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Biomedical subjects

G Neuhaus

Publications and source records attributed to G Neuhaus.

At least 37 records · Page 2Linked to original sources
PubMed1994

Cyclic GMP and calcium mediate phytochrome phototransduction.

We have previously used single-cell assays in a phytochrome-deficient tomato mutant to demonstrate that phytochrome signaling involves heterotrimeric G proteins, calcium, and calmodulin. While G protein activation could stimulate full chloroplast development and anthocyanin pigment biosynthesis, calcium and calmodulin could not induce anthocyanins and were only able to stimulate the development of immature chloroplasts lacking cytochrome b6f and photosystem I core components. We now report that cyclic GMP is able to trigger the production of anthocyanins, and that a combination of cyclic GMP with calcium can induce the development of fully mature chloroplasts containing all the photosynthetic machinery. Furthermore, using reporter genes for these different pathways (cab-gus, chs-gus, and fnr-gus) we demonstrate that cGMP and calcium act primarily by modulating gene expression.

Anthocyanins↗
PubMed1994

Microinjection technique: routine system for characterization of microcapillaries by bubble pressure measurement.

Five tubing types with different outer and inner diameter dimensions were used to pull injection capillaries with different openings. The correlation between threshold bubble pressure and tip inner and outer diameter was established for each type of tubing. Statistical analysis revealed that the bubble pressure is an accurate measure for the tip inner diameter independent of the tubing used to pull the capillary. A graph directly relating the tip inner diameter to the threshold bubble pressure is presented. The tip outer diameter could not be related to the bubble pressure for tubings of different size. This diameter depends on the wall thickness of the tubing and the puller configuration. Data on the inner tip diameter were used to test the relationship between volume released from injection capillaries and their tip radius. It was found that the volume increases with the fourth power of the radius. Strategies for optimizing the injection capillary are discussed.

Capillary Action↗
PubMed1994

An approach towards genetically engineered cell fate mapping in maize using the Lc gene as a visible marker: transactivation capacity of Lc vectors in differentiated maize cells and microinjection of Lc vectors into somatic embryos and shoot apical meristems.

To establish a system for genetically engineered cell fate mapping, different vectors carrying the Lc gene, a member of the R gene family, were delivered into embryonic and meristematic cells of maize by the microinjection technique. Vectors in which the Lc cDNA is driven either by a constitutive promoter (CaMV 35S), with or without the Adh1 intron 1 of maize, or a tissue-specific promoter (phosphoenolpyruvate carboxylase, PEPC) as well as self-replicating wheat dwarf virus (WDV) vectors carrying a Lc-expression-cassette, have been tested. The ability of these vectors to transactivate was evaluated in mesophyll-derived protoplasts of the maize genotype appropriate for these microinjection experiments. The expression product of the introduced Lc gene can substitute for mutated R and B loci, resulting in anthocyanin production. Analogous results were obtained by microinjection into organized tissues, where transactivation of anthocyanin biosynthesis resulted in pigmented sectors in somatic embryos (B79) and in the leaves of plants regenerated from the cultivated shoot apical meristems (K55, r-g, b). The tissue-specific appearance of pigmented sectors in leaves, using the mesophyll-specific PEPC promoter suggests the possibility of using this approach for layer-specific cell fate studies. The presence of the introduced plasmids in leaves showing red sectors 20-30 days after injection was proven by PCR analysis.

Base Sequence↗
PubMed1993

Calcium/calmodulin-dependent and -independent phytochrome signal transduction pathways.

Phytochrome is a well-characterized plant photoreceptor, able to modulate many morphological, physiological, and biochemical events through as yet undefined mechanisms. By developing single-cell assays to visualize phytochrome responses, we have studied the effects of microinjecting putative signaling intermediates into phytochrome-deficient tomato cells. We demonstrate that phytochrome phototransduction initially involves the activation of one or more G proteins that are coupled to at least two different pathways; one pathway requires calcium and activated calmodulin and can stimulate expression of a photoregulated cab-GUS reporter gene together with the synthesis and assembly of some, but not all, of the photosynthetic complexes. The other pathway, controlling anthocyanin biosynthesis, does not require calcium. Furthermore, our results reveal that phytochrome signaling is cell autonomous and is not likely to require any light-activated steps downstream of the G protein.

ATP Synthetase Complexes↗
PubMed1991

An improved approach for transformation of plant cells by microinjection: molecular and genetic analysis.

A new culture method for the injection of tobacco mesophyll protoplasts has been established. The protoplasts are embedded in a thin layer of alginate and are nourished from the medium in the underlying basis layer. In the alginate layer the protoplasts regenerate to calli at a frequency of up to 80%. Embedded protoplasts can be selected either with 50 mg l-1 kanamycin or 5 mg l-1 paromomycin. Single resistant cells can be recovered from about 10,000 sensitive cells in one alginate layer. Injection of the neo gene (coding for neomycin phosphotransferase II) into protoplast derived single cells in the alginate layer results in kanamycin resistant colonies that can be regenerated to mature plants. These plants express the neomycin phosphotransferase as shown by enzyme activity assay. The integration of the transgene into the plant genome could be proved by Southern hybridization to high molecular weight DNA. With this culture method 100 cells can be injected per hour. Transformation frequencies range from 2 to 20%. In crossing experiments, it was shown that the foreign gene is transmitted to the next generation in a Mendelian fashion.

Base Sequence↗
PubMed1991

Micro-targeting: high efficiency gene transfer using a novel approach for the acceleration of micro-projectiles.

We have constructed a novel micro-projectile accelerating system for efficient gene transfer into cells in situ that avoids binding DNA to micro-projectiles and keeps the DNA in solution. Further, instead of a macro-projectile (or the equivalent), it accelerates the particles in a Bernoulli air stream. The micro-targeting approach directs highly dispersed particles to sites with diameters as little as 0.15 mm, allowing precise aiming to restricted tissues. The system is physically flexible and should therefore be adaptable to different tissues and species. Transient expression of the Escherichia coli beta-glucuronidase gene in immature wheat embryo scutella was obtained at a frequency of up to 3% of the treated cells in the surface layer. In tobacco SR1, we achieved many transgenic plants, and the efficiency of stable transformation with the neomycin phosphotransferase (NPTII) gene was approximately 10(-3) per exposed cell.

Cloning, Molecular↗
PubMed1989

[Nephrotoxicity and myelotoxicity of antineoplastic Pt(II) and Pt(IV) coordination compounds in rats].

In comparison with cis-DDP four new platinum (II) and platinum (IV) complexes were evaluated for their acute nephrotoxic and myelotoxic potency in male rats following i.v. administration of maximum tolerated doses on 5 consecutive days. Parameters for nephrotoxicity determined on day 6, 13 and 22 after the first administration of the drugs included blood, urea nitrogen, serum creatinine, urine volume, urinary glucose and tubule cell excretion. Parameters for myelotoxicity determined on the same days included leucocytes, platelets, hemoglobin and hematocrit. Cis-DDP was found to be the most nephrotoxic compound. The myelotoxicity of the new platinum complexes appeared to be similar to that of cis-DDP with exception of trans-ODDP.

Animals↗
PubMed1988

Transmission and scanning electron microscopy investigations on the structure of the ultrafilter of glomeruli in human acute renal failure.

In 4 cases of human acute renal failure (ARF) with oligo-anuria, normuria and polyuria the following findings were made. (1) The diameter of endothelial cell fenestrae is on average larger than that of the control values, but not significantly. (2) In ARF the ratio of the endothelial cell fenestral area to the total endothelial area is not significantly lower than in control kidneys. (3) In ARF the average density of fenestrae per unit of area is not significantly lower than in control kidneys. (4) The structure of the podocytes does not differ from that of control kidneys.

Acute Kidney Injury↗
PubMed1987

[Right ventricular stroke volume--comparison of various methods of angiography and equilibrium radionuclide ventriculography].

In 21 patients with various heart diseases RVEF was measured angiographically and by radionuclide ventriculography. Using biplane angiocardiography evaluation was performed by 7 different methods (Simpson's rule, Dogde, Arcilla, Ferlinz, Duebel). Using equilibrium RNV, evaluation was performed by 9 modifications of analysis. Problems were evident to separate the right atrium from the ventricle and to define the site of the pulmonary valve. The results show that when using the various methods of angiography considerable variations of the absolute volumes occur, but least so with RVEF. When using RNV with one single enddiastolic ROI, the RVEF was much too low. By means of the enddiastolic/endsystolic Double-ROI-method a good agreement with angiography was found, with correlation coefficients up to r = 0.85. There was only a minor effect of background correction.

Adult↗
PubMed1986

High yield and stable transformation of the unicellular green alga Acetabularia by microinjection of SV40 DNA and pSV2neo.

SV40 DNA and pSV2neo were microinjected into isolated nuclei of Acetabularia mediterranea. The injected nuclei were implanted into anucleate cell fragments of the same species. Such combinations not only survived but also formed progeny. The F(1), F(2) and F(3) generations of these combinations were analyzed. In the case of SV40-treated cells T-antigen was expressed and accumulated in the nuclei of all three generations studied as shown by indirect immunofluorescence. Nuclear exchange experiments revealed expression of the T-antigen only if a transformed nucleus but not if only a transformed cytoplasm was involved. Transformation by pSV2neo, a chimeric gene with a selectable marker was demonstrated by the induction of G-418 resistance as well as immunofluorescence. Genomic DNA was isolated from gametes, originating in cysts from the F(1), F(2) and F(3) generations of injected cells, and subjected to Southern analysis. These experiments demonstrated that both types of DNA are integrated into the host genome.

Journal Article↗
PubMed1984

Enhancer-controlled expression of the simian virus 40 T-antigen in the green alga Acetabularia.

Nuclei from Acetabularia mediterranea were isolated, microinjected with simian virus 40 (SV40) DNA and fused with cytoplasts from the same species. Various times after fusion of the injected nuclei the fusion products were screened for expression of the T-antigen by indirect immunofluorescence. One and two days after injection a bright fluorescence could be observed in the nuclei of Acetabularia. On the basis of this immunofluorescence we conclude that in Acetabularia cells the T-antigen is expressed and accumulated in the nucleus. Moreover, evidence is presented that the Acetabularia cell recognizes the SV40 enhancer sequence. The expression product of the SV40 DNA appears significantly earlier than the expression products of other foreign genes in Acetabularia. The results suggest that the well characterized SV40 can be used as a vector system for the introduction and expression of foreign genes in Acetabularia.

Cell Nucleus↗
PubMed1983

Gene expression in Acetabularia. III. Comparison of stained cytosolic proteins and in vivo and in vitro translation products.

A comparison of stained cytosolic proteins, in vivo 80 S ribosome translation products and in vitro translation products of poly(A)+ RNA from three species of Acetabularia was performed after characterization of their molecular weights and isoelectric points via two-dimensional electrophoresis. A total of 803 stained proteins, and 121 in vivo and 77 in vitro translation products, representing the most abundant proteins in each category, were analysed. In interspecies comparisons, approximately 10% of the stained proteins were common to all three species and more than 50% were found to be species-specific. Approximately 25% of the in vivo translation products were common to all three species and more than 30% were found to be species-specific. The majority of the in vivo and in vitro translation products were detected by one or both of the other methods employed. Even though the analysis was limited to the most abundant proteins detected by each of the three methods and to one stage of development, the results suggest that the translation of some proteins is not regulated, that the in vivo translation of others, whose mRNA is present and translated in vitro, is turned off while the translation in vivo of others is enhanced relative to the total. This feature makes them candidates for stage-specific proteins. The results provide a firm basis for the extended analysis of the biological activity of heterologous messenger RNA in Acetabularia cytoplasm and for a more complete cataloguing of the mRNA population and translational activity at different stages in the development of Acetabularia.

Acetabularia↗
PubMed1980

[Extracranial arterial occlusive disease in arteriopathies with peripheral vascular disease (author's transl)].

Aortography and angiography of the aortic arch were carried out in 176 patients with peripheral arterial occlusive disease. In 63,6% there were haemodynamically relevant stenoses or occlusions of the supraaortic vessels, the carotid arteries with 39,2% and the vertebral arteries with 35,2%, being the most commonly involved. Peripheral arterial disease included haemodynamically relevant changes in the femoro-popliteal arteries in 83%, in the aorto-iliac region in 67,1% and in the calf vessels in 58,5%. There was a statistically significant correlation between the clinical severity of the cerebrovascular insufficiency and of the Frontaine stages with the angiographically demonstrable extent of the arteriosclerosis. In addition there was an increasing statistical risk of extracranial arterial occlusion if the disease affected more than one arterial level.

Aorta, Abdominal↗
PubMed1979

Management of concomitant occlusive disease of the supraaortic and lower-limb arteries.

Angiography examinations of the extracranial cerebral arteries in patients with peripheral occlusive disease of the lower limbs indicate cerebro-vascular disease more often than might be assumed from clinical-neurological examinations alone. In total, 61.5% of the patients examined showed lesions of the extracranial cerebral arteries which necessitated an operation. The elimination of risks in an operation requiring extensive peripheral vessel reconstruction necessitates initial supraaortic vessel reconstruction. Of the 48 patients with reconstructions in both vascular systems, none has suffered any postoperative neurological dysfunction. Concomitant occlusive disease of the supraaortic and peripheral arteries should not be treated simultaneously.

Aortography↗
PubMed1979

[Operative treatment of deep vein thrombosis (author's transl)].

From 1973 to 1977 a total of 63 patients with thrombosis of the deep veins in leg and pelvis and in the V. cava inferior was treated by operative thrombectomy. Prior to the operation all patients were submitted to phlebography. The mean age of all was 52 years. One patient died from pulmonary embolism during thrombectomy, there was no further hospital mortality. Because of low mortality incidence and rarely postthrombotic complications we prefer the operative treatment of deep vein thrombosis. The preoperative cavography helps to avoid pulmonary embolism during thrombectomy.

Adolescent↗