Search PubMed⌕ Search

Biomedical subjects

G Ronquist

Publications and source records attributed to G Ronquist.

At least 145 records · Page 8Linked to original sources
PubMed1990

Isoenzyme pattern of lactate dehydrogenase associated with human prostasomes.

Lactate dehydrogenase (LD, EC 1.1.1.27) activity was determined in serum, seminal plasma and prostasomes from normozoospermic and azoospermic (due to vasectomy) men. A 10-fold higher activity was noted in seminal plasma as compared with serum. LD activity was enriched in prostasomes although a fairly large amount of enzyme activity seemed to be free in solution. Isoenzymes LD1, LD2 and LD3, present in prostasomes in about equal amounts, gave rise to a characteristic isoenzyme pattern that differed distinctly from that found in seminal plasma of normozoospermic men, the main isoenzyme of which was LD-X.

Body Fluids↗
PubMed1990

Nucleic acid association to human prostasomes.

Human prostasomes isolated from seminal plasma were subjected to phenol extraction and then to absorbance (A) measurements at 260 nm (A260) and 280 nm (A280). The A260/A280 ratio was about 2 for prostasome extract and lower for seminal plasma extract, indicative of the presence of nucleic acid. The ratio of nucleic acid to protein in prostasomes was about 1:100, and the ratio in seminal plasma was 1:1,000. Hence nucleic acid is enriched in prostasomes (compared to seminal plasma of 10). Treatment of prostasome samples with 2% sodium dodecyl sulfate resulted in an efficient dissociation of nucleic acid from prostasomes as demonstrated by electrophoresis. The association of nucleic acids of various sizes (range; 200 to 20,000 base pairs) to prostasome membranes was most probably genuine and not the result of contamination from spermatozoa, erythrocytes, leukocytes, or bacteria. The results of experiments employing nucleic acid-degrading enzymes favored the concept that double-stranded DNA but not RNA is present at the prostasome membrane surface.

DNA↗
PubMed1990

Interaction between prostasomes and spermatozoa from human semen.

Prostasomes are prostate-derived organelles that occur freely in human seminal plasma. They promote forward motility of spermatozoa probably by closely interacting with them in an unknown manner. We have studied the interaction between human prostasomes and spermatozoa by applying them as two separate samples in free-zone electrophoresis. During the run these samples approached each other and finally fused into one single peak that was not further dissociated. Both the spermatozoa and prostasomes displayed a net-negative surface charge, the latter being less negative. This discrepancy in charge was even more pronounced by pretreatment of prostasomes with neuraminidase, which, however, did not affect the interaction. This implies a strong interaction of a probable hydrophobic character between cells and organelles. The presence of prostasomes and spermatozoa in the fused, single peak was confirmed by transmission electron microscopy. Evidence for interaction was apparent in transmission electron microscopy after embedding in a hydrophilic, but not in a hydrophobic, resin. This observation supports the view that the bonds between prostasomes and spermatozoa are of hydrophobic character. This type of interaction enables the prostasomes to act in close vicinity to spermatozoa and may create the prerequisites for a proper microenvironment of the spermatozoa favoring their forward motility.

Cell Adhesion↗
PubMed1990

Bubble and membrane oxygenators--comparison of postoperative organ dysfunction with special reference to inflammatory activity.

Bubble and membrane oxygenators (2 types of each) were compared in a randomized study of 96 patients undergoing coronary bypass grafting. Cardiac performance, assessed from postoperative need of inotropic support, was significantly better in the membrane oxygenator group. After perfusion lasting more than 2 hours, respiratory function, measured as alveolar-arterial oxygen pressure gradient, was less compromised in that group and renal function, quantified as postoperative rise of serum creatinine was less disturbed. Cerebral function, studied in terms of psychometric test results and concentration of adenylate kinase in cerebrospinal fluid, did not differ between the bubble and membrane oxygenator groups. In investigations concerning changes in inflammatory activity during bypass, complement activation could not be related to the mentioned clinical parameters. Release of the neutrophil granulocyte factors lactoferrin and myeloperoxidase was greater in the bubble oxygenator group and correlated to impaired cardiac and renal performance, but not to pulmonary or cerebral dysfunction.

Adult↗
PubMed1989

Human prostasome membranes exhibit very high cholesterol/phospholipid ratios yielding high molecular ordering.

Lipid analysis and ESR studies were carried out on prostasomes isolated from human semen. Cholesterol plus phospholipids amounted to approximately 0.80 mumol per mg protein with a striking quantitative domination of cholesterol over the phospholipids, the molar ratios of cholesterol/sphingomyelin/glycerophospholipids being 4:1:1. Saturated and monounsaturated fatty acids were dominating both in the glycerophospholipids and in sphingomyelin. The order parameters, S, deduced from ESR spectra of spin-labelled fatty acids incorporated into prostasome membranes order parameters, S, deduced from ESR spectra of spin-labelled fatty acids incorporated into prostasome membranes were very high, viz. 0.75 for 5-doxylstearic acid and 0.30 for 16-doxylstearic acid at 25 degrees C. Slightly lower values were obtained for the spin-labelled fatty acids when they were incorporated into dispersions of extracted prostasome lipids or into synthetic lipid mixtures of similar composition. The highly ordered lipids in the prostasome membrane thus seemed to be minimally perturbed by proteins in the membrane and ESR spectra showed no signs of immobilized lipids.

Adenosine Triphosphatases↗
PubMed1989

Adverse effects on the brain in connection with isoflurane-induced hypotensive anaesthesia.

As a marker of brain cell injury, adenylate kinase (AK) was measured in cerebrospinal fluid (CSF) in 10 patients given anaesthesia with isoflurane-induced hypotension for corrective surgery of dentofacial deformities. Nine out of 10 patients displayed a marked increase in CSF-AK postoperatively compared with preoperative values. The postoperative mean value displayed a 400% increase compared to the corresponding preoperative value. This difference was statistically significant (P = 0.001). The rise in CSF-AK was most probably the result of an enhanced efflux of AK into CSF subsequent to a presumed hypoxic injury to brain cells.

Adenylate Kinase↗
PubMed1989

Reversible brain cell damage due to hypoglycemia in a patient with insulinoma.

A case of an insulinoma with hypoglycemic attacks accompanied by episodes of unconsciousness in a 57-year-old woman is described. During the hypoglycemic spells the level of adenylate kinase (AK) in the cerebrospinal fluid (CSF) was elevated 6-fold above the normalized level obtained later from the patient being in a normoglycemic condition. CSF-AK was previously found to be a sensitive marker of subtle brain cell damage due to hypoxia. The increased efflux of AK into CSF during the insulinoma-induced hypoglycemia was most probably the result of a brain cell injury caused by shortage of glycolytic fuel.

Adenoma, Islet Cell↗
PubMed1989

The effect of vitamin D treatment on decreased levels of ATP and energy charge in the thoracic aorta of uraemic rats.

The contents of ATP, ADP, AMP and calcium in the thoracic aorta were determined in rats with moderate uraemia, and in rats with the same degree of uraemia following treatment with 1,25-dihydroxycholecalciferol (1,25-DHCC). The contents of ATP, ADP and total nucleotides were decreased in the thoracic aorta in the uraemic rats but not in uraemic rats following 1,25-DHCC treatment. The content of calcium in the aorta increased substantially in uraemic rats given 1,25-DHCC. The results indicate that the development of arterial calcifications in uraemic rats following vitamin D treatment is dissociated from an impaired energy metabolism, since vitamin D may simultaneously restore impaired energy metabolism and accumulate calcium in the aortic wall.

Adenine Nucleotides↗
PubMed1988

Decreased 45calcium uptake in red cells of patients with essential hypertension.

Decreased 45calcium uptake was observed in red cells of 20 patients with essential hypertension. Equilibration of extracellular 45calcium with intracellular calcium was not achieved within 60 min in red cells of either hypertensive patients or control subjects. By introducing the ionophore A23187, equilibrium conditions were attained for red cells of both categories of individuals. Still the discrepancy in 45calcium uptake was preserved between them. These results support the view that red cells of hypertensive patients have an altered membrane permeability to calcium, possibly reflecting also a greater exchangeable pool of cytosolic free calcium.

Adult↗
PubMed1988

Prostasome membrane associated enzyme activities and semen parameters in men attending an infertility clinic.

Seminal plasma from 22 men attending an infertility clinic was subjected to preparative ultracentrifugation for 2 h at 105,000 g. The pelleted material as well as the supernatant thus obtained were investigated with regard to prostasome membrane-linked enzyme activities in relation to other semen parameters. The mean activity of Zn2+-dependent adenosine triphosphatase in the sedimented prostasome fraction was 1.45 +/- 1.02 mumol (range 0.29-4.79) orthophosphate released per milligram protein and 20 min, while the corresponding figures for the supernatant were 0.56 +/- 0.30 (range 0.12-1.29). Hence, 72% of the specific activity was sedimented, and 28% remained in the supernatant. The same pattern was recognized with regard to the other two enzymes investigated, although they displayed individual characteristics with regard to distribution after ultracentrifugation. The pelleted prostasome-linked mean aminopeptidase activity was 0.39 U/mg protein (81.9%), with only 0.087 U (18.1%) remaining in the supernatant. The corresponding figures for gamma-glutamyltransferase were 7.89 (60.4%) and 5.17 (39.6%) mu kat/g protein, respectively. The different enzyme activities in the prostasome fraction and supernatant, respectively, were interrelated to each other and correlated significantly with r values between 0.73 and 0.93 (p less than 0.001). It was concluded that a minor fraction of prostasomes remained in the supernatant after ultracentrifugation. A relationship existed between prostasomes and semen volume revealing a rather consistent pattern in that small volumes favoured the presence of comparatively more prostasomes in the supernatant and less prostasomes in the pelleted fraction than large volumes. In addition, the sperm concentration seemed to be another determinant of the distribution of prostasomes in seminal plasma on subsequent ultracentrifugation.

Adenosine Triphosphatases↗
PubMed1988

Zinc ion stimulation of ATP cleavage by prostasomes from human seminal plasma.

A stimulation by zinc ions of the hydrolysis of ATP by prostasomes prepared from human semen has been observed. Stimulation was maximal at a Zn2+/ATP stoichiometry of 0.5/l, and increasing this ratio resulted in a gradual decrease in ATPase activity. The pH optimum was 6.0. The apparent Km for Zn2+-dependent ATPase was 0.43 mmol/l and apparent Vmax 5.60 mumol/mg protein/20 min. Other divalent cations could replace Zn2+ as cofactor more or less effectively in the order Mn2+ greater than Cd2+ greater than Ba2+ greater than Sr2+. Potassium ions produced a further activation of the Zn2+-dependent ATPase system by about 10%. Such a stimulation was also attained to some extent by other monovalent cations as Rb+, NH4+, Li+ and to a lesser extent by Cs+. Orthovanadate in the concentration interval 5-1,000 mumol/l was inhibitory of the Zn2+-dependent ATPase system in a dose-dependent fashion. An aminopeptidase activity was also linked to the prostasomes. This enzyme activity was dramatically inhibited by 2 mmol/l orthophenantroline. A reactivation of the orthophenantroline-inhibited aminopeptidase activity was possible by adding Zn2+ to the reaction mixture. Hence, prostasomes contained ATPase as well as aminopeptidase activities both of which being dependent upon Zn2+. These two activities did not seem to be expressions of an ATP-dependent protease activity associated with prostasomes.

Adenosine Triphosphatases↗
PubMed1988

Anatomy of the prostate. Aspects of the secretory function in relation to lobar structure.

Anatomic studies have shown the prostate to be a heterogeneous organ in which at least three morphologically differing zones or lobes are identifiable. This indicates that the endocrinologic sensitivity of the prostate is not uniform, and that there may also be intraprostatic functional variations. Few studies have so far been done to prove such differences. Although interlobar differences in zinc content have been observed, their significance is not clear. The field is therefore open for further studies concerning both the anatomic and the functional heterogeneity of the human prostate.

Body Fluids↗
PubMed1987

Improved myocardial protection by creatine phosphate in cardioplegic solution. An in vivo study in the pig during normothermic ischemia.

The effect of creatine phosphate in potassium cardioplegia was studied in a pig heart model in vivo. Fifteen pigs divided into two groups were placed on cardiopulmonary bypass and subjected to 1 hour of cardioplegic arrest at normothermia. In group I (control), in which a potassium cardioplegic solution was used, only two out of eight animals could successfully be weaned from bypass. In group II, on the other hand, in which creatine phosphate (10 mmol/l) was added to the cardioplegic solution, six out of seven animals could be weaned from bypass and the heart performance assessed by volume loading. Group II also exhibited better maintenance of high-energy phosphates during ischemia, with significantly higher adenylate charge potential, than group I. In all animals weaned from bypass--two in group I and six in group II--the ventricular performance was decreased compared with that before induction of ischemia. The results indicate that creatine phosphate could be an effective constituent in potassium cardioplegia.

Animals↗
PubMed1987

Prediction of outcome after cardiac arrest.

Neurologic outcome of hypoxic ischemic coma after cardiac arrest was studied in 32 patients. Observations were made and samples collected 24 and 48 h after the ischemic insult. The Glasgow-Pittsburgh coma score was assessed for its prognostic value. Other variables studied were the EEG and adenylate kinase, lactate and glutathione in the cerebrospinal fluid (CSF). Outcome was termed good if the patients resumed an independent life within a 6-month follow-up period. The closest correlations between prediction and good outcome occurred with the Glasgow-Pittsburgh coma score (94%) and the EEG (77%) at the 48-h examination, a modified coma score (96%) at 48 h, and CSF lactate (78%) at 24 h. Some simple neurologic signs (e.g., no withdrawal response to pain) at stated points in time was 100% associated with a bad outcome, although their absence was not associated necessarily with a good prognosis.

Adenylate Kinase↗
PubMed1987

Effect of modulators on prostasome membrane-bound ATPase in human seminal plasma.

The Mg2+- and Ca2+-dependent ATPase system in human seminal fluid is linked to membranes encasing small organelles denoted 'prostasomes'. This activity was completely pelleted after ultracentrifugation at 105,000 X g, provided the seminal plasma was diluted 1:10. On the contrary, prostatic acid phosphatase activity remained in the supernatant and was inhibited to about 75% by tartrate (0.5 mmol l-1) contrasting with the ATPase system that was not inhibited. Calmodulin, in the concentration interval 0.30-0.90 mumol l-1, did not further activate the ATPase system. Calmidazolium, which is a highly lipophilic substance, was a competitive inhibitor of the Mg2+- and Ca2+-dependent ATPase and half maximal inhibition was attained at 2-3 mumol l-1 calmidazolium. This inhibition was antagonized to a moderate degree (25%, P less than 0.02) by calmodulin, 0.60 mumol l-1. Quercetin, at concentrations of 30-60 mumol l-1, did not influence the prostasome membrane ATPase in any direction. Oleate was an inhibitor of the ATPase system at any concentration up to 50 mumol l-1. This inhibition was not counteracted to an appreciable extent by calmodulin. These results displayed a pattern giving support to the view that the Mg2+- and Ca2+-dependent ATPase of the prostasome membrane may be the molecular basis for vectorial transport of Ca2+ into prostasomes.

Adult↗
PubMed1987

Functional effects of phosphoenolpyruvate and ATP on pig hearts in cardioplegia and during reperfusion. An in vivo study with cardiopulmonary bypass.

The effects of phosphoenolpyruvate (PEP) and ATP in cardioplegia and during early reperfusion were studied in pigs. Twenty pigs divided into three groups were placed on cardiopulmonary bypass and subjected to 2 h of hypothermic cardioplegic arrest. Group I (n = 7) served as a control. In group II (n = 7) PEP (14.4 mM) and ATP (0.067 mM) were added to the cardioplegic solution. Group III (n = 6) was given PEP (28.8 mM) and ATP (0.134 mM) with 500 ml of isotonic NaCl in the aortic root during early reperfusion. All animals in group III were weaned from bypass compared with 6 of 7 in group I and 5 of 7 in group II. Forty minutes after ischemia group III was assessed to be the only group with an unchanged aortic flow and stroke volume. The total peripheral resistance and arterial pressure were reduced in this group. The results demonstrate that PEP and ATP administered during reperfusion have a beneficial effect and that this may be exerted both on the myocardium and on the peripheral vessels.

Adenosine Triphosphate↗
PubMed1987

Seminal plasma levels of fucosyltransferase, galactosyltransferase and sialyltransferase in normospermic and oligospermic men.

The activities of fucosyltransferase, galactosyltransferase, and sialyltransferase were estimated in ultracentrifuged seminal plasma samples from normospermic and oligospermic men. There was no significant difference with regard to these activities between the two groups. Hence, fucosyltransferase activity was high in both normospermic (mean value: 190.2 nmol/l) and oligospermic men (mean value: 157.2 nmol/l) and exceeded that of blood plasma (mean value: 7.6 nmol/l) by 20-25 times. On the contrary, the activity ratio between seminal plasma and blood plasma of galactosyltransferase and sialyltransferase was low and fairly close to 1. A significant correlation was noted between seminal plasma galactosyltransferase activity and semen volume only in normospermic men. Significant inverse correlations in oligospermic men were observed between seminal plasma sialyltransferase activity and sperm concentration (and total sperm count) as well as between galactosyltransferase and fucosyltransferase activities.

Adult↗