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J Schultz

Publications and source records attributed to J Schultz.

At least 91 records · Page 5Linked to original sources
PubMed1994

A mechanochemical study of MgDNA fibers in ethanol-water solutions.

Highly oriented calf-thymus MgDNA fibers, prepared by a wet spinning method, were studied with a simple mechanochemical set-up. The relative fiber length, L/Lo, was measured with the fibers submerged in ethanol-water solutions. In one type of experiment L/Lo was measured as a function of ethanol concentration at room temperature. No substantial decrease in L/Lo with increasing ethanol concentration was observed, indicating that MgDNA fibers stay in the B form even when the water activity is very low. For low ethanol concentrations the fiber structure is stable and does not dissolve even at very high water activities. In a second type of experiment, the heat-induced helix-coil transition was manifested by a marked contraction of the fibers. The transition temperature decreases linearly with increasing ethanol concentration between 52 and 68% ethanol. At higher ethanol concentrations the helix-coil transition temperature increases due to strong aggregation within the DNA fibers, and above 77% ethanol the fibers do not contract at all, not even at the upper temperature limit of the experiments, approximately 80 degrees C. This behavior is discussed with reference to dried DNA and the P form of DNA. The helix-coil transition temperature of the MgDNA fibers in 70% ethanol does not show any dependence on the MgCl2 concentration. It is shown that the Poisson-Boltzmann cylindrical cell model can account qualitatively for this lack of salt dependence.

Animals↗
PubMed1994

The yeast pheromone response pathway: new insights into signal transmission.

The yeast (Saccharomyces cerevisiae) pheromone response pathway is one of the best understood eukaryotic signal transduction pathways. Nonetheless, it is likely that components and regulators of the pathway remain to be identified. We have employed three approaches to learn about interactions among known pathway components and to identify new components. First, the two-hybrid system of Fields and Song revealed that STE5, a protein of unknown biochemical function, interacts with each member of the MAP kinase cascade. One interpretation of this finding is that STE5 facilitates interactions between members of the cascade and thereby makes signal transmission more efficient. Second, genetic studies have identified new gene functions that appear to be involved in pheromone response. One of these is homologous to RHO-GAP proteins, an observation that suggests that a RHO protein (members of the RAS super-family) is part of the response pathway. A second gene function, FAR3, appears to be required only for a specific facet of pheromone response, arrest of the mitotic cell division cycle in G1.

Adaptor Proteins, Signal Transducing↗
PubMed1993

Efficient enzymatic synthesis of the sialyl-Lewisx tetrasaccharide. A ligand for selectin-type adhesion molecules.

Sialyl-Lewisx (NeuAc alpha 2-->3Gal beta 1-->4[Fuc alpha 1-->3]GlcNAc] has been identified as a ligand for E-selectin, P-selectin and recently also for L-selectin. We have synthesized the sialyl-Lewisx tetrasaccharide by total enzymatic synthesis from N-acetyllactosamine using a placental alpha 2-->3-sialyltransferase specific for type-2 chain acceptors, followed by a cloned human alpha 1-->3-fucosyltransferase (FucTV, the 'plasma-type' enzyme). This procedure resulted in the tetrasaccharide in a 61% overall yield.

Amino Sugars↗
PubMed1993

Localized interaction of the polyamine methylspermidine with double-helical DNA as monitored by 1H NMR self-diffusion measurements.

The 1H NMR pulsed field gradient self-diffusion method has been used to measure the diffusion coefficient of the polyamine analogue methylspermidine (completely N-methylated spermidine) in DNA solution, as a function of the concentration ratio of methylspermidine to DNA phosphate. Three different DNA's have been investigated: d(GC)4 (8 base pairs), core length calf thymus DNA (approximately 120 base pairs), and sonicated high molecular weight calf thymus DNA (average 7500 base pairs). For a constant ratio of methylspermidine to DNA phosphate, the diffusion coefficient decreases with increasing DNA length. Moreover, at low concentration ratios the diffusion coefficient of methylspermidine approaches a limiting value that is close to that of the DNA molecule. The experimental data are well reproduced by a two-state diffusion model. In this model the diffusion coefficient of the polyamine is a population-weighted average of polyamine associated with DNA (with a diffusion coefficient given by that of the DNA molecule) and polyamine free in solution.

Animals↗
PubMed1993

Association cortex, cerebellum, and serum concentrations of C1q and factor B in Alzheimer's disease.

Concentrations of C1q, the first subcomponent of the classical complement pathway, were assayed by Western blot analysis of sera and brain homogenates from Alzheimer's disease (AD) and nondemented (ND) control patients. Immunoreactive serum C1q concentrations did not differ in the two groups, whereas AD superior frontal gyrus exhibited nearly 4-fold more immunoreactive C1q than ND superior frontal gyrus. Cerebellar C1q concentrations were significantly lower than those in superior frontal gyrus, and ND cerebellar C1q was lowest of all. Parallel immunohistochemical experiments showed a linkage between the extent of beta-amyloid immunoreactivity or AD pathology in a structure and the extent of C1q immunoreactivity. These data support and extend the hypothesis that complement mediated processes are related to beta-amyloid deposition and may be involved in the pathogenesis of AD.

Adult↗
PubMed1993

[Coronary artery fistula--surgical or percutaneous embolization treatment?].

Three children aged 4 months, 2.7 and 7 years with the unusual fistula of the left coronary artery to the right atrium were observed over a 2-year period. The two younger children underwent emergency surgery although they showed no clinical symptoms. The reasons for surgical intervention were an aneurysm in the right atrium with obstruction of the vena cava superior and a considerably enlarged fistula, respectively. In the older child, we percutaneously embolized a terminate fistula of the ramus circumflexus with two platinum microcoils without complications. Two-dimensional-echocardiography and color flow mapping were used to confirm the diagnosis. After such diagnosis we recommend a coronary angiography in every case. The transcatheter-coil-embolization is an alternative method to surgical closure in selected cases. We recommend an early onset intervention in case of congenital coronary artery fistula.

Aortography↗
PubMed1992

Complement activation by beta-amyloid in Alzheimer disease.

Alzheimer disease (AD) is characterized by excessive deposition of the beta-amyloid peptide (beta-AP) in the central nervous system. Although several lines of evidence suggest that beta-AP is neurotoxic, a mechanism for beta-AP toxicity in AD brain remains unclear. In this paper we provide both direct in vitro evidence that beta-AP can bind and activate the classical complement cytolytic pathway in the absence of antibody and indirect in situ evidence that such actions occur in the AD brain in association with areas of AD pathology.

Alzheimer Disease↗