[Low-dose cytosine arabinoside in treatment of 17 patients with acute nonlymphocytic leukemia]

Low dose Ara-C (LDAra-C, Ara-C 10-15 mg/12 h, i.m. x 14-21 days) was used in the treatment of 17 patients with ANLL, and from 14 patients blast cells were isolated before chemotherapy and cultured in the presence of Ara-C (10(-8) and 10(-7) mol/L), no definite induction of differentiation of leukemic cells was found. Of the 17 cases, 5 obtained CR, only one of them with M4 entered CR without pancytopenia or bone marrow aplasia during the LDAra-C treatment. For the rest, 4 with M2 obtained PR, and 8 did not respond. Toxic effects, including pancytopenia and bone marrow aplasia, were observed in most of the patients. Laboratory results showed that differentiation was not induced by Ara-C in low concentration in in vitro culture. LDAra-C is thought to be effective in the treatment of ANLL, and the mechanism may involve both the cytotoxicity and the induction of differentiation of leukemic cells, but the former is far more important.

Intraoperative determination of thoracic duct injury with 131I-fat. An experimental study on dogs

The creation of an experimental animal model of traumatic chylothorax was verified by 131I labelled fat (peanut oil). 15 dogs of 3 groups were administered 131I labelled oil via a gastric tube. The results were compared between the two experimental groups and a control group with nonchylous pleural effusion. Dynamic radioactive studies on the blood and pleural fluid showed that the absorption curve of the dog's blood and chyle to 131I labelled oil was identical regardless of different attitudes, and was also similar to that of the human blood because the peak appeared 4 hours after the administration of 131I labelled oil, at which the radioactivity of chyle reached its maximum, more powerful than that of the blood collected at the same time (P less than 0.01). The 99% confidence limitation of radioactivity of the pleural fluid, and the radioactivity ratio of the pleural fluid to blood in the experimental groups were 1.8-10.5 and 493-2340 cpm respectively. The specific characteristics of chyle was then determined qualitatively according to the quantitative norms. We conclude that the technique is parallel with the normal physiological pattern and seems to be more simple and reliable than the conventional methods for detection of intraoperative injury of the thoracic duct and early diagnosis of postoperative chylothorax.

Development of a microsphere-based fluorescent immunoassay and its comparison to an enzyme immunoassay for the detection of antibodies to three antigen preparations from Candida albicans

A sensitive assay for the simultaneous detection of multiple serum antibodies by flow cytometry was developed. Polystyrene microspheres of 5, 7 and 9.3 micron in diameter were used as solid supports for the attachment of three different antigen preparations from Candida albicans. These antigens were a whole cell extract; a cytoplasmic protein extract and a cell wall polysaccharide. Microsphere-associated fluorescence was quantitated by flow cytometry, with the different sized microspheres analyzed separately using electronic volume gating. This procedure allowed for different antigen-coated microspheres with discrete sizes to be analyzed independently for immunofluorescence. The assay detected antibody levels in human serum at dilutions up to 10(-6) and provided complete discrimination, using all three antigen preparations, between antibody levels seen in healthy subjects and those seen in patients suspected of having a systemic Candida infection. A standard enzyme immunoassay (EIA) failed to provide complete discrimination between healthy subjects and patient samples: at least 17% of patient values fell within the healthy subject range using all three antigen preparations. The microsphere assay which allowed for the simultaneous detection of multiple antibodies, has increased dynamic range over EIA and provides for better discrimination of patients from healthy subjects in comparison to EIA. Precise quantitation of antibodies is possible and the rapid analysis of thousands of microspheres markedly enhances the statistical accuracy of the assay. We suggest this assay is likely to have many other important applications in immunologic testing.

Identification of the erythropoietin receptors of erythroleukemic cells

Erythropoietin (epo) is the physiologic regulator of red blood cell development. We have demonstrated the presence of epo receptors on two erythroleukemia cell lines, IW32 and IW201. IW32 produces epo constitutively while IW201 is a nonproducing cell line. Neither cell lines respond to epo to differentiate. In this study, we have shown that these cells bound 125I-epo specifically. Binding could be displaced by the presence of unlabeled epo but not by insulin or epidermal growth factor. In contrast to that found in epo responsive cells isolated from Friend virus infected mouse spleen, which were reported to contain both "high" and "low" affinity receptors, our finding indicated only a single class of "low" affinity receptors with apparent dissociation constants of 1.7 nM and 2.0 nM for IW32 and IW201 cell lines, respectively. It is suggested that the absence of "high" affinity receptors may account for the lack of responsiveness of these cells to epo.

The cobalt(II)-alkaline phosphatase system at alkaline pH

The uptake of cobalt(II) ions by apoalkaline phosphatase at pH 8 (the pH optimum for activity) has been investigated by the combined use of electronic and 1H NMR spectroscopies. The presence of fast-relaxing high spin cobalt(II) ions in the active site cavity of the protein induces sizable isotropic shifts of the 1H NMR signals of metal-coordinated protein residues, allowing us to propose a metal uptake pattern by the various metal binding sites both in the presence and in the absence of magnesium ions. In the absence of magnesium the active site is not organized in specific metal binding sites. The first equivalent of cobalt(II) ions per dimer binds in an essentially unspecific and possibly fluxional fashion, giving rise to a six-coordinated chromophore. The second and third equivalents induce the formation of increasing amounts of metal ions pairs, cooperatively arranged into the A and B sites of the same subunit with a five- and six-coordinated geometry, respectively. The fourth and fifth equivalents induce the formation of fully blocked A-B pairs in both subunits. Magnesium shows the property of organizing the metal binding sites, probably through coordination to the C sites. Electronic and 1H NMR titration with Co2+ ions show that the initial amount of fluxional cobalt is smaller than in the absence of magnesium and that A-B pairs are more readily formed. Titration of fully metalated Co4Mg2alkaline phosphatase samples with phosphate confirms binding of only one phosphate per dimer.

Identification of erythropoietin receptors in isolated membranes from Friend virus infected mice spleen cells

It has been shown that radiolabeled erythropoietin (epo) specifically binds to homogeneous epo-responsive spleen cells from mice infected with the anemic variant of the Friend virus. We now report that membranes isolated from these cells retain the ability to specifically bind epo. Spleen cells were swollen in ice-cold 10 mM Tris-Cl pH 7.4 containing 0.2 mM phenylmethyl sulfonylfluoride for 5 minutes, after which the cells were homogenized and centrifuged to remove nuclear fraction. Membranes were collected by centrifuging the supernatant at 75,000 g for 90 min. Utilizing 3H-epo labeled at the terminal sialic acids of the carbohydrate moieties or 125I-epo labeled at the tyrosine residues, it was shown that the isolated membranes contained specific epo binding sites. About 90% of the binding could be inhibited by the presence of unlabeled epo whereas no inhibition was seen with other glycoproteins and growth factors. Equilibrium could be reached in approximately 2.5 hr at 25 degrees C or 1.5 hr at 37 degrees C. Binding could be saturated at an epo concentration of about 3 nM, Scatchard analysis indicated a single class of receptors with a Kd of approximately 1.5 nM.

Interstitial microwave antennas for thermal therapy

This paper presents a new microwave antenna design with improved heating at the tip for interstitial hyperthermia and thermocoagulation. Temperature distribution patterns surrounding a conventional insulated antenna and the new sleeved coaxial slot radiator are measured in a saline phantom under transient and steady-state conditions. The new design provides an improved steady-state temperature distribution over the active region of the radiator. In contrast to the cold zone at the tip of a conventional insulated antenna the new sleeved coaxial slot antenna provides maximal (sixfold greater) power deposition at its tip.