Evaluation of a new polyacrolein microsphere (acrobead) protein A column: an in vitro study using the blood of patients with immune thrombocytopenia or malignancies.

The present study describes the use of a new polyacrolein microsphere (acrobead) protein A column. This method enables immunomodulation by the perfusion of whole blood. The efficacy of the column and its adverse effects following perfusion of blood of patients with immune thrombocytopenic purpura (ITP) or malignancies were investigated. Concurrent experiments in which blood was perfused through an acrobead lactoglobulin column were carried out. Cellular blood components were mildly affected during the procedure. A moderate decrease in platelet number, to a nadir of 90 x 10(3) per microL (90 x 10(9)/L), was documented. During the hemoperfusion of ITP patients' blood, plasma hemoglobin reached levels of 25 to 40 mg per dL, a level similar to that found in banked blood during storage. Plasma tumor necrosis factor level, which serves as an indicator of monocytic activation, increased after 90 minutes of hemoperfusion. IgG and immune complexes were removed. The specific activities (removal of mg Ig/mL bead) of acrobead protein A columns, using blood from patients with ITP or malignancies, were 4.9 and 4.5 mg IgG per mL of bead, respectively. The diminution of platelet-specific IgG in the plasma of patients with ITP was documented as well. There was no activation of the fibrinolytic system as examined by D-dimers. The use of this new technique, which incorporates the method of direct hemoperfusion, is suggested for future clinical studies.

Detection of genotoxic substances in cancer patients receiving antineoplastic drugs.

A short-term bacterial mutation test, the SOS Chromotest, has been used to detect the excretion in urine of genotoxic metabolites of antineoplastic drugs administered to cancer patients. In this test, the damage to the DNA of the test bacteria is expressed by the production of beta-galactosidase, which can be quantitatively assessed and is proportional to the concentration of the drug. Kinetic curves of excretion for adriamycin, bleomycin, dacarbazine, cis-platinum and vincristine and their mixtures have been constructed from standard curves relating the intensity of the beta-galactosidase response to the concentration of drugs dissolved in normal urine. Comparative data on extraction and concentration of the drugs from urine or serum by means of selective resin or silica columns are presented.

Detection and quantitation of aflatoxin B1 in orange juice by SOS-Chromotest.

A new method for the detection and quantitation of aflatoxin B1 in liquids is described. The method is based on the SOS Chromotest, in which damage caused by aflatoxin B1 to the DNA of suitably engineered E. coli induces beta-galactosidase. Aflatoxin B1 developing in orange juice inoculated with spores of Aspergillus parasiticus is detectable equally well by TLC as by the SOS-Chromotest.

Simulation of calcium homeostasis: modeling and parameter estimation.

The system that regulates plasma calcium in the bird has been formalized into a model based on a series of differential equations and solved by computer simulation. Bone, kidney, and intestine have been considered as the control subsystems, with parathyroid hormone and 1,25-dihydroxycholecalciferol as the regulating hormones. The parameters used in the simulation model have been computed either from published results or by specifically designed experiments described here. For the estimation of parameters, an iterative procedure has been developed that was designed to minimize the sum of square errors between observed and system-simulated values. Parameters of 1,25-dihydroxycholecalciferol metabolism were experimentally obtained from the kinetic behavior of the 3H-labeled hormone in rachitic birds after a single dose. Model parameters have been adjusted using the results of in vivo calcium loading and validated by an EDTA infusion experiment. The simulation model has been used to study the hierarchy of the activities of the three control subsystems and of the regulating hormones, at different calcium intakes. Positive or negative errors in plasma calcium resulted in an asymmetry in the activities of the controlling systems, bone and kidney, whereas the intestine is characterized by its relatively long response time.

Handling of water and dietary monovalent ions by the young turkey.

Sodium and water turnover rates were measured in young turkeys fed diets with three concentrations of NaCl and kept at 12, 18 or 30 degrees C. Sodium absorption averaged approximately 60% and was unaffected by temperature. Water and sodium pools were affected by temperature and sodium intake. Water turnover was linear to sodium turnover at the lower two temperatures. No significant relationship was apparent in birds kept at 30 degrees C. The reciprocal of the slope of the function of water turnover on sodium turnover was 125-170 mM, suggesting an increase in isotonic urine excretion with sodium intake and a corresponding increase in water intake. Dietary sodium and potassium stimulated water turnover similarly. Dietary chloride concentration did not affect water turnover. In the turkey plasma pH and pCO2 were unaffected by a wide range of the anion-cation balance. It is concluded that excess sodium or potassium intakes is handled effectively in the turkey by increased water intake and excretion.

Glucose homeostasis in the chicken.

Plasma glucose level and glucose turnover rate were studied in chicks (Gallus domesticus) fed isocaloric diets containing glucose, fructose or soybean oil as the main energy supplement. Plasma glucose level and body weight gain were not affected by glucose intake. Glucose turnover rate decreased from 15.6 to 10.2 mg/(min . kg) in chicks fed glucose- or carbohydrate-free diets, respectively, showing a limited dependence on glucose intake. Glucose conversion to lactate in the intestinal wall in vivo was studied by the introduction of radioactive glucose into a duodenal loop and fractionation of the labeled metabolites in plasma of the duodenal vein and peripheral blood. Up to 37% of the glucose was converted to lactate by the intestinal wall during absorption. Thus, by quenching the perturbations resulting from ingestion and absorption of glucose, the intestine assumes an important role in glucose homeostasis.

Glucose absorption and starch digestion in the intestine of the chicken.

Starch digestion and glucose absorption were determined in vivo along the chick's (Gallus domesticus) intestine, using 91Y and 51Cr-EDTA as unabsorbed reference substances. About 65% of the ingested starch was digested up to the end of the duodenum, 85% up to the end of the jejunum and about 97% at the terminal ileum. A fraction of about 97% of the glucose, ingested or released from ingested starch, was absorbed. The duodenum was the major site of glucose absorption which continued at a decreased rate down the small intestine. Glucose absorption increased linearily with luminal concentration with no indication of saturation. The apparent permeability for glucose was similar for the jejunum and ileum.