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Biomedical subjects

A Sørensen

Publications and source records attributed to A Sørensen.

18 recordsLinked to original sources
PubMed2001

Multibit gates for quantum computing.

We present a general technique to implement products of many qubit operators communicating via a joint harmonic oscillator degree of freedom in a quantum computer. By conditional displacements and rotations we can implement Hamiltonians which are trigonometric functions of qubit operators. With such operators we can effectively implement higher order gates such as Toffoli gates and C(n)-NOT gates, and we show that the entire Grover search algorithm can be implemented in a direct way.

Journal Article↗
PubMed2001

Many-particle entanglement with Bose-Einstein condensates.

The possibility of creating and manipulating entangled states of systems of many particles is of significant interest for quantum information processing; such a capability could lead to new applications that rely on the basic principles of quantum mechanics. So far, up to four atoms have been entangled in a controlled way. A crucial requirement for the production of entangled states is that they can be considered pure at the single-particle level. Bose-Einstein condensates fulfil this requirement; hence it is natural to investigate whether they can also be used in some applications of quantum information. Here we propose a method to achieve substantial entanglement of a large number of atoms in a Bose-Einstein condensate. A single resonant laser pulse is applied to all the atoms in the condensate, which is then allowed to evolve freely; in this latter stage, collisional interactions produce entanglement between the atoms. The technique should be realizable with present technology.

Journal Article↗
PubMed2001

Signals of adiposity.

Adipose tissue, a reserve of energy, has played an essential role in mammalian evolution. Adipose tissue differs from other tissues in that its mass has considerable capacity to expand, which while beneficial in decreasing the risk of starvation, increases the risk of predation. Adipose tissue mass is thus under tight control in nondomestic species. Adipose tissue secretes a variety of factors, some of which (leptin, tumor necrosis factor (TNF) alpha, resistin) are thought to be involved in modulation of adipose mass. Leptin has a variety of functions, primarily targetting the hypothalamus where it acts to decrease appetite and increase energy expenditure. Leptin is also involved in the adaptations to fasting, and leptin is also required for normal reproductive and immune function. TNF alpha and resistin appear to have key paracrine roles, attenuating the anabolic effects of insulin on adipose tissue metabolism.

Adipose Tissue↗
PubMed2000

[Agressive fibromatosis].

Aggressive fibromatosis is a rare soft tissue tumour with a high tendency to local recurrence. The patients often present with a deeply sited, firm mass with or without pain. Genetic, physical and endocrine factors seem to be important in the development of the disease. Patients with Gardner's syndrome and familial adenomatous polyposis have a higher risk of developing aggressive fibromatosis and often develop tumours in the mesentery, retroperitoneally or in the abdominal wall. Infantile fibromatosis is a variant of aggressive fibromatosis. The standard treatment of aggressive fibromatosis is surgical resection with wide free margin, in some cases supplemented with radiotherapy. Chemotherapy and hormonal treatment of non-resectable tumours has been described without convincing results and more data from clinical studies are needed.

Desmoid Tumors↗
PubMed2000

Squeezing and entanglement of atomic beams.

We propose and analyze a scheme for generating entangled atomic beams out of a Bose-Einstein condensate using spin-exchanging collisions. In particular, we show how to create both atomic squeezed states and entangled states of pairs of atoms.

Research Support, Non-U.S. Gov't↗
PubMed2000

Separation and determination of alditols and sugars by high-pH anion-exchange chromatography with pulsed amperometric detection.

Carbohydrates such as alditols (polyols or sugar alcohols), monosaccharides and disaccharides are separated as anions by anion-exchange chromatography with a sodium hydroxide eluent, MA1 CarboPac column and pulsed amperometric detection. We report a high-pH anion-exchange chromatographic-pulsed amperometric detection (HPAEC-PAD) method that determines all the polyols used as food additives in food products and the most commonly found mono- and disaccharides on a routine basis. The linearity, repeatability, internal reproducibility and accuracy are described. The applicability of the method has been demonstrated by the analysis of 46 relevant samples and by participation twice in the Food Analysis Performance Assessment Scheme (FAPAS) testing programme for food additives.

Anion Exchange Resins↗
PubMed2000

Correlations of receptor binding and metabolic and mitogenic potencies of insulin analogs designed for clinical use.

In recent years, analogs of human insulin have been engineered with the aim of improving therapy for people with diabetes. To ensure that the safety profile of the human hormone is not compromised by the molecular modifications, the toxico-pharmacological properties of insulin analogs should be carefully monitored. In this study, we compared the insulin and IGF-I receptor binding properties and metabolic and mitogenic potencies of insulin aspart (B28Asp human insulin), insulin lispro (B28Lys,B29Pro human insulin), insulin glargine (A21Gly,B31Arg,B32Arg human insulin), insulin detemir (NN304) [B29Lys(epsilon-tetradecanoyl), desB30 human insulin], and reference insulin analogs. Receptor affinities were measured using purified human receptors, insulin receptor dissociation rates were determined using Chinese hamster ovary cells overexpressing the human insulin receptor, metabolic potencies were evaluated using primary mouse adipocytes, and mitogenic potencies were determined in human osteosarcoma cells. Metabolic potencies correlated well with insulin receptor affinities. Mitogenic potencies in general correlated better with IGF-I receptor affinities than with insulin receptor off-rates. The 2 rapid-acting insulin analogs aspart and lispro resembled human insulin on all parameters, except for a slightly elevated IGF-I receptor affinity of lispro. In contrast, the 2 long-acting insulin analogs, glargine and detemir, differed significantly from human insulin. The combination of the B31B32diArg and A21Gly substitutions provided insulin glargine with a 6- to 8-fold increased IGF-I receptor affinity and mitogenic potency compared with human insulin. The attachment of a fatty acid chain to LysB29 provided insulin detemir with reduced receptor affinities and metabolic and mitogenic potencies but did not change the balance between mitogenic and metabolic potencies. The safety implications of the increased growth-stimulating potential of insulin glargine are unclear. The reduced in vitro potency of insulin detemir might explain why this analog is not as effective on a molar basis as human insulin in humans.

Adipocytes↗
PubMed1998

[Sternocleidomastoid tumor].

A case of pseudotumour of the sternocleidomastoid muscle in a three-week old child is reported. The tumour resolved spontaneously within four months. Seventeen months later there was no sign of torticollis. This tumour is the most common cause of torticollis in newborn children. In 80-90% of the cases the tumour disappears within six months, the rest develop either a progressive or delayed torticollis, known as congenital muscular torticollis (CMT). Thus, CMT is a related condition, usually appearing at three to four years of age, and it may require surgical correction.

Diagnosis, Differential↗
PubMed1997

Transduction potential of human retroviruses in highly proliferating small-cell lung cancer cells as well as non-proliferating hematopoietic stem cells.

Direct gene transfer to solid tissues or metastatic cancer cells requires vectors capable of in vivo transduction to specific cells. The predominant retroviral vectors of murine origin are inactivated by human complement, which precludes their use in vivo. Such inactivation does not take place with vectors based on human retroviruses. Murine retroviral vectors are also limited to proliferating cells, which human retroviruses are not. In this study we examined whether or not a vector using components from the human retroviruses HIV-1 and HTLV-1 could infect small-cell lung cancer cells and resting CD34+ hematopoietic stem cells. While HIV-1 itself was unable to infect cells lacking the CD4-membrane molecule, chimeric viral particles (pseudotype virus) with HIV-1 genome and HTLV-1 envelope components were able to infect both CD4-containing lymphocytic cells, CD4-negative tumour cells and hematopoietic stem cells. After infection with the pseudotype vector, the RNA genome was reverse transcribed and integrated. Transduction efficiency and gene expression under the HIV-1 LTR promoter in both tumour and stem cells were found to be of a similar or greater magnitude than in lymphocytic cells. These results suggest that gene transfer targeting proliferating as well as resting cells in vivo may be realized using components from human retroviruses.

Antigens, CD34↗
PubMed1993

[Ulcer surgery during 1976-1978 and 1986-1988. Significance of H2 blockaders in surgical training].

A retrospective study of all operations done for duodenal or stomach peptic ulcers in 1976-1978 and 1986-1988 was performed so as to evaluate elective and emergency surgery before and after the introduction of H2-receptor antagonists and to evaluate the influence of medical treatment on surgical training in ulcer surgery. The number of elective operations fell by 80%, the number of emergency operations was unchanged. In 1986-1988 the number of elderly patients who underwent emergency surgery increased, no change in age was seen in elective surgery. The rate of complications was unchanged after elective operations, but has increased considerably after emergency surgery in 1986-1988. Surgeons in training performed a greater share of operations, both elective and emergency, but without an increase in complications. The introduction of H2-receptor antagonists has not reduced the number of emergency operations.

Adult↗
PubMed1993

High lysozyme activity in a Norwegian bovine family co-segregates with a restriction fragment length polymorphism.

Analysis of restriction fragment length polymorphism (RFLP) of the lysozyme gene cluster was performed in a Norwegian bovine family segregating a single dominant Mendelian factor for high lysozyme activity in serum. An RFLP site with allelic bands of 16kb and 5.9 kb turned out to be linked to the locus for the high lysozyme activity factor with a lod score of 6.8 at a recombination fraction of 3.4%. This implies that we have revealed a genetic marker for the high lysozyme activity trait.

Abomasum↗
PubMed1992

High levels of linkage disequilibria between serologically defined class I bovine lymphocyte antigens (BoLA-A) and class II DQB restriction fragment length polymorphism (RFLP) in Norwegian cows.

Serum defined BoLA-A antigens, together with BoLA-DQB RFLP patterns, were determined in 87 almost unrelated Norwegian cattle. Statistical analysis revealed strong linkage disequilibria between these loci at the population level. A total of 13 haplotypes were found to be present at frequencies significantly greater than those predicted on the basis of their component gene frequencies. Among these, the subgroups 1A and 1B of the DQ1 haplotype were found to be closely associated with the class I antigens A11 and w16, respectively. The association between A11 and DQ1A is of particular interest, as two independent studies, one employing class I serology, and the other RFLP analysis of the class II locus DQ, have previously indicated that A11 and DQ1A confer relative susceptibility to mastitis.

Alleles↗
PubMed1985

A pilot study of natural radiation in Danish houses.

A pilot study was carried out to establish techniques and procedures for the measurement of indoor radiation in Denmark. A passive cup dosemeter was designed containing CR39 track detectors and TLD's to measure radon and external radiation, respectively. A total of 82 dwellings were selected covering most regions of the country. The dwellings were monitored in two three-month periods, one in winter and the other in summer. The average dose rate in air from external radiation was 0.09 muGy h-1. In the winter the average radon concentrations were 88 Bq m-3 and 24 Bq m-3 for single-family houses and flats, respectively; and in the summer the corresponding values were 52 Bq m-3 and 19 Bq m-3.

Denmark↗
PubMed1984

Treatment of alcohol withdrawal symptoms in hospitalized patients. A randomized, double-blind comparison of carbamazepine (Tegretol) and barbital (Diemal).

Seventy-two hospitalized patients with alcohol withdrawal symptoms were treated with either carbamazepine (Tegretol) or barbital ( Diemal ) in a randomized, double-blind trial. The dose of trial medication as well as the duration of treatment was individual, corresponding to the conventional treatment schedule. During the trial period daily records were kept of target withdrawal symptoms, global evaluation, the patient's subjective feeling and unwanted effects. Sixty patients completed the treatment successfully. The two treatment groups were homogeneous as regards patient characteristics, pre-treatment disease severity and drop-out rate. No statistically significant differences were found in efficacy between the two treatments, and both drugs were well tolerated. It is concluded that carbamazepine is a valuable alternative drug in the treatment of mild and moderate alcohol withdrawal symptoms.

Adult↗