PubMed Health⌕ Search

Biomedical subjects

S Christen

Publications and source records attributed to S Christen.

34 records · Page 2Linked to original sources
PubMed1998

[Successful coping with declining objective life style by institutionalized long-term patients. Results of a follow-up analysis of quality of life in long-term care institutions with the Zurich Quality of Life Inventory].

Measurement of quality of life in institutionalized frail patients is difficult considering the high prevalence of dementia. The Zurich quality of life inventory was developed specifically for this purpose and applied to describe longitudinally 103 institutionalized long-term care patients 3-12 months after entry: 11 slow-stream-rehabilitation patients (SSR), 16 severely dependent patients (ASL), 61 moderately dependent patients (ALL), and 15 young severely dependent patients, all of whom were assessed at least twice. The objective conditions of life deteriorated in all 4 groups, significantly in the SSR and ASL, and with high significance in the whole population from 121 +/- 54 to 139 +/- 58 (P < 0.001). Well-being did not change significantly in any of the groups or overall (from 122 +/- 59 to 117 +/- 54, p = 0.90). Deteriorating life conditions were due to a decline in clinical dementia rating, (p < 0.01) and living space diameter (p < 0.001), whereas the remaining subscores of life condition, i.e., number of falls, days of sickness, life style rating, and all subscores of well-being, i.e., number of medicines, valuation of handicap and of suffering, visual self-rating of well-being and caregivers' stress did not change significantly.

Activities of Daily Living↗
PubMed1997

Inflammation and NO(X)-induced nitration: assay for 3-nitrotyrosine by HPLC with electrochemical detection.

The identification of 15N-labeled 3-nitrotyrosine (NTyr) by gas chromatography/mass spectroscopy in protein hydrolyzates from activated RAW 264.7 macrophages incubated with 15N-L-arginine confirms that nitric oxide synthase (NOS) is involved in the nitration of protein-bound tyrosine (Tyr). An assay is presented for NTyr that employs HPLC with tandem electrochemical and UV detection. The assay involves enzymatic hydrolysis of protein, acetylation, solvent extraction, O-deacetylation, and dithionite reduction to produce an analyte containing N-acetyl-3-aminotyrosine, an electrochemically active derivative of NTyr. We estimate the level of protein-bound NTyr in normal rat plasma to be approximately 0-1 residues per 10(6) Tyr with a detection limit of 0.5 per 10(7) Tyr when > 100 nmol of Tyr is analyzed and when precautions are taken to limit nitration artifacts. Zymosan-treated RAW 264.7 cells were shown to have an approximately 6-fold higher level of protein-bound NTyr compared with control cells and cells treated with N(G)-monomethyl-L-arginine, an inhibitor of NOS. Intraperitoneal injection of F344 rats with zymosan led to a marked elevation in protein-bound NTyr to approximately 13 residues per 10(6) Tyr, an approximately 40-fold elevation compared with plasma protein of untreated rats; cotreatment with N(G)-monomethyl-L-arginine inhibited the formation of NTyr in plasma protein from blood and peritoneal exudate by 69% and 53%, respectively. This assay offers a highly sensitive and quantitative approach for investigating the role of reactive byproducts of nitric oxide in the many pathological conditions and disease states associated with NO(X) exposure such as inflammation and smoking.

Animals↗
PubMed1997

gamma-tocopherol traps mutagenic electrophiles such as NO(X) and complements alpha-tocopherol: physiological implications.

Peroxynitrite, a powerful mutagenic oxidant and nitrating species, is formed by the near diffusion-limited reaction of .NO and O2.- during activation of phagocytes. Chronic inflammation induced by phagocytes is a major contributor to cancer and other degenerative diseases. We examined how gamma-tocopherol (gammaT), the principal form of vitamin E in the United States diet, and alpha-tocopherol (alphaT), the major form in supplements, protect against peroxynitrite-induced lipid oxidation. Lipid hydroperoxide formation in liposomes (but not isolated low-density lipoprotein) exposed to peroxynitrite or the .NO and O2.- generator SIN-1 (3-morpholinosydnonimine) was inhibited more effectively by gammaT than alphaT. More importantly, nitration of gammaT at the nucleophilic 5-position, which proceeded in both liposomes and human low density lipoprotein at yields of approximately 50% and approximately 75%, respectively, was not affected by the presence of alphaT. These results suggest that despite alphaT's action as an antioxidant gammaT is required to effectively remove the peroxynitrite-derived nitrating species. We postulate that gammaT acts in vivo as a trap for membrane-soluble electrophilic nitrogen oxides and other electrophilic mutagens, forming stable carbon-centered adducts through the nucleophilic 5-position, which is blocked in alphaT. Because large doses of dietary alphaT displace gammaT in plasma and other tissues, the current wisdom of vitamin E supplementation with primarily alphaT should be reconsidered.

Antioxidants↗
PubMed1997

[School type, school stress and health problems in 17-year-old Zurich middle school students].

In the present study a sample of 661 seventeen-year-old students of different undergraduate colleges of the Canton of Zurich were investigated by questionnaire. They were asked about various psychosocial variables, their consumer behavior, school-life and their physical and mental health. The aim of the study was to investigate whether students of different college types differ in regard to their psychosocial and morbidity characteristics: Out of the sample two subgroups were formed: Students of the traditional college type B (classical/modern languages) and C (mathematics and sciences) on the one hand, and students of the modern college type D (modern languages) and L (modern languages/fine arts) on the other. Regarding sociodemographic variables and social contact there were no differences for both sexes between the two college types. Female students of the modern colleges reported to drink alcohol more regularly. There was a significant difference, however, taking college type into account in regard to eating behavior, body image, and physical and mental complaints. Girls of the modern colleges showed more symptoms and disturbances on all applied check lists. Regardless the college type, the results indicated that low academic grades and stressfully assessed school life were accompanied with significantly higher symptom scores in female students. The findings of the study indicate that targeted concepts for prevention and health promotion should be advanced especially in the classes of the modern colleges.

Adolescent↗
PubMed1996

[Is a clinical positional control for nasogastric tubes good enough? A prospective study of 43 patients].

OBJECTIVE: Nasoenteric tubes are usually introduced blindly by nursing staff, i.e. without visual or radiological control. A prospective study was undertaken to determine how often such blind procedure results in potentially dangerous tube placement and how often such faulty positioning remains undetected in a standardised clinical check. PATIENTS AND METHODS: 43 patients (23 men, 20 women; age 24-90 years) requiring the introduction by nursing staff of a nasoenteric tube were studied, 12 in an intensive care unit (seven intubated) and 31 in an ordinary ward. At most 24 hours after the customary check of the tube's position by the nursing staff (air injection with epigastric auscultation), specially experienced medical and nursing personnel determined and recorded the tube's placement in a standardised manner. Subsequent radiological examination documented the position. RESULTS: All 43 tubes lay in the gastrointestinal tract. Only one tube was in a potentially dangerous position in the lower end of the oesophagus, as had already been diagnosed by the examiners. Of four other tubes which were not optimally placed (three in the region of the cardia, one in the duodenum) three were found to be "not correctly placed" by the clinical check, and one was detected only radiologically. CONCLUSIONS: Clinical control of a nasoenteric tube's position suffices in most instances. Checking the position further by an experienced person adds to safety. The study's findings suggest that radiological control can be safely limited to cases in which there was a problem in positioning the tube or the clinical control was unclear.

Adult↗
PubMed1996

Suicidal behavior in Swiss students: an 18-month follow-up survey.

Suicidal behavior and its relationship with other mental disturbances was assessed in an epidemiological study of 1937 Swiss adolescents aged 14 to 19 years. During the most recent 12 months, 27.5% of the females and 16.1% of the males reported suicidal ideation, while 3.3% of the girls and 1.0% of the boys reported suicidal ideation. Suicidality was significantly correlated with physical and mental impairment, alcohol and drug abuse. Of the total epidemiological sample, 475 students (24.5%) were reassessed 12 and 18 months later. Of this follow-up sample, 37 females (12.4%) and 10 males (5.6%) described suicidal ideation as a continuing problem. They revealed significantly more psychiatric symptoms than nonpersistent ideators. Three girls (1.0%) and one boy (0.6%) reported suicide attempts during the follow-up period of 18 months. Only one out of six of the ideators of both sexes received psychiatric treatment. The findings indicate that transient suicidal ideation is common in adolescents. Persistent suicidal behavior appears to be a sign of severe social and psychological disturbances and is associated with serious physical and mental impairment. There is a high risk of completed suicide for youths who demonstrate persistent suicidal ideation, and far more substantial prevention efforts should be designed and implemented to address the circumstances of these youths.

Adolescent↗
PubMed1995

Does recombinant human erythropoietin not only treat anemia but reduce postpartum (emotional) distress as well?

Based on the established rhEPO treatment of anemia in endstage renal failure, which results in improved quality of life, and on the clinical observation that patients with postpartum anemia treated with rhEPO seemed to gain a more stable mood, we inferred that there is a beneficial side-effect of rhEPO on postpartum blues. The aim of this study was to test the hypotheses 1) that postpartum anemia aggravates, and 2) that treatment of postpartum anemia with rhEPO reduces maternity blues. The results show that on the fifth day postpartum anemic patients score consistently worse than nonanemic women on the Symptom Checklist SCL-90-R, indicating more symptoms and distress in general, and also more symptoms characteristic of maternity blues (p < 0.05). On a "Blues Questionnaire," postpartum anemia expresses itself with a reduced "well-being" (p < 0.001). Thus, our first hypothesis was verified. There were no differences by the fifth day postpartum between anemic patients receiving either rhEPO or placebo. Our second hypothesis was thus not confirmed within this limited time. We conclude as clinicians that postpartum anemia should be treated effectively to reduce distress and hence the risk for postpartum affective disorders. Follow-up studies after rhEPO treatment beyond the first week post partum are needed. In addition, in investigations on postpartum affective disorders, the hemoglobin concentration should be considered.

Anemia↗
PubMed1994

Inhibition by interferon-gamma of human mononuclear cell-mediated low density lipoprotein oxidation. Participation of tryptophan metabolism along the kynurenine pathway.

In this study we examined the potential inhibition by interferon-gamma (IFN gamma) of the early stages of low density lipoprotein (LDL) oxidation mediated by human peripheral blood mononuclear cells (PBMC) and monocyte-derived macrophages (MDM) in Ham's F-10 medium supplemented with physiological amounts of L-tryptophan (Trp). We assessed LDL oxidation by measuring the consumption of LDL's major antioxidant (i.e., alpha-tocopherol) and targets for oxidation (cholesteryllinoleate and cholesterylarachidonate), together with the accumulation of cholesterylester hydroperoxides and the increase in relative electrophoretic mobility of the lipoprotein particle. Exposure of PBMC or MDM to IFN gamma induced the degradation of extracellular Trp with concomitant accumulation of kynurenine, anthranilic and 3-hydroxyanthranilic acid (3HAA) in the culture medium. Formation of 3HAA, but neither Trp degradation nor formation of kynurenine and anthranilic acid, was inhibited by low amounts of diphenylene iodonium (DPI) in a concentration-dependent manner. In contrast to oxidative Trp metabolism, exposure of human PBMC or MDM to IFN gamma failed to induce degradation of arginine, and nitrite was not detected in the cell supernatant, indicating that nitric oxide synthase was not induced under these conditions. Incubation of LDL in Trp-supplemented F-10 medium resulted in a time-dependent oxidation of the lipoprotein that was accelerated in the presence of PBMC or MDM but inhibited strongly in the presence of both cells and IFN gamma, i.e., when Trp degradation and formation of 3HAA were induced. In contrast, when IFN gamma was added to PBMC or MDM in F-10 medium that was virtually devoid of Trp, inhibition of cell-accelerated LDL oxidation was not observed. Exogenous 3HAA added to PBMC or purified monocytes in the absence of IFN gamma also strongly and in a concentration-dependent manner inhibited LDL oxidation. Selective inhibition of IFN gamma-induced formation of 3HAA by DPI caused reversion of the inhibitory action of this cytokine on both PBMC- and MDM-mediated LDL oxidation. These results show that IFN gamma treatment of human PBMC or MDM in vitro attenuates the extent of LDL oxidation caused by these cells, and indicate that Trp degradation with formation of 3HAA is a major contributing factor to this inhibitory activity.

3-Hydroxyanthranilic Acid↗
PubMed1992

Oxidation of 3-hydroxyanthranilic acid to the phenoxazinone cinnabarinic acid by peroxyl radicals and by compound I of peroxidases or catalase.

Since 3-hydroxyanthranilic acid (3HAA), an oxidation product of tryptophan metabolism, is a powerful radical scavenger [Christen, S., Peterhans, E., & Stocker, R. (1990) Proc. Natl. Acad. Sci. U.S.A. 87, 2506], its reaction with peroxyl radicals was investigated further. Exposure to aqueous peroxyl radicals generated at constant rate under air from the thermolabile radical initiator 2,2'-azobis[2-amid-inopropane] hydrochloride (AAPH) resulted in rapid consumption of 3HAA with initial accumulation of its cyclic dimer, cinnabarinic acid (CA). The initial rate of formation of the phenoxazinone CA accounted for approximately 75% of the initial rate of oxidation of 3HAA, taking into account that 2 mol of 3HAA are required to form 1 mol of CA. Consumption of 3HAA under anaerobic conditions (where alkyl radicals are produced from AAPH) was considerably slower and did not result in detectable formation of CA. Addition of superoxide dismutase enhanced autoxidation of 3HAA as well as the initial rates of peroxyl radical-induced oxidation of 3HAA and formation of CA by approximately 40-50%, whereas inclusion of xanthine/xanthine oxidase decreased the rate of oxidation of 3HAA by approximately 50% and inhibited formation of CA almost completely, suggesting that superoxide anion radical (O2.-) was formed and reacted with reaction intermediate(s) to curtail formation of CA. Formation of CA was also observed when 3HAA was added to performed compound I of horseradish peroxidase (HRPO) or catalytic amounts of either HRPO, myeloperoxidase, or bovine liver catalase together with glucose/glucose oxidase.(ABSTRACT TRUNCATED AT 250 WORDS)

3-Hydroxyanthranilic Acid↗
PubMed1992

Simultaneous determination of 3-hydroxyanthranilic and cinnabarinic acid by high-performance liquid chromatography with photometric or electrochemical detection.

A convenient and rapid method for the simultaneous determination by HPLC of 3-hydroxyanthranilic acid and the dimer derived by its oxidation, cinnabarinic acid, is described. Buffers or biological samples containing these two Trp metabolites were acidified to pH 2.0 and extracted with ethyl acetate with recoveries of 96.5 +/- 0.5 and 93.4 +/- 3.7% for 3-hydroxyanthranilic and cinnabarinic acid, respectively. The two compounds were separated on a reversed-phase (C18) column combined with ion-pair chromatography and detected photometrically or electrochemically. The method was applied successfully to biological systems in which formation of either 3-hydroxyanthranilic or cinnabarinic acid had been described previously. Thus, interferon-gamma-treated human peripheral blood mononuclear cells formed and released significant amounts of 3-hydroxyanthranilic acid into the culture medium and mouse liver nuclear fraction possessed high "cinnabarinic acid synthase" activity. In contrast, addition of 3-hydroxyanthranilic acid to human erythrocytes resulted in only marginal formation of cinnabarinic acid. We conclude that the method described is specific, sensitive, and suitable for the detection of the two Trp metabolites in biological systems.

3-Hydroxyanthranilic Acid↗
PubMed1992

Oxidative stress in lungs of mice infected with influenza A virus.

As oxidative stress has been implicated in the pathogenesis of certain viral diseases we determined antioxidant and prooxidant parameters in lungs and bronchoalveolar lavage fluid (BALF) of mice infected with a lethal dose of influenza A/PR8/34 virus. Viral infection was characterized by massive infiltration of leukocytes, mainly polymorphonuclear leukocytes, into the alveolar space. The total number of BALF cells increased up to 8-fold (day 3 post-infection) and these cells appeared activated as judged by their increased rates of superoxide anion radical (O2-.) generation upon stimulation. Maximal rates of radical generation by BALF cells during the early stages of infection were 15- or 70-fold higher than those of cells from control animals when expressed per cell or total BALF cells, respectively. At the terminal stages of infection the total capacity of BALF cells to release O2-. declined to approximately 35-fold the control values. Infection also resulted in increased in vivo formation of hydrogen peroxide (H2O2) within the lungs at a time that coincided with the maximal capacity of BALF cells to release O2-.. Whereas pulmonary activities of glutathione peroxidase and reductase remained unaltered, levels of ascorbate in the cell-free BALF decreased significantly during the early stages of the infection and then returned to normal levels and above, late in infection. The oxidation state of the dehydroascorbic acid/ascorbate couple increased concomitantly with the decrease in ascorbate concentrations early in infection and remained elevated throughout the infection. As assessed by the prevention of peroxyl radical-induced loss of phycoerythrin fluorescence, the total antioxidant capacity present in lung tissue homogenate from terminally ill animals was not diminished when compared to that prepared from lungs of control mice. We conclude that although early stages of influenza infection are associated with the presence of oxidative stress in the lung tissue and alveolar fluid lining the epithelial cells, this stress does not appear to overwhelm local antioxidant defenses. The results therefore do not support a direct causative role of oxidative tissue damage in the pathogenesis of influenza virus infection.

Animals↗
PubMed1990

Antioxidant activities of some tryptophan metabolites: possible implication for inflammatory diseases.

The antioxidant properties of tryptophan and some of its oxidative metabolites were examined by measuring how efficiently they inhibited peroxyl radical-mediated oxidation of phosphatidylcholine liposomes and B-phycoerythrin. Low micromolar concentrations of 5-hydroxytryptophan, 3-hydroxykynurenine, xanthurenic acid, or 3-hydroxyanthranilic acid, but not their corresponding nonhydroxylated metabolic precursors, scavenged peroxyl radicals with high efficiency. In particular, 3-hydroxykynurenine and 3-hydroxyanthranilic acid protected B-phycoerythrin from peroxyl radical-mediated oxidative damage more effectively than equimolar amounts of either ascorbate or Trolox (a water-soluble analog of vitamin E). Enzyme activities involved or related to oxidative tryptophan metabolism, as well as endogenous concentrations of tryptophan and its metabolites, were determined within tissues of mice suffering from acute viral pneumonia. Infection resulted in a 100-fold induction of pulmonary indoleamine 2,3-dioxygenase (EC 1.13.11.17) as reported [Yoshida, R., Urade, Y., Tokuda, M. & Hayaishi, O. (1979) Proc. Natl. Acad. Sci. USA 76, 4084-4086]. This was accompanied by a 16- and 3-fold increase in the levels of lung kynurenine and 3-hydroxykynurenine, respectively. In contrast, endogenous concentrations of tryptophan and xanthurenic acid did not increase and 3-hydroxyanthranilic acid could not be detected. The activity of the superoxide anion (O2-.)-producing enzyme xanthine oxidase increased 3.5-fold during infection while that of the O2-.-removing superoxide dismutase decreased to 50% of control levels. These results plus the known requirement of indoleamine 2,3-dioxygenase for superoxide anion for catalytic activity suggest that viral pneumonia is accompanied by oxidative stress and that induction of indoleamine 2,3-dioxygenase may represent a local antioxidant defence against this and possibly other types of inflammatory diseases.

Animals↗
PubMed1989

Further observations on the isometricity of the anterior cruciate ligament. An anatomical study using a 6-mm diameter replacement.

Six anatomical specimens were used to evaluate the ligament length pattern and mean maximal ligament length change (MMLLC) of the anterior cruciate ligament (ACL) using a ligament replacement with a 6-mm diameter. Three femoral and three tibial attachment sites were selected. Nine different combinations were studied in intact knees and also in knees whose posterior capsule and arcuate ligament complex were sequentially divided, whose menisci were resected, and whose capsule and arcuate complex were repaired. The smallest ligament length change (5.6 mm) was obtained in the intact knee with the anatomic femoral and tibial attachments. Moving the femoral origin either anteriorly or to the over-the-top position significantly increased the MMLLC. Moving the tibial insertion posteriorly had a negligible effect, but changing to an anterior attachment site increased (but not significantly) the MMLLC. Even for anatomically positioned ligaments, the instability caused by sectioning the posterior capsule and arcuate ligament complex increased the MMLLC by more than 80%. Resection of both menisci did not result in a further increase in the MMLLC, but repairing the posterior capsule and arcuate complex restored the length changes to those of the intact knee. These data confirm the importance of precise anatomic placement of the femoral and tibial tunnels when performing intraarticular ACL grafts for anterolateral rotatory instability. The adverse effect of certain other associated instabilities on the ligament length change, even with correct tunnel placement, has been demonstrated and may be one explanation for the variability in the clinical results of these procedures.

Biometry↗