Polymer-bound derivatives of sarcolysin and their antitumour activity against mouse and human leukaemia in vitro

A series of N-(2-hydroxypropyl)methacrylamide (HPMA) copolymers containing different oligopeptide side-chains terminated in an alkylating anticancer agent-sarcolysin isopropyl ester (SL-OiP) and occasionally fucosylamine were synthetized. In the first step reactive polymeric precursors were prepared by radical precipitation copolymerization of HPMA with p-nitrophenyl esters of N-methacryloylated dipeptides (Gly-Phe or Gly-Leu). In the second step the former were aminolyzed with a dipeptide or amino acid derivatives of SL-OiP, thus forming tripeptide or tetrapeptide side-chains terminated in SL-OiP. Two of the polymers synthetized contained also fucosylamine as the terminal moiety, which was introduced as a targeting moiety, able to interact with fucose-specific membrane receptors of mouse leukaemia L 1210 cells. These polymers were synthetized by consecutive aminolysis of reactive polymeric precursors with fucosylamine and SL-OiP derivatives. To test the influence of the oligopeptide side-chain structure on the rate of drug release, the polymers synthetized were incubated with a mixture of lysosomal enzymes isolated from rat liver (tritosomes) and with cathepsin B. The relationship between the structure of polymer bound anticancer drugs and their biological activity was determined in vitro by their effect on the growth of mouse leukaemia L 1210 cells and human lymphoblastoid leukaemia (CCRF) cells. The results demonstrate the potential of these compounds as new types of targetable anticancer agents.     

Utilization of screening mammography: comparison of different physician specialties

Data obtained on 426 consecutive patients referred to a breast center by 122 physicians, including family practitioners, general surgeons, and other specialists, showed that the obstetricians-gynecologists referred the greatest average number of patients per physician, with more than 50% of these referrals for screening mammography. Internists referred fewer patients by nearly a factor of ten, with only one-third of these patients referred for screening mammography. Internists may be the weakest link in the utilization of screening mammography.     

ABO compatibility can influence the results of platelet transfusion. Results of a randomized trial

Sixty consecutive patients with untreated acute leukemia alternately received either ABO-matched or ABO-mismatched random-donor platelet transfusions prepared from pooled platelet concentrate stored for 1 to 3 days. Patients were assigned randomly to receive matched or mismatched platelets as their first transfusion, and the first four transfusions were analyzed. In 40 evaluable patients, there was no significant difference (paired t test) between the 10-minute posttransfusion corrected count increments (CCI) of the initial transfusions of matched and mismatched platelets. In contrast, the second matched transfusion was significantly better than the second mismatched transfusion. This effect of ABO compatibility was particularly pronounced in a subset of patients. Six patients in whom mismatched transfusions were consistently inferior to matched transfusions had either a significant increase in anti-A or -B isoagglutinin titers following the first transfusion or elevated titers before or at the conclusion of the study. Conversely, in five patients in whom there was no apparent effect of ABO mismatching, only one had an increase in isoagglutinin titer. Platelet survival was not altered as the ratio of 18-hour to 10-minute posttransfusion CCl was 0.6 for both matched and mismatched platelet transfusions. These data demonstrate that ABO compatibility can affect the results of random-donor platelet transfusions and that patients who experience poor increments from ABO-mismatched platelets may benefit from a trial of ABO-compatible platelets before the initiation of HLA-matched platelet transfusion.     

Polymer-conjugated bovine pancreatic and seminal ribonucleases inhibit growth of human tumors in nude mice.

The hydrophilic poly[N-(2-hydroxypropyl)methacrylamide] (PHPMA) was used for RNase A or BS-RNase modification to prevent their degradation in bloodstream or fast elimination. Two PHPMA chains (classic and star-like) were synthesized and their conjugates with both enzymes were tested on the CD-1 nude mice bearing various human tumors. These RNase conjugates injected intravenously or intraperitoneally into the mice bearing melanoma, neuroblastoma or ovarian tumor caused significant reduction of transplanted tumors following ten daily doses of 2.5 and/or 1 mg/kg, respectively, while free RNase A or BS-RNase injected in doses of 10 mg/kg exerted only negligible antitumor activity. Histological examination confirmed potent cytotoxic effect of RNase A conjugates in ovarian tumor. Despite the antitumor activity observed in vivo, the in vitro cytotoxic activity of RNase A conjugates was not pronounced and did not differ from that caused by the free RNase A. The in vitro experiments with 125I-labeled preparations demonstrated that polymer conjugates were internalized by tumor cells very poorly in contrast to the dose-dependent internalization of the wild enzyme preparation. Surprisingly, mice injected with EL-4 leukemic cells, which were preincubated for 4 h with BS-RNase conjugates, exerted significantly prolonged survival compared with the control non-treated mice. It may be supposed that both BS-RNase and RNase A conjugates with PHPMA act after administration in vivo by a mechanism different from that or those occurring under in vitro conditions because in vivo they exert an antitumor action, whereas in vitro, they are ineffective. The experiments proved that RNase A, when conjugated to PHPMA, produced identical aspermatogenic and antitumor effects as BS-RNase conjugated to this polymer and that this preparation may be regarded as a potential anticancer drug.     

Studies on the mechanism of bacterial resistance to complement-mediated killing. II. C8 and C9 release C5b67 from the surface of salmonella minnesota S218 because the terminal complex does not insert into the bacterial outer membrane

The mechanism for consumption of terminal complement components and release of bound components from the surface of serum-resistant salmonella minnesota S218 was studied. Consumption of C8 and C9 by S218 occurred through interaction with C5b67 on the bacterial surface because C8 and C9 were consumed when added to S218 organisms previously incubated in C8-deficient serum and washed to remove all C5b67 on the bacterial surface because C8 and C9 were consumed when added to S218 organisms previously incubated in C8- deficient serum and washed to remove al but cell bound C5b67. Rapid release of (125)I C5 and (125)I C7 from the membrane of S218 was dependent on binding of C8 because (125)I C5 and (125)I C7 deposition in C8D serum was stable and was twofold higher in C8D than in PNHA, and addition of purified C8 or C8 and C9 to S218 previously incubated in C8D serum caused rapid release of (125)I C5 and (125)I C7 from the organism. Analysis by sucrose density gradient ultracentrifugation of the fluid phase from the reaction of S218 and 10 percent PNHS revealed a peak consistent with SC5b-9, in which the C9:C7 ratio was 3.3:1, but the NaDOC extracted bound C5b-9 complex sedimented as a broad peak with C9:C7 of less than 1.2:1. Progressive elution of C5b67 and C5b-9 from S218 but not serum-sensitive S. minnesota Re595 was observed with incubation in buffers of increasing ionic strength. Greater than 90 percent of the bound counts of (125)I C5 or (125)I C9 were released from S218 by incubation in 0.1 percent trypsin, but only 57 percent of (125)I C9 were released by treatment of Re595 with trypsin. These results are consistent with the concept that C5b-9 forms on the surface of the serum-sensitive S. minnesota S218 in normal human serum, but the formed complex is released and is not bactericidal for S218 because it fails to insert into hydrophobic outer membrane domains.     

Experimental use of new absorbable tracheal stent

Background/purpose

Silicone and metallic stents are not effective in children with tracheobronchial stenosis or tracheomalacia. Herein, we aimed to evaluate the clinical manifestations and histological reaction of rabbit trachea to the presence of a new poly(lactic-co-glycolic acid) with polyisoprene (PLGA/PI) polymer absorbable stent.

Bedeutung von Phosphodiesteraseisoenzymen in der Kontrolle der humanen Detrusormuskulatur

Objectives

The use of inhibitors of phosphodiesterase (PDE) isoenzymes 1 and 5 to treat overactive bladder has been suggested. To further evaluate the significance of PDE isoenzymes in detrusor smooth muscle relaxation, we investigated the effects of selective PDE inhibitors on the tension induced by carbachol of isolated human detrusor tissue. Using immunohistochemical methods, the expression of PDE1, PDE4, and PDE5 in human detrusor was also investigated.

Material and Methods

The expression of PDE1, PDE4, and PDE5 was evaluated by means of conventional immunohistochemistry (IHC). Using the organ bath technique, the effects of the PDE inhibitors vinpocetine, rolipram, sildenafil, tadalafil, and vardenafil on the tension induced by the muscarinic agonist carbachol (1 µM) were investigated.

Results

The tension induced by carbachol was dose-dependently reversed by the PDE inhibitors; the maximum reversal of tension ranged from 7% (tadalafil) to 34% (vardenafil). IHC revealed that the expression of PDE isoenzymes was limited to the smooth musculature of the detrusor. While there was prominent expression of PDE4 and PDE5, immunoreactions indicating the presence of PDE1 were less abundant.

Conclusion

Despite the fact that inhibitors of PDE1, PDE4, and PDE5 exerted only a weak relaxant response on detrusor strips precontracted by carbachol, our findings indicate that both the cAMP and cGMP pathways might be involved in the relaxation mechanism of human detrusor smooth muscle.