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R B Pollack

Publications and source records attributed to R B Pollack.

3 recordsLinked to original sources
PubMed1991

Effects of intracarotid and intravenous infusion of human TNF and LT on established intracerebral rat gliomas.

The effects of recombinant human tumor necrosis factor (TNF) and lymphotoxin (LT) were investigated against two different established rat gliomas. Single preestablished intracarotid (ic) or intravenous (iv) doses (1.5-2.0 x 10(6) units) were administered to Wistar rats with intracerebral C6 gliomas and Fischer 344 rats with intracerebral T9 gliomas. Five days after cytokine treatment, animals were sacrificed and tumor size determined by histopathologic techniques. In Wister rats, ic TNF produced a greater reduction in size of C6 tumors than iv TNF. Experiments with Fischer rats showed that both TNF and LT were more effective when administered ic compared to iv. Furthermore, LT induced a greater reduction in tumor size than TNF. Additional studies on the age-related susceptibility of these gliomas revealed early, 8-day tumors were more sensitive to ic LT than advanced, 14-day tumors. No direct toxicity of these cytokines against the tumor cells was detected in vitro indicating their autitumor effect was mediated by alternate mechanisms in vivo. Thus for regionally confined gliomas ic therapy was superior to iv therapy and LT was more effective than TNF. Cytokine treatment was most effective on earlier tumors and there appeared to be differences in efficacy related to the tumor-host combination.

Animals↗
PubMed1990

Histochemical heterogeneity of dispersed human lung mast cells.

Cytocentrifuge preparations of enzymatically dispersed human lung parenchymal mast cells were examined by light microscopy after fixation in either Mota's basic lead acetate or 10% neutral buffered formalin followed by toluidine blue staining at pH 0.5. Fixation in Mota's basic lead acetate allowed detection of all mast cells. However, after formalin fixation only 10.8 +/- 1.3%, range 4.7 to 17%, n = 8 remained detectable (i.e., formalin "resistant"). Therefore, the vast majority of human lung mast cells lose their metachromatic staining after formalin fixation (i.e., are formalin "sensitive"). Mast cells were then separated on the basis of diameter by countercurrent elutriation and on the basis of density by discontinuous Percoll gradients. Histochemically distinct populations of mast cell types emerged in all lungs studied. The proportion of formalin-resistant mast cells increased as a function of diameter: less than 5% at diameters of less than or equal to 11 mu and densities less than or equal to 1.063 g/ml, to 30 to 40% in cells of diameters greater than or equal to 16 mu and densities greater than or equal to 1.100 g/ml. Maximum anti-IgE challenge of nearly homogeneous formalin-sensitive mast cells (94.3 +/- 2.1% purity, n = 6) caused the generation of both leukotriene C4 (64.6 +/- 26.4 pg/mast cell) and PGD2 (114.8 +/- 37.5 pg/mast cell). Six- to eight-fold enrichment of formalin-resistant mast cells did not significantly alter the histamine release response or profiles of arachidonate metabolites. Similar results were obtained for the nonimmunologic stimulus ionophore A23187. We conclude that two histochemically distinct subpopulations, of mast cells are present in human lung suspensions. Although formalin-sensitive cells account for almost 90% of lung mast cells, formalin-resistant cells are separable by their large diameters and higher densities. Both subtypes show similar histamine release responses and arachidonate oxidation profiles.

Antigen-Antibody Complex↗