Sensitivity of Limulus amebocyte lysate (LAL) to LAL-reactive glucans.

The sensitivity of Limulus amebocyte lysate (LAL) to LAL-reactive glucans (LRGs) and lipid A was tested by using commercially available and experimentally formulated LAL reagents. The glucans included two kinds of beta-(1,3)-D-glucans, laminarin and curdlan, and cellulosic material, LAL-reactive material (LAL-RM), extracted from a hollow-fiber (Cuprophan) hemodialyzer. LAL-RM loses its LAL activity when it is digested with cellulase and thus appears to be a beta-(1,4)-D-glucan or a mixed glucan containing a substantial proportion of beta-(1,4) linkages.

Plastics, endotoxins, and the Limulus amebocyte lysate test.

A variety of polypropylene and polystyrene tubes have been tested for use with the Limulus amebocyte lysate (LAL) test. Polypropylene tubes tended to be more contaminated with endotoxin than polystyrene. One brand of polypropylene tube contained a water extractable inhibitor of the LAL test.

Single-step, chromogenic Limulus amebocyte lysate assay for endotoxin.

A new reagent for the chromogenic Limulus amebocyte lysate (LAL) assay is described. LAL was formulated for optimal performance in either an endpoint procedure or a kinetic procedure with the chromogenic substrate, buffer, and LAL components colyophilized as a single reagent. The kinetic chromogenic method required an incubating microplate reader coupled to a computer for collection and analysis of data.

Labor and infection. II. Bacterial endotoxin in amniotic fluid and its relationship to the onset of preterm labor.

We have previously reported the detection of endotoxin in the amniotic fluid of patients with gram-negative intraamniotic infection. Endotoxin or lipopolysaccharide is a potent biologic product capable of inducing prostaglandin release from several cell types and, therefore, may be involved in the onset of human parturition in the presence of intraamniotic infection. This article describes a technique for the quantification of endotoxin in amniotic fluid.

Role of interleukin-1 in augmenting serum neutralization of bacterial lipopolysaccharide.

We have previously described an assay to quantify the serum neutralization of bacterial lipopolysaccharide which is based on a spectrophotometric Limulus amoebocyte lysate test (T.J. Novitsky, P.

Quantitation of endotoxin in products using the LAL kinetic turbidimetric assay.

The data presented here show the kinetic turbidimetric LAL assay to be a highly quantitative and effective method for determining endotoxin concentrations in products. The assay allows for the accurate assessment of inhibiting or enhancing effects in products when related to a LRW standard curve. However, designating some products as inhibitors or enhancers can be both misleading and erroneous unless qualified as to the dilution and/or endotoxin concentration.

Neutralization of bacterial lipopolysaccharides by human plasma.

To quantify the neutralization of bacterial lipopolysaccharide (LPS) by human plasma, dilutions of Escherichia coli O113 LPS were incubated with plasma, followed by the addition of Limulus amebocyte lysate (LAL). The reaction between the LPS and LAL was monitored spectrophotometrically, and the concentration of LPS resulting in 50% lysate response (LR50) was determined. Analysis of 145 outdated plasma samples yielded a range of LR50 between 6 and 1,500 ng/ml.

Significant potassium ion accumulation at the external surface of Myxicola giant axons.

Potassium accumulation associated with outward membrane potassium current was investigated experimentally in Myxicola giant axon. During prolonged voltage-clamp pulses to positive transmembrane potentials, the K+ equilibrium potential may approach zero mV, suggesting massive K+ accumulation outside the axonal membrane to concentrations many-fold higher than those in the bathing medium. The potassium accumulation can be satisfactorily described by a three-compartment model, consisting of the nerve fiber, a restricted physiological periaxonal space and the bulk solution.

Turbidimetric method for quantifying serum inhibition of Limulus amoebocyte lysate.

This study describes a method to quantify the inhibition of lipopolysaccharide (LPS) activity by serum with a turbidimetric Limulus amoebocyte lysate assay. Assays were performed in multiwell microplates, and turbidity was measured as the optical density at 380 nm with a microplate spectrophotometer. LPS potency was measured as the 50% maximal Limulus amoebocyte response (LR50) of LPS diluted with saline.

Quantification of endotoxin inhibition in serum and plasma using a turbidimetric LAL assay.

A modified Limulus amebocyte lysate (LAL) test was developed which quantifies the inhibition associated with lipopolysaccharide (LPS) in serum and plasma. The assay utilized the LR50 value to determine relative inhibition. The LR50, measured in ng/ml, represented the concentration of endotoxin needed to elicit a turbidimetric response equal to 50% of the maximum above the control (no added endotoxin).

Polypeptide composition of squid neurofilaments.

Neurofilaments, 10 nm in diameter, from the axoplasm of the squid Loligo pealei have been isolated by a combination of sonication and Millipore filtration. The presence of neurofilaments during the isolation procedure was confirmed by negative staining and transmission electron microscopy. By use of this technique, which results in minimal or no chemical alteration of the native neurofilament proteins, it was shown that actin (43,000 daltons) and tubulin (56,000 daltons) are physically separable from intact neurofilaments.