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Peptide-based Inhibitors of HIV-1 RT Dimerization and Pol-polyprotein Maturation
The application of the two-drug combination sequences maintained stable CD4 levels in two subjects whose viral load (the evaluation of which had became available) was, at the end of this period, of 4,486 and 39,238 RNA copies. The third subject who had received, an intensive UV irradiation for a psoriasis, presented an irreversible decrease in his CD4 count and a high viral load (1,352,495 RNA copies/mL) at the end of the two-drug period.
Fifteen to 25 months after the shift to the three-drug combinations, the viral load decreased, from 39,328 to 13,291 in one of the non-UV irradiated subjects, and from 1,352,495 to 314,387 in the irradiated one. No subject had an increase in CD4 number.
In the three patients having initially received the three-drug combinations, a very strong decrease of viral load was registered after periods of observation varying from 77 to 40 months, while the CD4 counts increased moderately in two subjects, and noticeably in the third (from 126 to 266).
Out of the four subjects initially treated with four-drug combinations, the two with less than 10 CD4/mm3 had a moderate decrease in viral load in about three months, and the CD4 increased from 9 to 34/mm3 in one. But the two subjects, because of opportunistic infections and psychological reasons, abandoned their treatments.
In the two subjects who had more than 100 CD4/mm2 at initiation of the four-drug combination treatment, the viral load decreased to undetectable levels after four months: but their CD4 counts, after some oscillations, had very moderately increased at the end of the observation period (respectively, from 200 to 222, and from 129 to 134).
In practice, these results suggest the interest of conducting phase II or III studies of AIDS treatment protocols, starting with the four-drug combination model, and attempting to maintain the effect with the three-drug combination one.
As for theoretical considerations, one must underline the contrast between the remarkable reduction of the viral load and the usually moderate increase of the CD4 counts.
The study but not the trial has been interrupted, due to the unavailability of three antiproteases, saquinavir, ritonavir and indinavir, which are now introduced in the same type of combinations, one by one, in replacement of one of the studied agents as shown in figure 1. The effect of increasing the total number of virostatics from five to eight will be published in the second part of this article series.
Azidothymidine inhibits mitogen stimulated growth and D... Biochemical and Biophysical Research Communications |
Azidothymidine inhibits mitogen stimulated growth and DNA Biochemical and Biophysical Research Communications, Volume 157, Issue 3, 30 December 1988, Pages 1369-1375 B. Munch-Petersen Abstract SummaryUntil now, 3′-Azido-3′-deoxythymidine (AZT) is the most widely used drug in AIDS therapy, but the positive anti HIV effect of the drug is often accompanied by severe side effects such as bone-marrow suppression. In the present study, the effect of AZT on UV induced DNA strand-break rejoining and on phytohemagglutinin stimulated growth of lymphocytes from 7 healthy volunteers has been examined, and inhibitory effects of the drug was observed at therapeutic concentrations, i.e. 1–10 uM AZT.Purchase PDF (406 K) |
The pc12 cell as a model for studies of the mechanism o... Biochemical Pharmacology |
The pc12 cell as a model for studies of the mechanism of induction of peripheral neuropathy by anti Biochemical Pharmacology, Volume 42, Issue 1, 21 June 1991, Pages R5-R8 Sue A. Keilbaugh, William H. Prusoff, Melvin V. Simpson Abstract The ability of DNA polymerase gamma to utilize ddNTPs+ as substrates, incorporating these chain terminators into DNA (see citations in[1]), has led us to propose that AZT-induced bone marrow suppression results from inhibition of mtDNA replication [1]. This could alter metabolism since mtDNA encodes proteins involved in ATP synthesis and mitochondrial ultrastructure. We have shown that AZT and some other ddNs used in AIDS therapy inhibit DNA replication by purified DNA polymerase gamma and by isolated mitochondria [1,2]. Moreover, proliferation of a hemopoietic cell, the Friend erythroleukemic cell, is strongly inhibited by AZT [2], and mitochondria from these cells show impairment of DNA replication++ [2]. Additional evidence comes from studies on the effect of ddC on the Molt-4F cell [3], and on the involvement of mitochondria in AZT-induced myopathy [4]. We propose that inhibition of mtDNA replication is also the primary step in ddC-induced [5], ddI-induced [6] and d4T-induced [7] peripheral neuropathy. We have found that a transformant of the PC12 cell, GS-ras-1+++, is a promising neuronal cell model for such studies. The PC12 cell line [8] is derived from a pheochromocytoma, an adrenal medullary tumor; cells of the adrenal medulla share their embryological origin with neuronal cells. When the PC12 cell is induced by NGF (or by dexamethasone in GS-ras-1) to differentiate, neurite outgrowth and increased synthesis of acetylcholine and other neuronal markers occur. We describe the effects of some ddNs on both the uninduced and the induced cell. Purchase PDF (305 K) |
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Peptide-based Inhibitors of HIV-1 RT Dimerization and Pol-polyprotein Maturation