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Biomedical subjects

J Bakker

Publications and source records attributed to J Bakker.

118 records · Page 7Linked to original sources
PubMed1979

Photoactivation of the nematicidal compound alpha-terthienyl from roots of marigolds (Tagetes species). A possible singlet oxygen role.

The nematicidal compound alpha-terthienyl from roots of Tagetes species generates upon irradiation with near ultraviolet light reactive oxygen species on which the in vitro nematicidal activity depends. This system was studied by following the inhibition of glucose-6-phosphate dehydrogenase by photoactivated alpha-terthienyl and protection of the enzyme activity in the absence of oxygen and by various additions. Addition of mannitol, benzoate, superoxide dismutase or catalase did not have any effect nor did H2O2. This suggests that OH., O-.2, and H2O2 are not the reactive oxygen species involved. The enzyme was protected against photoactivated alpha-terthienyl in air-saturated solutions by singlet oxygen quenchers such as histidine, methionine, tryptophan, bovine serum albumin, and NaN3. Furthermore, inactivation of the enzyme was about 3.5 times faster in D2O than in H2O. When alpha-terthienyl in CH2Cl2 was irradiated in the presence of the olefin adamantylideneadamantane, a stable dioxetane was formed which decomposed to adamantanone when heated above its melting point. These results indicate a singlet oxygen-mediated process.

Animals↗
PubMed1977

Thermoregulatory effects of intraventricularly injected dopamine in the goat.

Dopamine (DA) was injected in the third brain ventricle of goats and the thermoregulatory effects were studied under different ambient conditions. The effects depended on dose, ambient conditions and cannula used. In the cold, there was a drop in body temperature, sometimes accompanied by suppression of shivering and by vasodilatation. Both temperature decrease and suppression of shivering were dose-dependent but there was no relation between magnitude of temperature drop and occurrence of shivering suppression. In a thermoneutral environment, there was either a slight vasoconstriction or hypothermia, occasionally accompanied by induction of panting. In the heat, either hypothermia or hyperthermia was observed. Hypothermia was accompanied by an increase in panting. Hyperthermia only occurred when the animals became excited as a result of the injection of DA. It is concluded that DA acts by stimulating the thermoregulatory pathway from heat sensors to heat loss effectors at a locus similar to that for 5-hydroxytryptamine in the thermoregulation model of Bligh et al. (1971).

Animals↗
PubMedDate not supplied

Infectious complications of radiologically inserted Hickman catheters in patients with hematologic disorders.

PURPOSE: To assess the incidence of infections and its influence on the survival of radiologically inserted Hickman catheters (HCs) in patients with hematologic disorders and to determine factors associated with premature HC removal. METHODS: Survival and complications of 175 HCs in 115 patients were studied retrospectively. To describe the data the Kaplan-Meier method and the log-rank test were used, using the date of HC removal due to HC-related infection as endpoint. A stratified Cox regression model was used to determine explanatory factors. RESULTS: Seventy (40%) HCs were removed prematurely because of proven or probable HC-related infections. The incidence of infection leading to HC removal was 4. 78 per 1000 catheter-days for proven HC infections. Univariate analysis revealed that acute myeloid leukemia, acute lymphocytic leukemia, or treatment for these diseases, gender, each subsequent catheter in the same patient and insertion site increased the risk of premature removal of the catheter due to infection. CONCLUSION: Infection is a major problem in patients with HCs. Unfortunately, the factors associated with increased infection rates that were found in this study cannot be influenced. Further studies are necessary to determine the role of environmental conditions in a radiology suite in relation to the risk of developing a catheter-related infection.

Adolescent↗
PubMedDate not supplied

The Erasme study: a multicenter study on the safety and technical results of the Palmaz stent used for the treatment of atherosclerotic ostial renal artery stenosis.

PURPOSE: To assess, in a multicenter setting, safety, technical results, and restenosis rate of the Palmaz stent for treatment of atherosclerotic ostial renal artery stenosis. METHODS: Ten centers enrolled 106 patients (120 treated renal artery stenoses) in the study. Patient selection was based on unsuccessful percutaneous transluminal renal angioplasty (residual stenosis >/= 20%) performed for treatment of ostial stenosis >/= 50%, in patients with hypertension and/or impaired renal function. Safety was assessed by means of the complication rate, and technical results by the number of successful stent placements and occurrence of restenosis (>50%) at intraarterial angiographic follow-up. RESULTS: Stent placement was successful (n = 112) or partially successful (n = 5) in 117 (98%) arteries. Complications occurred in 19 procedures; seven were of serious clinical significance. Angiographic follow-up was performed in 89 of 117 (76%) cases, at a mean of 8 months (range 2. 5-18 months). Fifteen stents (16.9%) showed restenosis (at a mean of 8.5 months), of which 10 were successfully redilated. CONCLUSION: Renal artery stenting has a high technical success rate, a complication rate comparable to percutaneous transluminal renal angioplasty, and a low rate of restenosis at 8 months angiographic follow-up.

Aged↗
PubMedDate not supplied

Duplex ultrasonography in assessing restenosis of renal artery stents.

PURPOSE: To determine the accuracy and optimal threshold values of duplex ultrasonography (US) in assessing restenosis of renal artery stents. METHODS: Twenty-four consecutive patients with 33 renal arteries that had previously been treated with placement of a Palmaz stent underwent duplex US prior to intraarterial digital subtraction angiography (DSA), which was the reference standard. Diagnostic accuracy of in-stent peak systolic velocity (PSV) and reno-aortic ratio (RAR = PSV renal stent/PSV aorta) in detecting > 50% in-stent restenosis were evaluated by the receiver operating characteristic curve. Sensitivity and specificity were determined using the optimal threshold values, and using published threshold values: RAR > 3.5 and in-stent PSV > 180 cm/sec. RESULTS: Six examinations were technically inadequate. Nine stents had residual or restenosis > 50% at DSA. The two duplex parameters were equally accurate since areas under the curves were similar (0.943). With optimal threshold values of 226 cm/sec for PSV and 2.7 for RAR, sensitivities and specificities were 100% and 90%, and 100% and 84%, respectively. Using the published duplex criteria resulted in sensitivities and specificities of 100% and 74% for PSV, and 50% and 89% for RAR. CONCLUSION: Duplex US is a sensitive modality for detecting in-stent restenosis if laboratory-specific threshold values are used.

Aged↗
PubMedDate not supplied

Sequential occupational dexterity assessment (SODA): a new test to measure hand disability.

Measuring hand-related disability poses a problem due to a lack of validated tests. This report introduces the sequential occupational dexterity assessment (SODA), a test that measures bimanual dexterity in daily life. The design of the SODA is described. Validity and reliability of the SODA are demonstrated in a sample of patients with rheumatoid arthritis (RA), in whom impairment of the hands may cause serious disability in daily life. Good reliability was found, as measured by internal consistency, test-retest correlation, and interrater stability. Validity was established by relating the SODA to a number of other variables. Current disease activity was only weakly related to the SODA score. Impairment of the hands is more strongly related to dexterity than to current disease activity. However, dexterity could vary considerably in patients with similar degrees of impairment. Pain during the SODA proved to be more important for dexterity than general level of pain. Considerable variation was found in self-reported and observed dexterity. It was concluded that the SODA may guide the therapist in making decisions about hand therapy. The use of the SODA allows standardized evaluation of the effects of hand surgery on bimanual dexterity.

Activities of Daily Living↗