Biomedical subjects

A Jansen

Publications and source records attributed to A Jansen.

At least 73 records · Page 4Linked to original sources

PubMed1997

[Complication rate in laparoscopic cholecystectomy not different for residents in training and surgeons].

OBJECTIVE: To assess the difference in safety of laparoscopic cholecystectomy performed by residents and staff surgeons. SETTING: St. Antonius Hospital, Nieuwegein, the Netherlands. DESIGN: Retrospective study. METHOD: Results of 649 laparoscopic cholecystectomies performed by staff surgeons experienced in laparoscopic surgery, by residents under supervision of a staff surgeon, by residents without supervision and by inexperienced surgeons, were compared. RESULTS: Patients were comparable, except for liver function disorders and raised sedimentation rates, of which there were more in the group operated by the non-supervised residents, compared with the staff surgeons. Average operation time was 57 minutes in all four groups. Non-supervised residents had more retained stones than staff surgeons (19 vs 6%) and reported more bleeding during surgery than staff surgeons (21 vs 8%). Conversion rate was the same (3.9%) in all four groups. Complications occurred in 5.7%; this also was the same in the four groups. CONCLUSION: Residents following a traditional surgical training without practice on animals, perform laparoscopic cholecystectomy as quickly as and with the same conversion and complication rates as their teachers.

Cholecystectomy, Laparoscopic↗

PubMed1997

Conditioned insulin and blood sugar responses in humans in relation to binge eating.

This study proposed to demonstrate a classically conditioned blood sugar decrease in humans and to clarify its relevance for binge eating. Six conditioning trials were run in healthy females. The conditioned stimulus (CS) was a compound peppermint flavor/fragrance, whereas the unconditioned stimulus (UCS) consisted of 50 g of oral glucose. Control subjects received an aspartame drink as the UCS. Ad lib glucose intake, blood parameters, and subjective craving were monitored before and after conditioning. Results showed that the experimental group failed to show conditioned blood sugar and glucagon decreases or C-Peptide increases. Although an increased insulin response was found in the experimental group, the effect size did not exceed that of spontaneous fluctuations. No increases in craving for sweet substances were found. An impressive increase (mean: 78%) in glucose intake after conditioning was found in both conditions, as well as in a subsequently run third condition with plain water as the UCS. The increased glucose intake probably resulted from an initial neophobia to the laboratory setting that subsided as subjects had experienced more lab sessions. Importantly, because no conditioned hypoglycemia occurred in the present study, its relationship with subjectively experienced craving for sweet substance could not be determined.

Adolescent↗

PubMed1997

The Dutch EPIC food frequency questionnaire. I. Description of the questionnaire, and relative validity and reproducibility for food groups.

BACKGROUND: A self-administered food frequency questionnaire was developed for the Dutch cohort of the European Prospective Investigation into Cancer and Nutrition (EPIC). Habitual consumption of 178 food items can be calculated from the questionnaire data. METHODS: Reproducibility and relative validity for food group intake were investigated in a population of 121 Dutch men and Women. The questionnaire was administered three times at 6-month intervals in order to determine the reproducibility. To assess the relative validity 12 monthly 24-hour recalls served as the reference method. RESULTS: Spearman rank order correlation coefficients between estimates of food group intake assessed by repeated questionnaires ranged from 0.45 to 0.92. For men, Spearman correlation coefficients between estimates of food group intake based on the questionnaire and those based on 24-hour recalls ranged from 0.21 for cooked vegetables to 0.78 for sugar and sweet products, with a range of 0.61. For women the median was 0.53, with a minimum of 0.31 for vegetables and a maximum of 0.87 for alcoholic beverages. The photographs in the questionnaire for the estimation of portion sizes contributed little to the relative validity of the ranking of subjects. However, on the group level most median food group estimates based on photographic portion sizes were closer to the median intakes as assessed by 24-hour recalls than those based on standard portion sizes. CONCLUSIONS: The questionnaire seems adequate for ranking Dutch EPIC subjects according to intake of most food groups, although the relative validity for some food groups, such as vegetables and fish, remains of concern.

Adult↗

PubMed1997

[Aggression and psychiatry--does training have any effect?].

This study with a quasi-experimental design was conducted into the effects of an aggression management training on the perception of safety and self-confidence of the participants. Also it was studied whether the participants of the training were less likely to be involved in aggressive incidents. It was found that the perception of safety of the participants had significantly increased compared to the control subjects. No significant differences in perceived self-confidence were found between the two groups. In both the experimental and the control group the frequency of aggressive incidents was lower during the posttest period. This reduction had taken place regardless of the aggression management training. Possibly, the systematic registration of aggression by means of the Staff Observation Aggression Scale (SOAS) initiates a learning process in the staff.

Adult↗

PubMed1996

Behavior of various cholesterol crystals in bile from patients with gallstones.

Besides classical plate-like cholesterol monohydrate crystals, a variety of crystal shapes have recently been described in model biles but their relevance for human gallstone formation is unknown. We therefore studied crystallization behavior in gallbladder bile from cholesterol stone patients (54 untreated, 13 ursodeoxycholate-treated) and 6 pigment stone patients. Bile preparation by ultrafiltration or ultracentrifugation left biliary lipid composition unchanged but plates and their aggregates, and arcs and needles crystallized more extensively while spirals and tubules crystallized less extensively in ultra-centrifuged bile than in ultrafiltered bile. Plates, aggregates, and arcs/needles were seen in 90 percent, 36 percent, and 18 percent of the cases respectively of fresh unfiltered biles of untreated cholesterol stone patients, while spirals and tubules were always absent. In ultrafiltered biles arcs/needles, plates and aggregates progressively developed as persistent forms. Spirals and tubules occurred transiently and were associated with increased deoxycholic acid (+41 percent, P = .039) and with more extensive cholesterol crystallization. Rate/extent of crystallization of all crystal forms was higher (P < .0001) for multiple than solitary cholesterol stone patients. Ursodeoxycholate-treated patients had atypical platelike cholesterol crystals in fresh unfiltered biles that decreased in size at prolonged observation and in 2 cases even dissolved after 15 and 20 days. No crystals ever developed in ultra-filtered bile of ursodeoxycholic acid (UDCA)-treated patients during 21 days. Pigment stone patients seldom developed crystals. Thus, plates, aggregates and arcs/needles are persistent forms with high crystallization rate in multiple cholesterol stone patients. Tubules and spirals are transient forms that are associated with more extensive crystallization. Patients treated with ursodeoxycholate often have atypical crystals in their fresh bile.

Adult↗

PubMed1996

Effect of prophylactic insulin treatment on the number of ER-MP23+ macrophages in the pancreas of NOD mice. Is the prevention of diabetes based on beta-cell rest?

Prophylactic insulin treatment has been shown to have beneficial effects in type 1 diabetes, both in humans and in various animal models of the disease. In experimental models, the protective effect of prophylactic insulin treatment was observed in two parameters: (1) progression of insulitis and (2) diabetes incidence. The mechanism of protection still remains to be investigated. We therefore analysed by immunohistochemistry the effect of prophylactic insulin treatment vs placebo treatment (from 4 to 13 weeks of age) on ER-MP23+ macrophage infiltration in and around pancreatic islets in the non-obese diabetic (NOD) mouse, a spontaneous model for type 1 diabetes. BALB/c mice were used as diabetes-free controls. Using conventional haematoxylin-eosin staining, we detected a protective effect of prophylactic insulin treatment in NOD females on the lymphocytic insulitis, significant at 13 weeks, but not at 9 weeks of age. However, when assessed by immunostaining for early infiltration of ER-MP23+ macrophages around islets, the reduction in severity of insulitis could already be detected as early as 9 weeks of age. With regard to the early accumulation of ER-MP23+ cells, we observed that their numbers per mm2 surface area of the exocrine pancreas and per micron at the circumference of the islet were higher in placebo-treated NODs (197 +/- 13.8 and 14 +/- 0.9, respectively) as compared to age-matched BALB/c mice (123.1 +/- 7.1 and 3.5 +/- 0.9, respectively). Prophylactic insulin treatment of NODs lowered the attraction of ER-MP23+ macrophages to the exocrine pancreas and to the circumference of the islets (156.3 +/- 8.5 and 7.9 +/- 1, respectively). Interestingly also, the islet size was found to be larger in placebo-treated NODs (51% was larger than 10 microns2) than in age-matched BALB/c mice (9% larger than 10 microns2). Prophylactic insulin treatment of NODs reduced their islet size to sizes found in the control BALB/c strain. In conclusion, the decrease in islet size by early insulin administration, and the lower attraction of ER-MP23+ macrophages to the islets are morphological indications that prevention of diabetes development by prophylactic insulin treatment results from a down-regulation of islet metabolism and growth, with a concomitant decline in the release of islet factors attracting macrophages.

Animals↗

PubMed1996

L-arginine depletion inhibits glomerular nitric oxide synthesis and exacerbates rat nephrotoxic nephritis.

Nitric oxide (NO) synthesis is induced in glomeruli in glomerulonephritis; its role in the pathogenesis of glomerular injury is unknown. Interpretation of its role using the currently available analogues of L-arginine as in vivo inhibitors of NO is complicated by their lack of specificity for inducible NO synthase (iNOS). As NO synthesis by iNOS depends on extracellular L-arginine, we have here examined effects of L-arginine depletion on glomerular NO synthesis and the course of accelerated nephrotoxic nephritis (NTN). Arginase, which converts L-arginine to urea and L-ornithine, was used to achieve L-arginine depletion. A single dose of i.v. arginase produced complete depletion of plasma arginine for four hours. Two forms of NTN were induced in preimmunised rats by nephrotoxic globulin: (1) the systemic form of the model by intravenous nephrotoxic globulin; or (2) the unilateral form of model by left kidney perfusion with nephrotoxic globulin, which avoids the complications of systemic administration of nephrotoxic globulin. Arginase reduced plasma arginine levels and the synthesis of nitrite (the stable end-product of NO) by NTN glomeruli (95% inhibition). Proteinuria was exacerbated. There was no effect on early (24 hr) leukocyte infiltration. In the systemic form of the model arginine depletion by i.v. arginase increased glomerular thrombosis at 24 hours, and the severity of histological changes at four days, accompanied by systemic hypertension. In the unilateral form of the model, where i.v. arginase did not induce hypertension, there was no increase in thrombosis or histological severity of nephritis. These results show that arginine depletion, which inhibits glomerular NO synthesis in NTN, leads to increased proteinuria. Where injury is severe, or accompanied by systemic hypertension, the disease is further exacerbated by glomerular thrombosis. These results suggest that NO has an important role in limiting acute glomerular injury.

Animals↗

PubMed1996

Specificity of a placental factor inhibiting breathing in fetal sheep.

We have found previously that the infusion of a placental extract inhibits breathing induced by 100% O2 plus umbilical cord occlusion in the fetal sheep, suggesting that a placental factor is responsible for the inhibition of fetal breathing. To test whether this factor is specific to the placenta and whether it also inhibits spontaneous fetal breathing (occurring in the absence of cord occlusion), we administered extracts from the placenta, muscle and liver of the pregnant ewe, extracts of fetal liver, and Krebs solution to 16 chronically instrumented fetal sheep at 135 +/- 5 days of gestation. Infusions were made during low-voltage electrocortical activity, 5 to 15 min after a switch from high voltage, when breathing was well established. Within 90 s of the infusion of the placental extract in the carotid artery of the fetus, breathing decreased in 79% (33/42) of the experiments and was completely abolished in 71% (30/42) of them (P < 0.0001 compared with the other infusates). No apnoeas were observed with the Krebs solution (0/19) and the maternal muscle (0/20). Extracts of maternal and fetal liver abolished breathing in only 17% (4/23) and 21% (6/29) of the experiments respectively (NS compared with Krebs solution). There were no significant changes in blood gas tensions, pH, blood pressure and heart rate associated with the infusion of the extracts. The electrocortical activity (ECoG) switched from low to high voltage in 50% of the experiments using placental extract compared with 0% with Krebs solution and maternal muscle, and with 9% and 17% with maternal and fetal liver respectively (P < 0.005). Breathing output (integral of EMGdi x f) during and after the infusions significantly decreased only with the placental extract. These findings indicate the presence of a factor produced by the placenta which inhibits fetal breathing and may be responsible for the normal inhibition of breathing observed in fetal life.

Animals↗

PubMed1996

CD4 masking during human immunodeficiency virus type 1 infection, quantified on peripheral blood lymphocytes, is a potential marker of disease progression.

In human immunodeficiency virus type 1 (HIV-1)-infected adults, the proportion of gp120-free CD4 molecules on the surface of T lymphocytes was measured by double-epitope EIA and expressed as a CD epitope concentration ratio. In 51% of these patients (n=81), CD4 T cells showed a significant decrease (up to 100%) in the accessibility of the CD4 epitope in the D1 domain remained accessible. Of interest, a significant increase in the CD4 gp120 binding site concentration, without a change in T cell counts, was observed within 10 days after initiation of zidovudine treatment. Furthermore, CD4 masking by gp120 was associated with a poor clinical patient status. The assessment of the CD4 epitope concentration ratio is proposed as a surrogate marker of disease progression in HIV-1-infected patients.

Adult↗

PubMed1996

How restrained eaters perceive the amount they eat.

The cognitive model of binge eating states that it is the awareness of a broken diet that disinhibits the restrained eater. It is, according to that model, the perception of having overeaten that triggers disinhibited eating. However, although the perception of the amount eaten plays a central role in cognitive restraint theory, it has never directly been tested how restrained subjects perceive the amount of food they eat. In the present studies, participants were given ad libitum access to large amounts of palatable food and both their perception of the amount eaten and their estimated caloric intake were compared with the amount they actually ate. The restrained participants in these studies ate more than the unrestrained participants. In the first and second studies, the restrained participants consumed 571 and 372 'forbidden' calories respectively, without having the feeling that they had eaten very much, let alone too much. Moreover in both studies, the restrained eaters underestimated their caloric intake, whereas unrestrained eaters estimated their caloric intake quite well. The potential implications of the present findings for the cognitive restraint model are discussed.

Adult↗

PubMed1996

Allergy to pine nuts in a bird fancier.

A patient is described with the bird-egg syndrome who experienced an anaphylactic reaction after eating some of her parrot's food (pine nuts: Pinus pinea). Specific IgE against this nut and another pine nut (P. cembra) was demonstrated by RAST. Cross-reactivity between these botanically related seeds was shown by RAST inhibition. Besides avian antigens, bird food antigens should be taken into consideration when symptoms of allergy occur on exposure to birds.

Anaphylaxis↗

PubMed1995

Average intake of anti-oxidant (pro)vitamins and subsequent cancer mortality in the 16 cohorts of the Seven Countries Study.

This ecologic study aimed to investigate whether differences in population mortality from lung, stomach and colorectal cancer among the 16 cohorts of the Seven Countries Study could be explained by differences in the average intake of anti-oxidant (pro)vitamins. In the 1960s, detailed dietary information was collected in small sub-samples of the cohorts by the dietary record method. In 1987, food-equivalent composites representing the average food intake of each cohort at baseline were collected locally and analyzed in a central laboratory. The vital status of all participants was verified after 25 years of follow-up. The average intake of vitamin C was strongly inversely related to the 25-year stomach-cancer mortality (r = -0.66, p = 0.01), also after adjustment for smoking and intake of salt or nitrate. The average intake of alpha-carotene, beta-carotene, and alpha-tocopherol were not independently related to mortality from lung, stomach or colorectal cancer, nor was vitamin C related to lung and colorectal cancer.

Adult↗

PubMed1995

Flavonoid intake and long-term risk of coronary heart disease and cancer in the seven countries study.

OBJECTIVE: To determine whether flavonoid intake explains differences in mortality rates from chronic diseases between populations. DESIGN: Cross-cultural correlation study. SETTING/PARTICIPANTS: Sixteen cohorts of the Seven Countries Study in whom flavonoid intake at baseline around 1960 was estimated by flavonoid analysis of equivalent food composites that represented the average diet in the cohorts. MAIN OUTCOME MEASURES: Mortality from coronary heart disease, cancer (various sites), and all causes in the 16 cohorts after 25 years of follow-up. RESULTS: Average intake of antioxidant flavonoids was inversely associated with mortality from coronary heart disease and explained about 25% of the variance in coronary heart disease rates in the 16 cohorts. In multivariate analysis, intake of saturated fat (73%; P = 0.0001), flavonoid intake (8%, P = .01), and percentage of smokers per cohort (9%; P = .03) explained together, independent of intake of alcohol and antioxidant vitamins, 90% of the variance in coronary heart disease rates. Flavonoid intake was not independently associated with mortality from other causes. CONCLUSIONS: Average flavonoid intake may partly contribute to differences in coronary heart disease mortality across populations, but it does not seem to be an important determinant of cancer mortality.

Adult↗

PubMed1995

Defective maturation and function of antigen-presenting cells in type 1 diabetes.

Macrophages and dendritic cells are important as antigen-presenting cells in the islet autoimmune response. We report decreased maturation of dendritic cells from blood monocytes of 61 patients with type 1 diabetes compared with 31 healthy controls (medians 26 and 35%, respectively, p = 0.0005). The dendritic cells also had reduced ability to cluster (96 and 124 clusters, respectively, p = 0.0005), and to stimulate autologous and allogeneic T cells. Because optimum antigen presentation is primarily required for tolerance induction rather than for immunisation, the defective maturation and function of diabetic dendritic cells might be the basis for disturbed activation of regulatory (suppressor) T cells.

Adolescent↗

PubMed1995

Stroop interference and food intake.

OBJECTIVE: The Stroop task is aimed at assessing attentional bias. Words are displayed one by one on a computer screen and subjects are instructed to name the color in which every word is printed. The attentional bias is supposed to be reflected in the extent to which the word meanings interfere with the speed of color naming: The longer the color naming latency, the larger the attentional bias. Experiments using this task have demonstrated attentional bias for eating and body shape-related words in bulimic, anorexic, and restrained subjects. Explanations of these results have generally been formulated in terms of restricted food intake or emotional concerns about food and body shape-related themes. In contrast, in the present article it was proposed that Stroop interference might reflect a tendency either to withdraw or approach food or body shape-related stimuli. METHOD: Fifty-one subjects (25 unrestrained, 26 restrained) were administered a Stroop task containing neutral, food, and body shape-related words. There were two conditions to which subjects were randomly allocated: the "appetizer" and "no-appetizer" condition. The appetizer was a bit of pudding to be ingested by the subject just before the Stroop task. Following the Stroop task an ice cream taste test was presented in which the subjects were allowed to eat as much as they liked. The amount of ice cream eaten was registered secretly. RESULTS: The results show that in unrestrained subjects Stroop interference for food words was found only in the appetizer condition. Restrained subjects, however, showed a permanent interference for food words. A significant correlation of .58 between Stroop food-word interference and ice cream intake was found only in unrestrained subjects. In restrained eaters the correlation was near 0. No effect of condition or restraint was found on Stroop body shape-word interference. DISCUSSION: The findings indicate that (1) ingestion of an appetizer seems to have evoked an attentional bias for food words in nonrestraints that correlated with food intake; (2) restrained eaters showed continuous attentional bias. This appears to support the urge-to-act explanation of Stroop interference. The lack of correlation between restraints' attentional bias and ad lib food intake could have been caused by inhibition of approach which is one of the characteristics of restrained eating: The present procedure seems not to have triggered disinhibited eating in these subjects. Among other things it is concluded that Stroop interference, as a measure of "craving" triggered by food cue, might be a useful aid in assessing the risk of relapse in treated binge eating patients.

Anorexia Nervosa↗

PubMed1995

Dietary saturated and trans fatty acids and cholesterol and 25-year mortality from coronary heart disease: the Seven Countries Study.

BACKGROUND: In the Seven Countries Study associations between intake of individual fatty acids and dietary cholesterol were studied in relation to serum cholesterol and 25-year mortality from coronary heart disease. All analyses concern only intercohort comparisons. METHODS: In the baseline surveys carried out between 1958 and 1964, risk factors for coronary heart disease were measured among 12,763 middle-aged men constituting 16 cohorts in seven countries. In 1987 and 1988 equivalent food composites representing the average food intake of each cohort at baseline were collected locally and analyzed in a central laboratory. The vital status of all participants was verified at regular intervals during 25 years of follow-up. RESULTS: Of the individual saturated fatty acids, the average population intake of lauric and myristic acid was most strongly related to the average serum cholesterol level (r > 0.8, P < 0.001). Strong positive associations were observed between 25-year death rates from coronary heart disease and average intake of the four major saturated fatty acids, lauric, myristic, palmitic, and stearic acid (r > 0.8, P < 0.001); the trans fatty acid elaidic acid (r = 0.78, P < 0.001); and dietary cholesterol (r = 0.55, P < 0.05). CONCLUSIONS: Interpreted in the light of experimental and clinical studies, the results of these cross-cultural analyses suggest that dietary saturated and trans fatty acids and dietary cholesterol are important determinants of differences in population rates of coronary heart disease death.

Adult↗

PubMed1995

Phenotypical heterogeneity of testicular macrophages/dendritic cells in normal adult mice: an immunohistochemical study.

The distribution of macrophage/dendritic cell antigens was investigated immunohistochemically in frozen testis sections of normal A/J mice using a panel of rat monoclonal antibodies against murine macrophage/dendritic cell antigens (F4/80, BM8, MP23, MOMA1, MOMA2, M5/114, BMDM1 and NLDC145). Sections of lymphoid organs were employed as positive controls. Stained-macrophages/dendritic cells in the testicular interstitium were various in shape, such as irregular-, elongate-, round- or oval-shaped cytoplasm with short or long cytoplasmic protrusions, but, the most conspicuous morphology was irregular. The testicular macrophages/dendritic cells were subdivided into four types of cells by their localization; various-shaped cells associated with Leydig cells and other interstitial cells (Type I); stretched cells attached to the seminiferous tubular wall (Type II); stretched cells attached to the blood vessel wall (Type III); and stretched cells attached to the inner side of the testicular capsule (Type IV). Examination of the staining pattern of the various antibodies showed that the macrophage/dendritic cell antigens differed from each other in amount present and localization, indicating phenotypical heterogeneity of the testicular macrophages. Additionally, a few macrophages were identified in the testicular capsule and in the tubuli recti but never in the seminiferous tubules.

Animals↗

PubMed1995

Inducible nitric oxide synthase in inflammation.

Inflammation, the reaction of vascularized tissue to local injury, not only limits the effects of injury; it may also be the underlying pathological process which initiates or sustains disease. In this paper, the evidence is reviewed for a role for nitric oxide (NO) as a chemical indicator of inflammation and inflammatory diseases.

Animals↗