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Biomedical subjects

L Nilsson

Publications and source records attributed to L Nilsson.

At least 361 records · Page 20Linked to original sources
PubMed1984

High mutagenic activity formed in pan-broiled pork.

Lean pork was pan-broiled at various temperatures between 100 and 290 degrees C. Cooking was performed in an open frying pan common for domestic use in Sweden. No fat was added. Cooking procedures are clearly defined in order to facilitate inter-laboratory comparisons. The crust was extracted with organic solvents of varying polarity. The mutagenic activity was assayed with Ames' Salmonella mutagenicity test. Large amounts of mutagenic activity were detected in samples pan-broiled at 200-290 degrees C. The mutagenic activity recovered was about 10 times higher than that reported by previous investigators to be found during cooking of meat under similar conditions. This discrepancy could be due to differences in the composition of Swedish pork as compared to the meat samples used by other investigators or to different methodology in cooking and extraction procedures.

Animals↗
PubMed1984

Beta-endorphin administered into the lateral ventricle of the brain causes pulmonary platelet trapping in rabbits.

Human beta-endorphin was injected into the cerebrospinal fluid in rabbits by means of a needle inserted into the lateral ventricle of the brain. Control rabbits received an equal amount of saline. beta-Endorphin induced a significant pulmonary platelet trapping compared to control. beta-Endorphin had no effect on arterial blood pressure, heart rate, platelet aggregability ex vivo or fibrinolytic activity (fibrinolytic plates). The plasma activity of antithrombin III, kallikrein-like activity and kallikrein inhibitor determined by means of chromogenic substrates was not influenced by beta-endorphin.

Adenosine Diphosphate↗
PubMed1984

Short-term bioassays of nitro derivatives of benzo[a]pyrene and perylene.

Several nitroarenes derived from benzo[a]pyrene and perylene and the parent hydrocarbons have been assayed for mutagenicity in the Salmonella microsome test and for affinity for the 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD)-receptor protein in rat liver cytosol. 1- and 3-nitrobenzo[a]pyrene are mutagenic in the absence of S9 and have a response pattern in several Salmonella strains resembling that shown by 1-nitropyrene. 6-Nitrobenzo[a]pyrene, 3-nitroperylene as well as the parent unsubstituted hydrocarbons require S9 for activation. The 3,6- and 3,7-dinitroperylenes and a mixture of 3,9-/3,10-dinitroperylene are all mutagenic in the absence of S9. The response pattern of 3,9-/3,10-dinitroperylene resembles that shown by 1,6- and 1,8-dinitropyrenes. The nitro derivatives which are active in the absence of S9 are all inactivated by the addition of an incomplete S9 lacking NADP but activity is regained in the presence of the complete S9 for 1-and 3-nitrobenzo[a]pyrene and 3,6-dinitroperylene, showing that these compounds are also activated by S9 enzymes. Benzo[a]pyrene, 1- and 3-nitrobenzo[a]pyrene, 3-nitroperylene and the mixture of 3,9-/3,10-dinitroperylene have a high affinity for the TCDD-receptor protein whereas the affinity is low or below the detection level for the other compounds. These results are in good agreement with known structural requirements for receptor binding.

Animals↗
PubMed1984

Direct membrane-damaging effect of ketoconazole and tioconazole on Candida albicans demonstrated by bioluminescent assay of ATP.

Bioluminescent assays of fungal ATP in cultures of Candida albicans exposed to tioconazole and ketoconazole demonstrated that intracellular ATP levels were directly related to cell viability. At high concentrations of drug, a fungicidal effect was indicated by a very rapid and heavy leakage of ATP and a simultaneous, dramatic decrease in intracellular ATP. This leakage was due to direct membrane damage, which was less pronounced after exposure to ketoconazole than to tioconazole. After exposure to lower imidazole concentrations, intracellular ATP indicated growth inhibition without significant leakage of ATP. These findings support the hypothesis that imidazole antifungal agents basically act in the same manner but at different concentrations.

Adenosine Triphosphate↗
PubMed1984

Regrowth of aminoglycoside-resistant variants and its possible implication for determination of MICs.

Regrowth of aminoglycoside-resistant variants was seen when large inocula of two strains of Escherichia coli were incubated with gentamicin in concentrations well above their MICs (0.5 micrograms/ml). The extent of the selection of resistant variants was proportional to the concentration of gentamicin during incubation; after incubation with gentamicin (greater than or equal to 2 micrograms/ml for 24 h), all bacteria were resistant to at least 8 micrograms/ml. Bacteria resistant to these concentrations always formed small colonies, whereas variants resistant to lower concentrations (1 to 2 micrograms/ml) could form both small and normal colonies. The regrowth of resistant variants could be monitored by luciferase assay of intracellular ATP in cultures incubated with gentamicin (less than or equal to 2 micrograms/ml). In cultures incubated with higher concentrations, regrowth did occur, although this did not result in viability (CFU per milliliter) or ATP levels above those of the initial inocula. The implications of this regrowth for MIC determinations in broth and the possible clinical revelance of the resistant variants are discussed.

Aminoglycosides↗
PubMed1984

Correlation of bioluminescent assay of gentamicin in serum with agar diffusion assay, latex agglutination inhibition card test, enzyme immunoassay, and fluorescence immunoassay.

An improved bioluminescent assay of gentamicin in serum, based on the dose-dependent effect of the agent on the accumulation of extracellular ATP in Escherichia coli LU 14 cultures, is presented. The accuracy of the bioluminescent assay of gentamicin, expressed as the mean coefficient of variation over the therapeutic range, was 2.8%. Corresponding figures for an agar diffusion assay, a latex agglutination inhibition card test, an enzyme immunoassay, and a fluorescence immunoassay were 6.4, 17.5, 4.2, and 9.4%, respectively. All of the methods correlated well (r = 0.926 to 0.976), with the possible exception of the card test (r = 0.777 to 0.841). The bioluminescent assay requires only 1 microliter of serum, which allows for capillary sampling, and results are available within 75 min.

Adenosine Triphosphate↗
PubMed1984

In vitro effect of danazol on steroidogenesis in developing human follicles. An interim report.

In order to show whether or not danazol exerts direct effects on the cells of the human ovarian follicle, follicular granulosa and thecal cells of follicles in different stages of development are currently being investigated in short-term incubation experiments and during more prolonged cell culture. Cells are isolated by free-hand dissection from follicles of 8 to 25 mm diameter, corresponding approximately to cycle day 7 to 14. Granulosa and thecal cells have so far been incubated for 2 to 4 hours in the presence or absence of hCG and/or danazol. A small number of cell cultures of granulosa cells have been performed for up to 6 days in the presence or absence of danazol, hFSH, and hLH, in various combinations. The progesterone (P), estradiol-17 beta (E) and androstenedione (A) content of the incubation or culture medium and the tissue content of cyclic AMP (cAMP) were measured. Danazol (10 micrograms/ml) inhibited thecal cAMP production in most short-term experiments but only the hCG-stimulated cAMP production of granulosa cells. Short-term production of P and E by granulosa and of A and E by thecal cells was also inhibited by danazol in certain circumstances. In tissue cultures of granulosa cells lasting up to 4 days, danazol (1 and 10 micrograms/ml) inhibited both the FSH and LH-stimulated P production. Provided that any unspecific effects of the concentrations of danazol used can be ruled out, the results seem to indicate that this substance may act directly upon steroidogenesis at the ovarian follicular level.

Androstenedione↗
PubMed1983

The influence of spermine on the structural dynamics of yeast tRNAPhe.

A tRNAPhe derivative carrying ethidium at position 37 in the anticodon loop has been used to study the effect of spermine on conformational transitions of the tRNA. As previously reported (Ehrenberg, M., Rigler, R. and Wintermeyer, W. (1979) Biochemistry 18, 4588-4599) in the tRNA derivative the ethidium is present in three states (T1-T3) characterized by different fluorescence decay rates. T-jump experiments show two transitions between the states, a fast one (relaxation time 10-100 ms) between T1 and T2, and a slow one (100-1000 ms) between T2 and T3. In the presence of spermine the fast transition shows a negative temperature coefficient indicating the existence of a preequilibrium with a negative reaction enthalpy. Spermine shifts the distribution of states towards T3, as does Mg2+, but the final ratio [T2]/[T1] obtained with spermine is higher than with Mg2+, which we tentatively interpret to mean that spermine stabilizes one particular conformation of the anticodon loop.

Kinetics↗
PubMed1983

Rapid bioluminescent assay for determining netilmicin and tobramycin concentrations in serum.

A rapid bioluminescent assay for determining netilmicin and tobramycin concentrations in serum based on the dose-dependent effect of these agents on the accumulation of extracellular ATP in Escherichia coli LU 14 cultures is presented. This strain of Escherichia coli is unaffected by antibiotics used in combination with aminoglycosides and it lacks significant ATP-ase activity, which is a prerequisite for extracellular ATP accumulation. ATP was quantified by the firefly bioluminescence system. The accuracy of the bioluminescent assay expressed as mean coefficient of variation over the therapeutic range was 3.2%; corresponding figures for EMIT and an agar disk diffusion assay were 4.2% and 4.8% respectively. All methods used correlated well (r = 0.935-0.986) when they were evaluated on clinical serum specimens. The bioluminescent assay requires 25 microliters serum and results are available within 75 min.

Adenosine Triphosphate↗
PubMed1983

Collection of human oocytes by the use of sonography.

A technique for ultrasonically guided percutaneous oocyte aspiration was developed utilizing standard real-time, linear-array ultrasound equipment. Forty-four patients attending our in vitro fertilization and embryo transfer (IVF-ET) program were included in this study. In 38 patients, follicular puncture was performed under general anesthesia and in 6 cases performed under local anesthesia. Fifty-two follicles with a mean diameter greater than or equal to 18 mm were punctured, and 40 mature oocytes were recovered corresponding to a success rate of 77% per follicle. Six of the punctured follicles were considered cystic when the aspirated granulosa cells were examined microscopically and, if these were excluded, the corrected recovery rate was 87% per follicle. In two patients, ovulation had occurred at the time for oocyte collection. In one of these patients, a mature oocyte was, however, recovered from the pouch of Douglas by the use of sonography. On the basis of these results, ultrasonically guided puncture of follicles for collection of human oocytes in our IVF-ET program seems suitable for use in all cases where laparoscopy is presently used and, moreover, in cases with severe adhesions, where laparoscopy may fail.

Embryo Transfer↗
PubMed1983

Rapid detection of bacterial growth in blood cultures by bioluminescent assay of bacterial ATP.

A method for rapid detection of bacterial growth in blood cultures by bioluminescent assay of bacterial ATP was developed. Samples from blood cultures were treated with a blood-lysing detergent combined with an ATP-hydrolyzing enzyme to destroy blood cell ATP. Blood cell ATP which was bound to cell debris and escaped the ATPase activity was then separated from the bacteria on Percoll density gradients. Bacterial ATP from the bacterial layer was determined by the firefly bioluminescence system. In simulated blood cultures inoculated with 10 CFU of bacteria per ml of blood, bacterial ATP levels exceeded the detection limit (10(-10) M) after 6 to 10 h of incubation. This ATP level corresponds to approximately 10(4) CFU of bacteria per ml.

Adenosine Triphosphate↗
PubMed1983

Inhibition of progesterone secretion in cultured human granulosa cells by a low molecular weight fraction of human follicular fluid.

Previous studies demonstrated that a low molecular weight peptide fraction (G10-3) from human follicular fluid (FFl) could inhibit steroidogenesis by rat granulosa cells in vitro. In the present study this FFl fraction was tested upon human granulosa cells. The G10-3 fraction (less than 1000 mol wt) was obtained by sequential gel filtration on Sephadex G50 and G10 of a steroid-free extract of a pool of human FFl collected from various-sized follicles at different stages of the menstrual cycle. Human granulosa cells were obtained from large, healthy follicles in the mid- to late follicular phase of eight patients, and cultured for 4-6 days in the absence or presence of G10-3. In all cases G10-3 produced a dose-dependent inhibition of basal progesterone secretion and, when tested, also of FSH-stimulated progesterone secretion. Inhibition of progesterone secretion appeared to be greater in cells obtained from less mature follicles as compared to cells obtained from follicles that were periovulatory. The results suggest the presence of a low molecular weight luteinizing inhibitor in human FFl.

Body Fluids↗
PubMed1983

Aspects concerning the role of prostaglandins for ovarian function.

The present review briefly summarizes the current view of the mechanisms whereby prostaglandins (PGs) may act to modulate ovarian function. Particular concern is devoted to the aspects of ovarian function which are under current investigation by the authors, namely follicular maturation and rupture, granulosa cell and oocyte maturation, and the formation and maintenance as well as the regression of the corpus luteum (CL). PGs are formed in the granulosa cells of the preovulatory follicle in response to gonadotropin action and are at their highest levels around the time of ovulation. PGs are believed to be obligatory for follicular rupture, but their mechanism of action is still unknown. In the process of oocyte maturation PGs can mimic the stimulatory effects induced by LH or hCG, but are probably not obligate mediators of these effects. The importance of PGs for CL formation and maintenance is so far unsettled, and PGs may be regarded more as modulators than as inducers for these processes. The most well-documented effect of PGs is the induction of CL regression. Evidence is presented that PGs may have this effect also in the human.

Alprostadil↗
PubMed1983

Actinomyces israelii in the genital tract of women with and without intra-uterine contraceptive devices.

Actinomycosis involving the female genital tract is more common among IUD users than others. The diagnosis is difficult and often delayed. It has been suggested that the finding of Actinomyces-like organisms or A. israelii in cervical smears indicates a risk of developing actinomycosis. A. israelii has not been regarded as a part of the indigenous genital flora. A group of IUD users without symptoms of genital tract infections were compared with a control group without IUDs. No Actinomyces-like organisms were found on cytological examination of cervical smears. Immunofluorescent staining and cultures identified A. israelii in 4% of the IUD users and in 3% of the non-users. Serologic precipitin tests for actinomycosis were negative in all women. None developed actinomycosis on follow-up of positive cases. The study indicates that A. israelii is a commensal of the female genital tract. The identification of A. israelii alone does not indicate that the patient risks developing actinomycosis. Other methods such as a serology test should be useful in defining the clinical significance of the findings.

Actinomyces↗
PubMed1983

Studies of antibodies to lipid A and Tamm-Horsfall in patients with inflammatory bowel disease.

Sera from patients with inflammatory bowel disease, ulcerative colitis (UC), or Crohn's disease (MC) were analysed for antibodies to lipid A and Tamm-Horsfall protein (TH), Escherichia coli O antigens, and food antigens, using enzyme-linked immunosorbent assay, indirect haemagglutination, and thin-layer immunoassay, respectively. C-reactive protein (CRP), an indicator of acute inflammation, was also studied. The MC and UC groups were not separated by any of the factors tested. The extent of the disease, however, seemed to influence the IgG antibody response to lipid A and TH. Patients with extended inflammatory areas in the intestine had decreased anti-lipid-A levels during the active phase of the disease compared with patients with less inflammation. In contrast, the IgG anti-TH levels were increased in these patients during both the active and inactive phases compared with less affected patients. Compared with healthy individuals, MC or UC patients showed decreased IgG anti-lipid-A levels. Both IgG and IgA anti-TH and total anti-O levels were increased compared with controls. Antibodies to cow's milk were lower in patients with inflammatory bowel disease than in the control group. CRP was increased in patients with active inflammatory bowel disease compared with inactive.

Adolescent↗
PubMed1983

Influence of human chorionic gonadotropin in vivo on steroid formation and gonadotropin responsiveness of isolated human preovulatory follicular cells.

Granulosa and thecal cells of preovulatory follicles taken from 12 women were isolated and incubated separately for 2 hours in the presence and absence of human chorionic gonadotropin (hCG). To six of these women, an ovulatory dose of hCG (9000 IU) had been given 24 to 30 hours before excision of the follicle. Following incubation, 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 appeared healthy and well developed, and the oocytes recovered were morphologically normal and mature. Exposure to hCG in vivo caused a shift in steroidogenesis from A toward P formation in isolated thecal cells and a marked increase in the P production by the granulosa cells of the preovulatory follicles. Furthermore, the thecal cells, but not the granulosa cells, developed refractoriness to further stimulation with hCG in vitro.

Adult↗