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Biomedical subjects

J Lutz

Publications and source records attributed to J Lutz.

At least 73 records · Page 4Linked to original sources
PubMed1995

Several methods utilized for the assessment of biocompatibility of perfluorochemicals.

An overview is presented on methods used to judge the effect of different perfluorochemicals (PFCs) on functional organ changes. By some of these methods the function of the reticuloendothelial system (RES) after a load with PFC was tested, either globally in form of the clearance of colloidal carbon particles or by a magnetometric method to test the phagocytosing function of macrophages within the liver of rats. An endotoxin test on survival of mice after the combined treatment with lipopolysaccharides of E. coli and PFCs showed the importance of a cumulative effect of multiple factors influencing phagocytosis. Other methods examined the influence of PFCs on lipid peroxidation during reperfusion of the ischemic intestine or on the effects of hyperbaric oxygen on the lung. The half-life (mean dwell time) of PFCs within organs with a high storage rate could optimally be determined by means of 19F magnetic resonance imaging in longitudinal studies within the same animal. An influence of PFCs on hepatocytes was tested by determining the time required for detoxifying pentobarbital as measured by the sleeping time (until reappearance of the righting reflex). By all these tests a strong dose-dependence was found, so that effects observed with a high load may become negligible with smaller dosages.

Animals↗
PubMed1995

Beliefs and practices regarding childhood vaccination among urban pediatric providers in New Jersey.

BACKGROUND: In 1991, the fourth largest measles outbreak in the nation (824 cases) occurred in the Jersey City, New Jersey area. Data from a subsequent intervention trial in Jersey City demonstrated that vaccinations were more likely to be delayed for children who had received care from private rather than public clinic providers. In addition, failure to administer multiple indicated vaccines at a single visit was associated with vaccination delay, and reluctance to administer multiple vaccines was more common among private providers. These findings prompted an investigation of vaccination beliefs and practices among urban pediatric providers. METHODS: A telephone survey of vaccination beliefs and practices was administered to all pediatric providers in both private and public clinics in the Paterson and Jersey City areas. RESULTS: Private providers were less likely than public clinic providers to consider vaccinating children during emergency room visits (relative risk [RR] = 2.2; 95% confidence interval [CI] = 1.2-4.2) or hospital admissions (RR = 13.2; 95% CI = 1.9-92.7) and less likely to believe that all recommended vaccine doses should be administered simultaneously (RR = infinite; lower 95% confidence limit = 3.0). Private providers were less likely to consider administering live-virus vaccines to children with minor acute illnesses and low-grade fever (RR = 2.2; 95% CI = 1.2-3.8) or killed-virus vaccines to children with minor acute illnesses without fever (RR = 3.4; 95% CI = 1.4-8.5) or with low-grade fever (RR = 2.2; 95% CI = 1.2-3.9). Private providers were more likely to believe that multiple injections should be avoided because of potential psychological and physical trauma to the child (RR = 4.0; 95% CI = 1.3-12.3). CONCLUSIONS: Adherence to Standards for Pediatric Immunization Practices by pediatric providers could improve vaccine coverage rates among urban children.

Ambulatory Care Facilities↗
PubMed1995

Protective effects of the mixed endothelin receptor antagonist bosentan in rats with CCL4-induced liver injury.

We determined whether the paracrine liver endothelin (ET) system participates in the pathogenesis of CCl4-induced hepatotoxicity. Wistar-Kyoto rats were divided into four groups: a bosentan-treated group with CCl4 intoxication, a vehicle-treated group with CCl4 intoxication, a nontreated control group, and a bosentan-treated control group. Hepatotoxicity was assessed by determination of serum levels of alanine aminotransferase (ALT), aspartate aminotransferase (AST) and lactate dehydrogenase (LDH). Tissue ET-1 concentrations and expression of endothelin receptor subtypes were analyzed. The liver tissue levels of ET-1 in rats with CCl4 intoxication were significantly higher than in normal rats. Scatchard analysis revealed no differences in the density and binding constants of ETA and ETB receptors between rats with CCl4 intoxication and controls. Bosentan treatment of rats undergoing CCl4 inhalation resulted in significant protection against elevation of ALT, AST, LDH, and bilirubin. In conclusion, this study showed that the paracrine ET system in involved in the pathogenesis of CCl4-induced hepatotoxicity and that blockade of the stimulated liver endothelin system reduces CCl4-induced liver injury.

Animals↗
PubMed1994

Magnetometric measurements of macrophage activity in the liver after administration of different perfluorochemicals.

The activity of liver macrophages was evaluated using a magnetometric method after administration of different perfluorochemicals. Following treatment with perfluoroctylbromide a significant shorter time period of diminished macrophage activity was found compared with a mixture of perfluorodecalin and perfluorotripropylamine. Results obtained with the magnetometric method on liver macrophages were more sensitive compared with those of colloidal carbon clearance of total body RES.

Animals↗
PubMed1994

Phagocytosis of colloidal carbon after administration of perfluorochemicals of first and second generation.

By means of colloidal carbon clearance loading of cells of the reticulo-endothelial system (RES) in rats was estimated after administration of perfluorochemicals. Perfluorocylbromid revealed a significant lower depression of RES function than an equally dosed (g/kg b.wt.) mixture of perfluorodecalin and perfluorotripropylamine. Compared with a magnetometrical measurement of liver macrophage activity, shorter periods of cell loading was determined.

Animals↗
PubMed1994

Increased lipid peroxide level and myeloperoxidase activity in the vitreous of patients suffering from proliferative vitreoretinopathy.

BACKGROUND: Retinal pigment epithelium cells and activated phagocytes are believed to be involved in the pathogenesis of proliferative vitreoretinopathy (PVR). Both cell types are capable of producing oxygen free radicals and other molecules with a high oxidative potential which can lead to a propagation of oxidative damage. It was the aim of this study to investigate whether products of oxidative reactions are detectable in the vitreous body of patients suffering from PVR. METHODS: In vitreous aspirates of patients vitrectomized because of PVR (n = 27), macular pucker (n = 9), or other reasons (controls, n = 31), the following parameters were determined: lipid peroxides (LPO), determined as malondialdehyde-like substances (MDA) and as thiobarbituric acid-reactive substances (TBARS), and myeloperoxidase activity (MPO). RESULTS: Compared with the controls, both LPO levels and MPO activities were significantly elevated in the vitreous of patients suffering from PVR. Vitreous of patients with macular pucker did not reveal any significant differences from controls in the parameters analyzed. CONCLUSION: Our results suggest that both oxygen free radicals and inflammation-related reactions participate in the process of PVR. Oxidative tissue damage is obviously not involved in the pathogenesis of macular pucker.

Free Radicals↗
PubMed1994

Fast 19F-NMR imaging in vivo using FLASH-MRI.

The goal of this study was the development of a method that allows the acquisition of chemical shift selective 19F NMR images within a short measuring time. A train of small tip angle frequency selective pulses, each followed by a dephasing gradient of random strength, was used as a presaturation experiment for the suppression of the unwanted chemical shift components. Imaging was performed after presaturation using a SNAPSHOT-FLASH experiment. The acquisition time for a 64 x 128 image including the presaturation experiment amounted to only 470 ms. The sequence was applied in a 4.7 Tesla magnet to perform a longitudinal pharmacological study on the clearance of perfluoroocytlbromide (PFOB) in the liver and spleen of rats.

Animals↗
PubMed1994

Determinants of growth in children with the obstructive sleep apnea syndrome.

Failure to thrive is a common complication of childhood obstructive sleep apnea syndrome (OSAS). To further evaluate its cause, we obtained 3-day dietary records, anthropometric measurements, polysomnography, and measurements of energy expenditure during sleep (SEE) in children with OSAS before and after tonsillectomy and adenoidectomy. Fourteen children were studied (mean age, 4 +/- 1 (SD) years). During initial polysomnography, patients had 6 +/- 3 episodes of obstructive apnea/hr, an arterial oxygen saturation nadir of 85% +/- 8%, and peak end-tidal carbon dioxide tension of 52 +/- 6 mm Hg. After surgery, OSAS resolved in all patients. The standard deviation score (z score) for weight increased from -0.30 +/- 1.47 to 0.04 +/- 1.34 (p < 0.005), despite unaltered caloric intake (91 +/- 30 vs 90 +/- 27 kcal/kg per day; not significant). The initial SEE (averaged over all sleep states) was 51 +/- 6 kcal/kg per day; postoperatively, it decreased to 46 +/- 7 kcal/kg per day (p < 0.005). Although SEE decreased during all sleep stages, the greatest decrease occurred during rapid eye movement sleep. The patients with the highest SEE on initial study had the lowest z scores (r = -0.62; p < 0.05). We conclude that SEE decreases and weight improves after resolution of OSAS. We speculate that the poor growth seen in some children with OSAS is secondary to increased caloric expenditure caused by increased work of breathing during sleep.

Child↗
PubMed1994

Influence of perflubron on the creation of oxygen free radical products in mesenteric artery occlusion shock.

The influence of a temporary occlusion of the superior mesentery artery on the generation of oxygen free radical products was tested in controls and after administration of perflubron. The occlusion time lasted for 90 min and a reperfusion time of 150 min was chosen until examination of tissue samples took place. The content of thiobarbituric acid reactive substances (TBARS), glutathione (GSH) and myeloperoxidase (MPO) was determined in homogenized tissue samples. A protective effect of antioxidants or radical scavengers was tested in form of alpha-tocopherol and allopurinol. A highly significant increase of TBARS was found in the operated control group, still higher under perflubron (perfluoroocytylbromide, PFOB). However, under alpha-tocopherol as well as under allopurinol the effect of radical products could be diminished below the values of controls. GSH and MPO were not significantly changed under PFOB as compared to the operated control group.

Allopurinol↗
PubMed1994

Perfluorodecalin emulsion tested for biocompatibility in macrophages by means of a magnetometric method.

The effect of a stable perfluorodecalin (FDC) emulsion, based on addition of 0.2-0.5% (W/V) of perfluoroperhydrophenanthrene and 4% egg yolk lecithin was tested for its influence on Kupffer cells in vivo by means of a magnetometric procedure in rats. It was also compared with the effect of a perfluoro-chemical emulsion (PFC) of the first generation (FluosolR-DA, FDA). While doses of 0.1 g/kg body weight of both PFCs caused a small increase of activity in these cells (as measured by an increase in a ratio factor r after magnetization), doses of 1 g/kg b.wt. led to a significant retardation of intracellular movements after FDC and FDA for two and four days, respectively. A dose of 3 g/kg b.wt. of FDC effected a significant depression for 8 days, whereas after the same dose of Fluosol-DA the intracellular motility remained depressed for as long as 32 days.

Animals↗
PubMed1994

Free radical scavenging and antioxidant activity of allopurinol and oxypurinol in experimental lens-induced uveitis.

PURPOSE: In addition to the inhibition of xanthine oxidase, allopurinol is known to act, dependent on the dose, as a free radical scavenger, an antioxidant, and a "scavenger" of hypochlorous acid. This activity was investigated using a model of lens-induced uveitis. METHODS: Lipid peroxides (LPO) were determined in aqueous humor and in retinal tissue. Reduced and oxidized glutathione (GSH and GSSG) of the aqueous humor and myeloperoxidase (MPO) activity in the iris-ciliary body complex were analyzed. Allopurinol and oxypurinol concentrations were determined by high-performance liquid chromatography in aqueous humor and retinal tissue of both control eyes and eyes with uveitis. These measurements were performed 6 hours after intravenous application of allopurinol. RESULTS: In lens-induced uveitis, LPO are significantly elevated, GSH is reduced, and GSSG and MPO are increased. A xanthine oxidase inhibition dose (< 10 mg/kg body weight) of allopurinol showed no effects on oxidative tissue damage in the model used in this study. Higher doses, however, were able to reduce the oxidative damage. Allopurinol (20 mg/kg body weight) had slight effects on GSH and GSSG. All parameters improved using a dose of 50 mg/kg body weight; a dose of 100 mg/kg body weight only showed additional improvement in GSH and GSSG. There was no further change in the other parameters. Allopurinol and oxypurinol concentrations in aqueous humor and retinal tissue showed a dose dependency reaching scavenger concentrations after application of 50 mg/kg body weight of allopurinol. CONCLUSIONS: These results suggest that the xanthine oxidase mechanism plays a minor role in the oxidative tissue damage due to lens-induced uveitis. Free radicals and oxidants are generated by activated leukocytes; therefore, the effect of higher doses of allopurinol is due to its free radical scavenging and antioxidative activity.

Allopurinol↗
PubMed1993

Increased lipid peroxide levels and myeloperoxidase activity in the vitreous of patients suffering from proliferative diabetic retinopathy.

Lipid peroxide (LPO) levels, as determined by high-performance liquid chromatography (HPLC) and by the thiobarbituric acid (TBA) method, and myeloperoxidase (MPO) activity in vitreous of patients vitrectomized because of proliferative diabetic retinopathy were compared with LPO levels and MPO activity in vitreous of patients with no vitreoretinal proliferation. Both LPO levels and MPO activity were significantly elevated in the vitreous of patients with fibrovascular vitreoretinal proliferations secondary to diabetes. The TBA method produced higher values for LPO levels than did the HPLC method. The correlation between the two methods was 0.94. Our results suggest that both oxygen-free radicals and inflammation-related reactions can participate in the pathogenesis of diabetic retinopathy.

Chromatography, High Pressure Liquid↗
PubMed1993

Applications of epidemiology in the operation and marketing of managed care plans.

This article discusses the background and use of epidemiology by managed care plans. The relevance of the outcomes-oriented approach used in epidemiology is explained with regard to operational and marketing decisions. Examples from the research literature are provided that illustrate the types of decisions that can benefit from epidemiologic input. Finally, the implications for health services administration training are discussed.

Decision Making, Organizational↗
PubMed1992

Influence of anti-inflammatory drugs and free radical scavengers on intestinal ischemia induced oxidative tissue damage.

The influence of oxygen free radical scavengers and anti-inflammatory drugs on postischemic lipid peroxidation and myeloperoxidase activity was shown. The best results were obtained from vitamin E and the antiinflammatory treatment with CP and SUL, whereas an iron elimination only showed slight effects on myeloperoxidase activity above all. In experiments without therapy a linear increase of lipid peroxides dependent on reperfusion durance was found, whereas myeloperoxidase already showed a remarkable increase during ischemia and early reperfusion. This difference can be interpreted by scavenging mechanisms, which are overcharged after an appointed durance of reperfusion.

Animals↗
PubMed1992

Influence of free radical scavengers on myeloperoxidase activity and lipid peroxidation in acute skin grafts.

Activated neutrophil granulocytes are an important source of oxygen free radicals in acute skin grafts. Lipid peroxidation and immigration of PMNs, indicating inflammatory mechanisms, affect each other to a variable extent. The effect of the scavengers allopurinol and alpha-D-tocopherol on both lipid peroxidation and neutrophilic infiltration was investigated. A possible mechanism for the superior effect of allopurinol compared to vitamin E was discussed.

Allopurinol↗