Search PubMed⌕ Search

Biomedical subjects

L Nilsson

Publications and source records attributed to L Nilsson.

At least 325 records · Page 18Linked to original sources
PubMed1987

Effect of clomiphene isomers on progestin synthesis in cultured human granulosa cells.

The effect of en-clomiphene and zu-clomiphene (10(-9)-10(-5) M) on progestin synthesis in cultured human granulosa cells was studied under basal conditions and in the presence of LH (100 ng/ml). Granulosa cells were obtained from either pre-ovulatory follicles of clomiphene-HMG-stimulated cycles or from large follicles of mid-to-late follicular phase of spontaneous cycles. The basal and LH-stimulated progesterone accumulation was dose-dependently reduced by en- and zu-clomiphene (10(-6)-10(-5) M) in cells from both groups studied, an effect similar to that of oestradiol. In contrast to oestradiol, both en- and zu-clomiphene (10(-6)-10(-5) M) reduced the basal and LH-stimulated pregnenolone accumulation in cells of stimulated cycles. The effect of clomiphene on progesterone, and pregnenolone accumulation was more pronounced in LH-stimulated cells than under basal conditions. There were no qualitative differences between the two isomers and the results were principally the same in cells from both groups of follicles studied. It is concluded that en-clomiphene and zu-clomiphene have similar inhibitory effects on progestin synthesis in human granulosa cells in vitro.

Cells, Cultured↗
PubMed1987

Oocyte retrieval under the guidance of a vaginal transducer: evaluation of patient acceptance.

Follicle puncture under the guidance of ultrasound has now been used for some years. The most important advantage of the ultrasound-guided technique compared with the laparoscopic technique is that the former can be performed under local anaesthesia. However, both the trans-vesical and the perurethral ultrasound-guided puncturing routes may be quite painful for the patient. For that reason we have developed a trans-vaginal follicle puncture technique using a vaginal transducer. The aim of this study was to evaluate the patients' experience of pain with this new technique. Scanning of follicles was performed using a specially designed vaginal transducer that makes the patients having a full bladder unnecessary. Local anaesthesia was applied as a paracervical block. Follicles were then punctured through the vagina with a needle inserted through a needle guide attached to the transducer. Fifty-one patients answered a questionnaire about their experience of the puncture procedure. Only 10% of the patients found the puncture painful. Ninety-eight per cent of the patients felt no anxiety about going through the procedure again. We therefore conclude that trans-vaginal oocyte pick-up using a vaginal transducer is very well accepted by most women.

Anesthesia, Local↗
PubMed1987

Effect on fertilization of intra-peritoneal exposure of oocytes to carbon dioxide.

Follicular aspiration is generally performed via laparoscopy after creating a pneumoperitoneum with carbon dioxide (CO2). Adverse effects on embryo development may occur following exposure to CO2, which is known to cause a decrease in follicular fluid pH. Such a reduction in pH may affect fertilization and early embryonic development and this study was carried out to study these effects. Oocytes obtained by laparoscopy were compared with those obtained under ultrasonic guidance to determine whether CO2 exposure had any adverse effect. The results suggest that CO2 may affect fertilization, but once this has occurred, there is no effect of CO2 on the rate of cleavage of the embryos.

Carbon Dioxide↗
PubMed1987

Serum and plasma measurements of neutrophil granule proteins during cardiopulmonary bypass: a model to estimate human turnover of lactoferrin and myeloperoxidase.

During extracorporeal circulation (ECC), granule proteins such as lactoferrin and myeloperoxidase escape to the plasma in large amounts. ECC was used to study the turnover of these proteins and compare their variations in plasma and serum. During ECC both proteins rose to very high levels and the variations were similar in both serum and plasma (r = 0.93 for lactoferrin and 0.80 for myeloperoxidase). The initial elimination after termination of operation (t 1/2) was, for lactoferrin 0.75 and for myeloperoxidase 0.5 h. Both proteins followed a second order kinetics of elimination with a t 1/2 for lactoferrin of about 9 and for myeloperoxidase of about 25 h. 48 and 72 h postoperatively serum levels, but not plasma levels, of myeloperoxidase rose again 10-fold. We conclude that serum and plasma measurements of neutrophil granule proteins are complementary. The period after disconnection of the patient from the extracorporeal device may be used to estimate the turnover kinetics of neutrophil granule proteins.

Aged↗
PubMed1986

The mechanism of the protein-synthesis elongation cycle in eukaryotes. Effect of ricin on the ribosomal interaction with elongation factors.

The functional significance of the post-translocation interaction of eukaryotic ribosomes with EF-2 was studied using the translational inhibitor ricin. Ribosomes treated with ricin showed a decreased rate of elongation accompanied by altered proportions of the different ribosomal phases of the elongation cycle. The content of ribosome-bound EF-2 was diminished by approximately 65% while that of EF-1 was unaffected. The markedly reduced content of EF-2 was caused by an inability of the ricin-treated ribosomes to form high-affinity pre-translocation complexes with EF-2. However, the ribosomes were still able to interact with EF-2 in the form of a low-affinity post-translocation complex. Ricin-treated ribosomes showed an altered ability to stimulate the GTP hydrolysis catalysed by either EF-1 or EF-2. The EF-1-catalysed hydrolysis was reduced by approximately 70%, resulting in a decreased turnover of the quaternary EF-1 X GTP X aminoacyl-tRNA X ribosome complex. In contrast, the EF-2-catalysed hydrolysis was increased by more than 400%, despite the lack of pre-translocation complex formation. The effect was not restricted to empty reconstituted ribosomes since gently salt-washed polysomes also showed an increased rate of GTP hydrolysis. The results indicate that the EF-1- and EF-2-dependent hydrolysis of GTP was activated by a common center on the ribosome that was specifically adapted for promoting the GTP hydrolysis of either EF-1 or EF-2. Furthermore, the results suggest that the GTP hydrolysis catalysed by EF-2 occurred in the low-affinity post-translocation complex.

Animals↗
PubMed1986

Reduced turnover of the elongation factor EF-1 X ribosome complex after treatment with the protein synthesis inhibitor II from barley seeds.

The effect of the protein synthesis inhibitor II from barley seeds (Hordeum sp.) on protein synthesis was studied in rabbit reticulocyte lysates. Inhibitor treatment of the lysates resulted in a rapid decrease in amino acid incorporation and an accumulation of heavy polysomes, indicating an effect of the inhibitor on polypeptide chain elongation. The protein synthesis inhibition was due to a catalytic inactivation of the large ribosomal subunit with no effect on the small subparticle. The inhibitor-treated ribosomes were fully active in participating in the EF-1-dependent binding of [14C]phenylalanyl-tRNA to poly(U)-programmed ribosomes in the presence of GTP and the binding of radioactively labelled EF-2 in the presence of GuoPP[CH2]P. Furthermore, the ribosomes were still able to catalyse peptide-bond formation. However, the EF-1- and ribosome-dependent hydrolysis of GTP was reduced by more than 40% in the presence of inhibitor-treated ribosomes, while the EF-2- and ribosome-dependent GTPase remained unaffected. This suggests that the active domains involved in the two different GTPases are non-identical. Treatment of reticulocyte lysates with the barley inhibitor resulted in a marked shift of the steady-state distribution of the ribosomal phases during the elongation cycle as determined by the ribosomal content of elongation factors. Thus, the content of EF-1 increased from 0.38 mol/mol ribosome to 0.71 mol/mol ribosome, whereas the EF-2 content dropped from 0.20 mol/mol ribosome at steady state to 0.09 mol/mol ribosome after inhibitor treatment. The data suggest that the inhibitor reduces the turnover of ribosome-bound ternary EF-1 X GTP X aminoacyl-tRNA complexes during proof-reading and binding of the cognate aminoacyl-tRNA by inhibiting the EF-1-dependent GTPase.

Animals↗
PubMed1986

Structure refinement of oligonucleotides by molecular dynamics with nuclear Overhauser effect interproton distance restraints: application to 5' d(C-G-T-A-C-G)2.

The solution structure of the self-complementary DNA hexamer 5' d(C-G-T-A-C-G)2 is refined by restrained molecular dynamics in which 192 interproton distances, determined from pre-steady-state nuclear Overhauser enhancement measurements, are incorporated into the total energy of the system in the form of effective potentials. First the method is tested by applying an idealized set of distance restraints taken from classical B-DNA to a simulation starting off from A-DNA and vice versa. It is shown that in both cases the expected transition between A- and B-DNA occurs. Second, a set of restrained molecular dynamics calculations is carried out starting from both A- and B-DNA with the experimental interproton distances for 5' d(C-G-T-A-C-G)2 as restraints. Convergence to the same B-type structure is achieved with the interproton distances equal to the measured values within experimental error. The root-mean-square atomic difference between the two average restrained dynamics structures (less than 1 A) is approximately the same as the root-mean-square fluctuations of the atoms.

DNA↗
PubMed1986

Physostigmine restores 3H-acetylcholine efflux from Alzheimer brain slices to normal level.

A technique was developed, which made it possible to study the in vitro release of 3H-acetylcholine (3H-ACh) from human post mortem brain tissue, collected with short post-mortem delay (2,5-22 hours), both from controls and patients with Alzheimer's disease (AD/SDAT). The tritium (3H) release was investigated during potassium stimulation, and AD/SDAT cortical slices were found to release a decreased amount of 3H compared to control brain slices. Physostigmine, 10(-5) and 10(-4) M, has no significant effect on the release of 3H from control slices, while physostigmine 10(-4) M increased the evoked release from AD/SDAT brain slices over threefold, nearly to the control level.

Acetylcholine↗
PubMed1986

The immunosuppressive effect of streptozotocin-induced diabetes in rats.

Streptozotocin-diabetic isogenous Brown-Norway (BN) rats received heterotopic Wistar-Furth (WF X BN) F1 heart transplants. The functional graft survival time after different duration of diabetes and during insulin-treated diabetes was recorded. Some diabetic rats were challenged with sheep red cells, and their spleens were used in PHA stimulation and plaque-forming assays. Prolongation in heart transplant survival was found to be independent of the duration of diabetes. The prolongation disappeared promptly when insulin was administered to the diabetic rats. A depression of cellular immunoresponsiveness as measured by PHA stimulation assay was recorded during diabetes. Valid results were not obtained in the plaque-forming assay.

Animals↗
PubMed1986

Effects of danazol on steroidogenesis and gonadotropic responsiveness in isolated human preovulatory follicular cells.

In order to investigate the influence of danazol on steroidogenesis and gonadotropic responsiveness of human follicular cells, granulosa and thecal cells of preovulatory follicles were isolated and separately incubated for short term periods. Human chorionic gonadotropin (hCG) (100 IU/ml), FSH (0.5 IU/ml) and danazol (10 micrograms/ml) alone or in combination were added to the incubation medium. Following incubation the cellular cyclic adenosine 3'5' monophosphate (cAMP) levels and the medium content of progesterone (P), androstenedione (A) and 17 beta-estradiol (E2) were determined. All follicles included in the study were classified as nonatretic and well developed, i.e. less than 3 days before ovulation. Human chorionic gonadotropin caused an increase in cAMP formation in both cell-types and this effect was significantly counteracted by danazol in vitro. In granulosa cells danazol tended to counteract a stimulatory effect of FSH on cAMP formation. No significant influence of danazol was found on the basal steroid formation of both cell types during short term incubation. On the other hand, danazol significantly counteracted the FSH stimulated P formation of the granulosa cells and the hCG stimulated A and E2 formation of the thecal cells. It is concluded that danazol inhibits gonadotropin-stimulated steroidogenesis locally in the human follicular cells and that this effect of danazol is mediated via the cyclic AMP system.

Adult↗
PubMed1986

Subchronic treatment of rats with nicotine: effects on tolerance and on [3H]acetylcholine and [3H]nicotine binding in the brain.

The effects of subchronic nicotine treatment on the development of tolerance and on two nicotinic ligand binding sites were investigated. After subcutaneous injection of nicotine (0.45 mg nicotine base/kg) or saline twice a day for 14 days the body weight of rats was significantly lower than that of control animals. A significant tolerance to the acute effects of nicotine on locomotor activity and body temperature was observed after the treatment period. Nicotine treatment also resulted in a significant increase in [3H]acetylcholine (3H-ACh) binding in the midbrain (48.3% increase in comparison with controls) and hippocampus (38.3% increase), whereas the binding of [3H]nicotine (3H-NIC) was unaffected in all brain areas investigated. These results indicate that subchronic s.c. injections of nicotine can differentially affect the binding of two different nicotinic ligands in the brain. It is also concluded that the development of tolerance to the acute effects of nicotine on locomotor activity and temperature is not directly dependent upon changes in binding of [3H]nicotine to the brain.

Acetylcholine↗
PubMed1986

Selective growth of resistant variants during incubation of Enterobacteriaceae with four aminoglycosides.

The selective growth of resistant variants, present at low frequencies, varied with different strains of Enterobacteriaceae and different aminoglycosides. This phenomenon was more pronounced during incubation with amikacin than with gentamicin, netilmicin and tobramycin. Selective growth of the resistant variants resulted in an inoculum effect and an increase in MIC with longer incubation. In-vitro evaluation of this phenomenon may be justified when choosing an aminoglycoside for therapy.

Adenosine Triphosphate↗
PubMed1986

Oxygen consumption by human oocytes and blastocysts grown in vitro.

Oxygen consumption by human oocytes and blastocysts was analysed using a sensitive micro-spectrophotometric technique. Oocytes were obtained from women undergoing laparotomy for sterilization or hysterectomy, and blastocysts were obtained as spare embryos from the local in-vitro fertilization programme. There was no significant difference between oocyte oxygen consumption on the day of isolation and after 1 day of culture, 0.53 +/- 0.08 (n = 9) and 0.35 +/- 0.06 (n = 5) nl/h oocyte, respectively. Blastocyst oxygen consumption was measured after a culture period of 5-8 days after in-vitro fertilization. Mean oxygen consumption by healthy looking blastocysts was 0.34 +/- 0.03 (n = 15) nl/h blastocyst, and there was no change in oxygen consumption with culture time. This level of respiration was lower than expected, both when compared with the oocytes and when compared with levels reported for blastocysts of other species.

Blastocyst↗
PubMed1986

Influence of clomiphene citrate in vivo on subsequent steroid formation and gonadotropic responsiveness in vitro of isolated human follicular cells.

Granulosa and thecal cells from human preovulatory follicles, extirpated from the ovaries of women undergoing sterilization by minilaparotomy, were incubated for 2 hours in the presence or in the absence of human gonadotropin (hCG). The follicles were obtained from 16 women, 8 of whom had previously been treated with clomiphene citrate (CC) to induce follicular maturation. The tissue contents of cyclic AMP (cAMP) and the content of progesterone (P), testosterone (T) and estradiol-17 beta (E2) in the incubation medium were measured. Granulosa and thecal cells from control and CC-induced follicles all responded to hCG in vitro with increased formation of cAMP. Both granulosa and thecal cells from CC-induced follicles produced larger amounts of P in vitro than cells from spontaneously matured follicles. There were no other differences in the patterns of steroid formation or reactivity to hCG between the cells from the two types of follicle. It is concluded that CC treatment in vivo induces the growth and maturation of preovulatory follicles with apparently normal biochemical characteristics, as far as the content of and capacity to form cyclic AMP, progesterone, testosterone and estradiol-17 beta are concerned.

Adult↗
PubMed1986

In vitro aminoglycoside resistance of gram-negative bacilli and staphylococci isolated from blood in Sweden 1980-1984.

The in vitro susceptibility to gentamicin, tobramycin, amikacin and netilmicin in septicaemia isolates was followed during 1980-1984 in 6-8 Swedish laboratories. The bacterial distribution was similar over the years and was dominated by Escherichia coli and staphylococci. Resistance to gentamicin was found in 2.3-3.6%, to tobramycin in 1.4-3.4%, to amikacin and netilmicin in 0.5-0.9%. Production of aminoglycoside modifying enzymes was observed among resistant strains.

Amikacin↗