Biomedical subjects

C Holz

Publications and source records attributed to C Holz.

6 recordsLinked to original sources

PubMed2006

Local and systemic hemorheological effects of cerebral hyper- and hypoperfusion in a porcine model.

Using a well defined pig model, we investigated whether cerebral hypertension and hypotension influence hemorheological factors. After surgical preparation and stabilization, periods of hyperventilation, controlled periods of cerebral perfusion pressure increases and decreases were utilized. After each period, blood samples were collected from the cannulated femoral artery and vein, and from the superior sagittal sinus. Erythrocyte deformability, whole blood and plasma viscosity and hematological parameters were determined. Erythrocyte deformability significantly worsened in arterial samples after hypertension and hypotension, and in sinus samples it was impaired after hypotension period. Hematocrit significantly increased in arterial and sinus samples during hypertensive period, accompanied by similar alterations in whole blood viscosity. We conclude that hemodynamic changes caused by hyperventilation, hyper- or hypotension can influence hemorheological factors, and suggest that the rheological alterations can affect local hemodynamic and metabolic conditions.

Analysis of Variance↗

PubMed2005

Full-genome RNAi profiling of early embryogenesis in Caenorhabditis elegans.

A key challenge of functional genomics today is to generate well-annotated data sets that can be interpreted across different platforms and technologies. Large-scale functional genomics data often fail to connect to standard experimental approaches of gene characterization in individual laboratories. Furthermore, a lack of universal annotation standards for phenotypic data sets makes it difficult to compare different screening approaches. Here we address this problem in a screen designed to identify all genes required for the first two rounds of cell division in the Caenorhabditis elegans embryo. We used RNA-mediated interference to target 98% of all genes predicted in the C. elegans genome in combination with differential interference contrast time-lapse microscopy. Through systematic annotation of the resulting movies, we developed a phenotypic profiling system, which shows high correlation with cellular processes and biochemical pathways, thus enabling us to predict new functions for previously uncharacterized genes.

Animals↗

PubMed2001

A human cDNA expression library in yeast enriched for open reading frames.

We developed a high-throughput technique for the generation of cDNA libraries in the yeast Saccharomyces cerevisiae which enables the selection of cloned cDNA inserts containing open reading frames (ORFs). For direct screening of random-primed cDNA libraries, we have constructed a yeast shuttle/expression vector, the so-called ORF vector pYEXTSH3, which allows the enriched growth of protein expression clones. The selection system is based on the HIS3 marker gene fused to the C terminus of the cDNA insert. The cDNAs cloned in-frame result in histidine prototrophic yeast cells growing on minimal medium, whereas clones bearing the vector without insert or out-of-frame inserts should not grow on this medium. A randomly primed cDNA library from human fetal brain tissue was cloned in this novel vector, and using robot technology the selected clones were arrayed in microtiter plates and were analyzed by sequencing and for protein expression. In the constructed cDNA expression library, about 60% of clones bear an insert in the correct reading frame. In comparison to unselected libraries it was possible to increase the clones with inserts in the correct reading frame more than fourfold, from 14% to 60%. With the expression system described here, we could avoid time-consuming and costly techniques for identification of clones expressing protein by using antibody screening on high-density filters and subsequently rearraying the selected clones in a new "daughter" library. The advantage of this ORF vector is that, in a one-step screening procedure, it allows the generation of expression libraries enriched for clones with correct reading frames as sources of recombinant proteins.

Antibodies, Monoclonal↗

PubMed2000

A system for dual protein expression in Pichia pastoris and Escherichia coli.

We have constructed a novel Pichia pastoris/Escherichia coli dual expression vector for the production of recombinant proteins in both host systems. In this vector, an E. coli T7 promoter region, including the ribosome binding site from the phage T7 major capsid protein for efficient translation is placed downstream from the yeast alcohol oxidase promoter (AOX). For detection and purification of the target protein, the vector contains an amino-terminal oligohistidine domain (His6) followed by the hemaglutinine epitope (HA) adjacent to the cloning sites. A P. pastoris autonomous replicating sequence (PARS) was integrated enabling simple propagation and recovery of plasmids from yeast and bacteria (1). In the present study, the expression of human proteins in P. pastoris and E. coli was compared using this single expression vector. For this purpose we have subcloned a cDNA expression library deriving from human fetal brain (2) into our dual expression T7 vector and investigated 96 randomly picked clones. After sequencing, 29 clones in the correct reading frame have been identified, their plasmids isolated and shuttled from yeast to bacteria. All proteins were expressed soluble in P. pastoris, whereas in E. coli only 31% could be purified under native conditions. Our data indicates that this dual expression vector allows the economic expression and purification of proteins in different hosts without subcloning.

Brain Chemistry↗

PubMed2000

Endoscopic third ventriculostomy is the treatment of choice for obstructive hydrocephalus due to pediatric pineal tumors.

Pineal lesions in the pediatric patient are often complicated by the development of hydrocephalus due to obstruction of the aqueduct or the third ventricle by tumor masses. In such cases, hydrocephalus treatment has the highest priority and should be performed prior to any surgical treatment of the pineal tumor itself. The golden standard in obstructive hydrocephalus treatment remains placement of a temporary or permanent cerebrospinal fluid shunt, although there are many long-term complications associated with a shunt system. To avoid these and to render the patients independent from a failure-prone shunt system, we employed endoscopic third ventriculostomy for permanent relief of elevated intracranial pressure prior to surgical removal of the pineal lesions. The present study summarizes the results of this approach in 7 pediatric patients with obstructive hydrocephalus. No complications of the endoscopic procedure were encountered, and the ventriculostomy remained patent in all cases, as confirmed by motion sensitive MRI. The advantages of endoscopic third ventriculostomy as compared with other techniques are discussed, and its increasing role in the management of children with space occupying lesions of the pineal region is defined.

Adolescent↗

PubMed1980

[Therapeutical treatment of primiparae to reduce anxieties in connection with pregnancy and delivery (author's transl)].

Two groups of primiparae were subjected to two different forms of basically behavior therapeutic treatments which aimed to reduce birth anxiety. In comparison with an untreated control-group a significant reduction of birth anxieties was found. There was no significant effect between the treatment-groups. Therapeutical success did not depend on anxiety-level before therapy. In relation to behavior during delivery a higher degree of relaxation was only found in the second experimental group.

Anxiety↗