Comparative effectiveness of alternative clinical pathways for primary hip and knee joint replacement patients: a pragmatic randomized, controlled trial

OBJECTIVE

Total hip replacement (THR) and total knee replacement (TKR) (arthroplasty) surgery for end-stage osteoarthritis (OA) are ideal candidates for optimization through an algorithmic care pathway. Using a comparative effectiveness study design, we compared the effectiveness of a new clinical pathway (NCP) featuring central intake clinics, dedicated inpatient resources, care guidelines and efficiency benchmarks vs. the standard of care (SOC) for THR or TKR.

METHODS

We compared patients undergoing primary THR and TKR who received surgery in NCP vs. SOC in a randomised controlled trial within the trial timeframe. 1,570 patients (1,066 SOC and 504 NCP patients) that underwent surgery within the study timeframe from urban and rural practice settings were included. The primary endpoint was improvement in Western Ontario and McMaster University osteoarthritis index (WOMAC) overall score over 12 months post-surgery. Secondary endpoints were improvements in the physical function (PF) and bodily pain (BP) domains of the Short Form 36 (SF-36).

RESULTS

NCP patients had significantly greater improvements from baseline WOMAC scores compared to SOC patients after adjusting for covariates (treatment effect=2.56; 95% confidence interval (CI) [1.10-4.01]). SF-36 BP scores were significantly improved for both hip and knee patients in the NCP (treatment effect=3.01, 95% CI [0.70-5.32]), but SF-36 PF scores were not. Effects of the NCP were more pronounced in knee patients.

CONCLUSION

While effect sizes were small compared with major effects of the surgery itself, an evidence-informed clinical pathway can improve health related quality of life (HRQoL) of hip and knee arthroplasty patients with degenerative joint disorder in routine clinical practice for up to 12 months post-operatively. CLINICALTRIALS.GOV IDENTIFIER: NCT00277186.

Synthesis and antiviral evaluation of analogs of adenosine-N1-oxide and 1-(Benzyloxy)adenosine

The activity of a series of compounds related to adenosine-N1-oxide (1) and 1-(benzyloxy)adenosine (42) against vaccinia virus has been determined both in vitro and in a vaccinia mouse tailpox model. Significant activities have been found both in vitro and in vivo for a number of the synthetic compounds.

Metabolism in human cells of the D and L enantiomers of the carbocyclic analog of 2'-deoxyguanosine: substrate activity with deoxycytidine kinase, mitochondrial deoxyguanosine kinase, and 5'-nucleotidase

The carbocyclic analog of 2'-deoxyguanosine (CdG) has broad-spectrum antiviral activity. Because of recent observations with other nucleoside analogs that biological activity may be associated the L enantiomer rather than, as expected, with the D enantiomer, we have studied the metabolism of both enantiomers of CdG to identify the enzymes responsible for the phosphorylation of CdG in noninfected and virally infected human and duck cells. We have examined the enantiomers as substrates for each of the cellular enzymes known to catalyze phosphorylation of deoxyguanosine. Both enantiomers of CdG were substrates for deoxycytidine kinase (EC 2.7.1.74) from MOLT-4 cells, 5'-nucleotidase (EC 3.1.3.5) from HEp-2 cells, and mitochondrial deoxyguanosine kinase (EC 2.7.1.113) from human platelets and CEM cells. For both deoxycytidine kinase and mitochondrial deoxyguanosine kinase, the L enantiomer was the better substrate. Even though the D enantiomer was the preferred substrate with 5'-nucleotidase, the rate of phosphorylation of the L enantiomer was substantial. The phosphorylation of D-CdG in MRC-5 cells was greatly stimulated by infection with human cytomegalovirus. The fact that the phosphorylation of D-CdG was stimulated by mycophenolic acid and was not affected by deoxycytidine suggested that 5'-nucleotidase was the enzyme primarily responsible for its metabolism in virally infected cells. D-CdG was extensively phosphorylated in duck hepatocytes, and its phosphorylation was not affected by infection with duck hepatitis B virus. These results are of importance in understanding the mode of action of D-CdG and related analogs and in the design of new biologically active analogs.

Characterization of S-adenosylmethionine decarboxylase induced by human cytomegalovirus infection

Infection of human diploid embryonic lung (MRC5) cells by human cytomegalovirus (HCMV), strain AD169, increased the activity of a key enzyme in the synthesis of polyamines: S-adenosylmethionine decarboxylase (E.C. 4.1.1.50). The initial peak of S-adenosylmethionine decarboxylase activity occurred about 15 h postinfection. S-Adenosylmethionine decarboxylase was purified using a highly specific affinity chromatography step from HCMV-infected and control uninfected MRC5 cells. No difference was found between the two enzymes in their stability to heat or effect of pH on activity. Both enzymes were activated only by putrescine. The appKm for S-adenosylmethionine for the virus-induced enzyme was 1.7 times higher than the appKm for the control enzyme. The most dramatic difference observed was in the effect of high salt concentration on enzyme activity. S-Adenosylmethionine decarboxylase from HCMV-infected cells was unaffected by 0.8 M NaCl, whereas the enzyme from uninfected cells was inhibited by 50% at 0.45 M NaCl and was significantly inhibited at a concentration of 0.8 M NaCl. Thus, different forms of S-adenosylmethionine decarboxylase probably exist in infected and uninfected MRC5 cells.

Phosphorylation of the enantiomers of the carbocyclic analog of 2'-deoxyguanosine in cells infected with herpes simplex virus type 1 and in uninfected cells. Lack of enantiomeric selectivity with the viral thymidine kinase

CdG, the carbocyclic analog of 2'-deoxyguanosine, is active against herpes, hepatitis B, and human cytomegaloviruses. We have studied the interaction of the tritiated enantiomers of CdG with the herpes simplex virus type 1-specific thymidine kinase (HSV-1 TK) and have examined their metabolism in uninfected and HSV-1-infected cells. D- and L-CdG were equally effective competitive inhibitors of the phosphorylation of thymidine (dThd) by the partially purified HSV-1 TK (Ki values were 2.1 and 3.4 microM, respectively) and were also equal as substrates (Km values were 17 and 26 microM, respectively, and Vmax values of the enantiomers were equal and about 50% greater than the Vmax for dThd). The partially purified enzyme preparation, which contained cellular nucleotide kinase activities (pyruvate kinase also was present in the assay medium), converted D-CdG almost exclusively to the triphosphate and L-CdG almost exclusively to the monophosphate. Similarly, in virus-infected cells the D-enantiomer was converted predominantly to the triphosphate and the L-enantiomer predominantly to the monophosphate. In uninfected cells the results were qualitatively similar. In CEM cells deoxycytidine (dCyd) kinase (EC 2.7.1.74) seemed to be the enzyme principally responsible for the phosphorylation of both enantiomers, as shown by competition studies. Thus, both the HSV-1 TK and cellular dCyd kinase (of CEM cells) showed no selectivity for the enantiomers of CdG. This lack of enantiomeric specificity has obvious implications for the design of inhibitors of both viral proliferation and cellular metabolism.

Incorporation of the carbocyclic analog of 2'-deoxyguanosine into the DNA of herpes simplex virus and of HEp-2 cells infected with herpes simplex virus

The carbocyclic analog of 2'-deoxyguanosine (CdG) is active against herpes simplex virus (HSV), human cytomegalovirus, and human hepatitis-B virus. In order to understand the mechanism of action of this compound against HSV, we have evaluated (a) the incorporation of [3H]CdG into viral and host DNA in HEp-2 cells infected with HSV and (b) the interaction of the 5'-triphosphate of CdG (CdG-TP) with the HSV DNA polymerase and human DNA polymerases alpha, beta, and gamma (EC 2.7.7.7). Incubation of HSV-1-infected HEp-2 cells with [3H]CdG resulted in the incorporation of CdG into both the HSV and the host cell DNA. These results indicated that CdG-TP was used as a substrate for HSV DNA polymerase and for at least one of the cellular DNA polymerases. Degradation of both viral and host DNA with micrococcal nuclease and spleen phosphodiesterase indicated that CdG was incorporated primarily into internal positions in both DNAs. The viral DNA containing CdG sedimented in neutral and alkaline sucrose gradients in the same way as did viral DNA labeled with [3H]thymidine, indicating that the HSV DNA containing CdG was similar in size to untreated HSV DNA. CdG-TP was a competitive inhibitor of the incorporation of dGTP into DNA by the HSV DNA polymerase (Ki of 0.35 microM) and the human DNA polymerase alpha (Ki of 1 microM). CdG-TP was not a potent inhibitor of either DNA polymerase beta or gamma. Using DNA-sequencing technology, CdG-TP was found to be an efficient substrate for HSV DNA polymerase. Incorporation of CdG monophosphate (CdG-MP) into the DNA by HSV DNA polymerase did not interfere with subsequent chain extension. These results suggested that the antiviral activity of CdG was due to its incorporation into the DNA and subsequent disruption of viral functions. In contrast, CdG-TP was not as good as dGTP as a substrate for DNA synthesis by DNA polymerase alpha, and incorporation of CdG-MP by DNA polymerase alpha inhibited further DNA chain elongation.

Novel method for evaluating antiviral drugs against human cytomegalovirus in mice

A virus-host cell system in which human cytomegalovirus-infected human cells are entrapped in agarose plugs has been developed. This model provides an inexpensive method for the in vivo evaluation (with outbred, immunocompetent mice) of antiviral drugs against human viruses such as cytomegalovirus that replicate primarily or only in human cells.

Phosphorylation of the carbocyclic analog of 2'-deoxyguanosine in cells infected with herpes viruses

The carbocyclic analog of 2'-deoxyguanosine [(+-)-2-amino-1,9-dihydro-9-[(1 alpha,3 beta,4 alpha)-3-hydroxy-4-(hydroxymethyl)cyclopentyl]-6H-purine-6-one] (2'-CDG) is highly active in cell culture against strains S148 and E377 of herpes simplex virus type 1 (HSV-1), both of which code for thymidine kinase, and much less active against strain BW10168 which is deficient in this enzyme activity. Antiviral activity is associated primarily with the D-enantiomer; the L-enantiomer has much lower but significant activity. The metabolism of racemic 2'-CDG and its D- and L-enantiomers was studied in uninfected HEp-2 cells and in HEp-2 cells infected with the S148 or BW10168 strains of HSV-1. Nucleotides were separated by HPLC, and their elution was monitored by spectrophotometry. The chromatograms of extracts of cells infected with the S148 strain and treated with (+/-)-2'-CDG or D-2'-CDG included a new peak which appeared in the triphosphate region. This peak, the area of which exceeded that of the GTP peak, was shown to be due to the triphosphate of 2'-CDG. The new peak was not observed by HPLC of extracts of uninfected cells treated with (+/-)-2'-CDG or either of its enantiomers, cells infected with the S148 strain and treated with L-2'-CDG, or cells infected with the BW10168 strain and treated with (+/-)-2'-CDG or either of its enantiomers. The results were similar when these studies were performed with uninfected Vero cells and with Vero cells infected with strain S148 of HSV-1. In experiments with D-[8-3H]-2'-CDG, small amounts of phosphates of 2'-CDG could also be detected in uninfected HEp-2 cells and in cells infected with the BW10168 strain of HSV-1. Thus, 2'-CDG apparently is a good substrate for the virus-coded kinase and a very poor substrate for cellular phosphorylating enzymes. The selective phosphorylation of 2'-CDG by the virus-specific kinase presumably is critical for its antiviral activity as it is for that of acyclovir and other acyclic derivatives of guanine.

Primary or delayed closure for open tibial fractures

Of 110 consecutive open tibial fractures 90 were reviewed and analysed retrospectively with particular reference to wound closure, method of stabilisation, infection rate and the incidence of non-union. There were 41% Gustilo type I, 39% type II and 20% type III injuries. The incidence of deep infection was 20% after primary wound closure compared with 3% after delayed closure, and eight of the nine non-unions followed primary closure. We conclude that primary wound closure should be avoided in the treatment of open tibial fractures.

Synthesis of 3-deazaneplanocin A, a powerful inhibitor of S-adenosylhomocysteine hydrolase with potent and selective in vitro and in vivo antiviral activities

The neplanocin A analogue 3-deazaneplanocin A (2b) has been synthesized. A direct SN2 displacement on the cyclopentenyl mesylate 3 by the sodium salt of 6-chloro-3-deazapurine afforded the desired regioisomer 4 as the major product. After deprotection, this material was converted to 3-deazaneplanocin A in two steps. X-ray crystallographic analysis confirmed the assigned structure. Consistent with its potent inhibition of S-adenosylhomocysteine hydrolase, 3-deazaneplanocin A displayed excellent antiviral activity in cell culture against vesicular stomatitis, parainfluenza type 3, yellow fever, and vaccinia viruses. Antiviral activity was also displayed in vivo against vaccinia virus by using a mouse tailpox assay. The significantly lower cytotoxicity of 3-deazaneplanocin A, relative to its parent compound neplanocin A, may be due to its lack of conversion to 5'-triphosphate and S-adenosylmethionine metabolites.

Synthesis and antiviral activity of carbocyclic analogues of xylofuranosides of 2-amino-6-substituted-purines and 2-amino-6-substituted-8-azapurines

(+/-)-(1 alpha,2 beta,3 alpha,5 alpha)-3-[(2,5-Diamino-6-chloro-4- pyrimidinyl)amino]-5-(hydroxymethyl)-1,2-cyclopentanediol (7) was synthesized from 2-amino-4,6-dichloropyrimidine and the carbocyclic xylofuranosylamine (+/-)-(1 alpha,2 beta,3 alpha,5 alpha)-3-amino-5-(hydroxymethyl)-1,2-cyclopentanediol (2) by subsequent preparation of the 5-[(4-chlorophenyl)azo] derivative of the resulting pyrimidine and reduction of the azo moiety with zinc and acetic acid. The carbocyclic analogue of 2-amino-4-chloropurine xylofuranoside (8) and the corresponding 8-azapurine 11 were prepared from 7. The carbocyclic analogues xylofuranosylguanine (9), xylofuranosyl-2,6-diaminopurine (10), xylofuranosyl-8-azaguanine (13), and xylofuranosyl-8-aza-2,6-diaminopurine (14) were prepared from 8 and 11. Compounds 9 and 13 were active against herpes simplex virus (types 1 and 2), with 9 being the more potent against both viruses. Analogue 9 also exhibited potent activity against human cytomegalovirus and varicella-zoster virus.

Synthesis and antiviral evaluation of carbocyclic analogues of 2-amino-6-substituted-purine 3'-deoxyribofuranosides

Carbocyclic analogues of 2-amino-6-substituted-purine 3'-deoxyribofuranosides were synthesized by beginning with (+/-)-(1 alpha,3 alpha,4 beta)-3-amino-4-hydroxycyclopentanemethanol and 2-amino-4,6-dichloropyrimidine. The route parallels the earlier syntheses of the corresponding ribofuranoside and 2'-deoxyribofuranoside analogues. The 2-amino-6-chloropurine, guanine, and 2,6-diaminopurine derivatives and the analogous 8-azapurines were prepared. The analogue (3'-CDG) of 3'-deoxyguanosine is active in vitro against a strain of type 1 herpes simplex virus (HSV-1) that induces thymidine kinase and is modestly active against a thymidine kinase inducing strain of type 2 HSV. 3'-CDG is not active against a strain of HSV-1 that lacks the thymidine kinase inducing capacity, whereas the carbocyclic analogue of 2-amino-6-chloropurine 3'-deoxyribofuranoside is active against that strain. The carbocyclic analogue of 2,6-diaminopurine 3'-deoxyribofuranoside displayed modest activity in vitro against influenza virus.

Carbocyclic analogues of 5-halocytosine nucleosides

Carbocyclic analogues of 5-halocytosine nucleosides were prepared by direct halogenation of the carbocyclic analogues of cytidine, 2'-deoxycytidine, 3'-deoxycytidine, or ara-C. The 5-chloro and 5-bromo derivatives of the cytidine (carbodine) and of the 2'-deoxycytidine analogues and the 5-iodo derivatives of all four of the cytosine nucleoside analogues were prepared. All of the C-5-halocytosine nucleosides, as well as the parent C-cytosine nucleosides, were tested against a strain of herpes simplex virus type 1 (HSV-1) that induces thymidine kinase in host cells. Carbodine, 5-bromocarbodine, C-2'-deoxycytidine, C-5-bromo-2'-deoxycytidine, the four C-5-iodocytosine nucleosides, and C-ara-C inhibited replication of this strain of HSV-1 in cultured cells. Most of these compounds were tested also against the type 2 virus (HSV-2) in vitro and were active. The greatest activity observed was exerted by C-5-iodo-2'-deoxycytidine in inhibiting replication of HSV-1 in L929 cells. In tests against these DNA viruses, carbodine, a ribofuranoside analogue that had been shown previously to be highly active against human influenza A virus in vitro, was the most active compound against HSV-2 and one of the most active compounds against HSV-1 in Vero cells. 5-Bromocarbodine was active against influenza virus, but it was less active than carbodine.

Carbocyclic analogues of 5'-amino-5'-deoxy- and 3'-amino-3'-deoxythymidines

The carbocyclic analogue of 5'-amino-5'-deoxythymidine was synthesized from the carbocyclic analogue of 2,5'-O-anhydrothymidine acetate. The carbocyclic analogues of 3'-amino-3'-deoxythymidine and of 1-(3'-amino-2',3'-di-deoxylyxofuranosyl)thymine (an all-cis structure) were synthesized from the carbocyclic analogues of 5'-O-trityl-2,3'-O-anhydrothymidine and 5'-O-trityl-3'-O-(methylsulfonyl)thymidine, respectively. The carbocyclic analogue of 5'-amino-5'-deoxythymidine inhibited cytopathogenic effects (CPE) induced by a TK+ strain of type 1 herpes simplex virus replicating in L929 (mouse connective tissue) cells, but it did not inhibit CPE in Vero cells. In contrast, the all-cis-3'-azido-3'-deoxythymidine analogue demonstrated modest inhibition of CPE in Vero cells, but not in L929 cells.

Synthesis and antiviral activity of the carbocyclic analogues of 5-ethyl-2'-deoxyuridine and of 5-ethynyl-2'-deoxyuridine

The carbocyclic analogue of the antiviral agent 5-ethyl-2'-deoxyuridine (EDU) was synthesized by two routes. The pivotal step in the first route is the reaction of lithium dimethylcuprate with the carbocyclic analogue of 5-(bromomethyl)-2'-deoxyuridine dibenzoate (6). The second route is based on the synthesis of the carbocyclic analogue of 5-ethynyl-2'-deoxyuridine (12) by a coupling reaction catalyzed by bis(triphenylphosphine)palladium(II) chloride and copper(I) iodide, a method reported recently (Robins and Barr) for the synthesis of the true nucleoside 5-ethynyl-2'-deoxyuridine (1b). The carbocyclic analogue of EDU inhibits the replication of type 1 and type 2 herpes simplex viruses in Vero cells. The carbocyclic analogue of 5-ethynyl-2'-deoxyuridine has modest activity against herpes simplex virus, types 1 and 2.

Synthesis and antiviral activity of carbocyclic analogues of 2'-deoxyribofuranosides of 2-amino-6-substituted-purines and of 2-amino-6-substituted-8-azapurines

(+/-)-(1 alpha, 2 beta, 4 alpha)-4-[(2,5-Diamino-6-chloro-4-pyrimidinyl) amino]-2-hydroxycyclopentanemethanol (9) was synthesized by beginning with 2-amino-4,6-dichloropyrimidine and (+/-)-1 alpha, 2 beta, 4 alpha)-4-amino-2-hydroxycyclopentanemethanol, preparing the 5-[(4-chlorophenyl)azo] derivative of the resulting pyrimidine, and reducing the azo derivative. The carbocyclic analogue of 2-amino-6-chloropurine 2'-deoxyribofuranoside (10) was prepared from 9 and triethyl orthoformate, and the analogous 8-azapurine (11) was obtained by diazotizing 9. From 10 or 11, the carbocyclic analogues of 2'-deoxyguanosine, 2'-deoxythioguanosine, 2,6-diaminopurine 2'-deoxyribofuranoside, 2'-deoxy-8-azaguanosine, and 2,6-diamino-8-azapurine 2'-deoxyribofuranoside were prepared. All of these 2'-deoxyribofuranoside analogues were active against herpes simplex virus (types 1 and 2) replicating in cells in culture; some demonstrated potent activity.

Synthesis and antiviral evaluation of carbocyclic analogues of ribofuranosides of 2-amino-6-substituted-purines and of 2-amino-6-substituted-8-azapurines

Carbocyclic analogues of ribofuranosides of 2-amino-6-substituted-purines and of 2-amino-6-substituted-8- azapurines were prepared from the 2-amino-6-chloropurine ribofuranoside analogue (2) and the 2-amino-6-chloro-8- azapurine ribofuranoside analogue (9), respectively. Analogues of purine ribofuranosides with the chloro, amino, methylamino, or methylthio group at position 6, the thioguanosine analogue, and the previously reported guanosine analogue were evaluated in vitro against herpes simplex virus, type 1 (HSV-1). 8- Azapurine ribofuranoside analogues with the chloro, amino, or methylthio group at position 6 and the previously reported 8- azaguanosine analogue were also evaluated against HSV-1. The carbocyclic analogue (6) of 2,6-diaminopurine ribofuranoside is highly active against HSV-1 and, also, against vaccinia virus. The 2-amino-6-chloropurine, 2-amino-6-(methylamino)purine, and the 2,6-diamino-8- azapurine derivatives also demonstrated significant activity against HSV-1.

Synthesis and evaluation of a series of 2'-O-acyl derivatives of 9-beta-D-arabinofuranosyladenine as antiherpes agents

A series of four 9-(2-O-acyl-beta-D-arabinofuranosyl)adenines (5a-d) was synthesized by acylation of 9-[3,5-bis-O-(tert-butyldimethylsilyl)-beta-D-arabinofuranosyl]adenine (2), followed by removal of the tert-butyldimethylsilyl groups under conditions (HOAc, tetra-n-butylammonium fluoride) that prevented acyl migration. The four 2'-O-acyl derivatives 5a-d showed activity in vitro against herpes type 1 viruses [virus ratings = 1.5-2.6; MIC50 = 26-72 micrograms/mL (8.48-21.3 X 10(-5) M)]. The 2'-O-acetyl (5a) and 2'-O-valeryl (5d) derivatives were evaluated in a guinea pig model for genital herpes (herpes type 2); only 5a showed potent activity when given 6 or 24 h postinfection.

Evaluation of prodrugs of 9-beta-D-arabinofuranosyladenine for therapeutic efficacy in the topical treatment of genital herpesvirus infections in guinea pigs

Prodrugs of the antiviral agent 9-beta-D-arabinofuranosyladenine (araA), which were more effective than the parent compound in penetrating vaginal membranes in vitro, were synthesized and examined for efficacy in the topical treatment of genital infections with herpes simplex virus type 2 in female guinea pigs. Treatment with 10% araA-5'-monophosphate or 10% araA-5'-monovalerate twice a day for 7 days, starting 6 h after intravaginal inoculation with virus, completely aborted the primary infection. When initiation of treatment was delayed until 24 h postinfection, araA-5'-monophosphate and araA-5'-monovalerate were no longer effective in reducing the mean lesion scores or mean vaginal virus titers. Treatment with 5% acyclovir, starting at 24 h postinfection, failed to prevent genital lesion development but significantly reduced the peak mean lesion score (approximately 50%). Topical therapy with 10% araA-2',3'-diacetate, initiated at 24 h postinfection, was as effective as, if not more effective than, acyclovir in reducing the severity of herpes genitalis in guinea pigs. Treatment with 10% araA-2',3'-dipropionate or 10% araA-2',3'-dibutyrate was without benefit. Among a series of 5'-monoesters of araA, araA-5'-monobutyrate appeared to be the most effective but was less active than araA-2',3'-diacetate. These data indicate that araA-2',3'-diacetate may be an effective antiviral agent for topical use against genital herpesvirus infections.

Comparison of the efficacy of vidarabine, its carbocyclic analog (cyclaradine), and cyclaradine-5'-methoxyacetate in the treatment of herpes simplex virus type 1 encephalitis in mice

The relative therapeutic effects of vidarabine (9-beta-D-arabinofuranosyladenine), cyclaradine (the adenosine deaminase-resistant carbocyclic analog of vidarabine), and cyclaradine-5'-methoxyacetate in the parenteral treatment of systemic herpes simplex virus type 1 infections in Swiss mice were determined. Among control mice inoculated intraperitoneally with virus, a mortality rate of 95% was observed. The intraperitoneal administration of nontoxic doses of vidarabine (125 to 250 mg/kg per day) or cyclaradine (113 to 450 mg/kg per day), by daily injections for 7 days beginning 4 h after virus inoculation, reduced mortality to 0 to 10%. Among control animals inoculated intracerebrally with 32 50% lethal doses of virus, 100% mortality was observed, with a mean survival time of 4.6 days. Treatment with either drug at equimolar dose levels ranging from ca. 32 to 750 mg/kg per day produced significant (P less than 0.0005), dose-dependent increases in the mean survival time of animals dying of herpesvirus encephalitis. Mice inoculated intracerebrally with 10 50% lethal doses of virus exhibited 97% mortality and a mean survival time of 5.5 to 6.4 days. Treatment with vidarabine, cyclaradine, or cyclaradine-5'-methoxyacetate significantly increased the mean survival time of dying animals and, at doses ranging from 250 to 750 mg/kg per day, produced significant increases in survival. The three drugs displayed equivalent antiviral efficacy in vivo. Drug toxicity (measured by weight loss) was not detected in mice treated with cyclaradine or cyclaradine-5'-methoxyacetate at 750 mg/kg per day, whereas severe toxicity (weight loss of greater than or equal to 3 g) was observed in mice treated with vidarabine at an equivalent dose level. Thus, cyclaradine or its 5'-methoxyacetic acid ester may possess some advantage over vidarabine in the treatment of severe herpesvirus infections and should therefore be considered for clinical trials in humans.

An evaluation of certain chain-extended analogues of 9-beta-D-arabinofuranosyladenine for antiviral and cardiovascular activity

Several nucleosides modified and chain extended at the 5'-position have been synthesized as follows: N6-benzamido- 9-(2,3-di-O-benzoyl-beta-D-arabino-pentodialdo-1,4-furanosyl)adenine, O=CHR, a leads to (E)-EtOCOCH=CHR (2) b leads to EtOCOCH2CH2R (3) c leads to H2NCOCH2CH2R (6) d leads to 1-(adenin-9- yl)-1,5,6-trideoxy-beta-D-arabino-hepto-1,4-furanuronamide (8); 3 e leads to ethyl 1-(adenin-9-yl)-1,5,6-trideoxy-beta-D-arabino-hepto-1, 4-furanuronate (5) f leads to 1-(adenin-9-yl)-1, 5,6-trideoxy-beta-D-arabino-hepto-1,4-furanuronic acid (4); 5 g leads to 9-(5,6-dideoxy-beta-D-arabino-hepto-1,4-furanosyl)adenine (7) [where a = EtOCOCH=PPh3; b = H2, Pd/C; c = Me2A1NH2; d = NH3/MeOH; e = NaOEt/EtOH; f = NaOH/MeOH; g = LiA1H4]. Both 7 and 8 show activity against herpes simplex virus type 1. The mechanism for such activity is unknown. Compounds 5 and 8 exhibited weak coronary vasodilation effects in dogs.

Carbocyclic arabinofuranosyladenine (cyclaradine): efficacy against genital herpes in guinea pigs

Carbocyclic arabinofuranosyladenine (cyclaradine), a novel nucleoside analog with such desired features as hydrolytic and enzymatic stability, adenosine deaminase resistance, and low systemic toxicity, inhibited the replication of herpes simplex virus types 1 and 2. The 5'-methoxyacetate prodrug form exhibited significant efficacy in the topical treatment of genital infections by herpes simplex virus type 2.

Carbocyclic analogues of 5-substituted uracil nucleosides: synthesis and antiviral activity

Carbocyclic analogues of 3'-deoxyuridines, 3'-deoxyuridines, and uridines with substituents at position 5 of the uracil moiety were prepared by direct halogenation (5-bromo and 5-iodo groups) and by displacement of the 5-bromo group by amino and substituted-amino groups. The analogue of 5-(hydroxymethyl)uridine was prepared via reaction of the isopropylidene derivative of the uridine analogue with paraformaldehyde. The carbocyclic analogues of thymidine and of 5-bromo-, 5-iodo-, and 5-(methylamino)-2'-deoxyuridine were highly active in vitro against herpes simplex virus, types 1 and 2. The corresponding analogues of 5-substituted 3'-deoxyuridines and of 5-substituted uridines were not active in this assay.

Carbocyclic analogue of 3-deazaadenosine: a novel antiviral agent using S-adenosylhomocysteine hydrolase as a pharmacological target

The carbocyclic analogue of 3-deazaadenosine (3-deaza-C-Ado) has been synthesized and found to have antiviral activity in cell culture against herpes simplex virus type 1, vaccinia virus, and HL-23 C-type virus. It is relatively noncytotoxic at effective antiviral concentrations and is not subject to deamination or phosphorylation. It acts as a competitive inhibitor of S-adenosyl-L-homocysteine hydrolase, is at best a poor substrate, and does not inactivate the enzyme significantly. 3-Deaza-C-Ado may cause a selective inhibition of the methylation of the polynucleotide 5' cap of viral mRNA via higher cellular concentrations of S-adenosyl-L-homocysteine, resulting from the inhibition of S-adenosylhomocysteine hydrolase in infected cells, since increases in the intracellular level of S-adenosylhomocysteine, but no effects on DNA or RNA synthesis, were observed after incubation of these cells with it.

Lack of efficacy of 2-deoxy-D-glucose in the treatment of experimental herpes genitalis in guinea pigs

Topical treatment of herpes genitalis in female guinea pigs with 2-deoxy-D-glucose in either agarose gels or miconazole nitrate ointments failed to prevent the development of genital lesions or to reduce the mean titers of recoverable virus in vaginal swabs from infected animals. In contrast, phosphonoacetic acid was therapeutically effective.

Evaluation of carbodine, the carbocyclic analog of cytidine, and related carbocyclic analogs of pyrimidine nucleosides for antiviral activity against human influenza Type A viruses

Carbodine, the carbocyclic analog of cytidine, was found to possess significant antiviral activity against influenza virus types A0/PR-8/34 and A2/Aichi/2/68 (Hong Kong) in vitro. The compound selectively inhibited PR-8 influenza virus-induced cytopathogenic effects in Madin-Darby canine kidney and inhibited Hong Kong influenza virus replication in primary rhesus monkey kidney cell cultures. The 50% minimum inhibitory concentration for inhibition of human influenza type A viruses by carbodine was approximately 2.6 microgram/ml (i.e., in the range of antiviral potency of ribavirin, but less potent than amantadine hydrochloride in concomitant assays). The fact that carbodine is metabolized to carbodine triphosphate in mammalian cells makes interference with the viral ribonucleic acid-dependent ribonucleic acid polymerase reaction a likely possibility for its principal mode of action. The carbocyclic analogs of uridine (the deamination product of carbodine), 2'-deoxycytidine, 3'-deoxycytidine, N,N-dimethylcytidine, N-methylcytidine, and some related carbocyclic analogs of pyrimidine nucleosides were inactive against PR-8 influenza virus in vitro. The combination of carbodine plus tetrahydrouridine was no more effective in vitro than carbodine alone, thus indirectly indicating that deamination of carbodine probably did not occur to a significant degree during the cell culture experiments. Although reproducibly active in vitro, carbodine did not exhibit any efficacy against lethal influenza virus infections in mice when administered by either the intraperitoneal or intranasal routes up to dose-limiting toxic levels.

Erythro-9-(2-hydroxy-3-nonyl) Adenine alone and in combination with 9-beta-D-arabinofuranosyladenine in treatment of systemic herpesvirus infections in mice

Although the antiviral activity of erythro-9-(2-hydroxy-3-nonyl)adenine, a potent adenosine deaminase inhibitor, against herpes simplex virus type 1 in cell culture was readily confirmed, the compound was found to be totally ineffective in the treatment of experimentally induced systemic herpes simplex virus type 1 infections in Swiss mice. Data were obtained, however, which clearly indicated that the antiviral potency of 9-beta-D-arabinofuranosyladenine in vivo could be enhanced by the co-administration of low, nontoxic doses of erythro-9-(2-hydroxy-3-nonyl)adenine.

2-Substituted derivatives of 9-alpha-D-arabinofuranosyladenine and 9-alpha-D-arabinofuranosyl-8-azaadenine

2-Substituted derivatives of 9-alpha-D-arabinofuranosyladenine were prepared via the fusion of tetra-O-acetyl-alpha-D-arabinofuranose with 2,6-dichloropurine followed by stepwise displacement of the chloro groups. A different approach, the reaction of 2,3,5-tri-O-benzoly-D-arabinofuranosyl bromide with 2,6-bis(methylthio)-8-azapurine in refluxing toluene in the presence of molecular sieve followed by stepwise reaction of the blocked nucleoside with methanolic ammonia and then other nucleophiles, gave 2-substituted derivatives of 9-alpha-D-arabinofuranosyl-8-azaadenine; In contrast to the parent compounds, none of these 2-substituted derivatives showed significant antiviral activity.

3-Deazauridine: inhibition of ribonucleic acid virus-induced cytopathogenic effects in vitro

3-Deazauridine, a synthetic analogue of uridine and a potential antitumor agent, was found to possess antiviral activity against a number of ribonucleic acid-containing animal viruses in mammalian cell culture. Inhibition of virus-induced cytopathogenic effects by 3-deazauridine was observed in cells infected with rhinovirus types 1A and 13, coxsackievirus type A21, and PR-8 influenza virus, but not in cells infected with poliovirus type 2 or echovirus type 12. The extracellular yield of progeny influenza virus was found to be significantly reduced in titer in 3-deazauridine-treated Madin-Darby canine kidney cell cultures at 12 to 24 hr after infection. Although the precise biochemical mechanism of action of this antimetabolite's antiviral activity is not known, the compound does not appear to exert a direct virucidal effect on the influenza virion itself.

Antiviral activity of carbobenzosy di- and tripeptides on measles virus

A series of simple carbobenzoxy peptides showed high and consistent antiviral chemotherapeutic activity in cell culture. In general, greatest activity was found against the measles-distemper or herpesvirus groups, or both, but various representatives of the series had quantitatively and qualitatively different antiviral activities. Several of the compounds, showing the highest antimeasles activity, were investigated extensively. In human cell culture plaque assays, these compounds were active against measles virus at levels of from 15 to 500 mug/ml. At single doses of about 250 to 500 mg/kg, orally in three animal species, significant serum levels of drugs were detected in virus cell culture assays. The mode of action appeared to be therapeutic, as an effect was seen in cell systems infected for at least 24 hr before treatment.

In vitro studies on the antiviral activity of 1, 3-bis(2-chloroethyl)-1-nitrosourea

Chemotherapy experiments carried out in vitro demonstrated that 1,3-bis(2-chloroethyl)-1-nitrosourea (BCNU) was active against lymphocytic choriomeningitis virus and had an equivocal antiviral effect on Semliki Forest, herpes simplex, and vaccinia viruses. No antiviral effect was observed with BCNU against western equine encephalomyelitis, polio, and parainfluenza (HA-1) viruses. Activity of the drug was determined by inhibition of viral-induced cytopathogenic effect in KB or chick embryo cells and by reduction of virus titer in cell culture supernatant fluid. Maximal activity against the viruses was observed when drug and virus were incubated together for 30 min prior to addition to cells; essentially no activity could be demonstrated if BCNU and virus were added to cells with no prior incubation.