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Biomedical subjects

P Olofsson

Publications and source records attributed to P Olofsson.

At least 37 records · Page 2Linked to original sources
PubMed2000

Continuous assessment of local metabolism by microdialysis in critical limb ischaemia.

OBJECTIVE: to investigate the feasibility of using microdialysate glucose, lactate and pyruvate concentrations for grading the severity of blood flow reduction in patients with critical limb ischaemia. PATIENTS AND METHODS: microdialysis catheters were inserted (two subcutaneously and one intramuscularly) in the symptomatic limb of ten patients. To further reduce limb perfusion, the lower leg was elevated during part of the experiment. RESULTS: elevation reduced ankle and toe blood pressure and transcutaneous oxygen tension. Microdialysate glucose concentration decreased at all three catheter sites, while lactate increased in the intramuscular catheter. Two patients interrupted the elevated position prematurely due to severe pain in the foot. They had among the highest lactate levels in the horizontal position and the most marked increases following provocation. Neither initial metabolite concentrations nor concentration changes during elevation were shown to correlate to conventional methods used to assess limb perfusion. CONCLUSIONS: in patients with critical limb ischaemia microdialysis can be used without complications. A significant decrease in glucose concentration may reflect lowered blood flow in the elevated position. Metabolic response, i.e. increase in lactate concentration during profoundly reduced limb perfusion was heterogeneous, indicating an overestimation of the presence of ischaemia in some patients using current diagnostic methods.

Arterial Occlusive Diseases↗
PubMed2000

Endovascular treatment of atherosclerotic lower limb lesions using a PTFE-collared stent-graft.

PURPOSE: To assess the feasibility of a polytetrafluoroethylene-collared (PTFE) endoluminal graft in the treatment of lower limb atherosclerosis. METHODS: We designed an endograft using a 3-mm-diameter balloon-expandable PTFE graft with terminal Palmaz stents placed on the outside of the graft, folding the PTFE back over the stents to form a collar at each end. Under protocol, this device was implanted in 8 symptomatic patients with lower limb ischemia. The lesions, ranging from 4 to 20 cm long, were located in the superficial femoral artery (n = 5), femoropopliteal segment (n = 1), and common (n = 1) and external (n = 1) iliac arteries. The device required a 14-F introducer system. RESULTS: Graft lengths varied from 4 to 35 cm. Implantation was successful in all cases, but procedural complications occurred in 4 patients (2 access site hematomas, 1 leading to endograft occlusion; 1 arterial injury, and 1 distal thromboembolism). At a mean 14-month follow-up, 5 endografts were patent (2 after reintervention for restenosis or thrombosis). The common iliac endograft and 2 superficial femoral artery devices occluded after 3, 2, and 12 months, respectively. CONCLUSIONS: Although this endoluminal graft system is technically feasible and showed encouraging intermediate-term patency in a small pilot study, the early and late complications identified several shortcomings of this design, which needs refinement.

Aged↗
PubMed1999

Stochastic models of telomere shortening.

Shortening of chromosome ends, known as telomeres, is one of the supposed mechanisms of cellular aging and death. We provide a probabilistic analysis of the process of loss of telomere ends. The first work concerned with that issue is the paper by Levy et al. [J. Molec. Biol. 225 (1992) 951-960]. Their deterministic model reproduced the observed frequencies of viable cells in the in vitro experiments. Arino et al. [J. Theor. Biol. 177 (1995) 45-57] reformulated the model of Levy et al. (1992) in the terms of branching processes with denumerable type space. In the present paper, the mathematical results of Arino et al. (1995) are extended to the case in which cell death is present, in cells with telomeres above and below the critical threshold of length, generally with differing probabilities. Both exact and asymptotic results are provided, as well as a discussion of biological relevance of the results.

Cell Death↗
PubMed1999

Sexual function in women suffering from aortoiliac occlusive disease.

OBJECTIVE: To describe the sexual function in women suffering aortoiliac occlusive disease (AIOD) and in an age-matched reference group. PATIENTS AND METHODS: Thirty-six women suffering from AIOD were included. Twenty were investigated before vascular intervention (untreated) and 16 different women after treatment (treated). Eighteen age-matched women served as a reference group. The patients answered a questionnaire including sexual, social and medical questions and a gynaecological examination was performed. RESULTS: Untreated patients with AIOD have a significantly impaired physical well-being compared to the other groups (p < 0.001). A negative effect of the vascular disease and its treatment on sexual life was experienced by 69% of treated compared to 40% affected among untreated (p = 0.05). Vulval sensibility was impaired in 44% of treated, 11% of untreated and 22% of reference patients. Defective anal sphincter function was found in 33% of treated, 17% of untreated and 6% in the reference group. Those differences were not statistically significant. CONCLUSIONS: Symptomatic AIOD in women is associated with a significantly impaired physical and sexual well-being. Though limited by size and methodology, the results indicate the possibility of iatrogenic nerve damage.

Adult↗
PubMed1999

The toe pole test for evaluation of arterial insufficiency in diabetic patients.

OBJECTIVES: to evaluate if the pole test at the toe level can be used for assessment of arterial insufficiency in diabetic patients. METHODS: twenty-five legs in 23 diabetic patients suffering from leg ischaemia were examined prospectively. A laser Doppler probe was attached to the pulp of the first toe to monitor perfusion continuously before and after occluding the arterial inflow with a cuff and during elevation of the leg until perfusion disappeared (the pole test). At ankle level the examinations were made similarly but with an ankle cuff and a hand-held Doppler. RESULTS: in the 44% (11/25) of the legs where it was possible to compare cuff blood pressure at ankle level with the pole test, the cuff measurements were significantly higher (p <0.01). In 13 of the remaining 14, maximal elevation did not result in disappearance of the Doppler signal. At toe level where 76% (19/25) of the legs could be compared, there was no significant difference between the two methods. CONCLUSION: the pole test can be used at the toe level to evaluate arterial insufficiency in diabetes. When used in the toe, the pole test can assess pressures below 55-70 mmHg, while only pressures below 45 mmHg can be determined at the ankle level. Falsely elevated blood pressure in diabetics is probably of less importance in digital arteries than in ankle arteries, which makes cuff pressure at toe level a more acceptable approximation.

Aged↗
PubMed1998

Prostanoid production in the umbilicoplacental arterial tree relative to impaired glucose tolerance.

The purpose of this study was to investigate prostanoid synthesis in different segments of the umbilicoplacental vascular tree and its relationship to impaired maternal glucose tolerance. Segments from the umbilical artery and vein, allantochorionic artery branches, and the cotyledon artery from 21 women with diabetes or impaired glucose tolerance and 10 healthy women were studied. Production of prostacyclin (PGI2) and thromboxane (TxA2) metabolites was determined. The Mann-Whitney U test, Wilcoxon signed-ranks matched-pairs test, Kruskal-Wallis test, analysis of variance, and simple linear regression analysis were used. A two-tailed P value of < 0.05 was considered statistically significant. From the umbilical artery distal to the cotyledon artery, the PGI2 synthesis decreased and the TxA2 synthesis increased gradually towards the periphery in normal pregnancy. The PGI2/TxA2 ratio was more than 200 times higher in the umbilical artery than in the cotyledon artery. The TxA2 production tended in general to be higher in the diabetic group than in the control group, resulting in significantly lower PGI2/TxA2 ratios in some vessels. The prostanoid production was not significantly correlated to maternal HbA1c or cord C-peptide concentrations. The balance between vascular prostacyclin and thromboxane synthesis in the umbilicoplacental arterial tree changed gradually towards the periphery: the more peripheral, the lower the prostacyclin and the higher the thromboxane production. The physiological role of this phenomenon is unknown, but may be of importance for the equilibration of vascular tone between arteries of different calibers. The altered prostanoid balance found in diabetic pregnancy was not directly attributable to the degree of maternal glycemic control, but may reflect increased free radical activity and peroxide production in diabetes.

6-Ketoprostaglandin F1 alpha↗
PubMed1998

Genetic control of arthritis onset, severity and chronicity in a model for rheumatoid arthritis in rats.

Rheumatoid arthritis (RA) is a chronic and genetically complex inflammatory disorder that leads to erosive destruction of peripheral joints. The use of animal models mimicking RA, such as pristane-induced arthritis (PIA) in rats, should facilitate its genetic analysis. Pristane is a non-immunogenic synthetic oil that, after a single subcutaneous injection into DA rats, induces arthritis restricted to peripheral joints with a chronic relapsing disease course. To identify genes involved in the control of chronic arthritis, we made crosses between susceptible DA rats and resistant E3 rats and analysed the progeny with microsatellite markers covering the entire rat genome. Our results show that different arthritis phenotypes are associated with different chromosomal loci. Loci on chromosomes 4 and 6 (Pia2 and Pia3) influence arthritis onset, whereas a locus on chromosome 12 (Pia4) is associated with severity and joint erosion. We found that chronicity is associated with a different set of loci, one on chromosome 4 and the other on chromosome 14 (Pia5, Pia6). These findings demonstrate for the first time that different phases of a chronic self-perpetuative disease which mimics RA are associated with distinct sets of genes.

Animals↗
PubMed1997

Reversed circadian blood pressure rhythm preserves fetal growth in preeclamptic pregnancy.

OBJECTIVE: To determine the clinical trait of hypertension in pregnant women with a reversed circadian blood pressure (BP) rhythm. STUDY DESIGN: 24-h BP monitoring was performed in 56 hypertensive pregnant women, of whom 12 had a reversed systolic BP (SBP) rhythm (day/night mean BP ratio < 1.0). Clinical data, ultrasound fetometry and umbilical artery velocimetry were compared to that in women with a normal rhythm. Statistical analyses were performed with simple linear regression, Mann-Whitney U test, analysis of variance, contingency table analysis and Fisher's test. A two-tailed P value of < 0.05 was considered significant. RESULTS: In the reversed SBP group, the nighttime BP, fetal weight, albuminuria and S-urate were higher, and the BP variations smaller. The birthweight correlated negatively to the SBP day/night ratio. Higher SBP day/night ratios and larger BP variations were associated with an increased vascular resistance in the umbilical artery and an impaired growth. CONCLUSION: A reversed SBP rhythm was associated with a more severe degree of preeclampsia, but also with a smaller BP variation, maintenance of fetal growth, and higher birthweight. A sustained high nighttime BP preserved fetal growth. These novel observations challenge the opinion that a reversed circadian BP rhythm is merely an ominous sign.

Adolescent↗
PubMed1997

Association between a low umbilical artery pulsatility index and fetal distress in labor in very prolonged pregnancies.

OBJECTIVE: To investigate the association between fetal, umbilical and uterine circulatory changes and adverse perinatal findings in very prolonged pregnancies. STUDY DESIGN: 44 women proceeding to 43 completed weeks of gestation with the intention of a trial of vaginal delivery were studied prospectively with ultrasound Doppler velocimetry. An intensified fetal surveillance was routinely commenced at 42 weeks and only uncomplicated pregnancies were allowed to proceed. The endpoint perinatal measures were oligohydramnios, fetal meconium release, fetal distress in labor and birth asphyxia. Flow variables in different groups were compared with the Mann-Whitney U test, Student's unpaired t-test, Wilcoxon signed-rank matched-pairs test, Fisher's exact test and contingency table analysis, and a two-tailed P value <0.05 was considered statistically significant. RESULTS: The umbilical artery pulsatility index was significantly lower in cases of fetal meconium release (n=12) and fetal distress (n=7). The umbilical venous flow velocity was significantly lower in cases of meconium, and the fetal aortic volume flow significantly higher in cases of fetal distress. No significant flow changes were found in connection with oligohydramnios (n=5) and birth asphyxia (n=2). Uterine flow was not significantly affected in any group. CONCLUSIONS: In very prolonged pregnancies, fetal distress in labor was not associated with an increased placental vascular resistance. In contrast to previous reports, the umbilical artery pulsatility index was low in cases of fetal distress and meconium release. The etiology is unknown, but a subclinical fetal hypoxia might have triggered a vasodilation of placental vessels. Vasodilation at an unchanged volume flow could also explain the decrease of umbilical venous flow velocity. The increased aortic volume flow indicates an increase of cardiac output in fetuses later developing distress in labor.

Blood Flow Velocity↗
PubMed1996

Fetal and uteroplacental circulatory changes in pregnancies proceeding beyond 43 weeks.

BACKGROUND: Practically all reference curves for Doppler blood flow variables in pregnancy end at 40 weeks. OBJECTIVE: To study fetal and uteroplacental circulatory changes in pregnancies proceeding beyond 43 weeks. STUDY DESIGN: Longitudinal comparisons from 42 to 43 weeks and comparisons with controls at term. MATERIAL: Thirty-four women delivered after 43 completed weeks (301 days) and a control group of 32 women delivered at 271 days of gestation. METHODS: From 42 weeks (294 days), serial Doppler blood flow measurements were performed in the fetal descending aorta, umbilical vessels, and maternal uterine artery. STATISTICAL METHODS: Student's unpaired t-test, Mann-Whitney U-test, and Fisher's exact test for comparison of groups; Student's paired t-test and Wilcoxon's signed-rank matched-pairs test for longitudinal data; simple linear regression analysis for comparison of variables. A two-tailed P-value of < 0.05 was considered statistically significant. RESULTS: From 42 to 43 weeks, the mean flow velocity decreased significantly in the fetal aorta and increased significantly in the umbilical vein. Compared to controls, the velocity and volume flow in the aorta and the umbilical artery flow resistance were significantly lower at 43 weeks. No significant change in uterine artery flow resistance was found. CONCLUSIONS: The changes in Doppler blood flow variables were all in accordance with physiological circulatory alterations enhancing continued fetal growth until the late post-term period. There were no signs of any general circulatory deterioration. Doppler velocimetry reference values at term may not be appropriate for evaluation of very advanced gestations.

Adult↗
PubMed1996

Iohexol clearance for assessment of glomerular filtration rate in diabetic pregnancy.

BACKGROUND: Plasma clearance of iohexol (Omnipaque) is well suited for determination of glomerular filtration rate (GFR) during pregnancy. OBJECTIVE: To settle guidelines for the use of iohexol clearance in diabetic pregnancy. STUDY DESIGN: Prospective comparative. MATERIAL AND METHODS: Iohexol (5 ml) was injected intravenously and plasma concentrations determined by high pressure liquid chromatography after 180-240 min in 44 diabetic pregnant women. RESULTS: Iohexol clearance was normal in most cases of nephropathy or albuminuria. Iohexol clearance correlated negatively with blood pressure, S-Urate, and S-Creatinine. When S-Urate was < 232 mumol/l or S-Creatinine < 70 mumol/l, iohexol clearance was always normal (sensitivity = 1.0). When, in combination, S-Urate was > 345 mumol/l, and S-Creatinine > 70 mumol/l, iohexol clearance was always subnormal (sensitivity = specificity = Kappa index = 1.0). CONCLUSIONS: In diabetic pregnancy, nephropathy or albuminuria cannot solely be used for selection of candidates for iohexol clearance determination. A S-Urate < 230 mumol/l (3.9 mg/dl) or S-Creatinine < 70 mumol/l (0.92 mg/dl) was reassuring for a normal GFR. We suggest iohexol clearance determinations in diabetic pregnancies when S-Urate is > 350 mumol/l (5.9 mg/dl) and/or S-Creatinine > 70 mumol/L.

Adult↗
PubMed1996

Prostanoid production in umbilical vessels and its relation to glucose tolerance and umbilical artery flow resistance.

OBJECTIVE: To study prostanoid synthesis in umbilical vessels relative to maternal glucose tolerance and umbilical artery blood flow resistance. STUDY DESIGN: Umbilical artery pulsatility index was determined by Doppler velocimetry in 21 women with diabetes or impaired glucose tolerance and 10 healthy women. Segments from the umbilical artery and vein were incubated and prostacyclin (PGI2) and thromboxane (TxA2) metabolites determined. Statistical analyses with the Mann-Whitney U test, Kruskal-Wallis test, Wilcoxon signed-ranks matched-pairs test, contingency table analysis, Fisher's exact test, and simple linear regression analysis were used and a two-tailed P value of < 0.05 considered statistically significant. RESULTS: No significant difference in PGI2 or TxA2 production was found in umbilical vessels between the women with diabetes/impaired glucose tolerance and controls, but the PGI2/TxA2 ratio in the vein was significantly lower in the diabetes/impaired glucose tolerance group. The umbilical artery pulsatility index was positively correlated to the PGI2/TxA2 ratio in cord vessel segments and to cord plasma TxA2 concentration. The cord plasma TxA2 concentration was significantly higher in cases with a high umbilical artery pulsatility index. The prostanoid production was not correlated to maternal HbA1c or cord plasma C-peptide concentrations. CONCLUSIONS: In association with diabetes, an increased 'peroxide vascular tone' and an enhanced 'endoperoxide shift' between platelets and vascular endothelium may explain the unexpected positive correlation found between the umbilical artery pulsatility index and the vascular PGI2/TxA2 synthesis ratio.

C-Peptide↗
PubMed1996

Uterine and umbilical circulation during the oxytocin challenge test.

Our objective was to study uterine and umbilical artery flow resistance during the oxytocin challenge test (OCT). The study population was 21 women with suspected placental insufficiency; one woman was excluded because of a positive OCT with reactive fetal heart rate pattern. We carried out simultaneous electronic fetal heart rate monitoring and Doppler velocimetry of uterine and umbilical artery flow during the OCT. The uterine artery flow resistance increased significantly during contractions in both OCT-positive (n = 5) and OCT-negative (n = 15) cases compared with basal values, but the increase was significantly higher in positive cases. The umbilical artery flow resistance increased significantly during contractions in OCT-positive cases, but was almost unchanged in negative cases. During uterine inactivity, there were no differences between the groups for any vessel. This study showed that fetal heart rate decelerations during the OCT are associated with rapid and exaggerated increases of vascular resistance in both uterine and umbilical arteries. The causal relationship is unknown, but the findings indicate pathophysiological mechanisms revealed only during uterine contractions.

Blood Flow Velocity↗
PubMed1996

Functional status and well-being in a group of patients with abdominal aortic aneurysm.

The aim of the present study was to investigate how abdominal aortic aneurysm (AAA) affects the patient's functional status, health and well-being. Forty-two consecutive patients at a university clinic were included. Twenty were operated on and 22 were on regular, conservative check-ups. The patients answered questionnaires regarding perceived functional status (Sickness Impact Profile, SIP), general health (Health Index, HI) and psychological well-being. Two reference groups were used. The non-operated patients scored significantly worse for functional status on the psycho-social subscale than the operated patients. In comparison with the reference group they had the worst scores for functional status on the overall SIP scale and the physical, eating and home-management scales. Regarding the HI, there was no difference between the patient groups themselves, but as a whole they had significantly lower scores than the reference group. Thus, the patients perceived their well-being as worse than a healthy reference group. In their attitudes to well-being, the non-operated patients, were significantly less hopeful than the operated patients. It is obvious that asymptomatic AAA has a significant effect on the patient's self-perceived, functional status and well-being, irrespective of the surgical or conservative management.

Activities of Daily Living↗
PubMed1996

The prospects for vaginal delivery in gestations beyond 43 weeks.

OBJECTIVE: To reveal factors influencing the prospect for vaginal delivery in very prolonged pregnancy. MATERIAL AND METHODS: Thirty-six nulliparae and 14 multiparae delivered beyond 43 weeks followed a routine surveillance protocol. Labor was induced on strict indications (n = 11; oligohydramnios, large fetus, hypertension) and on "soft' indications (n = 24; favorable cervix, emotional stress). STATISTICS: Receiver operating characteristic curves were obtained for maternal stature and birthweight with regard to mode of delivery. Student's unpaired t-test, Mann-Whitney U test, and Fisher's exact test were used with a two-tailed p < 0.05 considered statistically significant. RESULTS: Labor started spontaneously within three days in > 50% of cases managed expectantly. All multiparae had nonoperative vaginal deliveries. Of nulliparae, 89% delivered vaginally if spontaneous labor and 56% if induced. Failure to progress was the most common reason for operative delivery. A maternal height of < or = 160 cm, a very unripe cervix, and a birthweight > 4250 g were unfavorable factors in induced nulliparae. No case of perinatal mortality, severe birth asphyxia, meconium aspiration, or shoulder dystocia occurred. Fetal meconium release, fetal distress in labor, and birth asphyxia did not significantly differ with regard to parity or mode of labor. CONCLUSIONS: The prospect for vaginal delivery was strongly associated with parity. All multiparae had nonoperative vaginal deliveries, irrespective of spontaneous or induced labor. In nulliparae, a spontaneous onset was favorable but a maternal height of < or = 160 cm, a very unripe cervix, and a birthweight > 4250 g were unfavorable factors. In uncomplicated pregnancy with favorable factors spontaneous labor can be awaited for a few days.

Birth Weight↗
PubMed1996

Postocclusive reactive hyperemia estimating peripheral vascular resistance: a noninvasive method to predict outcome of infrainguinal vascular reconstructions?

OBJECTIVE: The peripheral vascular resistance is an important factor determining the outcome of infrainguinal revascularizations. When measured intraoperatively, it correlates to graft patency, but to select patients to surgery a preoperative, preferably noninvasive, method is necessary. The aim of the present study is to test if parameters recorded during postocclusive reactive hyperemia can be used for that purpose. EXPERIMENTAL DESIGN: This prospective study compares patients with occluded grafts within 30 days postoperatively to patients with patent grafts. SETTING: University Hospital. PATIENTS: Thirty patients with critical ischemia scheduled for infrainguinal bypass surgery. MEASURES: Correlations between intraoperatively measured peripheral resistance and preoperatively recorded parameters of postocclusive reactive hyperemia. The ability of the values to predict outcome. RESULTS: Peripheral resistance correlated significantly to two parameters during postocclusive reactive hyperemia recorded after thigh occlusion, flux reappearance time (r=0.47, p=0.01) and time to peak flux (r=0.41, p=0.03). Intraoperative peripheral resistance predicted graft occlusion at 30 days with a 90% accuracy, while parameters obtained during reactive hyperemia, only tended to predict adverse outcome. CONCLUSIONS: Several parameters during reactive hyperemia show weak correlation to intraoperatively measured peripheral resistance, but none was able to accurately predict graft failure. Further studies are needed to evaluate its capability for patient selection.

Aged↗