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Biomedical subjects

H Eriksson

Publications and source records attributed to H Eriksson.

At least 181 records · Page 10Linked to original sources
PubMed1984

Combination of solid-phase second antibody and internal sample attenuator counting techniques. Radioimmunoassay of thyroid-stimulating hormone.

A method is described for the quantitation of free and bound antigen in a new radioimmunoassay which does not require centrifugation or decantation steps. The method involves coupling a second antibody to agarose spheres which also contain entrapped crystals of bismuth oxide (Bi2O3) in order to attenuate the gamma-radiation from the bound fraction of the 125I-labelled antigen. The system is designed so that the samples may be measured in a gamma counter 15 min after the spheres have been added. This new method was compared to a conventional radioimmunoassay for the analysis of the thyroid-stimulating hormone (TSH). Data were obtained with the modified radioimmunoassay which showed both high sensitivity and precision and also had a good correlation (r = 0.951) with data obtained using a conventional method.

Animals↗
PubMed1984

Receptors for estrogens and progesterone in the porcine cervix.

In vitro binding and exchange methods were used to determine the levels of estradiol and progesterone receptors in cytosolic and nuclear fractions of cells obtained from the porcine cervix at different stages of the estrous cycle. The concentration of estradiol cytosolic receptors was about 4500 sites/cell during the luteal phase and increased to a maximum of approximately 7600 sites/cell on day 1 of the cycle, decreasing to a level of 2700 sites/cell on days 3-4. The estradiol nuclear receptor level increased between the end of the luteal phase and the onset of heat from 300 to 1200 sites/cell. No reduction in the number of nuclear sites was seen between day 1 and 3-4. The level of the progesterone cytosolic receptor and its cycle profile was very similar to that of the estradiol receptor. The nuclear receptor, however, reached its lowest level of 760 sites/cell on day 1 of the cycle, increased to a value of 4700 sites on days 3-4 and showed a steady level of about 1000 sites/cell during the luteal phase. The data obtained agree with present theories on the endocrine mechanisms regulating receptor levels in the uterus. Furthermore, these data support a concept in which the constriction of the cervix occurring in response to increased concentrations of circulating estradiol is mediated via steroid receptors.

Journal Article↗
PubMed1984

Health and aging characteristics of highly physically active 65-year-old men.

Eighteen highly physically active men aged 65 years, training since youth, were compared to 67-year-old men from the general population. Body fat was low in the well-trained men, particularly in the central regions of the body. They smoked less. They characterized themselves as being in a general state of good health and well-being. Plasma insulin values were remarkably low. Blood pressure and resting heart rate were lower and ventilatory capacity better than in controls, and they had less heart diseases. The "juvenile" traits in their energy metabolism as well as in blood pressure and in their own perception of being highly energetic were not associated with less aging characteristics of hair, skin, or function of senses. The results obtained in this selected group suggest that physical activity protects against several age-dependent conditions as well as obesity, also at a fairly advanced age. These findings as well as the observations of differences in ventilatory function, smoking habits, and well-being between the group of highly physically active men and the control group deserve further studies.

Aged↗
PubMed1984

Health and ageing characteristics of highly physically active 65-year-old men.

Eighteen highly physically active men at mean age of 65 years, and who had training since youth, were compared with men from the general population at 67 years of age (N = 644). Body fat was low in the well-trained men, particularly in central regions of the body. They smoked less and characterized themselves as being in a general state of good health and well-being. Plasma insulin values were remarkably low and blood pressure and resting heart rate were lower and ventilatory capacity better than in controls. The 'juvenile' traits in their energy metabolism, as well as in blood pressure and in their own perception of being highly energetic were not associated with less ageing characteristics of hair, skin or function of senses. The results obtained in this highly selected group suggest that physical activity might retard the rate of decline of some age-dependent factors, also at a fairly advanced age.

Aged↗
PubMed1984

Effects of manganese on the nervous system.

The acute effect of manganese on the synaptosomal sodium-dependent choline uptake was studied. Manganese (Mn) revealed a mixed competitive-noncompetitive inhibition of the choline uptake, at Mn concentrations in the mM range. We do not believe that lack of choline for transmitter synthesis is of importance in Mn poisoning. Manganese chloride intubation of neonatal rats resulted in reduced homovanillic acid content in the striatum and hypothalamus. No other alteration in the dopamine or serotonin metabolism was revealed. A mechanism of cytotoxic action of manganese is discussed in terms of its transition metal properties and interaction with reactive oxygen compounds which result in the production of substances that alkylate or oxidize the cellular thiols.

Animals↗
PubMed1983

Extraction of peripheral proteins from nicotinic acetylcholine receptor-enriched membranes.

The solubilisation of membrane proteins from nicotinic acetylcholine receptor-enriched membranes from the electric organ of Torpedo marmorata was studied. Chaotropic ions were shown to be ineffective in extracting peripheral proteins from these membranes. Two different anhydrides, 2, 3-dimethylmaleic and 3,4,5,6-tetrahydrophthalic anhydride, released certain peripheral membrane proteins but not the integral receptor protein. Treatment of membranes containing greater than 3 nmol alpha-bungarotoxin binding sites per mg protein with anhydride resulted in a 43 kDa polypeptide as the major constituent of the solubilised material. The nature of the 43 kDa polypeptide is discussed. Gentle anhydride treatment did not change the alpha-bungarotoxin and carbamoylcholine binding properties of the receptor.

Animals↗
PubMed1983

Changes in the redox state of neuroblastoma cells after manganese exposure.

The toxicological effects of manganese chloride on the redox state of thiols and on the lipid peroxidation in cultures of the neuroblastoma clone N1E 115 were studied. The cell cultures were exposed, after a stationary growth phase was attained, to manganese chloride (25-100 microM) for up to 9 days. The non-protein thiols decreased at the most 27% as compared to the controls. Significant effects were obtained at all manganese concentrations tested. The total thiol content was maximally reduced by 40%. This reduced thiol content was also reflected in a lowered activity of the thiolenzyme, glyceraldehyde-3-phosphate dehydrogenase in manganese exposed cells. In addition the lipid peroxide level in the cells was decreased during the manganese treatment.

Cells, Cultured↗
PubMed1983

Radioimmunoassay of triiodothyronine (T3) and thyroxine (T4). An assay with both the bound and free fraction of the hormone present in the counting vessel.

A radioimmunoassay for triiodothyronine T3 and thyroxine T4 without any manual separation is described. By the use of an aqueous two-phase system the free hormone was separated from the immunologically bound fraction and lifted out of the counting area of the gamma counter. The coefficient of correlation between results obtained with this method and with a conventional RIA was 0.97 and 0.93 for T3 and T4, respectively.

Humans↗
PubMed1983

Microanalysis of endogenous acetylcholine released from the hemidiaphragm of the rat.

A chemiluminescence method for the determination of endogenous acetylcholine was adapted to transmitter released from the hemidiaphragm of the rat. Released choline and acetylcholine were isolated and concentrated using KI3 precipitation. Between 1 and 20 pmol of acetylcholine may be measured without sample dilution. The detection limit for acetylcholine luminescence is 1.0 pmol; thus, with an observed precipitation recovery of approximately 30%, the lowest detectable released amount is 3.5 pmol. The limitations of the method are discussed.

Acetylcholine↗
PubMed1983

Methods of reducing the effect of spontaneous dissociation of antigen-antibody interactions in radioimmunoassays with special reference to internal sample attenuator counting (ISAC).

A time dependent decrease of sample counts was observed in an adsorption radioimmunoassay with internal sample attenuator counting. The drift caused a bias in the estimate of the amount of antigen in the samples. The size of this deviation was dependent upon the length of time after the calibration curve was made that the samples were measured. This was essentially due to dissociation of the antigen-antibody complexes as the adsorber can act as a second receptor to the antigen. Addition of slowly sedimenting starch microspheres or starch particles inhibited the drift by forming a diffusion barrier on the attenuating pellet.

Adsorption↗
PubMed1982

Gas chromatographic-mass spectrometric analysis of endogenous levels of estradiol in plasma and in cytosol from rat uterus.

A method that permits the analysis of low levels of estradiol in plasma from women, men and rats and in cytosolic fractions of uterine tissue is described. The samples are extracted with Amberlite XAD-2 and a phenolic fraction is isolated on a lipophilic ion exchanger. Less polar contaminants in this fraction are separated from estradiol on Sephadex LH-20. Estradiol from human plasma can then be analysed by gas chromatography-mass spectrometry (GC-MS) as the trimethylsilyl ether using a capillary column and single ion monitoring of m/z 416. Samples from rat plasma and uterine cytosol require final purification by high-performance liquid chromatography prior to the GC-MS analysis. The approximate detection limits with the GC-MS instrument used were 1 x 10(-11)--2 x 10(-11) moles/l in plasma and 5 x 10(-11) moles/kg in the uterus. Problems in the purification procedures and the specificity and sensitivity of GC-MS analyses are discussed.

Animals↗
PubMed1982

Effects of estradiol-17 alpha on nuclear occupancy of the estrogen receptor, stimulation of nuclear type II sites and uterine growth.

Estriol and estradiol-17 alpha (E2-17 alpha) have classically been described as weak or impeded estrogens since they are incapable of stimulating true uterine growth when administered acutely by single injection. We have demonstrated [16] that estriol is capable of stimulating true uterine growth when the hormone is administered by paraffin implant. The possibility that E2-17 alpha is similar to estriol was examined. A single injection of E2-17 alpha causes a rapid accumulation of the estrogen receptor in uterine nuclei and this is correlated with the stimulation of early uterotropic responses. The nuclear receptor content declines rapidly and no stimulation of nuclear type II sites or true uterine growth is observed. E2-17 alpha does however stimulate the replenishment of cytoplasmic estrogen receptor. This receptor-response profile is typical of a short acting estrogen such as estriol. Chronic exposure (96 h) of mature-ovariectomized rats to estradiol-17 alpha (4 mg) by beeswax implant results in continual nuclear occupancy by estrogen receptors, dramatic stimulation of nuclear type II sites and true uterine growth. It is not possible to determine whether the uterotropic stimulation was due to direct effects of E2-17 alpha since this isomer was partially metabolized to E2-17 beta and both isomers were found in uterine nuclei after an implant of E2-17 alpha. We conclude that E2-17 alpha is capable of acting as an estrogen, either by its inherent estrogenicity or by its conversion to E2-17 beta, and that it may be dangerous to consider this steroid to be an ineffective or inadequate estrogen.

Animals↗
PubMed1981

Liposome immune assay (LIA). Use of membrane antigens inserted into labeled lipid vesicles as targets in immune assays.

A new method is described for detection of membrane antigens and antibodies against such structures. By inserting partially purified rat transplantation antigen (RT-1) into iodine or fluorescein-labeled lipid vesicles, a precipitation of the liposome is demonstrated by the use of a specific alloantiserum and a heterologous anti-rat IgG serum. Precipitation of liposomes carrying WF transplantation antigens could be detected at a final dilution of the alloantiserum of 1:3000, which is comparable to that obtained in a 51Cr-release assay. Furthermore, when unpurified membrane proteins from WF splenocytes were incorporated into labeled liposomes, an amount of RT-1 corresponding to 8000 cells could be detected.

Animals↗
PubMed1981

Use of an internal sample attenuator in radioimmunoassay. Assay of triiodothyronine (T3) using starch particles containing entrapped charcoal and bismuth oxide in combination with free antibodies.

A radioimmunoassay for triiodothyronine involving no separate washing or separation steps is described. By using an internal sample attenuator, bismuth oxide, co-immobilized with the sorbent, charcoal, for the non-bound fraction of T3, a system was designed in which a suspension of starch spheres containing the sorbent and the attenuator was added after the immunological reaction had taken place. The particles sedimented and the whole test tube was counted in a gamma-counter. The coefficient of correlation between the results obtained with the present method and those from conventional procedures was 0.993.

Adsorption↗