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T A Niewold

Publications and source records attributed to T A Niewold.

45 records · Page 3Linked to original sources
PubMed1991

Fibril amyloid enhancing factor (FAEF)-accelerated amyloidosis in the hamster is not dependent on serine esterase activity and mononuclear phagocytosis.

Cells of the mononuclear phagocytic system (MPS) were described as playing a decisive role in amyloidogenesis. A relationship between the amyloid enhancing factor (AEF) and MPS cells was suggested and recently AEF activity was attributed to a serine esterase (SE) of leucocytic origin. In the present study, no correlation was found between the SE content and AEF activity in either peritoneal cell lysates or AEF preparations of different origin. Furthermore, pretreatment of fibril AEF (FAEF) with the SE inhibitor phenylmethylsulphonyl fluoride (PMSF) did not affect its activity in the hamster. Blockade of the MPS by dextran sulphate did not inhibit deposition of amyloid after intravenous injection of FAEF but amyloid deposition was inhibited when FAEF was administered intraperitoneally. These results suggest that MPS cells could be involved in transport of AEF, but that phagocytic activity of MPS cells is not essential in AA-amyloid fibrillogenesis. It is concluded that these results are not consistent with the previously suggested nature of the AEF or with the proposed central role of the MPS in amyloidogenesis.

Amyloidosis↗
PubMed1990

Purification and characterization of hamster serum amyloid A protein (SAA) by cholesteryl hemisuccinate affinity chromatography.

High-density lipoprotein (HDL) apolipoprotein was separated from hamster serum by cholesteryl hemisuccinate affinity chromatography (CHAC) in comparison with the density-gradient ultracentrifugation (DGUC). The apolipoprotein recovery from serum by CHAC was 70% and by DGUC 80%. This disadvantage is compensated for by the ease of purification by CHAC, a method particularly suited for the processing of large amounts of serum. From the acute-phase HDL CHAC fraction, apo SAA was isolated by gel filtration. Using isoelectrofocusing, two-dimensional gel electrophoresis, and titration curve, four isotypes of hamster apo SAA were identified and characterized. In the acute-phase serum, one of the isotypes was predominant (apo SAA1). In serum of amyloidotic animals, the relative contribution of apo SAA1 was considerably lower, suggesting selective removal of the latter during amyloidogenesis and possibly its deposition in hamster AA amyloid. Furthermore, the affinity chromatography method was modified with gradient elution of affinity-bound material. By this method HDL apolipoprotein was separated into three subclasses. Apo SAA was shown to associate with two different subclasses. In acute-phase serum most of the apo SAA1 was found in the subclass with the lowest affinity for the cholesteryl beads, whereas the latter was depressed in amyloidotic serum, suggesting that the amyloidogenicity of a particular apo SAA isotype is determined by its cholesteryl-binding properties.

Animals↗
PubMed1989

Monitoring of naturally acquired and artificially induced immunity to Amblyomma variegatum and Rhipicephalus appendiculatus ticks under field and laboratory conditions.

The ability of rabbits, goats and cattle to acquire immunity to the ixodid ticks Amblyomma variegatum and Rhipicephalus appendiculatus was studied under laboratory and field conditions. Rabbits were successfully immunized with crude salivary gland extract (SGE) and midgut extract (ME) obtained from flat or partly fed female R. appendiculatus ticks. The lowest numbers of larvae were produced by females fed on rabbits immunized with unfed midgut extract. Similar reductions in larval production could be induced after three infestations of rabbits with adult R. appendiculatus. Also, successive feedings of nymphs of R. appendiculatus on rabbits resulted in significantly reduced engorgement weights. Skin testing with SGE induced delayed-type hypersensitivity reactions, which could be correlated with immunity to R. appendiculatus in rabbits. Moreover, circulating antibodies were detected in rabbits with an ELISA using SGE of R. appendiculatus. Immunity to A. variegatum nymphs could be induced in rabbits by repeated infestations, but this failed in goats. Immunization of goats with midgut extract from adult A. variegatum did not protect against subsequent nymphal challenge, but strong skin reactions were noticed when adults ticks fed on immunized goats. Sodium dodecyl sulfate polyacrylamide gel electrophoresis of SGE and ME from A. variegatum revealed the presence of 48 protein bands in SGE and 29 bands in midgut extract. Western blotting employing serum from a rabbit immune to R. appendiculatus recognized a number of bands in SGE from R. appendiculatus, but also in SGE of A. variegatum. Immunity acquired by cattle to ixodid tick infestations under field conditions was monitored by skin testing with SGE and western blot analysis. In general, cattle with the lowest tick numbers manifested the strongest delayed-type hypersensitivity responses. Finally, western blot analysis employing sera from tick-infested and tick-naive cattle could not be related to actual immune status.

Animals↗
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↗
PubMed1989

Serum amyloid A concentrations in cows given endotoxin as an acute-phase stimulant.

The concentrations of serum amyloid A (SAA) in 4 cows given Escherichia coli endotoxin as an acute-phase stimulant were quantitatively evaluated by use of an indirect micro-ELISA method and compared with other clinical hematologic values. Serum amyloid A concentration changed minimally after intradermal infection of endotoxin. The concentration of SAA was increased 5 hours after IV injection of endotoxin, with maximal concentration after 17 to 20 hours. The increase in SAA concentration coincided with decreasing serum Zn and Fe concentrations; however, with decreasing serum Zn and Fe concentrations; however, Zn and Fe concentrations appeared to be restored when SAA concentration was still maximal. It was concluded that the SAA response of cattle is comparable with that of other species and can be used for monitoring the activity of clinical inflammation and tissue injury.

Acute-Phase Reaction↗
PubMed1988

A longitudinal study of starvation in piglets and the introduction of a modified liver biopsy technique.

The effect of starvation on blood glucose, muscle glycogen and liver glycogen concentration was measured in a group of newborn piglets. Liver biopsies were obtained by using a modified version of the Menghini technique. No difference in length of survival time was observed between piglets that received water and those that did not. Piglets with higher birth weight survived longer. No relationship was found between initial liver glycogen content and survival time. Moreover, we concluded that plasma glucose levels are not reliable indicators of length of survival time. The interrelated changes in liver glycogen, muscle glycogen, and plasmaglucose concentrations found in this study correspond with those reported elsewhere. Moreover, the number of experimental animals needed for the study was markedly reduced. We conclude that the liver biopsy technique is valuable in longitudinal hypoglycaemia studies of piglets.

Animals↗
PubMed1987

Enhancement of amyloid induction by amyloid fibril fragments in hamster.

An extract (fibril amyloid-enhancing factor) prepared by sonication of a suspension of water-purified hamster AA-amyloid fibrils showed an amyloid-enhancing effect upon intraperitoneal injection into hamsters. The fibril amyloid-enhancing factor was identical to the original fibrils according to the results of infrared spectroscopy, gel filtration, gel electrophoresis, and Western blotting; although lyophilized samples of the extract did not show any green birefringence after staining with Congo red. From these results, it was concluded that fibril amyloid-enhancing factor represents small fragments of amyloid fibrils which enhance in vivo formation of amyloid fibrils.

Amyloid↗
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↗