Effect of intraoperative heparin administration on some indices of the blood coagulatory-lytic system in the ischemic region of the small intestine with anastomosis.

Several parameters of blood coagulation-lytic system were estimated in an ischemic region of narrow intestine with anastomosis in absence of heparin therapy and after subcutaneous intraoperative heparin administration. Single heparin injection in high therapeutic doses (200 U/kg body weight) during the fi nal stage of surgery prevents not only thrombosis of mesenteric blood vessels, but to a certain extent intraperitoneal adhesions.

Synthesis and evaluation of oligo-1,3-thiazolecarboxamide derivatives as HIV-1 reverse transcriptase inhibitors.

A set of oligo-1,3-thiazolecarboxamide derivatives able to interact with the minor groove of nucleic acids was synthesized. These oligopeptides contained different numbers of thiazole units presenting dimethylaminopropyl or EDTA moieties on the C-terminus, and aminohexanoyl or EDTA moieties on the N-terminus. The inhibition of such compounds on HIV-1 reverse transcriptase activity was evaluated using different model template primer duplexes: DNA x DNA, RNA x DNA, DNA x RNA and RNA x RNA. The biological properties of the thiazolecarboxamide derivatives were compared to those of distamycin, another minor groove binder which contains three pyrrole rings. Similar to distamycin, the thiazole containing oligopeptides were good inhibitors of the reverse transcription reaction in the presence of DNA x DNA. But in contrast to distamycin, the oligothiazolide derivatives were able to inhibit reverse transcription in the presence of RNA x DNA or DNA x RNA template primers. Both distamycin and oligothiazolecarboxamides had low affinity for RNA x RNA duplexes. The inhibition obtained with the newly synthesized thiazolecarboxamides showed that these compounds were more powerful and versatile inhibitors of the RT-dependent polymerization than the natural minor groove binder distamycin.

Interaction of oligonucleotides conjugated to substituted chromones and coumarins with HIV-1 reverse transcriptase.

Ten different pyranone-related substituents (chromones or coumarins) were covalently linked to the 5' end of various oligonucleotides (ODN). The interaction of these compounds with human immunodeficiency virus type 1 (HIV-1) reverse transcriptase (RT) was analyzed. A different behavior was found to depend on the structure of the oligonucleotide derivatives. Some compounds activated the enzyme at relatively low concentrations (0.1-0.5 microM), followed by an inhibition of the activity at higher concentrations (5-20 microM), whereas others behave just as inhibitors. Because the presence of some coumarin or chromone derivatives conjugated to ODNs enhanced the interaction with the reverse transcriptase, we analyzed the capacity of such ODN derivatives to be used as primers. The introduction of substituent I, a chromone derivative, the 2-[(3-(aminopropyl)amino]-8-isopropyl-5-methyl-4-oxo-4H-1-benzopyran-3-c arbaldehyde], and II, a coumarin derivative, the 1-(3-aminopropoxy)-2-ethyl-3H-naphto[2,1-b]pyran-3-one, into the 5' end of a noncomplementary ODN allowed these compounds to be used as primers. In the case of complementary primers, the presence of conjugated derivatives enhanced the affinity with Km values that were two to three orders of magnitude lower than that of a complementary primer of the same length. After addition of a ddT-unit to the 3'-terminal end of the ODN, some of these primers became very effective inhibitors of RT with Ki values in the nanomolar range.

HIV-1 reverse transcriptase is capable of elongating derivatives of sequence specific noncomplementary oligodeoxynucleotides.

We have carried out a comparison of KM and Vmax values for various primers in the polymerization reaction catalyzed by the HIV-1 RT. The affinity of RT for complementary d(pT)6 containing two different 5'-end pyranone derivatives was 2-3 orders of magnitude higher (KM = 3-15 nM) than that of d(pT)6 (KM = 12.6 mM). Oligodeoxynucleotides (ODNs) noncomplementary to poly(A) template were not elongated by RT. However, derivatives of d(CAGGTG) containing the 5'-terminal chromone and coumarin related groups were efficient primers showing KM (30-300 nM) and Vmax (75-93%) values comparable with that for d(pT)10 (800 nM; 100%). The [d(CAGGTG)]ddT ODN derivatives were effective inhibitors of RT. The primer function of derivatives of noncomplementary ODNs appears to be due to the additional interactions of their 5'-terminal groups with the enzyme tRNA-binding site.