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Biomedical subjects

L Nilsson

Publications and source records attributed to L Nilsson.

At least 73 records · Page 4Linked to original sources
PubMed1999

Distinct requirements for optimal growth and In vitro expansion of human CD34(+)CD38(-) bone marrow long-term culture-initiating cells (LTC-IC), extended LTC-IC, and murine in vivo long-term reconstituting stem cells.

Recently, primitive human bone marrow (BM) progenitors supporting hematopoiesis in extended (>60 days) long-term BM cultures were identified. Such extended long-term culture-initiating cells (ELTC-IC) are of the CD34(+)CD38(-) phenotype, are quiescent, and are difficult to recruit into proliferation, implicating ELTC-IC as the most primitive human progenitor cells detectable in vitro. However, it remains to be established whether ELTC-IC can proliferate and potentially expand in response to early acting cytokines. Here, CD34(+)CD38(-) BM ELTC-IC (12-week) were efficiently recruited into proliferation and expanded in vitro in response to early acting cytokines, but conditions for expansion of ELTC-IC activity were distinct from those of traditional (5-week) LTC-IC and murine long-term repopulating cells. Whereas c-kit ligand (KL), interleukin-3 (IL-3), and IL-6 promoted proliferation and maintenance or expansion of murine long-term reconstituting activity and human LTC-IC, they dramatically depleted ELTC-IC activity. In contrast, KL, flt3 ligand (FL), and megakaryocyte growth and development factor (MGDF) (and KL + FL + IL-3) expanded murine long-term reconstituting activity as well as human LTC-IC and ELTC-IC. Expansion of LTC-IC was most optimal after 7 days of culture, whereas optimal expansion of ELTC-IC activity required 12 days, most likely reflecting the delayed recruitment of quiescent CD34(+)CD38(-) progenitors. The need for high concentrations of KL, FL, and MGDF (250 ng/mL each) and serum-free conditions was more critical for expansion of ELTC-IC than of LTC-IC. The distinct requirements for expansion of ELTC-IC activity when compared with traditional LTC-IC suggest that the ELTC-IC could prove more reliable as a predictor for true human stem cell activity after in vitro stem cell manipulation.

Animals↗
PubMed1999

The usage of veterinary antibacterial drugs for mastitis in cattle in Norway and Sweden during 1990-1997.

The prescribing patterns and annual incidence of use of antibacterial drugs for the treatment of mastitis in cattle in Norway and Sweden during the period 1990-1997 were estimated from drug wholesaler statistics. Although the drugs included in this study are also used in other species and/or other indications, mastitis in cattle is by far the most-common indication for their use. We used these sales figures to evaluate trends in the use of antibacterial drugs and changes in the incidence of treatment in bovine mastitis in Norway and Sweden. To facilitate comparisons (correcting for differences in activity and dosage) between the relative proportions of antibacterial drugs used in bovine mastitis, we introduced defined daily dose cow (DDDcow) as unit of measurement. Tentative DDDcow for the various injectable drugs were derived from doses recommended in Norway and Sweden. For intramammary drugs administered in the form of single-dose applicators, one applicator was defined as the DDDcow. The prescribing patterns of antibacterial drugs in bovine mastitis in Norway and Sweden during the study period seemed to be influenced by treatment policies, substances and formulations approved and treatment cost; length of the withdrawal period also seemed to play a role.

Animals↗
PubMed1999

Very low-density lipoprotein activates nuclear factor-kappaB in endothelial cells.

High plasma levels of VLDL are associated with increased risk for atherosclerosis. Here we show that VLDL (75 to 150 microg/mL) activates nuclear factor-kappaB (NF-kappaB), a transcription factor known to play a key role in regulation of inflammation. Oxidation of VLDL reduced its capacity to activate NF-kappaB in vitro, whereas free fatty acids such as linoleic and oleic acid activated NF-kappaB to the same extent as did VLDL. Intravenous injection of human VLDL (6 mg protein per kg) into rats resulted in arterial activation of NF-kappaB as assessed by electrophoretic mobility shift assay. Aortic endothelial cells showed positive nuclear staining for the activated RelA (p65) subunit of NF-kappaB at 6 to 24 hours after injection. There was also a parallel expression of the adhesion molecules intercellular adhesion molecule-1 and vascular cell adhesion molecule-1, as well as the cytokine tumor necrosis factor-alpha. Pretreatment of the rats with diet containing 1% of the antioxidant probucol for 8 weeks did not inhibit arterial activation of NF-kappaB in response to injection of VLDL. Moreover, injection of triglycerides (10% Intralipid, 5 mL/kg) activated arterial expression of NF-kappaB to the same extent as VLDL. Our results suggest that VLDL may promote the development of atherosclerotic lesions by activation of the proinflammatory transcription factor NF-kappaB. The effect appears to be mediated by a release of VLDL fatty acids but not to involve VLDL oxidation.

Animals↗
PubMed1999

Effect of G40R mutation on the binding of human SRY protein to DNA: a molecular dynamics view.

Molecular dynamics simulation was conducted to investigate the reason why the mutant G40R of hSRY protein has a low affinity for DNA. Compared with the previous dynamics results of the wild-type hSRY-HMG-DNA complex, the results of molecular dynamics simulation on the mutant G40R hSRY-HMG-DNA system demonstrated that the whole structure of DNA (especially the second strand) had a major deviation away from the short arm of the HMG box. Consequently, the DNA and the mutant protein could not specifically recognize each other, that is, very different, and low-occupancy, direct, and water-mediated hydrogen bonds were detected at the protein-DNA interface, no conformational changes occurred at the loop region around Met9 during the simulation, and residue IIe13 did not intercalate between the bases of A5 and A6. These results indicated that the mutant G40R did not form a specific complex with the DNA target, hence led to complete gonadal dysgenesis. From the simulation, we realized that the residue Gly40 played a critical structural role in the hSRY-DNA recognition. It might be a structural supporting point of DNA binding because of the absence of a side chain. The reason for the difficulty of the mutant G40R to form a complex with DNA might be that the long and positively charged side chain of Arg40 by its bulk and positive charge hindered the DNA's access to the active sites of the protein.

DNA-Binding Proteins↗
PubMed1999

Risk factors for sudden unexpected death in epilepsy: a case-control study.

BACKGROUND: Sudden unexpected death is substantially more common in people with epilepsy than in the general population. Our objective was to investigate the association between some clinical variables and sudden unexpected death in epilepsy (SUDEP) to identify risk factors. METHODS: This nested case-control study was based on a cohort of people aged between 15 and 70 years, who, during 1980-89, had been admitted to and discharged with a diagnosis of epilepsy from any hospital in the county of Stockholm. The study population was followed up through the National Cause of Death Register until Dec 31, 1991. Cases were individuals who had died, with a diagnosis of epilepsy registered on the death certificate, and who after review of medical and necropsy records were found to meet our SUDEP criteria. Three control participants, who were living epilepsy patients matched for age and sex, were selected from the same cohort for each case. All medical records were examined. Clinical data were collected and analysed on a predesigned protocol. FINDINGS: 57 SUDEP cases were included, of whom 91% had undergone necropsy. The relative risk of SUDEP increased with number of seizures per year. The estimated relative risk was 10.16 (95% CI 2.94-35.18) in patients with more than 50 seizures per year, compared with those with up to two seizures per year. The risk of SUDEP increased with increasing number of antiepileptic drugs taken concomitantly--9.89 (3.20-30.60) for three antiepileptic drugs compared with monotherapy. Other major risk factors were early-onset versus late-onset epilepsy (7.72 [2.13-27.96]), and frequent changes of antiepileptic drug dosage compared with unchanged dosage (6.08 [1.99-18.56]). The association between SUDEP risk and early onset, and SUDEP risk and seizure frequency, was weaker for female than for male patients, whereas frequent dose changes showed a stronger association in female patients. INTERPRETATION: Our data suggest that SUDEP is a seizure-related event, although the pathophysiological substrate that predisposes individuals to SUDEP may be established at an early age, and there may be some sex differences. Improvement of seizure control and possibly the avoidance of polytherapy may be ways to reduce the risk of SUDEP.

Adolescent↗
PubMed1999

Structural and dynamic differences of the estrogen receptor DNA-binding domain, binding as a dimer and as a monomer to DNA: molecular dynamics simulation studies.

Molecular dynamics (MD) simulations of the estrogen receptor DNA-binding domain (ERDBD) as a dimer in complex with its DNA response element (ERE) show a significant difference in both structure and dynamics, compared to a MD simulation of monomeric ERDBD bound to its half-site response element (EREH). The C-terminal zinc binding domain (ZnII), including a region (helix II) which is in a helical conformation in ERE-(ERDBD)2, is considerably more flexible in EREH-ERDBD than in the dimeric complex. In EREH-ERDBD, all helical hydrogen bonds in helix II are broken and the entire ZnII region is detached from a hydrogen bonding network that in ERE-(ERDBD)2 connects to other parts of the protein as well as to the DNA. The regions that become flexible in EREH-ERDBD are identical to the regions where the NMR solution structure of free ERDBD is poorly ordered. This strongly suggests that dimerisation of ERDBD is required for ordering of the ZnII region and that monomeric binding to DNA is not sufficient for the ordering. This contrasts to the glucocorticoid receptor DNA-binding domain (GRDBD) which has essentially the same mobility (uniform and limited), regardless of whether it is free as a monomer in solution, bound as a monomer to its half-site response element or in a dimeric complex with the full response element. The hydrogen bonding network that connects ZnII with other parts of the protein and to DNA is almost identical in ERDBD and GRDBD. However, in GRDBD there is also a serine (in the N-terminal zinc coordinating region) with a central role in this network, connecting to the ZnII region. This serine is replaced by a glycine in ERDBD and we suggest that this substitution is sufficient for destabilisation of the network, thus leading to a more flexible ZnII region, which becomes ordered first upon forming a complex with another ERDBD and DNA.

Amino Acid Sequence↗
PubMed1999

Molecular dynamics simulations of the complex between human U1A protein and hairpin II of U1 small nuclear RNA and of free RNA in solution.

RNA-protein interactions are essential to a wide range of biological processes. In this paper, a 0.6-ns molecular dynamics simulation of the sequence-specific interaction of human U1A protein with hairpin II of U1 snRNA in solution, together with a 1.2-ns simulation of the free RNA hairpin, is reported. Compared to the findings in the x-ray structure of the complex, most of the interactions remained stable. The nucleotide U8, one of the seven conserved nucleotides AUUGCAC in the loop region, was unusually flexible during the simulation, leading to a loss of direct contacts with the protein, in contrast to the situation in the x-ray structure. Instead the sugar-phosphate backbone of nucleotide C15 was found to form several interactions with the protein. Compared to the NMR structure of U1A protein complexed with the 3'-untranslated region of its own pre-mRNA, the protein core kept the same conformation, and in the two RNA molecules the conserved AUUGCAC of the loop and the closest CG base pair were located in very similar positions and orientations, and underwent very similar interactions with the protein. Therefore, a common sequence-specific interaction mechanism was suggested for the two RNA substrates to bind to the U1A protein. Conformational analysis of the RNA hairpin showed that the conformational changes of the RNA primarily occurred in the loop region, which is just involved in the sites of binding to the protein and in agreement with experimental observation. Both the loop and stem of the RNA became more ordered upon binding to the protein. It was also demonstrated that the molecular dynamics method could be successfully used to simulate the dynamical behavior of a large RNA-protein complex in aqueous solution, thus opening a path for the exploration of the complex biological processes involving RNA at a molecular level.

Amino Acid Sequence↗
PubMed1999

Structure, interaction, dynamics and solvent effects on the DNA-EcoRI complex in aqueous solution from molecular dynamics simulation.

A 0.7-ns molecular dynamics simulation of the DNA-EcoRI complex in a 7.0-A solvent shell indicated a stable behavior of the system. No significant evaporation or smearing of the solvent's outer boundary occurred. The structure and the intermolecular interactions were found to be well maintained during the simulation. The interaction pattern in the simulation was found to be very similar to that in the crystal structure. Most of the specific interactions between the DNA and the protein were found to be enhanced in the simulation compared to that in the crystal structure as a result of improved interaction geometry. The nonspecific interactions were found to be stronger than the specific ones. The specific interactions between the N7 atoms of Gua(4) or Ade(5) or Ade(6) and the protein were found to be present over almost the entire time of the simulation, whereas hydrogen bonds involving the amino groups of the Ade(5) and Ade(6) with the protein were found to be relatively weaker, with lower probability and shorter lifetime. The time evolution of the root mean square deviations of the DNA and the protein were highly correlated even at the later part of the simulation, showing the tight binding between them. Several long-lived water bridges were found between the DNA backbone atoms and the protein and also between the two protein monomers, which increased the overall stability of the complex. The two protein monomers were found to interact strongly with each other. The energy of the DNA kink deformation was estimated as approximately 31 kcal/mol.

Binding Sites↗
PubMed1999

Free energy calculations and molecular dynamics simulations of wild-type and variants of the DNA-EcoRI complex.

Molecular dynamics simulations and free energy calculations of the wild-type EcoRI-DNA complex and several variants have been performed in aqueous solvent. In general, he theoretical estimations of the free energy differences (DeltaDeltaA) qualitatively agree well with the corresponding experimental data. The modifications which were experimentally found unfavorable compared to the wild-type complex were also found to be so in theoretical estimates. The mutant where the amino group of the base Ade(6) was replaced by a hydrogen atom eliminating one H-bond between the DNA and the protein, was experimentally found to be more stable than the wild-type complex. It was speculated that the modification also caused a structural relaxation in the DNA making DeltaDeltaA favorable. Our theoretical estimate yields a positive DeltaDeltaA in this case, but the difference is small, and no significant local structural relaxation was observed. The major H-bonds between the DNA and the protein in the wild-type complex are found to be maintained in the different mutants although the specific and non-specific interaction energies between the interacting the DNA bases and the protein residues are different in different mutants. The interaction pattern of the other nearby nucleotides are significantly influenced by each modification. Thus, the alteration of the non-specific interactions may also play an indirect role in determining the specificity of the complex. The interaction of the Gua(4) of the DNA with the protein is found to be most sensitive to any alteration in the recognition site. Because Gua(4) is the nucleotide closest to the scissile bond, this extra sensitivity seems to play an important role in altering the functional activity of the complex.

Binding Sites↗
PubMed1999

Prospective study of the clinical and laboratory parameters of patients in whom ovarian hyperstimulation syndrome developed during controlled ovarian hyperstimulation for in vitro fertilization.

OBJECTIVE: To compare patient characteristics and clinical and laboratory parameters in patients in whom ovarian hyperstimulation syndrome (OHSS) develops with those in whom it does not develop. DESIGN: Prospective cohort study. SETTING: Reproductive medicine unit at a university medical center. PATIENT(S): All patients undergoing IVF (n = 428) who received controlled ovarian hyperstimulation during a 6-month period. INTERVENTION(S): Prospective data collection. MAIN OUTCOME MEASURE(S): Patient characteristics (age, body mass index, medical history, smoking habits) and clinical and laboratory data obtained during controlled ovarian hyperstimulation were evaluated in patients who had severe OHSS, any degree of OHSS, or a significant risk of OHSS and compared with the remaining populations. RESULT(S): Severe OHSS developed in 18 patients (4.2%) and mild or moderate OHSS developed in 7.3%. As a group, all the patients with OHSS were significantly younger, received lower doses of gonadotropins, had ovaries containing a higher number of total and large follicles, had a higher number of retrieved oocytes, and had a higher pregnancy rate than the patients without OHSS. The patients with severe OHSS also had an increased prevalence of allergy (56% versus 21%) and were more likely to ultimately give birth. CONCLUSION(S): The observed differences may be useful in elucidating the pathophysiology of OHSS and identifying patients who are at increased risk for OHSS.

Adult↗
PubMed1999

Allergic disease in teenagers in relation to urban or rural residence at various stages of childhood.

BACKGROUND: Higher prevalences of allergic diseases and IgE antibodies to inhalant allergens have been reported for persons living in urban areas than for persons living in rural areas. METHODS: Associations between cumulative incidences of allergic diseases in 1878 children aged 13-14 years and their place of residence (urban, semiurban, or rural) from birth were assessed by questionnaire (ISAAC), in order to find out whether there is a period of increased sensitivity to external influences during the first few years of life. Family history and exposure to pets, tobacco smoke, and damp were considered in multiple regression. RESULTS: There was a significantly higher prevalence of allergic diseases with urban residence than with rural residence during the first 2 years of life (e.g., for bronchial asthma, relative risk (RR) for the first year 2.1, 95% CI 1.2-3.7). An increased risk was still found after multiple regression (RR=1.7). Semiurban residence was associated with an intermediate cumulative incidence of allergic diseases. Maternal smoking during pregnancy was associated with asthma (RR=1.4, 95% CI 1.0-2.0). CONCLUSIONS: The findings support a period of increased susceptibility during the first years of life. Whether rural lifestyle protects against allergy or whether urban pollutants contribute to allergy has to be elucidated [corrected].

Adolescent↗
PubMed1999

Presence of arteriovenous shunting in transplanted but not in native single kidney in the rat.

OBJECTIVE: We previously reported the presence of renal arteriovenous (A-V) shunting in rats subjected to renal transplant rejection, hydronephrosis and severe hypotension caused by bleeding. The question as to whether blood partially by-passes the renal cortex under certain conditions is still controversial and an alternative explanation for the findings has been vasodilatation. The aim of this investigation was to determine whether A-V shunting is part of the haemodynamic changes taking place after unilateral nephrectomy and if the sympathetic nervous system is involved. MATERIAL AND METHODS: Unilateral nephrectomy was performed and radioactive microspheres (15.5 microm) were injected into the right remaining renal artery 30 min (n = 10), 24 h (n = 13) and 3 weeks (n = 14) later. The proportion of radioactivity in the lungs was considered to reflect A-V shunting in the kidney. Sham-operated animals (n = 30) and animals (n = 10) without previous sham operation, all with two kidneys, were used as controls. Isogenic renal transplantation (n = 10) was performed after bilateral nephrectomy to represent a denervated single kidney status. RESULTS: Renal A-V shunting was significantly (p < 0.001) reduced 30 min and 3 weeks after unilateral nephrectomy compared with controls. In isogenically transplanted rats, A-V shunting was not reduced compared with sham-operated animals, and significantly (p < 0.001) greater compared with the reduced levels of shunting at all times after unilateral nephrectomy. CONCLUSIONS: Reduced renal shunting of microspheres was observed after uninephrectomy and seems to require an intact renal innervation. It is likely that vasodilatation after unilateral nephrectomy and A-V shunting are two separate phenomena.

Animals↗
PubMed1999

Diagnostic epididymal and testicular sperm recovery and genetic aspects in azoospermic men.

Various procedures for sperm recovery in azoospermic men have been described, from open testicular biopsy to simple needle aspiration from the epididymis and the testis. Fifty-one obstructive and 86 non-obstructive azoospermic men were treated to compare the recovery of spermatozoa obtained by percutaneous aspiration from the epididymis (PESA) and aspiration/extraction from the testis (TESA, TESE) with histopathology. If TESA failed, the work up proceeded with TESE. All patients were karyotyped. Spermatozoa were recovered by PESA or TESA in all obstructive men (51/51 patients). In 22 out of 86 patients with non-obstructive azoospermia, testicular spermatozoa could be successfully recovered by TESA. In five additional patients TESE was successful in recovering spermatozoa where TESA had failed. In 43 patients, neither TESA nor TESE was successful. Sixteen patients chose not to proceed with TESE. Seven out of 86 patients had an abnormal karyotype in the non-obstructive group (8%), none in the obstructive group. In the non-obstructive patient group testicular histopathology showed hypospermatogenesis, incomplete maturation arrest and germ cell aplasia with focal spermatogenesis in cases where spermatozoa were recovered and complete germ cell aplasia, complete maturation arrest and fibrosis in cases where no spermatozoa were found. Spermatozoa were recovered by PESA or TESA from all patients with obstructive azoospermia and from approximately 40% of patients with non-obstructive azoospermia by TESA or TESE. Retrieval of viable spermatozoa in the infertility work-up was highly predictable for sperm recovery in subsequent ICSI cycles. TESA performed under local anaesthesia seems almost as effective as more invasive procedures in recovering testicular spermatozoa, both in obstructive and non-obstructive azoospermic men.

Epididymis↗
PubMed1999

A prospective randomized study of electro-acupuncture versus alfentanil as anaesthesia during oocyte aspiration in in-vitro fertilization.

The aim of the present study was to evaluate the anaesthetic effect during oocyte aspiration of a paracervical block (PCB) in combination with either electro-acupuncture (EA) or intravenous alfentanil. In all, 150 women undergoing in-vitro fertilization (IVF) and embryo transfer were randomized to receive either EA plus PCB or alfentanil plus PCB. Visual analogue scales (VAS) were used to evaluate subjective experiences during oocyte aspiration, and IVF outcome parameters were recorded. No differences in pain directly related to oocyte aspiration, adequacy of anaesthesia during oocyte aspiration, abdominal pain, or degree of nausea were found between the two groups in the VAS ratings. Before oocyte aspiration, the level of stress was significantly higher in the EA group than in the alfentanil group (P < 0.05), and the EA group experienced discomfort for a significantly longer period during oocyte aspiration (P < 0. 01). Compared with the alfentanil group, the EA group had a significantly higher implantation rate (P < 0.05), pregnancy rate (P < 0.05), and take home baby rate (P < 0.05) per embryo transfer. In conclusion, EA has been shown to be as good an anaesthetic method as alfentanil during oocyte aspiration, and we suggest that EA may be a good alternative to conventional anaesthesia during oocyte aspiration.

Adult↗
PubMed1999

Presence of uterine pinopodes at the embryo-endometrial interface during human implantation in vitro.

In order to study changes occurring on the surfaces of human endometrial epithelial cells in the presence of an implanted blastocyst, we used scanning electron microscopy for investigation of five endometrial biopsies and three human implantation sites obtained in vitro. All specimens showed areas with endometrial pinopodes, separated by cells displaying microvilli or cilia at the apical surface. Pinopode formation was more pronounced in endometrial biopsies than in cell cultures. All blastocysts adhered to pinopode presenting cells. Endometrial surface changes were not seen around the blastocysts. The results of this study demonstrate that cultured endometrial epithelial cells are capable of pinopode formation. Furthermore, endometrial epithelial pinopodes, generally considered as a marker of endometrial receptivity, seem to be directly involved in the adhesion of the blastocyst to the endometrial surface.

Blastocyst↗
PubMed1999

Obstetric outcome and psychological follow-up of pregnancies after embryo reduction.

The obstetric outcome and psychological follow-up of the parents after embryo reduction performed at Sahlgrenska University Hospital between 1993 and 1997 in 13 women treated for infertility is described. A comparison is made with non-reduced multiple pregnancies, both spontaneous and multiple pregnancies after assisted reproduction technology. Altogether 10 triplets, two quadruplets and one quintuplet pregnancy underwent embryo reduction. The surgical procedure was performed in gestation week 7-8 by transvaginal, ultrasound-guided aspiration of embryonic tissue. The psychological follow-up included personal interviews and psychological evaluations by a Psychological General Well-being Scale (PGWB) and Beck's Depression Inventory (BDI). In 11 cases reduction was performed to twin pregnancies. In two cases of triplets after in-vitro fertilization and transfer of two embryos, reduction was performed on the monozygotic, monochorionic twins. No complete miscarriages occurred. Ten women delivered twins and three women delivered singletons. The mean gestation length was 40.4 weeks for singletons and 35.9 weeks for twins. The mean birthweight was 3411 g for singletons and 2392 g for twins. No complications related to the reduction were detected in the children.The psychological follow-up showed that the psychological well-being of the parents was good. However, the events around the reduction were experienced as chaotic and emotionally disturbing. One woman regretted the reduction. All couples emphasized that avoidance of high order pregnancies should be of primary importance. In conclusion, embryo reduction appears to improve the perinatal outcome of multiple pregnancies obtained after assisted reproduction technology. It is important that the surgical procedure is performed at a centre with experience of this type of intervention, by a limited number of surgeons and in a regulated manner. Psychologically, however, the intervention is traumatic and psychological management is essential for good final outcome.

Adult↗