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Biomedical subjects

K Sieg

Publications and source records attributed to K Sieg.

12 recordsLinked to original sources
PubMed1989

A versatile phage lambda expression vector system for cloning in Escherichia coli.

By integrating fragments from the expression plasmids pJK2 and pJK4 into a derivative of the bacteriophage lambda, we constructed the phage expression vectors lambda JK2 and lambda JK4, which allow efficient cloning of genomic or cDNA either into the 5' end or the 3' end of the lacZ gene of Escherichia coli. Expression of barrier-free DNA in phase may lead to fusion proteins consisting of active beta-galactosidase (beta Gal) plus an additional polypeptide encoded by the inserted DNA. Analysis of distinct recombinant clones is quick and easy, due to the reversible integration of the plasmid into the genome. As an example, we constructed an expression library of genomic Plasmodium falciparum DNA in lambda JK2. We polymerised (amplified) and expressed a synthetic DNA fragment, which codes for a potential antigenic determinant of the 11-1 gene of Plasmodium falciparum as a fusion to the N terminus of active beta Gal. We demonstrate that such chimeric molecules can be affinity-purified and that polypeptides can be separated from the beta Gal part by cleavage with the protease factor Xa.

Amino Acid Sequence↗
PubMed1988

The 11-1 gene of Plasmodium falciparum codes for distinct fast evolving repeats.

The 11-1 gene of Plasmodium falciparum has been investigated by DNA sequence analysis. It begins at the 5' end with a putative miniexon coding for a polypeptide which has the characteristics of a signal sequence. The miniexon is followed by a small intron. This again is followed by a large exon consisting of 9-, 18- and 27-bp repeats embedded in unique DNA. Specific antibodies isolated by affinity chromatography on a purified recombinant fusion protein expressing the three- and six-amino acid repeats were used to identify the product of the 11-1 gene. In exhibits size variations from 260 to 350 kd in different strains. Southern blot analysis with synthetic DNA as probe demonstrates that the 18-bp repeat is absent or drastically altered in two strains whereas the other repeats are present in all seven strains investigated. The unusual preference for G in the third position of some codons of the repeats but not in the unique sequences indicates rapid evolution of the repeats. Slippage during replication, unequal crossing over and selection are discussed as possible mechanisms leading rapidly to extreme diversity.

Amino Acid Sequence↗
PubMed1985

Pitfalls in the diagnosis of tricuspid atresia: report of a new angiocardiographic sign.

Two patients with the classical clinical, angiographic, and echocardiographic signs of tricuspid atresia are reported, where the correct diagnoses were made at operation; one child had cor triatriatum dexter, the other child total anomalous systemic venous drainage to the left atrium. The literature on cor triatriatum dexter and total anomalous systemic venous drainage is discussed and a new angiographic sign for the differentiation from tricuspid atresia is reported: nonopacification of the right atrial appendage with right atrial angiocardiography.

Angiocardiography↗
PubMed1985

[Echocardiographic pressure-dimension analysis following anatomically corrective operation of d-transposition of the great arteries].

The major theoretical advantage of anatomic correction of transposition of the great arteries compared with intraatrial repair is that the left ventricle becomes the systemic pump. In 10 patients we analysed 5-12 months after anatomic correction the left ventricular echocardiographic pressure-dimension loop, meridional wall stress and left ventricular stiffness from the simultaneous recordings of the left ventricular pressure and M-mode echocardiogram. The low left ventricular diameters, left ventricular hypertrophy in 4 patients, and increased peak meridional wall stress in 3 patients indicate that left ventricular adaption to systemic impedance is still incomplete 5-12 months after anatomic correction. The cycle efficiency was reduced in 2 patients, indicating incoordinate left ventricular contraction and relaxation. In one of these patients the left ventricular stiffness was severely increased, while in another patient there was a slight increase in left ventricular stiffness. In all patients the right ventricular internal diameter was increased due to the long-standing preoperative pressure and volume overload.

Blood Pressure↗
PubMed1981

[Neurologic disorders and cerebral lesion in children with TGA (transposition of the great arteries) (author's transl)].

118 consecutive patients with TGA were examined for neurologic disorders (ND) and cerebral lesions (CL) between 1967--1979 of whom 43 are alive. 66 had simple TGA, 52 had VSD, PS and/or coarctation as additional lesion.--43 were corrected surgically of whom 32 are alive.--Neurologic examination was performed in all, EEG, CT, arteriography, scintigraphy and autopsy when necessary or possible. Patholog. findings (CL, ND) were detected in 66; 47 had definite ND or CL, while 19 showed gross motor development delay. 52 of 118 children with TGA were without neurolog. or cerebral pathology. --Several factors were investigated for their etiologic influence: 1. Additional cardiac lesions played no significant role. 2. The lower O2 saturation in the ascending aorta of the fetal circulation in TGA may be of importance. 3. Red blood count, hemoglobin, hematocrit were higher in the group with ND or CL. 4. Early appearance of cerebral lesion should suggest earlier corrective surgery.

Brain Damage, Chronic↗
PubMed1977

Straddling right atrioventricular valve in criss-cross atrioventricular relationship.

Two cases of complex congenital heart disease are described in which systemic and pulmonary bloodstreams crossed at the atrioventricular level. Both patients were examined clinically, echocardiographically, and by cardiac catheterization, including angiography, and both underwent cardiac surgery and had intraoperative mapping of their conduction systems. Both patients were found to have levocardia and situs solitus of viscera and atria, large ventricular septal defect, and straddling right atrioventricular valve. One patient had atrioventricular discordance but with the left ventricle anterior and alightly on the right and with pulmonary atresia and dextromalposition of the aorta. The other patient had atrioventricular concordance but with the left ventricle inferior and slightly on the left and with ventricular-arterial concordance to normally related great arteries and banded pulmonary trunk. To our knowledge, this combination including straddling right atrioventricular valve has not been reported in the literature before. In both patients the straddling atrioventricular valve was thought to preclude corrective operation at that time. A unique palliative procedure--left ventricle-to-pulmonary trunk shunt--was successful in the first case and partial debanding of the pulmonary trunk in the second.

Cardiac Catheterization↗
PubMed1977

A criss-cross heart. Detailed anatomic description and discussion of morphogenesis.

Hearts with criss-cross atrioventricular connections are rare. Reports in the literature describe great anatomic variations with regard to the atrioventricular connections, spatial relationships of the ventricles, and connections and spatial relationships of the great arteries. In the example described in this report, the basic anatomic picture was that of transposition of the great arteries, but the criss-cross atrioventricular valves had resulted in atrioventricular discordance; hemodynamically, therefore, the situation resembled congenitally corrected transposition. One hypothesis for this anatomic configuration is that pronounced counterclockwise rotation (as viewed from below) brought the ventricular septum into a frontal plane and altered the respective positions of the pulmonary and aortic valves from those usually seen in congenitally corrected transposition and thereby resulted in crossed atrioventricular connections. An alternative hypothesis is that in this case one of the atrioventricular valves (the anteriorly positioned valve) may represent an anomalous communication that developed early in embryogenesis and connected the left atrial appendage to the right ventricular infundibulum.

Child↗
PubMed1976

[Acquired internal hydrocephalus complicating mumps meningo-encephalitis (author's transl)].

A 6 1/2 years old girl is reported who developed internal hydrocephalus due to an occlusion of the rostral aquaeduct, 2 1/2 months after epidemic parotitis. Epileptic reactions of focal origin occurred during the clinical cause, the implications of this special event and pathogenetic aspects of mumps-meningo-encephalitis are discussed, recent advances in experimental animals are included.

Cerebral Aqueduct↗