When polystyrene 'latex' beads are centrifuged to equilibrium in gradients of Nalcoag 1030, Nalcoag 1034A and Ludox 130M, which are commercial formulations of colloidal silica, the beads band at densities that may be markedly lower or higher than the bulk density. Addition to the gradient ofsmall amounts ofcertain polymers restores the banding densities towards the expected value. These findings closely mimic previously observed 'density shifts' of biological particles. A possible model for this anomalous behaviour is discussed.
SummaryAntihemophilic factor was chromatographed on a homologous series of diaminoalkane- and aminoalkane-modified Sepharose beads. Both factor VIII procoagulant activity (VIII:C) and protein are retarded on these columns when compared to their elution on a column made of unmodified Sepharose. Longer chains bind VIII:C and protein more tightly than shorter chains. No bound activity could be eluted with ethylene glycol. Increasing ionic strength eluted VIII:C and protein from aminoalkane- as well as from alkane-Sepharose. It seems likely that hydrophobic, rather than ionic forces, are responsible for the binding of VIII:C to the latter carriers.
In this comparative study we investigated 14 immunoglobulin (Ig) preparations
for intravenous application ; they were prepared by various manufacturers who used either
placental or venous blood as the starting material. The pepsin- and plasmin-treated products
and a preparation which, according to the manufacturer, was not degraded enzymatically,
contained 17-86% of IgG split products. On the other hand, three chemically modified
preparations, one preparation treated at pH 4, four products treated with poly(ethylene
glycol) (PEG) and one preparation protected by albumin contained 90% or more of nonfragmented
IgG. The IgG subclass distribution corresponded to the distribution of subclasses
in normal serum only in the nonmodified and not enzymatically degraded preparations. All
samples except one contained 0.1 mg/ml IgA or more, all contained only traces of IgM. No
product had clinically relevant titers of irregular antibodies against erythrocyte antigens.
The content of those antiviral and antibacterial antibodies that were tested for was similar in
all preparations. Only the anti-HBs activity exhibited large variations. Some PEG-treated
preparations showed an elevated prekallikrein activator (PKA) level, whereas all other
preparations contained, if any, only traces of PKA.
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