Biomedical subjects

J Quandt

Publications and source records attributed to J Quandt.

At least 19 recordsLinked to original sources

PubMed2000

The ability of pea transformation technology to transfer genes into peas adapted to western Canadian growing conditions.

Transgenic pea plants can be produced by Agrobacterium-mediated transformation of thin slices from developing embryo axes. To determine if the method is effective for different pea genotypes, seven pea breeding lines adapted to western Canadian growing conditions were tested, using three different Agrobacterium tumefaciens transformation vectors. All vectors contained the gus (uidA) gene coding for the beta-glucuronidase (GUS) protein, but with different chemical selection genes. In total, 323 transgenic plants were recovered from 39 independent transformation events. Transgenic plants were recovered from each genotype and each selection system, but not from all combinations. GUS-positive explants were obtained from seeds harvested between 24 and 31 days after flowering. The mean time from Agrobacterium treatment to planting into soil averaged 186 days. Based on the initial number of seeds used, the transformation frequency was 0.6% (i.e. six independent transgenic events per 1000 axes sliced). The inserted genes were functional and inherited in a Mendelian fashion. Although more plants were recovered by selection on chlorsulfuron, GUS activity was generally greater in plants selected on kanamycin. GUS activity in the leaves of the original plants varied, but GUS activity in the second generation was correlated with that of the original transformants.

Journal Article↗

PubMed1997

Functional and regulatory analysis of the two copies of the fixNOQP operon of Rhizobium leguminosarum strain VF39.

DNA corresponding to two copies of the Rhizobium leguminosarum bv. viciae strain VF39 fixNOQP operon coding for a putative symbiotic terminal oxidase of the heme-copper oxidase superfamily was cloned, sequenced, and genetically analyzed. The first copy is located upstream of the fixK-fixL region on plasmid pRleVF39c, whereas the second copy resides on the nodulation plasmid pRleVF39d. Insertional mutagenesis with antibiotic resistance cassettes confirmed that both copies were functional, and that the presence of at least one functional copy was required for nitrogen fixation. The deduced amino acid sequences of both fixN genes are highly similar (95% identity) and contain 15 putative transmembrane helices, suggesting that the fixN gene products are integral membrane proteins. Furthermore, six histidine residues predicted to be the ligands for a heme-copper binuclear center and a low-spin heme b are conserved in both R. leguminosarum fixN proteins. The deduced fixO and fixP gene products show characteristics of membrane-bound monoheme and diheme cytochrome c, respectively. Upstream of both fixN copies putative Fnr-consensus binding sites (anaeroboxes) were found that differ in certain base pairs. As R. leguminosarum VF39 possesses two members of the Fnr/FixK regulator family, FnrN and FixK, the possible differential regulation of both fixN copies was analyzed with fixN-gusA reporter gene fusions. Both fixN fusions were induced under free-living microaerobic conditions and in the symbiotic zone of the root nodule. Induction of the expression of fixNc and fixNd was highly reduced in a fnrN mutant background and in a fixL mutant background, whereas fixK was only marginally involved in fixN regulation. Residual expression of fixN was observed in an fnrN/fixK double mutant.

Amino Acid Sequence↗

PubMed1997

[Not Available].

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Anxiety↗

PubMed1996

[Not Available].

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History, Early Modern 1451-1600↗

PubMed1995

[Not Available].

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Ethics, Medical↗

PubMed1993

Versatile suicide vectors which allow direct selection for gene replacement in gram-negative bacteria.

A set of vector plasmids which greatly facilitate gene replacement and reverse genetics in many Gram-negative bacteria was constructed. These vectors are based on the P15A origin of replication (ori) and incorporate sacB from Bacillus subtilis, which is inducible by sucrose and is lethal when expressed in Gram-negative bacteria. The vectors also have a convenient antibiotic-resistance marker (gentamicin resistance) and the lacZ alpha system which allows blue/white selection of cloned fragments. Three different multiple cloning sites, allowing several distinct cloning and gene replacement strategies, are available in the 5' end of lacZ on different vectors. One of these cloning sites, which we synthesised, contains only a NotI-SmaI-NotI sequence; this allows access to most of the restriction sites within the cloned fragment for the purpose of insertion of various cassettes and interposons. The vectors carry the mob region from the broad-host-range plasmid RP4 and are thus mobilizable by conjugation into a wide range of Gram-negative bacteria; since they will not replicate in bacteria other than enterobacteria, they function as 'suicide' vectors. Variants of the vectors carrying the phage lambda cos site were also constructed. We have used these vectors to carry out gene replacement experiments in the fixN region of Rhizobium leguminosarum and have demonstrated that they are extremely useful in eliminating long and tedious screening procedures.

Amino Acid Sequence↗

PubMed1989

New derivatives of transposon Tn5 suitable for mobilization of replicons, generation of operon fusions and induction of genes in gram-negative bacteria.

Three types of new variants of the broad-host-range transposon Tn5 are described. (i) Tn5-mob derivatives with the new selective resistance (R) markers GmR, SpR and TcR facilitate the efficient mobilization of replicons within a wide range of Gram-negative bacteria. (ii) Promoter probe transposons carry the promoterless reporter genes lacZ, nptII, or luc, and NmR, GmR or TcR as selective markers. These transposons can be used to generate transcriptional fusions upon insertion, thus facilitating accurate determinations of gene expression. (iii) Tn5-P-out derivatives carry the npt- or tac-promoter reading out from the transposon, and TcR, NmR or GmR genes. These variants allow the constitutive expression of downstream genes. The new Tn5 variants are available on mobilizable Escherichia coli vectors suitable as suicidal carriers for transposon mutagenesis of non-E. coli recipients and some on a phage lambda mutant to be used for transposon mutagenesis in E. coli.

Base Sequence↗

PubMed1989

[Morphology, clinical aspects and therapy of perinatal hypoxic central nervous system damage. A pedoneuropsychiatric follow-up analysis in relation to the neurohistologic spectrum of findings].

The histological localization and extent of ZNS-lesions caused by perinatal hypoxia has been examined in 83 cases. The neuropsychiatrical patterns of 71 in preschool and school age children after perinatal hypoxia were also investigated. Predominantly a brain stem damage with nerve cells lesions, hemorrhages and disturbance of neuroglia are found. In 1 fourth of the cases, nerve cell damage was localized in the medulla spinalis. Intramedullar hemorrhages can be observed in 10% of the cases. 41% of the cases showed subarachnoidal bleedings. Neuropsychiatrical examinations showed varying degrees of brain stem dysfunction in accordance with neurohistological findings. 1 third of the risk children demonstrated minimal brain dysfunction. In 10% an early rehabilitation of resulted in an amelioration of the ZNS-function. Special attention should be drawn to partial ZNS-disturbance-children. The problems of therapy are discussed.

Adolescent↗

PubMed1989

Direct selection for curing and deletion of Rhizobium plasmids using transposons carrying the Bacillus subtilis sacB gene.

We have constructed derivatives of the transposon Tn5 carrying the mob site (oriT) of plasmid RP4, and an nptI-sacB-sacR cassette [Ried and Collmer, Gene 57 (1987) 239-246]. The mob site, in conjunction with the antibiotic-resistance markers carried on the transposons, allows identification of transposon inserts in cryptic plasmids by mobilisation to other strains. The sacB-sacR genes allow direct selection for the loss or curing of plasmids, because only strains which no longer contain an active sacB gene are able to grow on media containing sucrose. We have tested these transposons in four strains of Rhizobium leguminosarum and two strains of Rhizobium meliloti, and have been able to demonstrate curing of several large cryptic plasmids, and generation of large deletions in many other plasmids. This method has enabled us to show that the R. leguminosarum plasmids pRL12JI and pR1eVF39f carry auxotrophic markers, and that the plasmid pR1eVF39c carries genes which affect colony morphology.

Bacillus subtilis↗

PubMed1988

[Affect from the biological and psychiatric viewpoint].

The human frame of mind is a biological and psychic problem. The man is able to influence his mood in contrast to the animal, because the human brain is functionally an open system. The questions, which result from this opinion will be demonstrated. The influence of psychopharmaca and of drugs is an actual problem of human behaviour and must be considered in the therapy of mental disturbances.

Animals↗

PubMed1988

[Neuropathology of hypertensive encephalopathy].

An account is given of hypertensive encephalopathy on the basis of neurohistological studies into 54 brains, with additional reference being made to autopsies. Vasculopathy of peripheral arteries and arterioles along with thickening of vascular walls, change of media, and lumen stenosis were primarily recorded by means of optical light and electron microscopy. A difference of more than seven per cent was found to exist between wall thicknesses of arterioles in hypertensive brains, on the one hand, and those in normotensive brains, on the other. Vessels with thickened walls were not rigid but were rather capable of dilation just as under normotensive conditions. Their inner diameters, however, were below normal. Vascular wall fibrosis, to which little attention had been given in the past, was repeatedly recordable from the venous and capillary systems. Impairment of the endothelial barrier function was quite often recorded, with lipid deposits being incorporated in peripheral arterioles and capillaries. No relevance to pathogenesis can be reliably attributed at present to detection of IgG in the arterial system. Microinfarction, micro-haemorrhage as well as disseminated damage to nerve cells are recordable from roughly one third of all hypertensive brains and are primarily located in brain stem ganglia. Demyelinisation and cerebral oedema are quite infrequent. High-protein cerebral oedema was found in some rare cases. Hypertensive encephalopathy should be considered as a nosological entity in which morphological and clinical phenomena are not always correlated to each other.

Arterioles↗

PubMed1983

[Current status of normocalcemic tetany].

The author describes the actual state of research of normocalcemic tetany. Since 1959 the infusion test with ethylene diamine tetraacetic acid (EDTA) has won a central position. The EDTA test gives the possibility to classify tetanic symptoms into the circle either of hypocalcaemic or normocalcaemic syndrome. In the latter case the functional disturbance is to be treated in a form of combined therapy by tranquilizers and psychosomatic measures.

Calcium↗

PubMed1982

[Critique of so-called outsider methods in medical therapy].

The manifold forms of the therapy always are of a complex nature. In pharmacological animal experiments, one can determine the parameters of the effect of a drug exactly, in humans there is often a discrepancy between these results and the actual therapy effect. Here the psychophysical mode of reaction has to be taken into account. For humans, not only the word is psychophysically effective because of its semantic property, similar effects are brought about by symbols, objects and pictures. These effects are known from the field of pre-scientific medicine and are in most cases the basis of the so-called miracle cures. Analogue effects can be seen in the field of outsider methods. They can be tolerated as long as they are not understood otherwise than as psychotherapeutic techniques with certain instrumental aids or as a psychophysical therapy with harmless substances or so-called placebos. Problems will arise when a thought process is developing.

Acupuncture Therapy↗

PubMed1979