PubMed Health⌕ Search

Biomedical subjects

S Krueger

Publications and source records attributed to S Krueger.

At least 55 records · Page 3Linked to original sources
PubMed1995

Uniparental isodisomy 13 in a normal female due to transmission of a maternal t(13q13q).

Chromosomes from a normal 23-year-old, primigravid woman were examined at 10 weeks of gestation because of her mother's history: 8 miscarriages and two liveborn infants (the proposita and a brother who died at 3 days with multiple anomalies). Karyotypes of the proposita and her normal mother were 45,XX,t(13q13q). No evidence of mosaicism was encountered. When the proposita inherited the t(13q13q), she received two copies of 13q from her mother. Moreover, she and her mother shared the same homozygous pattern of alleles from 7 highly polymorphic microsatellite repeats localized along 13q. No evidence of paternal markers from 13 was detected, although biparental inheritance was demonstrated with DNA markers from chromosomes 2 and 17. Cytogenetic and molecular findings indicated that the proposita's chromosomal complement included mUPD 13q. The proposita's normal phenotype suggested that no maternally imprinted genes map to 13q.

Abortion, Habitual↗
PubMed1995

Aggressive family communication, weight gain, and improved eating attitudes during systemic family therapy for anorexia nervosa.

During systemic family therapy with 15 hospitalized anorexics, family communication was evaluated, using a Family Aggression Scale developed by one of the authors. Initially members communicated aggression covertly. This finding may partially explain the common clinical observation that the families of anorexics present a strong facade of togetherness and avoid overt conflict. During therapy members shifted from covert communication of aggression to covert communication of aggression. This shift correlated with improvement in subjects' eating attitudes reflected by their EAT-26 scores. All subjects gained weight. Greater weight gain occurred in subjects whose families had low levels of covert or indirect aggression. A regression analysis showed that 86% of the variance in weight gain was predicted by two leading indicators in the middle phase of treatment. Two other factors accounted for 64% of the variance in EAT scores. The findings of this study suggest that family aggression as measured by the Family Aggression Scale is a significant index of pathology in anorexics' families and is also a clinically meaningful measure of improved conflict resolution during systemic family therapy.

Adolescent↗
PubMed1995

Clinical evaluation of Norplant in Kumasi, Ghana.

A non-comparative study of the Norplant contraceptive subdermal implant system was conducted in Kumasi, Ghana. A total of 100 acceptors were enrolled in the clinical trial, which began in 1987. There were no pregnancies during the first two years of use. Only nine post-insertion medical problems were reported during the first two years of use. One woman in this study requested removal for menstrual pattern changes through two years of use. As assessed through user-satisfaction questionnaires administered at approximately six months of use, there has been an overall positive user experience with Norplant in this study. Although the sample size in this study is small, our results seem to be consistent with other studies and it appears that Norplant offers an effective, safe and acceptable method of contraception for Ghanaian women.

Adult↗
PubMed1995

Spatial and temporal distribution of [Ca2+]i in normal human myotubes. A fura-2 imaging study.

The spatio-temporal distribution of intracellular, free calcium ions, [Ca2+]i, induced in human myotubes by electrical stimulation typically showed a relatively large increase of [Ca2+]i in the vicinity of the plasmalemma. The similarity of this distribution, with that observed after the application of caffeine, and the lack of any effect of lanthanum, strongly suggest that the main source of Ca2+ participating in the electrically induced transient is the sarcoplasmic reticulum. Aneurally cultured human myotubes therefore display a 'skeletal muscle type' coupling between membrane depolarization and calcium release. However, the relatively slow time course of the electrically induced transients compared to rat and mouse myotubes, together with the inability of Ca2+ released from the sarcoplasmic reticulum to activate the contractile machinery, implies that aneurally cultured human myotubes achieve only a limited degree of differentiation. The relevance this may have to an apparent delay between the electrically induced rise in intranuclear Ca2+ relative to cytosolic Ca2+ remains to be determined but, at this stage of differentiation, there appears to be some form of barrier to free diffusion between the two cellular compartments.

Caffeine↗
PubMed1994

Opposite effects of the CD30 ligand are not due to CD30 mutations: results from cDNA cloning and sequence comparison of the CD30 antigen from different sources.

CD30L, the ligand for the activation antigen CD30, is a member of the tumor necrosis factor family of cytokines. Binding of CD30L to CD30, which is a member of the nerve growth factor/tumor necrosis factor receptor family, induces proliferation in peripheral blood lymphocytes and Hodgkin's derived cell lines with a T-cell phenotype such as HDLM-2 and L540, while cell lines derived from anaplastic large cell lymphomas, such as Karpas 299, undergo cell death. In order to investigate whether mutations of the CD30 antigen are responsible for these opposite effects, we cloned the open reading frame of CD30 cDNAs from the cell lines L540 and Karpas 299 and from peripheral blood lymphocytes by reverse transcriptase polymerase chain reaction. Sequencing of independent plasmid clones revealed that these cells have a silent transition (A-->G) at position 771 of the open reading frame compared to the published sequence derived from the HTLV-1+ cell line HUT-102. As published data have shown that crosslinking of CD30 induces an elevation of cytosolic free calcium ([Ca2+]i) in TCR positive Jurkat cells, we have analysed the effect of crosslinking of CD30 on L540 and Karpas 299 cells. No elevations of [Ca2+]i have been observed in these cell lines after crosslinking of CD30 with HRS-4. We conclude (i) that the different functional effects of CD30 in PBL, L540 and Karpas 299 are not due to differences in the primary structure of the receptor; and (ii) that the different responses observed upon engagement with CD30L for the cell lines L540 and Karpas 299 do not correlate with differences in mobilization of [Ca2+]i after crosslinking of CD30.

Base Sequence↗
PubMed1994

Small angle neutron scattering studies of structural characteristics of agarose gels.

The 30 m small angle neutron scattering facility at the National Institutes of Standards and Technology has been used to examine neutron scattering from agarose gels formed in D2O. Differential scattering cross sections have been acquired over a continuous range of Q between 0.005 and 0.3 A-1. Subtle changes in gel structure are observed when pre-gelation agarose concentration is varied. Similarly, except when the gelling solution is rapidly cooled to a low temperature, the rate at which the gels are formed does not seem to have much effect. Clearer evidence of structural rearrangement is observed when the solvent quality is changed by the addition of dimethyl sulfoxide, or when the temperature of the gel is elevated above 70 degrees C. These data are consistent with a description of a randomly structured polymer network containing discrete self-similar, hydrogen-bonded, junctions normally of minimal thickness approximately 35-40 A.

Carbohydrate Conformation↗
PubMed1993

Characterization of the Binding of Gallium, Platinum, and Uranium to Pseudomonas fluorescens by Small-Angle X-Ray Scattering and Transmission Electron Microscopy.

Small-angle X-ray scattering (SAXS) was used to determine the binding of Ga, U, and Pt to Pseudomonas fluorescens in aqueous buffer. Atomic absorption spectrophotometry was used to quantify the heavy metals during bulk analysis, whereas transmission electron microscopy of whole mounts and thin sections was used to determine the locations of the cell-bound metal precipitates, as well as their sizes and physical structures. Energy-dispersive X-ray spectroscopy confirmed the compositions and identities of the precipitates and helped show that they were associated primarily with the envelope layers of the bacteria. Unlike Ga and Pt, which were located only at the cell surface, U was also found intracellularly in approximately 10% of the cells. This cytoplasmic location ultimately killed and lysed the cells. Surface-bound Ga and U were spread over the entire cell envelope (outer membrane-peptidoglycan-plasma membrane complex), whereas Pt was associated only with the lipopolysaccharide-rich, external face of the outer membrane. SAXS confirmed these data and showed that the bacteria were metal-enshrouded particles that were 1.0 to 1.5 mum in diameter. SAXS also provided a statistically significant representation of the bound metal precipitates, which ranged in size from 10 nm to 1 mum. The correlation between the microscopic data and the scattering data was extremely good. Since SAXS is performed in an aqueous milieu, it yields a more representative picture of the physical state of the metal bound to cell surfaces.

Journal Article↗
PubMed1992

Simplified microvascular suture techniques for rat liver transplantation as a microsurgical model with arterial blood supply.

The methods for liver transplantation in the rat mainly used do not include reconstruction of the arterial blood supply to the liver. Furthermore, to ensure a short anhepatic phase these methods almost all entail specially developed cuff anastomoses in the recipient operation instead of the conventional microvascular suture technique. Thus an acceptable survival rate can be attained in the experimental animals. This detailed description of simplified microvascular suture techniques is intended to present an alternative to the cuff anastomoses used almost exclusively. In the donor operation with this method, the liver is dissected with an arterial pedicle including the abdominal segment of the aorta, and the liver is flushed in situ not only via the portal vein, but also via the hepatic artery. The organ is implanted in the recipient animal using simplified microvascular suture reconstruction of the arterial blood supply to the liver. Use of telescopic spectacles with 2-fold magnification has proven to be adequate for the entire procedure. With mastery of this method of rat liver transplantation, the average duration of the anhepatic phase is about 20 min, substantially below the 30-min limit which is critical for the survival of the experimental animals. The donor operation requires about 60 min, and the recipient operation 70 to 80 min. With this method, the spectrum of investigations on liver transplantation which are possible in the rat is substantially extended in that clinical conditions can be reproduced very much more exactly by combination of portal and arterial in-situ flushing in the donor operation and rearterialization of the transplant in the recipient operation, as compared to the transplanted rat liver being supplied only with portal venous blood.

Anastomosis, Surgical↗
PubMed1991

Stringent control of replication of plasmids derived from coliphage lambda.

The first events of lambda plasmid replication in vivo, which probably regulate this process, are the transcriptional activation of the origin of replication by RNA polymerase and the binding of the initiator protein, lambda O, to this nucleotide sequence. The lambda O protein is known for its rapid proteolytic degradation; hence amino acid starvation of Escherichia coli should result in inhibition of lambda plasmid replication caused by inhibition of protein synthesis. However, contrary to this prediction, we found that lambda plasmid replication, as measured by the increase in plasmid content per bacterial mass, proceeds for hours in an amino acid-starved, relaxed mutant, whereas it is inhibited in its wild-type stringent partner. lambda plasmid replication in amino acid-starved, relaxed cells reveals absolute lambda O dependence and is not inhibited by chloramphenicol at 200 micrograms/ml. This process also occurs in wild-type cells treated with chloramphenicol. We conclude that lambda plasmid replication is under stringent control, probably as a result of the action of ppGpp, the indirect product of the relA gene, on RNA polymerase. The problem of stability of the lambda O initiator protein is discussed.

Bacteriophage lambda↗
PubMed1990

Neutron and light-scattering studies of DNA gyrase and its complex with DNA.

The solution structure of Escherichia coli DNA gyrase, an enzyme that catalyzes the ATP-dependent supercoiling of DNA, has been characterized by small-angle neutron scattering (SANS) and dynamic light-scattering (DLS). The enzyme and its complex with a 172 base-pair fragment of duplex DNA, in H2O or 2H2O solvent, were studied by contrast variation and the measurement of hydrodynamic parameters as a function of scattering angle. The complex was also measured in the presence of 5'-adenylyl-beta,gamma-imidodiphosphate (ADPNP), a non-hydrolyzable ATP analog that is known to support limited supercoiling. The values of the radius of gyration, Rg = 67 A, from SANS and the hydrodynamic radius, Rh = 64 A, from DLS predict a larger than expected volume for the enzyme, supporting the notion of channels or cavities within the molecule. In addition, several classes of models were rejected based on SANS data obtained in 2H2O at larger scattering angles. The best fit to both the SANS and DLS data is obtained for oblate, inhomogeneous particles approximately 175 A wide and 52 A thick. Such particles provide a large surface area for DNA interaction. Both Rg and Rh values change very little upon addition of DNA, suggesting that DNA binds in a manner that does not significantly change the shape of the protein. No appreciable change in structure is found with the addition of ADPNP. However, the higher-angle SANS data indicate a slight rearrangement of the enzyme in the presence of nucleotide.

Animals↗
PubMed1990

Small angle neutron scattering studies of HbA in concentrated solutions.

Differential cross-sections for neutrons scattered by normal human hemoglobin have been determined over the range of concentrations from 2 to approximately 35 weight percent. Data are compared with structure factors calculated from models of monodisperse hard spheres interacting through a screened Coulomb potential. Good agreement is noted when the volume fraction eta is adjusted during multivariate fitting of data, but the fitted value of eta is always lower than expected from the known Hb concentration of the samples. Calculations of cross-sections for polydisperse scatterers suggest that the samples may contain oligomers of the fundamental tetrameric Hb molecule.

Carboxyhemoglobin↗
PubMed1988

SANS studies of interacting hemoglobin in intact erythrocytes.

Small angle neutron scattering (SANS) was used to investigate interaction forces between hemoglobin (Hb) molecules contained within human red cells. The scattering separately attributable to cell membranes and intracellular Hb was identified. A series of D2O-H2O contrast variation measurements were made in order to establish conditions for which scattering from the cell membrane is minimized (approximately 15% D2O). Measurements then were performed to examine changes in intermolecular Hb interactions occurring when the cells are contracted or swollen by varying the ionic strength of the suspension buffer. The scattering cross-sections were fitted to structure factors computed by a mean spherical approximation, and molecular parameters thereby extracted. Oxygenation studies on normal cells were performed, and results contrasted with those of similar studies of erythrocytes obtained from sickle cell disease patients.

Anemia, Sickle Cell↗
PubMed1975

Correlation between segmental early relaxation of the left ventricular wall and coronary occlusive disease.

Fifty of 305 patients studied angiographically had segmental early relaxation phenomenon (SERP) of the anterolateral or apical left ventricular wall. Fourteen of the 50 patients had cardiac abnormality other than, or in addition to, coronary occlusive disease. Of the remaining 36 patients, 35 had significant lesions in the left anterior descending artery (LAD) and one had occlusion of the proximal left circumflex artery. SERP was noted in 35 (37.2 per cent) of 94 patients with LAD disease who did not have severe anteroapical contraction abnormality. SERP was found in none of 49 patients who had neither significant coronary occlusive disease nor other cardiac abnormality. Eight patients were restudied after bypass grafting of the LAD. Three patients with patent grafts no longer demonstrated SERP. Five had persistent SERP, but four of these had occluded LAD grafts or nongrafted disease in other vessels supplying the anterolateral wall. Myocardial ischemia appears to be one cause, but probably not the only cause, of SERP.

Angiocardiography↗