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Biomedical subjects

J Svensson

Publications and source records attributed to J Svensson.

At least 73 records · Page 4Linked to original sources
PubMed1992

Hemostatic effects of ephedrine.

The effects of ephedrine on coagulation and on fibrinolysis were studied in six healthy volunteers. Six volunteers, matched by age and sex, served as untreated controls. Ephedrine was found to significantly prolong mean bleeding time by 2 minutes. Ephedrine has been proposed to activate fibrinolysis, but we found no increased tPA activity. The platelet count, APTT, factor VIII and von Willebrand factor remained constant. In an in vitro study ephedrine was found to inhibit platelet aggregation induced by adrenaline and, to some extent, also by ADP. The inhibition was competitive and not mediated via beta 2 adrenoceptor stimulation. It is concluded that there are hemostatic effects of ephedrine and that these may be of clinical relevance, the drug being very commonly used in connection with procedures where blood loss as well as venous thromboembolism are considerable problems.

Adult↗
PubMed1992

Association between high levels of growth factors in plasma and progression of coronary atherosclerosis.

Although intimal proliferation of smooth muscle cells (SMC) is recognized as one of the key mechanisms in the development of atherosclerosis, our knowledge of the role of circulating growth factors for SMC in this process is limited. In the present study the plasma levels of platelet-derived growth factor (PDGF), beta-thromboglobulin (beta-TG), platelet factor 4 (PF 4) and total growth factor activity were determined in a group of 30 young postinfarction patients who had participated in an angiographic study of mechanisms associated with progression of coronary atherosclerosis. Significant correlations were found between the total growth factor activity in plasma and progression (r = 0.42, P < 0.05), as well as severity (r = 0.52, P < 0.01), of global coronary atherosclerosis. Attempts to identify the nature of the total growth factor activity indicated that less than 20% could be attributed to PDGF, the major serum mitogen for SMC. PDGF levels determined by radioimmunoassay were not related to progression or severity of global coronary atherosclerosis, but showed a significant association with the number and severity of distinct stenoses (r = 0.40, P < 0.05). Due to the retrospective design of this study, it is not possible to conclude whether there is a causal relationship between circulating growth factors and development of coronary atherosclerosis.

Adult↗
PubMed1992

Effect of antithrombin concentrate on haemostatic variables in critically ill patients.

In a controlled pilot study of 32 critically ill patients, we have attempted prospectively to identify laboratory variables which can be used to select and monitor patients on antithrombin (AT) therapy. Patients with plasma AT levels less than 70% of normal were randomized to receive (AT group) or not to receive AT concentrate (non-AT group). The groups did not differ in median age, sex, median APACHE II and TISS scores, number of days spent in the Intensive Care Unit or mortality rate. At the time of inclusion all patients had activated coagulation and fibrinolysis demonstrated as high levels of soluble fibrin, thrombin-antithrombin complexes and fibrin-D-dimers (twice, four and ten times the upper reference range, respectively). In the AT group these levels decreased faster and the prothrombin complex concentration increased more rapidly to normal (i.e. the prothrombin time decreased). The level of C-reactive protein which was high in both groups on inclusion (139 and 98 mg/l, respectively) decreased by 40% in the AT group but did not change in the control group. Our study indicates that laboratory variables normalize faster in seriously ill patients who have activated coagulation and fibrinolysis when they receive AT concentrate and that the variables mentioned above seem to be useful for monitoring the treatment.

Aged↗
PubMed1991

Effects on coagulation and fibrinolysis of desmopressin in patients undergoing total hip replacement.

Twelve patients undergoing total hip replacement, with regional anaesthesia and with dextran infusion for plasma expansion and thromboprophylaxis, were given the vasopressin analogue desmopressin (DDAVP) or placebo in a randomized, double-blind prospective study. In controls (n = 6) we found a prolongation of the bleeding time, low factor VIII (FVIII) and von Willebrand factor (vWF) and a decrease in antithrombin III to levels known to be at risk for venous thrombosis. Desmopressin shortened postoperative bleeding time, gave an early FVIII/vWF complex increase, prevented antithrombin III from falling to critically low values and appeared to activate the fibrinolytic system, both by tPA increase and PAI-1 decrease. Thus in the controls we found changes in both coagulation and fibrinolysis indicating a haemorrhagic diathesis as well as a risk for thromboembolism. Desmopressin induced factor changes that possibly reduce both risks.

Adult↗
PubMed1991

Effects of desmopressin and dextran on coagulation and fibrinolysis in healthy volunteers.

The effects of desmopressin and dextran on haemostasis and fibrinolysis were studied in four healthy volunteers. Both drugs were compared to placebo, each volunteer being subject to four experiments. Dextran 70 (30 g i.v.) moderately decreased VIII:C and vWF:Ag and slightly increased antithrombin III, also when haemodilution and diurnal variation were considered. Desmopressin (0.3 micrograms/kg BW i.v.), alone as well as in combination with dextran, increased VIII: C, vWF:Ag, protein C and tPA and decreased PAI-1. The combination of desmopressin and dextran stimulated coagulation and fibrinolysis and might be of relevance to surgical blood loss as well as to postoperative thromboembolism.

Adult↗
PubMed1991

Statistical problems in estimating elimination rates by compartmental models.

The rate of lead elimination in blood by occupationally exposed individuals has been studies using a compartment model with three exponential terms. The analysis of data by exponential regression leads to numerical problems. It is often a difficult task to decide how many measurements should be performed, the length of the observation period, and how the observations should be distributed to get high accuracy. In a simulation study, the sensitivity of the parameter estimates was investigated as a function of these three factors. The effects of missing observations in some interval was also studied. It is shown that a too short observation time leads to a relatively high frequency of outliers in the estimated values of all three half-times. It is also shown that missing values in one compartment affect the parameter estimates of that and faster compartments. The results obtained can be used as a help to decide what experimental accuracy is needed for a given accuracy of compartment model parameters for a variety of medical and biological problems.

Computer Simulation↗
PubMed1991

Vesicoureteral reflux in the adult. V. Unilateral disease.

We studied 37 patients with primary unilateral vesicoureteral reflux to compare medical (17) and surgical (20) management. Medical management consisted of observation and antimicrobial therapy as needed. During followup (mean 84.6 months) none of the patients in either management group had a significant decrease in total renal function, worsening of hypertension or progression of stone disease. The surgically treated group had a higher incidence of pyelonephritis preoperatively (75% versus 13%) but during followup these infections developed in only 10% of the surgical patients and in 13% of the medically managed group. The primary indication for surgical correction of unilateral reflux in adults is a history of pyelonephritis in patients in whom antibiotic prophylaxis has been unsuccessful or in women of childbearing age.

Adolescent↗
PubMed1990

Electrodermal responsivity in young hypotensive and hypertensive men.

Electrodermal responses were recorded during the presentation of 16 moderately intense (1000 Hz, 90dB) tones in three groups of young men: borderline hypertensives (138/79 mmHg), normotensives (112/65 mmHg), and hypotensives (104/63 mmHg). Electrodermal response habituation was measured as a decline in response over trials, number of trials to a response criterion of three successive nonresponses, and number of inversions of response amplitude (larger responses following smaller responses) in the stimulus sequence. Habituation was fastest in hypotensives. Nonspecific electrodermal responses at rest and during tone presentations were most frequent in borderline hypertensives, least frequent in the hypotensive group, with the normotensive group falling in between. There were no significant differences in electrodermal level. The rapid habituation rate in hypotensives is discussed in terms of cursory information processing associated with impulsive behaviour. The higher nonspecific electrodermal activity in borderline hypertensives is interpreted to indicate increased sympathetic nervous system activity.

Adolescent↗
PubMed1990

Coagulation factors and the increased risk of stroke in nonvalvular atrial fibrillation.

We studied whether hemostatic abnormalities contribute to the increased risk of stroke in patients with nonvalvular atrial fibrillation. Hemostatic function was studied in four age-matched groups: 20 patients with nonvalvular atrial fibrillation and a previous ischemic stroke, 20 patients with nonvalvular atrial fibrillation without a previous stroke, 20 stroke patients with sinus rhythm, and 40 healthy controls. Both groups with nonvalvular atrial fibrillation had significantly higher concentrations of von Willebrand factor, factor VIII:C, fibrinogen, D-dimer (a fibrinolytic product), beta-thromboglobulin, and platelet factor 4; a significantly higher fibrinogen/antithrombin ratio; and significantly higher spontaneous amidolytic activity than the healthy controls. Prekallikrein levels were significantly lower in both groups with nonvalvular atrial fibrillation. Stroke patients with sinus rhythm had normal hemostatic function, normal concentrations of platelet-related factors, and a slightly increased concentration of fibrinopeptide A compared with the healthy controls. Both groups with nonvalvular atrial fibrillation differed from the stroke patients with sinus rhythm as they did from the healthy controls. No difference in hemostatic function was seen between the nonvalvular atrial fibrillation patients with and without a previous ischemic stroke. Thus, alterations in hemostatic function may contribute to the increased risk of stroke in patients with nonvalvular atrial fibrillation.

Acute-Phase Reaction↗
PubMed1990

Dietary linoleate supplementation modulates formyl-peptide receptor expression and functional responses of rat neutrophils.

We studied effects of dietary supplementation with the essential fatty acid (EFA) linoleic acid (LA) to see if neutrophil responses would be modulated. Neutrophils from rats maintained on a diet supplemented with EFA to 10% of the energy content--the high EFA (HEFA) group--showed a significantly higher LA concentration (but similar arachidonic acid content) compared with neutrophils from control rats maintained on a standard diet with 3% of the energy content as EFA. The HEFA group showed a significantly higher neutrophil oxidative metabolism compared with controls in response to N-formyl-methionyl-leucyl-phenylalanine (FMLP), but this response was equal to control values when stimulated by ionophore A23187, sodium fluoride, or phorbol myristate acetate. Similarly, FMLP conferred a more pronounced increase of intracellular Ca2+ in HEFA neutrophils, whereas this response to ionomycin was equal to that in controls. In contrast, HEFA rat neutrophil migration was decreased to 71% of the value in controls in response to FMLP. Similar results were observed for aggregation responses. On A23187 stimulation, HEFA and control neutrophils generated equal amounts of leukotriene B4 and other 5-lipoxygenase products as well as thromboxane B2 and 6-keto-prostaglandin F1 alpha. However, assessment of binding of FMLP labeled with tritium revealed an increase of the low affinity state of the FMLP receptor population. Thus an increased intake of one unsaturated fatty acid, LA, leading to its accumulation in neutrophils, conferred alterations in formyl-peptide-elicited responses, not associated with the formation of the assessed arachidonate-derived mediators, but most likely through the observed modulation of FMLP receptor subpopulations.

6-Ketoprostaglandin F1 alpha↗
PubMed1988

Emotional coping and the psychophysiological substrates of elevated blood pressure.

A structured interview concerning emotional coping patterns was administered to 63 28-year-old men included in a psychophysiological study of blood pressure elevation. The interviews were tape recorded and subsequently evaluated by a rater not otherwise involved in the study. The interviews involved discussion of four emotions: anger, sorrow, anxiety, and joy. The results indicate that normotensives can express sorrow to significantly more people than hypertensives, and that their behavior in situations involving sorrow tends to be more instrumental than that of the group with labile pressure. Hypertensives also experienced significantly less joy than normotensives. In multiple regression analyses on physiological variables relevant for blood pressure elevation, the use of a somatic and unfocused way of describing sorrow was associated with significantly lower heart rate. The results show also that emotional coping explains a significant amount of the variance in three of the psychosocial functions involved in elevated blood pressure: ability to express anger at work, plus the social support variables of attachment and acquaintance.

Adaptation, Psychological↗
PubMed1988

Changes in job strain in relation to changes in physiological state. A longitudinal study.

A sample of 73 men and women aged 22-63 years and working in six different occupations (air traffic controllers, waiters, physicians, symphony orchestra musicians, baggage handlers, and airplane mechanics) participated in a longitudinal study four times during a year. The spontaneous variations in job strain (determined as the self-reported ratio between psychological demands and decision latitude) were substantial. The average difference between the occasion with the highest level of strain and the occasion with the lowest level was 25% of the total mean. Systolic blood pressure during workhours, as well as self-reported sleep disturbance, increased when demands increased in relation to decision latitude. Among men with a depressive tendency (according to a diary) morning plasma prolactin levels increased markedly with increasing job strain. Among subjects with a positive family history of hypertension the increase in systolic blood pressure at work was particularly pronounced, and among the men in this group a lower than expected level of morning cortisol was found measured during the period with the highest level of strain.

Adult↗
PubMed1986

Determination of platelet-megakaryocyte regeneration time in painters occupationally exposed to organic solvents.

An improved method for the determination of the regeneration time of human platelets is presented. The platelet-megakaryocyte regeneration times of painters exposed to organic solvents (n = 5; age range 23-48 years) were compared with a reference group (n = 5; age range 23-46 years) not occupationally exposed to solvents. After purification and extraction of the samples, they were analysed by high-performance liquid chromatography. The results showed that the painters have a shorter regeneration time (range 4.4-5.2 days) than the reference group (range 5.2-6.9 days) and indicate that solvent exposure may be associated with an increase in platelet turnover in man.

Adult↗
PubMed1986

Increased platelet-derived mitogenic activity in plasma of young patients with coronary atherosclerosis.

The early state of atherosclerosis is characterized by a nodular proliferation of smooth muscle cells in the arterial intima. It has been suggested that this proliferation is initiated by platelet-derived growth factor (PDGF) released from aggregating platelets in connection with endothelial injury. In the present study platelet reactivity and mitogenic activity of plasma and serum were compared in young male survivors of myocardial infarction with angiographically demonstrable coronary atherosclerosis and in healthy subjects of similar age. Young post-infarction patients with coronary atherosclerosis had lower ED50 values of ADP-induced platelet aggregation. Furthermore plasma and serum from the patients contained increased amounts of mitogenic activity. Experiments using antibodies against platelet-derived growth factor indicated that the increase in mitogenic activity represented elevated concentrations of free PDGF growth factor in plasma. The results raise the possibility of a connection between increased levels of free PDGF and the proliferative reaction that characterizes early lesion progression.

Adenosine Diphosphate↗