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Biomedical subjects

G Ronquist

Publications and source records attributed to G Ronquist.

At least 217 records · Page 12Linked to original sources
PubMed1982

New spectrophotometric method for the determination of hemoglobin A1 compared with a microcolumn technique.

We compared a spectrophotometric kit method (Glycospec) for determination of glycosylated hemoglobin (HbA1) with a microcolumn kit method (Bio-Rad). The Glycospec method is based on the change in absorbance when phytic acid binds to hemoglobin A. With glycosylated hemoglobin there is no such change because the binding is blocked by the sugar moiety. Inter-assay CVs were 2-6% for both methods. In healthy subjects the mean (+/- SD) value for HbAl was about 1% higher with the spectrophotometric than the microcolumn method. For samples from 122 diabetics the correlation between values for HbAl obtained with the two methods was acceptable (r = 0.89), although the spectrophotometric technique yielded 2-4% higher values, a difference at least partly due to the absence of 2,3-diphosphoglycerate from the spectrophotometric standards. Adding 1.8 mmol of it per liter to these standards caused displacement of the standard curve; HbAl values then agreed well with those of the microcolumn method. The spectrophotometric procedure is easily automated, and therefore is well suited for large-scale analyses if problems with standards and calibration can be solved.

Chromatography, Liquid↗
PubMed1981

The in vitro transport of 14C-alpha-aminoisobuturic acid into blastocysts from mice in delay and after activation for implantation.

The uptake of 14C-AIB (14C-alpha-aminoisobuturic acid) into mouse blastocysts was studied in vitro. The flushed blastocysts fell into two size categories, namely large or "expanded" and small or "contracted". The arithmetic mean volume for the large blastocysts grew from 0.58 nl for delayed blastocysts to 0.76 nl for 8 h activated ones, while both delayed and activated small blastocysts had a mean volume of 0.22 nl. Delayed and 8 h activated large blastocysts showed an enhanced uptake of 14C-AIB with time of incubation, the uptake increasing 3-fold from 15 min to 60 min. The small blastocysts generally showed a higher uptake than the large ones, but the activated small blastocysts were atypical in that they unexpectedly displayed a 3-fold decrease in uptake at 60 min incubation as compared with 15 min. The early peaks of 14C-AIB uptake in vivo by uterine tissue and blastocysts were shown to be well correlated to the uptake in vitro. The presence of a working System A carrier in the activated blastocysts was demonstrated by showing that the uptake of AIB was sodium dependent and could be inhibited by N-methyl-AIB. Ultrastructural studies by scanning and transmission electron microscopy revealed that the trophoblast of large blastocysts was elongated and covered by numerous microvilli on a slightly bulging surface. The small blastocysts on the other hand displayed cuboidal trophoblast cells, sometimes in a pseudostratified arrangement, with the outer surface covered by many ridges.

Amino Acids↗
PubMed1981

Abnormal deficiency of both Mg2+ and Ca2+-dependent adenosine triphosphatase and secretory granules and vesicles in human seminal plasma.

A pronounced deficiency of Mg2+ and Ca2+-dependent ATPase and of secretory granules and vesicles was demonstrated in the seminal plasma of a patient with infertility problems (person A) and with a lowered serum testosterone level. Both total ejaculates and different fractions of split-ejaculates were examined on repeated occasions. Divalent cations, fructose and protein were also determined in most of the samples. The low activity of the Mg2+ and Ca2+-dependent ATPase and the ultrastructure of the split-ejaculates of the seminal plasma of person A contrasted sharply against the high activity of the Mg2+ and Ca2+-dependent ATPase and the ultrastructure of the split-ejaculates of the seminal plasma of another individual (person B). The latter displayed a normal Mg2+ and Ca2+-dependent ATPase activity as well as an ordinary representation of the secretory granules and vesicles. The findings on the ATPase system in the seminal plasma of person A together with the lowered levels of divalent cations in the order Ca2+ less than Mg2+ less than Zn2+ are proposed to reflect a defective functioning of the prostate gland in person A.

Adenosine Triphosphatases↗
PubMed1981

The use of con A Sepharose as an affinity adsorbent in a simple assay of serum sialyl and fucosyltransferase and its application in tumour diagnosis.

A considerably simplified assay for recording sialyl- and fucosyltransferase in human serum is presented. Serum samples incubated with labeled nucleotide-sugar and glycosylated endogenous acceptor molecules were adsorbed to Con A Sepharose and quantitated by scintillation counting. The results correlated with those of a much more time consuming acid precipition method, and displayed a higher diagnostic sensitivity due to the improved specificity of the method and the combined recording of the two activities. A correlation between serum sialyl- and fucosyltransferase activities as well as quantitative agreement between the amount of incorporated sialic acid and fucose indicated that rhe endogenous acceptor molecules were rate-limiting for transfer and may themselves have diagnostic potential.

Adsorption↗
PubMed1980

Antitumor activity of L-2,4 diaminobuturic acid against mouse fibrosarcoma cells in vitro and in vivo.

Mouse fibrosarcoma cells were grown in vitro and incubated with L-2,4 diaminobuturic acid, a non-metabolizable amino acid. The tumor cells were irreversibly and totally damaged by incubation with 10 mM DAB for 24 h at 37 degrees C. The cell-destructive effect by DAB was probably due to an osmotic lysis induced by the non-saturated intracellular accumulation of DAB. The harmful effect of DAB could be abolished by concomitant incubation with L-alanine and L-methionine, that compete with DAB for the same transport system, while the D-forms of the same amino acids as well as sarcosine had a weak effect. The fibrosarcoma cells were also transplanted s.c. into mice that were subsequently treated with i.p. injections of an isotonic 0.1 M DAB solution. The neoplastic cells were transplanted into totally 90 animals. The mean tumor weight of 42 treated animals was 1.16 g (+/- 0.77 g) compared with the corresponding figures of the 27 untreated mice, that were 2.05 g (+/- 1.22 g), i.e., a 43.4% reduction of tumor growth. There were, however, 17 drug-related deaths. Treatment with DAB generally resulted in weight reduction, at least partly due to loss of appetite, in animals. In addition, neurological symptoms of a specific character could develop among several of the treated animals. The side effects apparently restrict the usefulness of DAB alone as an anti-tumor agent, but since the principle of action of DAB is unique and not shared by other known chemotherapeutics it might offer new possibilities in the combined treatment of neoplastic growth.

Aminobutyrates↗
PubMed1980

Cerebrospinal fluid markers of disturbed brain cell metabolism in patients with stroke and global cerebral ischemia.

Adenylate kinase activity was found in 32 of 34 samples of cerebrospinal fluid (CSF) from 21 patients with stroke and seven patients with global cerebral ischaemia (GCI). The light absorbance values of the spectrum 400-650 nm revealed the scanty occurrence of haemoglobin products in the CSF in some patients. No correlation was found between the absorbance values at 415 nm, reflecting oxyhaemoglobin, and the adenylate kinase activities. Thus, a main contribution to the adenylate kinase activity in CSF by leakage of this enzyme from erythrocytes could be ruled out. Instead increased leakiness of the brain cells, having an impaired metabolism due to insufficient supply of oxygen and glucose, was the most plausible cause of the findings. The quotient between the adenylate kinase activity and the light absorbance at 415 nm seemed to reflect the extent of ischaemically deranged brain tissue in the GCI patients, while the CSF-lactate values were not correlated to the clinical outcome. Glutathione, an intracellular tripeptide, was more often found in the CSF from GCI patients than from stroke patients.

Adenylate Kinase↗
PubMed1980

Reduced activity of Mg2+- and Ca2+-dependent adenosine triphosphatase in seminal fluid of patients with oligozoospermia.

Mg2+- and Ca2+-dependent ATPase activity, fructose and divalent cation concentrations were determined in seminal plasmas from men with oligozoospermic ejaculates and from those with normal sperm count. The mean activity of the Mg2+- and Ca2+-stimulated ATPase from the former was 59 nmol . 0.1 ml-1 . This is significantly (p less than 0.005) lower than for men with a normal sperm count (corresponding figure is 87 nmol . 0.1m1-1 . min-1). As regards the concentrations of Mg2+, Ca2+ and Zn2+ in the seminal plasmas from these two groups there was no significant difference. The same was also valid for the fructose concentrations. The Mg2+- and Ca2+-stimulated ATPase activity as well as fructose and divalent cation concentrations were also determined in seminal plasmas from men before and after vasectomy. After vasectomy, only the ejaculates devoid of spermatozoa were included in the comparative studies. No significant difference was observed between the seminal plasmas from men before and after vasectomy. These findings support the view that the Mg2+- and Ca2+-stimulated ATPase system does not derive from the spermatozoa. Possible explanations for the significantly lowered Mg2+- and Ca2+-dependent ATPase activity from patients with oligozoospermia are given.

Adenosine Triphosphatases↗
PubMed1979

Increased red cell content of Zn2+ in essential hypertension.

The zinc content in plasma as well as in erythrocytes was studied in 61 patients with untreated essential hypertension. They displayed an intraerythrocytic mean value of Zn2+ of 128.2 micromoles/l intracellular water, which is significantly higher than the corresponding mean of 101.5 micromoles/l from 42 normal persons. In plasma, on the other hand, the mean zinc value of the hypertensive persons was 15.2 micromoles/l plasma, i.e. well within the normal range of plasma Zn2+. Possible mechanisms underlying the elevated red cell zinc level in hypertension are discussed.

Adult↗
PubMed1979

Adenylate kinase activity in cerebrospinal fluid of schizophrenic and certain other psychiatric symptomatologies.

Adenylate kinase activity in the cerebrospinal fluid (CSF) was investigated in 29 patients with psychiatric symptomatologies. Such activity was demonstrated in 18 of the 19 individuals with schizophrenic or other psychotic or borderline psychotic symptomatology. No activity was seen in the remaining 10 patients with non-psychotic nervous and/or functional somatic complaints, nor in the 20 persons whose CSF was examined in connection with spinal anaesthesia, nor in four who were treated with neuroleptic drugs on nonpsychiatric indications. The findings are compatible with the assumption that in persons with psychotic or borderline psychotic symptomatology a lowered membrane electrochemical potential may be associated with some of the symptoms exhibited.

Adenylate Kinase↗
PubMed1979

Phosphorylation of endogenous proteins by endogenous protein kinase of density gradient--purified plasma membrane vesicles of Ehrlich cells.

A phosphorylation of endogenous acceptor protein(s) has been demonstrated to occur in membraneous vesicles prepared from Ehrlich ascites tumour cells. The reaction was catalyzed by endogenous protein kinase in the presence of exogenous (gamma32P)ATP. A considerable increase of the specific protein kinase activity took place when the plasma membrane preparation was subjected to a further gradient centrifugation in Dextran T 150. This was done in the presence of a slightly alkaline phosphate buffer containing Mg-ions which resulted in the formation of a well defined vesicular preparation at density 1.035 in the gradient. The apparent Km and Vmax for the reaction with vesicles and exogenous (gamma32P)ATP were determined and found to be 0.022 mM and 0.23 nmol x mg-1 x 10 min-1, respectively. Neither cyclic AMP nor cyclic GMP did stimulate the protein kinase-catalyzed reaction. Instead, a clear inhibition of the reaction by the cyclic nucleotides was unexpectedly registered. Adenosine at 0.5 mM also inhibited the reaction. Calcium ions were inhibitory at all concentrations tested in the presence of a fixed (gamma32P)ATP/Mg2+ ratio. When Mg-ions were stoichiometrically replaced by Ca-ions practically no activity was observed.

Adenosine↗
PubMed1979

The effect of alpha-aminoisobuturic acid and 2,4-diaminobuturic acid on mouse blastocyst outgrowth in vitro.

Blastocysts recovered from mice in a state of delay of implantation were incubated for 10 h with either alpha-aminoisobuturic acid (AIB) or 2,4-diaminobuturic acid (DAB), two non-metabolizable amino acids. The incubation medium was composed so as to maintain growth arrest of the inactive, delayed blastocysts in vitro. The blastocysts were then transferred to a complete outgrowth medium without the two non-metabolizable amino acids to test the capacity for trophoblast outgrowth. AIB, which displays saturation kinetics, was harmless to the blastocysts even at a high concentration, while DAB at a low concentration irreversibly damaged the trophoblast cells and prevented outgrowth, probably due to nonsaturation kinetics resulting in a high intracellular accumulation. The harmful effect of DAB could be abolished by concomitant incubation with L-alanine and L-methionine, which compete with DAB for the same transport system, while the D-forms of the same amino acids had little or no effect. The results suggest the presence of transport System A in mouse blastocysts growth arrested in vitro, indicating an operative carrier mechanism already during delay of implantation.

Alanine↗