Biomedical subjects

F W Snel

Publications and source records attributed to F W Snel.

9 recordsLinked to original sources

PubMed1997

Perceived control by "powerful others" in paranormal healers.

49 paranormal healers working by laying-on of hands (direct healing) and healing at a distance were compared with 56 nurses and a control group of 73 randomly selected persons on their locus of control and especially on the subscale Powerful Others of Levenson. The paranormal healers scored external in locus of control, and their scores differed significantly from those of the other two groups tested on the Powerful Others subscale. This finding may be associated with the dependent position of paranormal healers since their profession is tolerated by medical doctors and the law.

Adult↗

PubMed1996

Demographic differences in coping with uncertainty about the future.

Age, gender, and regional differences in the responses of a Dutch population to the Prediction of Future Events Scale (Tobacyk, Nagot, & Mitchell, 1989) were explored. The factor structure of the scale was found to be identical to that in the U.S. study of Tobacyk et al., although the latter study accounted for 40.6% of the variance, whereas the present study accounted for 63.1% of the variance. Only 3 of the 7 factors could be considered reliable. Age appeared to be an important factor; the younger groups had more confidence than the older groups did in all methods of predicting the future. The scores for the western part of the Netherlands were systematically and significantly lower than those of the other regions, for all scales, and the women's scores for methods of prediction involving psi were higher than those of the men.

Adaptation, Psychological↗

PubMed1994

Animal models for reactive amyloidosis.

For over 70 years animal experiments have been performed to elucidate the pathogenesis of reactive amyloidosis and to investigate the formation of the beta-pleated sheet-rich amyloid fibrils in general. In appropriate species, primarily rodents like mouse and hamster, amyloid is formed after stimulation with amyloid-inducing injections after a lag phase (secondary or reactive amyloid, AA amyloid). For the formation of this AA amyloid, elevated values in blood of its precursor protein, SAA, is the first prerequisite. SAA is an acute phase protein of hepatic origin, released after stimulation by cytokines, and is associated in serum with high-density lipoprotein (apoSAA). In mouse, hamster and mink amyloidogenic subtypes of SAA are found. In the rat SAA is absent, although its mRNA is transcribed. Evidence is increasing that SAA crystallizes to fibrils first, whilst loss of its C-terminal end can be a post-fibrillogenic phenomenon. Glycoproteins, proteoglycans, glycosaminoglycans and lipids are reintroduced in experimental amyloid research. Basement membrane heparan sulphate proteoglycans (perlecans) are attributed to have a primary role. The pentraxin serum amyloid P-component is a calcium-dependent secondary phenomenon. Membrane-bound, lipid-rich vesicles are found amongst the newly deposited pericellular amyloid fibrils. These vesicles probably have to be interpreted as indicators of primary membrane alteration during amyloid fibril crystallization. The vesicles will be formed after rupture of the membranes caused by the stiff intramembranously crystallized protein fibrils. Morphological evidence supporting this hypothesis has been found in immunoelectron microscopical studies. Accumulation of intramembranous SAA preceded amyloid fibril deposition. Fibril formation then might be related to conformational change of the intramembranous SAA. The lag phase for amyloid deposition is shortened after a single injection of a fraction of amyloid, the AEF. It is a low-molecular-weight glycoprotein that easily associates with other molecules. When isolated from amyloid fibrils, the (F)AEF contains a large proportion of beta-pleated sheet molecular structure. It is probable that this structure holds an explanation for its enhancing potency: forming a nidus for physical crystallization. The major substances and animal species used in animal experiments on amyloidosis, are mentioned. Overlooked by-effects of amyloidogenic stimuli are discussed. Polyarthritis after systemic endotoxin injections found in the hamster acts as a source of cytokines, further triggering the reactive amyloidosis.(ABSTRACT TRUNCATED AT 400 WORDS)

Amyloidosis↗

PubMed1994

Information-processing styles of paranormal healers.

49 paranormal healers working by laying-on-of-hands (direct healing) and distance healing were compared with 56 nursing staff and a control group of 73 on the information-processing styles of field-dependence and reflexivity-impulsivity. Apparently paranormal healers scored as more field-dependent than the other groups which is consistent with observations of paranormal healers when working. No differences appeared among groups on reflexivity-impulsivity.

Female↗

PubMed1989

Experimental amyloidosis in the hamster: correlation between hamster female protein levels and amyloid deposition.

Reactive systemic AA amyloidosis was induced in female, male and castrated male hamsters either by repeated injection of casein or by injection of amyloid enhancing factor (AEF) followed by casein. The circulating concentrations of serum amyloid A protein (SAA), the putative precursor of the AA amyloid fibril protein, and of female protein (FP), the pentraxin homologue of serum amyloid P component (SAP) of other species, were measured and correlated with the speed and extent of amyloid deposition. The SAA responses of the three groups of hamsters were indistinguishable in both experiments but, in confirmation of previous reports, castrated males had FP levels higher than those of control males though still lower than in females. No differences were seen between groups in amyloid induction by casein injection alone. However, in the accelerated model using AEF, amyloid deposition occurred sooner and was more extensive in both females and castrated males than in unoperated males. These results strengthen the association between SAP, of which FP is the hamster counterpart, and the pathogenesis of amyloidosis.

Alpha-Globulins↗

PubMed1987

The serum amyloid A stimulating factor (SAASF) in the hamster.

The acute phase SAA response was studied in hamsters. An SAA-stimulating factor (SAASF) was detected in the early acute phase blood plasma of hamsters which were subcutaneously injected with casein-LPS. The latter is routinely used in our laboratory for amyloid induction in hamsters. Acute (4 h) inflammatory exudates (greater than 80 per cent polymorphonuclear leukocytes) were produced by intraperitoneal injection with either casein-LPS, latex or Freund's incomplete adjuvant. Chronic inflammatory exudate macrophages (greater than 98 per cent) were elicited by intraperitoneal injection with Bacillus Calmette Guérin (BCG). Cells were stimulated in vitro with latex. SAASF was detected in the supernates and lysates of the acute exudate cells but not in those of the chronic peritoneal exudate macrophages. Lymphocyte activating factor (LAF), however, was evidently present in the latter samples, indicating that SAASF and LAF (IL-1) are functionally different substances in hamsters.

Animals↗

PubMed1987

C-reactive protein in dogs.

Serum concentrations of C-reactive protein (CRP) in dogs with various diseases or undergoing various procedures were measured by specific immunoassay. In 20 healthy dogs from various sources, values were all less than 5 mg/L, but in 22 healthy dogs from a single source, values ranged from less than 5 mg/L in 14 dogs and from 8 to 67 mg/L in 8 dogs. Increased concentrations of serum CRP were attained 24 hours after injection of casein (n = 9; median 188 mg/L), ovariohysterectomy (n = 11; median, 144 mg/L), or elective, nonacute orthopedic surgery (n = 10; median, 83 mg/L). After inoculation of Leptospira interrogans serovar canicola (n = 5), the behavior of serum CRP as an acute-phase reactant provided a sensitive and precise objective reflection of in vivo response. The CRP concentration in random single-serum samples from 73 dogs with other inflammatory and noninflammatory disorders ranged from normal (less than 5 mg/L) to 246 mg/L and generally correlated with the extent and activity of disease.

Animals↗

PubMed1986

Amyloid-enhancing factor (AEF) in the pathogenesis of AA-amyloidosis in the hamster.

AA-amyloidosis was induced in hamsters receiving amyloid-enhancing factor (AEF) by daily subcutaneous injection with either an aged casein solution or casein supplemented with lipopolysaccharide (LPS). Both amyloid inducers gave similar results with respect to amyloid development in spleen, liver and kidneys and to serum amyloid A (SAA) concentrations and plasma cathepsin D activities. AEF was isolated from amyloid-containing tissue by the method described by Hol et al. (1985), and amyloid-enhancing material was also extracted from isolated hamster amyloid fibrils by intensive sonification. This fibril-derived amyloid-enhancing material lacked typical green birefringence after staining with Congo red and appeared as amorphous material on electron microscopy. AEF shortened the pre-amyloid phase for splenic and hepatic amyloid development and also the subsequent interval before renal amyloid deposition. This indicates that endogenous AEF, unlike passively transferred preformed AEF, is not distributed throughout the body and is probably generated at the site of amyloid deposition. Moreover, these results suggest that amyloid deposition in the kidneys, like that in the spleen and liver, involves an AEF-dependent pathway. Thus redistribution of amyloid is probably not an important cause of renal amyloid involvement. In addition to the reduction in the lag phase for splenic and hepatic amyloid deposition, AEF also speeds the changes in SAA concentration and plasma cathepsin D activity. This indicates that AEF accelerates rather than eliminates the pre-amyloid phase.

Amyloidosis↗

PubMed1985

Activities of lysosomal enzymes and levels of serum amyloid A (SAA) in blood plasma of hamsters during casein induction of AA-amyloidosis.

Casein-induced amyloidosis in hamsters was found to be of the AA-type, as shown by SDS-polyacrylamide gel electrophoresis (SDS-PAGE) and amino acid analysis of the major low-molecular weight component of the amyloid fibrils. Levels of serum amyloid A (SAA) and the activities of cathepsin D, beta-N-glucosaminidase, serine esterase, lactate dehydrogenase (LDH) and gamma glutamyl transpeptidase (GGT) were measured in the blood plasma during induction of amyloidosis. During the pre-amyloid phase an increase was observed in all these parameters. During the deposition of amyloid, an increase was observed in the activities of the lysosomal enzymes cathepsin D and beta-N-glucosaminidase, which was significantly correlated with amyloid deposition. Serine esterase activities did not show any relationship to amyloid deposition. LDH and GGT activities were normal in the amyloid phase. SAA levels were lower during amyloid deposition than during the pre-amyloid phase. These findings indicate that a specific release of lysosomal contents from mononuclear phagocytic cells is involved in the pathogenesis of AA-amyloidosis. Amyloid deposition may be the result of: (i) extrusion of intralysosomal protein AA or pre-amyloid, followed by extracellular formation of amyloid fibrils; (ii) secretion of lysosomal enzymes, followed by extracellular cleavage of SAA and subsequent aggregation of protein AA with other components.

Amino Acids↗