It can be concluded that the non-recombining part of the Y-chromosomes including CDY and DAZ, was exposed to species-specific amplifications, diversifications and rearrangements. Evolutionary fast fixation of any of these variations was possible as long as they did not interfere with male fertility.

Animals↗
PubMed2002

The Azoospermia region AZFa: an evolutionar y view.

Compared to other regions on the human Y chromosome, the genomic segment encompassing the functionally defined AZFa locus has undergone higher X-Y sequence divergence, which is detectable by fluorescence in-situ hybridisation. This allows an evolutionary definition of an interval enclosing AZFa with a size of about 1.1 Mb. The region includes the genes USP9Y, DBY and UTY and is limited by evolutionary breakpoints within the PAC clones 41L06 and 46M11. These breakpoints restrict an area of possible male specific evolution that may have resulted in the acquisition of male specific functions, including a role in spermatogenesis.

Cells, Cultured↗
PubMed2001

Chemical investigations of aquifers affected by pyrite oxidation in the Bitterfeld lignite district.

In a large area around the former open-pit lignite mines near Bitterfeld, Germany, groundwater taken from wells was analyzed for the major cations, anions, and trace elements. Quaternary and Tertiary sediments were collected from aquifers exposed on the sides of the pits and from boreholes outside the mines and analyzed for major and trace elements, as well as for carbonate, pyritic sulfur and total organic carbon. The pH and electrical conductivity of the sediments in suspension were measured. Significant differences were determined between the Tertiary sediments of the aquifers that were exposed to atmospheric oxygen during the lowering of the groundwater table and those outside the cone of depression. The greatest differences were found in the pyrite content, the pH values, and the electrical conductivity. In order to map the degree to which the mining of the lignite has affected the quality of the groundwater in the study area, the water samples were divided into six classes on the basis of their sulfate content. The neutralization potential was calculated to estimate the potential for acidification. Prediction of future groundwater quality is based on both (i) the present composition of the groundwater, surface water, and Quaternary and Tertiary aquifer sediments and (ii) the present and future groundwater flow directions. These studies have shown which parameters are important for future groundwater monitoring.

Coal Mining↗
PubMed1999

NMR structure and metal interactions of the CopZ copper chaperone.

A recently discovered family of proteins that function as copper chaperones route copper to proteins that either require it for their function or are involved in its transport. In Enterococcus hirae the copper chaperone function is performed by the 8-kDa protein CopZ. This paper describes the NMR structure of apo-CopZ, obtained using uniformly (15)N-labeled CopZ overexpressed in Escherichia coli and NMR studies of the impact of Cu(I) binding on the CopZ structure. The protein has a betaalphabetabetaalphabeta fold, where the four beta-strands form an antiparallel twisted beta-sheet, and the two helices are located on the same side of the beta-sheet. A sequence motif GMXCXXC in the loop between the first beta-strand and the first alpha-helix contains the primary ligands, which bind copper(I). Binding of copper(I) caused major structural changes in this molecular region, as manifested by the fact that most NMR signals of the loop and the N-terminal part of the first helix were broadened beyond detection. This effect was strictly localized, because the remainder of the apo-CopZ structure was maintained after addition of Cu(I). NMR relaxation data showed a decreased correlation time of overall molecular tumbling for Cu(I)-CopZ when compared with apo-CopZ, indicating aggregation of Cu(I)-CopZ. The structure of CopZ is the first three-dimensional structure of a cupro-protein for which the metal ion is an exchangeable substrate rather than an integral part of the structure. Implications of the present structural work for the in vivo function of CopZ are discussed, whereby it is of special interest that the distribution of charged residues on the CopZ surface is highly uneven and suggests preferred recognition sites for other proteins that might be involved in copper transfer.

Amino Acid Sequence↗
PubMed1997

Internal rotation of mutually interacting methyl groups: A 13C NMR study

The overall and intramolecular rotational diffusion behavior of 1,3, 7,10-tetramethylbenzo[c]cinnoline was determined from longitudinal 13C NMR relaxation and 1H-13C NOE measurements in dilute chloroform solution. The four methyl groups in this compound represent three different situations of sterical hindrance. One pair of methyl groups is in close mutual sterical contact, forming the ends of an open six-membered ring. Assuming completely anisotropic overall molecular tumbling combined with a 120 degrees jump model for the internal methyl rotations the jump rates of methyl groups were evaluated and compared to earlier results on different sterically hindered compounds, in particular with respect to a potential cogwheel-like intermethyl interaction. To characterize intermethyl interactions in different sterical situations, a new gauge-the "methyl interaction volume"-is introduced. Implications for correlated rotational diffusion of methyl groups are discussed. Copyright 1997 Academic Press. Copyright 1997Academic Press

Journal Article↗
PubMed1997

BBReader: a computer program for the combined use of the BioMagResBank and PDB databases.

A computer program ('BBReader') was developed which performs an inverse search in the BioMagResBank database. Given (cross) peak positions of a protein, the program searches for atoms with matching chemical shifts and suggests possible assignments for user-specified homo- and heteronuclear one- to three-dimensional COSY- and NOESY-type experiments. It can handle 1H, 13C and 15N spectra. Distance information from PDB files can be utilized for filtering possible NOESY cross peak assignments.

Databases, Factual↗
PubMed1991

Gallium-67 scans as an adjunct to computed tomography scans for the assessment of a residual mediastinal mass in pediatric patients with Hodgkin's disease. A Pediatric Oncology Group study.

This study determines the utility of gallium-67 (Ga-67) scintigraphs as an adjunct to computed tomography (CT) scans for the assessment of residual mediastinal masses in children and adolescents with advanced-stage Hodgkin's disease. At diagnosis 42 patients with CT scan-documented mediastinal disease had a Ga-67 scan performed. Thirty-four of 42 patients (81%) had gallium-avid mediastinal lesions, whereas in eight (19%), the Ga-67 scan was negative. At the completion of eight cycles of therapy of Mustargen (mechlorethamine), Oncovin (vincristine), procarbazine, prednisone (MOPP) alternating with doxorubicin, bleomycin, vinblastine, dacarbazine (ABVD), 21 of 34 patients with initially positive Ga-67 scans had them repeated; 18 of 21 converted to negative results, and three remained positive. In 11 of 18 patients, the loss of gallium avidity was consistent with a negative mediastinal CT scan. In seven, although the gallium scan was negative, the CT scan remained positive; all seven patients had a mediastinal biopsy of suspected residual disease and in all seven the biopsy results were negative for Hodgkin's disease. These preliminary results in a small cohort of patients demonstrate that Ga-67 scans may be of benefit in evaluating residual mediastinal masses in patients with Hodgkin's disease.

Adolescent↗
PubMed1991

A pilot study of intermediate-dose methotrexate and cytosine arabinoside, "spread-out" or "up-front," in continuation therapy for childhood non-T, non-B acute lymphoblastic leukemia. A Pediatric Oncology Group study.

One hundred six children with newly diagnosed non-T-, non-B-cell acute lymphoblastic leukemia (ALL) were treated in a Pediatric Oncology Group (POG) pilot study in which six courses of intermediate-dose methotrexate (MTX) and cytosine arabinoside (Ara-C) (1 g/m2 each) were added to a "backbone" of standard continuation therapy. The dose and sequence of MTX/Ara-C administration were based on a preclinical model that demonstrated synergism between MTX and Ara-C. Poor-risk patients (n = 49) were assigned to "up-front" therapy, in which the MTX/Ara-C courses were administered during the initial 15 weeks of remission. Standard-risk patients (n = 57) were assigned to "spread-out" therapy, in which the MTX/Ara-C courses were interspersed at 12-week intervals within continuation treatment. Toxicity after intermediate-dose MTX/Ara-C, principally neutropenia and fever, was judged significant but manageable. Unexpectedly, the incidence of fever and neutropenia less than 500/mm3 was greater after "spread-out" therapy (38%) than after "up-front" therapy (6%). At 4 years, the Kaplan-Meier estimate of event-free survival (EFS) is 71% (+/- 7%) for standard-risk patients and 53% (+/- 8%) for poor-risk patients. The results of this pilot study support the use of intermediate-dose MTX/Ara-C in additional studies.

Adolescent↗