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Biomedical subjects

L Jensen

Publications and source records attributed to L Jensen.

At least 55 records · Page 3Linked to original sources
PubMed1999

Intravenous magnesium reduces infarct size after ischemia/reperfusion injury combined with a thrombogenic lesion in the left anterior descending artery.

Experimental studies have demonstrated that intravenous magnesium (Mg) can protect the ischemic myocardium and has an antithrombotic effect. In patients with myocardial infarction, the reperfusion injury is complicated by the presence of a thrombogenic area in the affected coronary artery that may cause repetitive thrombus formation and embolization. We investigated the effect of Mg on infarct size in a randomized study in pigs. Myocardial infarction was induced by a 50-minute mechanical occlusion of the left anterior descending artery combined with an arterial injury, which stimulated a dynamic thrombus formation with emboli shedding on reperfusion. Magnesium sulfate (6 mmol/20 min plus 3 mmol/h) or saline was started at 30 minutes after coronary occlusion. Real-time ventricular pressure-volume loops were generated from the left ventricle by using a microtip pressure manometer and a conductance catheter. Platelet accumulation in the myocardium was evaluated by using 111In-labeled platelets. After 4 hours of reperfusion, the infarct size/area at risk ratio in the placebo group was 46+/-0.06% (n=8) compared with 22+/-0.07% (n=6) in the Mg-treated animals (P=0. 03). Ejection fraction decreased significantly in the control group but not in the Mg-treated animals (P=0.03). Platelet accumulation in the myocardium did not change significantly between the Mg- and placebo-treated animals (placebo group, 191+/-19%; Mg group, 177+/-29%; NS). The present study demonstrates that intravenous Mg infusion is able to reduce infarct size by >50% and preserve the ejection fraction in this model where ischemia/reperfusion injury was evaluated in the presence of a thrombogenic area in the nutrient artery.

Animals↗
PubMed1999

Subsets of CD34+ hematopoietic progenitors and platelet recovery after high dose chemotherapy and peripheral blood stem cell transplantation.

BACKGROUND AND OBJECTIVE: Randomized clinical trials have shown that peripheral blood stem cell transplantations (PBSCT) with appropriate doses of CD34+ cells are associated with rapid, complete and sustained recovery of marrow functions. Nevertheless, in a minority af patients delayed platelet recovery may occur and it remains to be established whether analysis of transplanted CD34+ cell subsets may demonstrate correlation with this phenomenon. We studied a series of 80 consecutive transplanted patients with the aim of evaluating the effect of CD34+ stem cell numbers and, in a subgroup of 32 patients, the effect of the lineage specific subset numbers on time to platelet engraftment (i.e. time to platelet counts higher than 20x10(9)/L for two consecutive days without the need for platelet transfusions). DESIGN AND METHODS: Different clinical and paraclinical factors were examined in a multivariate analysis for effect on platelet engraftment in 80 patients. RESULTS: The number of CD34+ cells/kg infused was the most important factor predicting the time to platelet engraftment. Patients receiving more than 10x10(6) CD34+ cells/kg had prompt platelet engraftment. The majority of the patients (78%) received fewer than 10x10(3) CD34+ cells/kg and 17/62 (27%) of these patients experienced delayed platelet engraftment. In 32 patients receiving fewer than 10x10(6) CD34+ cells/kg we focused on the content of different lineage specific CD34+ subsets in the PBSC products. The most significant correlation was recognized for CD34+/CD61+ megakaryocytic cell number and platelet engraftment. An inverse correlation between the CD34+/CD38Eth subset and platelet engraftment was found, indicating that a high number of CD34+/CD38Eth in the PBSC product might increase the risk for delayed engraftment. These results were further confirmed by the observation that patients who experienced platelet engraftment after day 20 had significantly more CD34+/CD38Eth cells/kg infused than patients with fast engraftment. INTERPRETATION AND CONCLUSIONS: The number of total CD34+ cells/kg infused was the most important factor predicting time to platelet engraftment. CD34+ subset analysis in a subgroup of patients suggests that a high number of uncommitted progenitors may be associated with slower platelet recovery than transplantation with a higher fraction of more committed peripheral blood stem cells.

ADP-ribosyl Cyclase↗
PubMed1999

Mechanical circulatory support as a bridge to cardiac transplantation: toward the 21st century.

Mechanical circulatory support is used to sustain the lives of patients awaiting cardiac transplantation who would otherwise die before a donor organ became available. Currently available ventricular assist devices used for mechanical circulatory support, risk factors and complications associated with use of these devices, and selection of candidates for treatment with mechanical support as a bridge to cardiac transplantation are reviewed. The importance of early insertion of the devices before end-organ dysfunction occurs is examined.

Forecasting↗
PubMed1999

Evaluation of 3-hour ambulation post cardiac catheterization.

There is much variation in the length of immobilization for patients post cardiac catheterization. While it is generally agreed that a period of time on bedrest is necessary to prevent post procedural complications, the optimal duration remains unknown. The purpose of this study was to evaluate the effects of 3-hour ambulation post cardiac catheterization with a 7 french (F) arterial catheter on bleeding, hematoma formation, and vascular complications. Retrospective chart data were gathered for a period of 8 months for patients who were on the traditional 5-hour ambulation protocol, and prospective data were gathered for a period of 7 months for patients who received the 3-hour protocol. A total of 880 patients were included in the study, with 472 in the 5-hour ambulation group and 408 in the 3-hour ambulation group. The overall incidence of delayed bleeding and hematoma formation for the 15 month study period was 19.1%, with no occurrence of vascular complications in either group. Patients who received the 3-hour ambulation protocol experienced a significantly lower rate of bleeding and hematoma formation (13%) than patients who received the 5-hour ambulation protocol (24.4%) (p < 0.001). Ambulating patients 3 hours post cardiac catheterization with a 7F catheter was found to be safe, and thus has the potential to decrease hospital length of stay, as well as increase patient comfort.

Adolescent↗
PubMed1998

Incontinence after lateral internal sphincterotomy: anatomic and functional evaluation.

PURPOSE: This study was designed to evaluate the anatomic and functional consequences of lateral internal sphincterotomy in patients who developed anal incontinence and in matched controls. METHODS: The study includes 13 patients with anal incontinence after lateral internal sphincterotomy and 13 controls who underwent the same operation and were continent and satisfied with the results of the procedure. Patients underwent clinical evaluation, anorectal manometry, pudendal nerve terminal motor latency testing, and endoanal ultrasonography. RESULTS: Sphincterotomies were longer in incontinent patients (75 vs. 57 percent), but the resting pressure and length of the high-pressure zone were not different between groups. Surprisingly, maximum voluntary contraction was higher in incontinent patients than in continent controls (136 vs. 100 mmHg). Rectal sensation and pudendal nerve terminal motor latency were similar in both groups. The defect in the internal sphincter was wider in incontinent patients than in continent controls (17.3 vs. 14.4 mm), but these differences were not statistically significant. The thickness of the internal sphincter measured by endoanal ultrasound was identical in both groups, but the external sphincter was thinner in incontinent patients both at the site of the sphincterotomy (6.8 vs. 8.1 mm) and in the posterior midline (7.1 vs. 8.6 mm). CONCLUSIONS: Anal incontinence after lateral internal sphincterotomy is directly related to the length of the sphincterotomy. Whether secondary to preoperative sphincter abnormality or the result of lateral internal sphincterotomy, the external sphincter is thinner in incontinent patients than in continent controls.

Adult↗
PubMed1998

Adaptational effects during human split-belt walking: influence of afferent input.

The modification of the normal locomotor pattern of humans was investigated using a split-belt locomotion protocol (treadmill belt speeds of 4.5 km/h and 1.5 km/h for the right and left legs, respectively) and also by changing afferent input from the legs (30% reduction or increase in body weight by suspending subjects in a parachute harness or by wearing a lead-filled vest). After a control-speed training period (10 min) of symmetrical walking (3 km/h each leg) and a period (10 min) of split-belt walking, the adjustment back to the control speed resulted in a mean speed difference between the right leg and the left leg of 0.85 km/h. Adjustment of belt speed on either side was performed by the hands using a potentiometer. For comparison, also speed adjustment by the feet via feedback derived from changes in the treadmill drive current was studied. No significant difference was obtained when both modes of adjustment were compared. Body unloading or loading during the training period resulted in an improved adjustment of treadmill belt speed. This suggests that load receptor information plays a major role in the programming of a new walking pattern.

Adaptation, Physiological↗
PubMed1998

A study of virulence parameters for Toxoplasma gondii infections in mice.

With the aim of establishing assessments of the virulence of Toxoplasma gondii isolates for mice, we investigated weight loss, serum levels of haptoglobin, and serum levels of tumor necrosis factor-alpha (TNF-alpha) as alternative parameters to mouse mortality. Groups of BALB/c mice were inoculated i.p. with increasing parasite doses (5 x 10(1), 10(4), and 10(6)) of isolate 119 and with a low dose (5 x 10(1)) of isolates GT1 and NED. The inoculation dose was inversely correlated with the interval to the onset of weight loss (starting at days 9, 7, and 5, respectively) and the onset of increase in serum haptoglobin (starting at about days 8, 6, and 4, respectively). The GT1 strain (inducing 100% mortality at day 9) also gave the fastest response in terms of weight loss (onset by day 8) and increase in serum haptoglobin (onset by day 6), which occurred 1-2 days before these parameters were affected in the other low-dose groups. The low-dose NED and 119 inoculations were distinguished by continued weight loss, which lasted until day 20 in the former group (max. average weight loss 2.9 g as compared with 0.4 g).

Animals↗
PubMed1998

Monoclonal antibodies to Toxoplasma gondii strain 119 identify recently isolated Danish strains as one group.

Four mAb raised against the Danish Toxoplasma gondii strain 119, were selected by screening hybridoma supernatants by indirect immunofluorescence against tachyzoites of the RH strain in order to obtain strain-restricted markers. Strain restriction extended beyond discrimination of the 119 and RH strains, as demonstrated on a further six T. gondii reference strains [BK and GT1 (group A), NTE and 561 (group B), and NED and C56 (group C)]. The bradyzoite-specific mAb, 4.3, reacted to the GT1, NTE and 561 strains, but not to the BK, NED or C56 strains. The tachyzoite-specific mAb, 4.25, reacted to all strains tested except the RH strain, while mAb 5.1 reacted to tachyzoites of strains NTE and 561, but not to those of the BK, GT1, NED or C56 strains. Monoclonal antibody 5.15 reacted with the same strain restriction as monoclonal antibody 5.1, but to bradyzoites as well as tachyzoites. A T. gondii strain collection representative for a small geographic area (Denmark) was established within a short time span from a variety of animal species. Using the mAb as typing reagents to this Danish strain collection, all 36 animal and two human strains were identified as having the same reaction pattern as strains 119, NTE and 561.

Animals↗
PubMed1998

Knowledge of HIV-positivity had no impact on AIDS survival time among Danish AIDS patients 1980-95.

OBJECTIVE: To examine the impact of the time period from first positive HIV test to AIDS diagnosis and other variables on survival after AIDS diagnosis. MATERIALS AND METHODS: All adult AIDS patients diagnosed and reported to the national surveillance unit in Denmark in the period 1980 through June 1995. RESULTS: A total of 1745 patients was diagnosed in the period, and for 1631 (93.5%) the date of first positive HIV test was known. The median interval between this test and AIDS diagnosis was 912 d. Overall, 473 patients (29.0%) were found to be HIV-positive close to the AIDS diagnosis (< or = 4 months). The time interval between first positive HIV test and AIDS diagnosis varied by transmission categories. Patients older than 40 y had a higher mortality than younger patients. Patients infected by blood products had the highest mortality. The survival time was shortest for patients presenting with HIV-wasting or HIV-encephalopathy or with > or = 1 AIDS-defining disease. The time interval between first positive HIV test and AIDS diagnosis had no impact on survival. CONCLUSION: No association was found between survival time and the time interval between first positive HIV test and AIDS diagnosis. Older age and transmission by blood or blood products were associated with shorter survival from AIDS diagnosis.

Acquired Immunodeficiency Syndrome↗
PubMed1998

Evaluation of mobilized CD34+ cell counts to guide timing and yield of large-scale collection by leukapheresis.

We have previously reported a more than 50% risk of insufficient harvests (< 2 x 10(6) CD34+ cells/kg) following a fixed timing of leukapheresis in an unselected patient population collected for autologous stem cell transplantation. The failures were easily identified as patients who had < 20,000/ml CD34+ blood cells at the time of harvest. Consequently, in an attempt to optimize the timing strategy, we decided to perform daily analysis of the blood levels and perform leukapheresis within 24 h after the blood cell count exceeded 20,000 CD34+/ml. The results of this prospective study showed (a) that leukapheresis collections that were initiated based on the CD34+ blood level resulted in a success rate of 85% following 1-3 day harvests, (b) that high-level mobilizers with > 80,000 CD34+ cells/ml can be harvested successfully by only one procedure, and (c) that low-level mobilizers with < 40,000 CD34+ cells/ml still have a high risk of inadequate harvests. In summary, the optimized timing strategy is effective, but there is still room for improvement. First, new potent priming procedures for low-level and bad mobilizers are required, and second, algorithms to reduce the leukapheresis volume and time for high-level mobilizers should be established.

Adolescent↗
PubMed1998

Comparison of rhG--CSF primed bone marrow and blood stem cell autografts: an analysis of engraftment in malignant lymphomas and solid tumours.

Many studies have documented faster engraftment after transplantation with peripheral blood stem cells (PBSC) compared to bone marrow (BM) stem cells. Most comparisons, however, have been between unprimed BM and primed PBSC. We have collected engraftment data on 39 patients from 4 Danish centres and compared G-CSF primed BM with G-CSF primed PBSC in malignant lymphoma and solid tumours. In the lymphoma group 6 BM transplants were compared with 8 PBSC transplants, whereas in the testicular cancer group 16 BM transplants were compared with 9 PBSC transplants. In the lymphoma group, the time to platelet engraftment (platelets >20x10(9)/l unsupported) was median 15 d in PBSC transplants and median 34 d in BM transplants (p=0.003). In the solid tumour patients the difference in time to platelet engraftment was 11 and 18 d in PBSC and BM transplants, respectively (p<0.0001). In an attempt to explain this difference we performed CD34+ subset analysis of BM and PBSC. This analysis revealed a higher content of lineage restricted cells (CD34+CD61+ and CD34+GlyA+) in PBSC compared to BM. In conclusion, G-CSF mobilized PBSC seems to result in faster engraftment than G-CSF primed BM, which could be explained by an increased number of lineage specific progenitors in PBSC compared to BM.

Adolescent↗
PubMed1998

Experimental porcine neosporosis.

Six gilts were inoculated intramuscularly with 2.5x10(6) tachyzoites of Neospora caninum on three different days of gestation to study the pathogenic effect of Neospora infection in pigs, including possible transplacental transmission. The gilts were euthanized 59, 30, and 9/10 days postinoculation (p.i.), corresponding to days 107, 102/106 and 110/111 of pregnancy. With the exception of one animal (euthanized day 9 p.i.) all gilts seroconverted as measured by the indirect, fluorescent antibody test (IFAT). Neosporosis with multifocal intralobular necrotizing hepatitis was seen in the two gilts inoculated 9/10 days before euthanasia. The uterus of one gilt inoculated 59 days before euthanasia revealed granulomatous and focal necrotizing endometritis with a corresponding multifocal necrosis of the trophoblasts of two fetuses. Transplacental neosporosis was indicated in the two fetuses by strongly elevated Neospora IFAT titres in pleural fluid and by the presence of multifocal necrotizing encephalitis and hepatitis together with non-suppurative myocarditis, pneumonitis, nephritis and hepatitis. Furthermore, N. caninum was re-isolated in cell culture from one of these fetuses. A third fetus from the same gilt revealed only disseminated, pinpoint necroses in the liver. Immunohistochemically, N. caninum tachyzoites were detected in association with histopathological changes in the liver and the endometrium of the gilts, and in the brain, liver, and allantochorion of the three fetuses.

Animals↗
PubMed1998

Changing i.v. administration sets: is 48 versus 24 hours safe for neutropenic patients with cancer?

PURPOSE/OBJECTIVES: To examine the effects of changing i.v. administration sets at 48 versus 24 hours on the incidence of infusion-related septicemia in neutropenic patients with cancer. DESIGN: Prospective, randomized clinical trial with repeated measures. SETTING: Large urban cancer center. SAMPLE: 50 adult inpatients with a primary diagnosis of hematologic malignancy, breast cancer, or testicular cancer or who were receiving a stem cell transplant. METHOD: Subjects were assigned randomly to have their i.v. sets changed every 48 or 24 hours. Subjects continued in the study for a maximum of five measurements, until they were no longer neutropenic, or until transferred or discharged from the hospital. MAIN RESEARCH VARIABLES: Rates of infusate colonization, microorganisms identified, incidence of infusion-related septicemia. FINDINGS: Colonized infusate was detected in 18 (5%) of 413 i.v. sets; 9 (5%) of 177 sets were changed at 48 hours, and 9 (4%) of 236 sets were changed at 24 hours (p > 0.05). A trend toward increased colonization of i.v. sets used to administer parenteral nutrition (19%) and, to a lesser extent, electrolytes (9%) was identified in the 48-hour group. Coagulase-negative staphylococci were the most frequently isolated microorganisms in the i.v. infusate. Similar organisms were isolated from blood cultures and administration sets, however, no subject had identical organisms isolated from both i.v. infusate and blood cultures. No subject with colonized infusate developed infusion-related septicemia. CONCLUSIONS: No difference existed in the incidence of colonization or infusion-related septicemia between subjects whose i.v. administration sets were changed at 48 versus 24 hours. IMPLICATIONS FOR NURSING PRACTICE: Changing i.v. administration sets every 48 hours is recommended. Exceptions to this include i.v. administration sets used to administer blood products and total parenteral nutrition.

Adult↗
PubMed1998

Age and gender differences in value orientation among American adolescents.

This study investigated the development of a caring value orientation in four age groups. The sample included 1,247 students in grades 6, 8, 10, and 12 who were asked to complete a questionnaire, containing 14 contrasting word pairs and phrases, designed to measure preference for more caring, personal values. Gender differences were found across age groups and geographic regions. These findings are discussed in terms of theories that hypothesize gender differences in worldview.

Adolescent↗
PubMed1998

Impact of a decision tree on chronic wound care.

OBJECTIVE: To examine the use of a decision tree and its impact on the accuracy of decision making for chronic wound care. DESIGN: Descriptive comparative design; replication study. SETTINGS AND SUBJECTS: Data were collected from 2 groups of home care nurses in large urban centers. One group was measured after initial contact with the decision tree, and the other group was measured 2 years after implementation of the decision tree. INSTRUMENTS: The chronic wound management decision tree (CWMDT) designed by Knight was used, in combination with pictorial case studies developed by Willey and Swords. METHODS: Edmonton Home Care Program nurses, having used a decision tree for 2 years, completed 3 pictorial case studies without the aid of a written copy of the CWMDT. Current accuracy of wound care staging and treatment was compared with the Melchior-MacDougall and Lander results. After this procedure, Calgary Health Services home care nurses completed 3 pictorial case studies to assess the accuracy of wound care staging and treatment between 2 groups: with the CWMDT and without the CWMDT. A questionnaire was completed on factors identified to influence decision making in wound care. MAIN OUTCOME MEASURE: Accuracy and confidence of decision making in wound care staging and treatment. RESULTS: Accuracy of decision making with use of the CWMDT improved over time, as did accuracy of decision making after initial contact with the decision tree. Age, experience in nursing and home care, number of in-services attended, and number of chronic wounds treated, were not found to correlate with accuracy of decision making. CONCLUSION: A decision tree can assist with decision making by guiding the nurse through assessment and treatment options.

Adult↗
PubMed1997

Corticospinal input in human gait: modulation of magnetically evoked motor responses.

Transcranial magnetic stimulation (TMS) of the motor cortex was applied during locomotion to investigate the significance of corticospinal input upon the gait pattern. Evoked motor responses (EMR) were studied in the electromyogram (EMG) of tibialis anterior (TA), gastrocnemius (GM) and, for reference, abductor digiti minimi (AD) muscles by applying below-threshold magnetic stimuli during treadmill walking in healthy adults. Averages of 15 stimuli introduced randomly at each of 16 phases of the stride cycle were analysed. Phase-dependent amplitude modulation of EMR was present in TA and GM which did not always parallel the gait-associated modulation of the EMG activity. No variation of onset latency of the EMR was observed. The net modulatory response was calculated by comparing EMR amplitudes during gait with EMR amplitudes obtained (at corresponding background EMG activities) during tonic voluntary muscle contraction. Large net responses in both muscles occurred prior to or during phasic changes of EMG activity in the locomotor pattern. This facilitation of EMR was significantly higher in leg flexor than extensor muscles, with maxima in TA prior to and during late swing phase. A comparison of this facilitation of TA EMR prior to swing phase and prior to a phasic voluntary foot dorsiflexion revealed a similar onset but an increased amount of early facilitation in the gait condition. The modulated facilitation of EMR during locomotion could in part be explained by spinal effects which are different under dynamic and static motor conditions. However, we suggest that changes in corticospinal excitability during gait are also reflected in this facilitation. This suggestion is based on: (1) the similar onset yet dissimilar size of facilitatory effects in TA EMR prior to the swing phase of the stride cycle and during a voluntary dynamic activation, (2) the inverse variation of EMR and EMG amplitudes during this phase, and (3) the occurrence of this inversion at stimulation strengths below motor threshold (motor threshold was determined during weak tonic contraction and EMR were facilitated during gait). It is hypothesized that the facilitation is phase linked to ensure postural stability and is most effective during the phases prior to and during rhythmical activation of the leg muscles resulting in anticipatory adjustment of the locomotor pattern.

Adult↗