Molecular mechanisms of paclitaxel and NM-3 on human gastric cancer in a severe combined immune deficiency mice orthotopic implantation model

AIM: To explore the molecular mechanisms of action of paclitaxel and NM-3 on human gastric cancer in severe combined immune deficiency (SCID) mice.

METHODS: Human gastric cancer cells SGC-7901 were implanted into SCID mice and mice were treated with paclitaxel and NM-3. The effects of paclitaxel and NM-3 on apoptosis of human gastric cancer cells were analyzed using flow cytometry, TUNEL assays, and DNA fragment analyses.

RESULTS: Apoptosis of SGC-7901 cells was successfully induced by paclitaxel, NM-3, and the combination of paclitaxel and NM-3 24 h after injection as shown by the presence of apoptotic hypodiploid peaks on the flow cytometer before G1-S and a characteristic apoptotic band pattern in the DNA electrophoresis. The apoptotic rate detected by TUNEL assay was found to be significantly higher in the paclitaxel/NM-3 compared to the control group (38.5% ± 5.14% vs 13.2% ± 1.75%, P < 0.01).

CONCLUSION: Paclitaxel in combination with NM-3 is able to induce apoptosis of the human gastric cancer cells in SCID mice effectively and synergistically.

Suppression of influenza A virus nuclear antigen production and neuraminidase activity by a nutrient mixture containing ascorbic acid, green tea extract and amino acids

Influenza, one of the oldest and most common infections, poses a serious health problem causing significant morbidity and mortality, and imposing substantial economic costs. The efficacy of current drugs is limited and improved therapies are needed. A unique nutrient mixture (NM), containing ascorbic acid, green tea extract, lysine, proline, N-acetyl cysteine, selenium among other micronutrients, has been shown to exert anti-carcinogenic and anti-atherogenic activity both in vitro and in vivo. Many of the constituents of NM have been shown to have an inhibitory effect on replication of influenza virus and HIV. This prompted us to study the effect of NM on influenza A virus multiplication in infected cells and neuraminidase activity (NA) in virus particles. Addition of NM to Vero or MDCK cells post infection resulted in dose-dependent inhibition of viral nucleoprotein (NP) production in infected cells. NM-mediated inhibition of viral NP was selective and not due to cytotoxicity towards host cells. This antiviral effect was enhanced by pretreatment of virus with the nutrient mixture. Individual components of NM, namely ascorbic acid and green tea extract, also blocked viral NP production, conferring enhanced inhibition when tested in combination. Incubation of cell-free virus with NM resulted in dose-dependent inhibition of associated NA enzyme activity. In conclusion, the nutrient mixture exerts an antiviral effect against influenza A virus by lowering viral protein production in infected cells and diminishing viral enzymatic activity in cell-free particles.

Measurement of hepatitis B virus core-related antigen is valuable for identifying patients who are at low risk of lamivudine resistance

OBJECTIVE

The clinical usefulness of hepatitis B virus core-related antigen (HBVcrAg) assay was compared with that of HBV DNA assay in predicting the occurrence of lamivudine resistance in patients with chronic hepatitis B.

PATIENTS

Of a total of 81 patients who were treated with lamivudine, 25 (31%) developed lamivudine resistance during a median follow-up period of 19.3 months.

RESULTS

The pretreatment positive rate of HBe antigen, or pretreatment levels of HBVcrAg or HBV DNA did not differ between patients with and without lamivudine resistance. Levels of both HBVcrAg and HBV DNA decreased after the initiation of lamivudine administration; however, the level of HBVcrAg decreased significantly more slowly than that of HBV DNA. The occurrence of lamivudine resistance was significantly less frequent in the 56 patients whose HBV DNA level was less than 2.6 log copy/ml at 6 months of treatment than in the remaining 25 patients. The cumulative rate of lamivudine resistance was as high as 70% within 2 years in the latter group, while it was only 28% in the former group. Lamivudine resistance did not occur during the follow-up period in the 19 patients whose HBVcrAg level was less than 4.6 log U/ml at 6 months of treatment, while it did occur in 50% of the remaining patients within 2 years.

CONCLUSION

These results suggest that measurement of HBV DNA is valuable for identifying patients who are at high risk of developing lamivudine resistance, and that, conversely, measurement of HBVcrAg is valuable for identifying those who are at low risk of lamivudine resistance.

Clinical usefulness of total hepatitis C virus core antigen quantification to monitor the response to treatment with peginterferon alpha-2a plus ribavirin*

Early virological response may predict outcome following treatment with peginterferon alpha-2a and ribavirin in patients chronically infected with hepatitis C virus (HCV). As total HCV core antigen may constitute an alternative direct marker to HCV RNA for assessing the levels of viraemia in such patients, we evaluated the correlation between HCV core antigen and HCV RNA, and whether HCV core antigen at baseline, 4 and 12 weeks after treatment could predict sustained virological response (SVR) to combined therapy, in comparison with HCV RNA. A total of 290 serum samples from 58 previously treatment naïve chronic HCV patients were examined for HCV core antigen and HCV-RNA by means of quantitative HCV RNA when receiving combination therapy for the first time. SVR was significantly associated with basal HCV core antigen but not with HCV RNA. There was a good correlation between HCV core antigen and HCV RNA (r(2) = 0.781). The negative predictive value of HCV core antigen testing in predicting nonresponse at weeks 4 and 12 were 75 and 100%, and for undetectable or a 2-log drop in HCV RNA were 69.6 and 75% respectively. HCV core antigen detection is quick, and easy to perform alternative to HCV RNA, and could be used as a marker of HCV viraemia for monitoring the progress of therapy.

Proteomic profiling of cellular proteins interacting with the hepatitis C virus core protein

Hepatitis C virus (HCV) is a causative agent of chronic hepatitis and hepatocellular carcinoma. The core protein of HCV packages the viral RNA genome to form a nucleocapsid. In addition to its function as a structural protein, core protein is involved in regulation of cellular transcription, virus-induced transformation, and pathogenesis. To gain insights into cellular functions of the core protein by identification of cellular proteins interacting with the core protein, we employed a proteomic approach. Hepatocytes soluble cytoplasmic proteins were applied to the core proteins immobilized on Ni-nitrilotriacetic resin and total bound cellular proteins were resolved by 2-DE. Analyses of interacting proteins by matrix-assisted laser desorption/ionization-time of flight mass spectrometry allowed identification of 14 cellular proteins binding to the core protein. These proteins include DEAD-box polypeptide 5, similar in function to a known protein identified previously by yeast two-hybrid screening and 13 newly identified cellular proteins. Interestingly, nine protein spots were identified as intermediate microfilament proteins, including cytokeratins (five spots for cytokeratin 8, two for cytokeratin 19, and one for cytokeratin 18) and vimentin. Cytokeratin 8 and vimentin, which were previously shown to be involved in the infection processes of other viruses, were further analyzed to confirm their in vivo interactions with the core protein by immunoblotting and immunofluorescence microscopy. We discuss the functional implications of the interactions of the core protein with newly identified cellular proteins in HCV infection and pathogenesis.

Treatment of chronic hepatitis B virus infection via oral immune regulation toward hepatitis B virus proteins

OBJECTIVES

Hepatitis B virus (HBV) is a noncytopathic virus, and hepatocellular injury is mediated by a defective host antiviral immune response. We have previously shown that antiviral immunity can be modulated through oral feeding of viral proteins. The aims of this study were to determine the safety and efficacy of treatment of patients with chronic HBV by means of p.o. administration of HBV envelope proteins.

METHODS

A total of 42 chronic HBV patients were treated p.o. with HBV envelope proteins (HBsAg+preS1+preS2), three times/wk for 20-30 wk, and followed for an additional 20 wk. Patients were monitored for HBV-DNA levels, liver enzymes, and liver histology. HBV-directed T cell immune modulation was assessed in vitro by HBV specific T cell-proliferation, cytotoxicity, IFN gamma, and IL10 ELISPOT assays, and reverse transcription-polymerase chain reaction cytokines assay.

RESULTS

Favorable response in one of the primary endpoints was achieved in 28/42 patients (66.6%) by means of p.o. immune regulation. A significant decrease in viral load was observed in 15 patients (35.7%). HBsAg/HBcAg biopsy scores improved in 41% and 57.1% of patients, respectively. Histological improvement in liver necroinflammatory score was noted in 12/40 patients (30%). In all, 80% showed biochemical response. Five of 19 HBeAg positive patients (26.3%) became negative for HBeAg. A favorable augmentation in anti-HBV specific T cell response, with increased HbsAg specific T cell proliferation (78%), cytotoxicity (75%), and IFN gamma positive T cell clones (62.9%) was noted. In addition, a decrease in the IL10 gamma positive T cell clones was achieved (48.1%). Natural killer T (NKT) lymphocytes increased significantly in all treated patients.

CONCLUSIONS

Immune regulation of the anti-HBV immune response via p.o. administration of HBV envelope proteins alleviated the immune-mediated liver injury while augmenting the effective antiviral immunity.

Clinical relevance of total HCV core antigen testing for hepatitis C monitoring and for predicting patients' response to therapy

To study the correlation between total Hepatitis C virus (HCV) Core antigen (Ag) and HCV-RNA, and to assess the proficiency of HCV Core Ag testing in monitoring and predicting virologic response during and after pegylated interferon (PEG-IFN) and ribavirin combination therapy. A total of 307 samples from treated and untreated patients were used to assess the correlation between the total HCV Core Ag test and quantitative HCV-RNA assays (Superquant, and Quantiplex branched DNA 2.0 assay). Twenty-four patients received combination therapy for 48 weeks. Blood samples were collected at day 0, and week 2, 4, 12, 24, 48 and 72 for virologic evaluation. A linear relation exists between total HCV Core Ag and HCV-RNA levels. At 3 months the positive predictive value (PPV) of response to therapy was 100% with either HCV Core Ag or HCV-RNA. For HCV Core Ag the negative predictive value (NPV) was 100% whereas for HCV-RNA the NPV was 80% (P > 0.05). At month 1, the PPV was 95% and 100% when determined by HCV Core Ag and HCV-RNA, respectively. The NPV value was 100% for HCV Core Ag and 33% for HCV-RNA (P = 0.005). HCV Core Ag quantification could be useful in clinical practice to predict a sustained virological response early during therapy (4 weeks), reaching an optimal performance at month 3. The determination of total HCV Core Ag levels in serum, constitutes an accurate and reliable alternative to HCV-RNA for monitoring and predicting treatment outcome in patients receiving PEG-IFN/Ribavirin combination therapy.

Effects of interferon alpha therapy on the catalytic domains of the polymerase gene and basal core promoter, precore and core regions of hepatitis B virus

AIMS

The aim of the present study was to examine the catalytic domains of the polymerase gene, the basal core promoter and the precore and core regions of the hepatitis B virus (HBV) genome for specific mutations. These may account for the response to interferon alpha (IFN-alpha) treatment, which may have prognostic value.

METHODS

Multiple serum samples were collected prospectively from 30 patients with chronic active hepatitis B who were treated with IFN-alpha. Patients were assigned to one of three groups: group A (n = 11) and group B (n = 10) individuals were hepatitis B e antigen (HBeAg)-positive prior to treatment. Group A patients underwent HBeAg seroconversion after treatment while group B patients did not. Group C (n = 9) patients were HBeAg-negative prior to treatment. The HBV DNA was extracted from the sera collected before, during and after treatment and the various genomic regions were amplified, sequenced and examined for mutations.

RESULTS

During IFN-alpha therapy, multiple changes were found in the catalytic domains of the HBV polymerase gene in all groups. The frequency of mutations and associated amino acid changes were highest in virus from group C patients and lowest in group A patients. The interdomain regions of the viral polymerase were the most affected. Multiple mutations were also found in the precore, core and core promoter regions. However, no specific mutations were associated with clinical response or outcome.

CONCLUSIONS

During IFN-alpha treatment, multiple mutations occurred in the HBV genome, including the catalytic domains of the polymerase gene. Changes that did occur could not be correlated to the clinical response or treatment outcome. However, no mutations were found that have been linked to lamivudine escape, indicating that lamivudine therapy would be effective in IFN-alpha non-responder patients.

Isolation of human immunodeficiency virus type 1 cores: retention of Vpr in the absence of p6(gag)

Mature human immunodeficiency virus type 1 (HIV-1) virions contain a typically cone-shaped core that encases the viral genome. In this study, we established conditions which allowed the efficient isolation of morphologically intact HIV-1 cores from virions. The isolated cores consisted mostly of cones which appeared uniformly capped at both ends but were heterogeneous with respect to the shape of the broad cap as well as the dimensions and angle of the cone. Vpr, a nonstructural virion component implicated in the nuclear import of the viral genome, was recovered in core preparations of HIV-1 and simian immunodeficiency viruses from African green monkeys. Unexpectedly, p6(gag), a structural protein required for the incorporation of Vpr, was absent from HIV-1 core preparations. Taken together, our results indicate that the incorporation of Vpr into the virion core is a conserved feature of primate lentiviruses and that the interactions required for the uptake of Vpr into assembling particles differ from those which confine Vpr within the core.

Tick salivary gland extracts promote virus growth in vitro

Saliva of blood-feeding arthropods promotes infection by the vector-borne pathogens they transmit. To investigate this phenomenon in vitro, cultures of mouse L cells were treated with a salivary gland extract (SGE) prepared from feeding ticks and then infected with vesicular stomatitis virus (VSV). At low input doses of VSV, viral yield was increased 100-fold to 10,000-fold by 16-23 h post-infection compared with untreated cultures, and depending on the SGE concentration. SGE-mediated acceleration of viral yield corresponded with the earlier appearance of VSV nucleocapsid protein as detected by 2-dimensional electrophoresis of infected cells. The observation that physiological doses of virus (i.e. doses likely to be inoculated by an infected arthropod vector into its vertebrate host during blood-feeding) respond to SGE treatment in vitro provides a new opportunity for identifying the factors in tick saliva that promote virus transmission in vivo.

Long-term ganciclovir chemotherapy for congenital duck hepatitis B virus infection in vivo: effect on intrahepatic-viral DNA, RNA, and protein expression

Long-term antiviral chemotherapy using the nucleoside analogue ganciclovir was undertaken with the aim of eliminating hepadnaviral covalently closed circular (CCC) DNA from the livers of ducks that were congenitally infected with the duck hepatitis B virus (DHBV). Twenty-four weeks of ganciclovir therapy caused a substantial reduction in viremia, intrahepatic viral DNA replicative intermediates, and viral core proteins. Unfortunately, ganciclovir therapy did not substantially affect CCC DNA or viral RNA levels, and the treatment resulted in an increase in the intrahepatic expression of the viral envelope proteins, pre-S and S. By the completion of therapy, the viral envelope proteins had assembled into large aggregates within the cytoplasm of most hepatocytes. Viral replication in the bile duct epithelial cells and in the extrahepatic sites was likewise not affected by long-term ganciclovir therapy. In conclusion, 24 weeks of ganciclovir therapy decreased most viral replication markers within the liver, except for those of viral CCC DNA, RNA, and envelope proteins. Long-term therapeutic strategies using nucleoside analogs such as ganciclovir should be used with caution in chronic hepatitis B virus (HBV) infection. The careful monitoring of serum and hepatic markers of viral replication may therefore be important to avoid possible toxic consequences, such as the selective accumulation of viral proteins.

The in vitro ejection of zinc from human immunodeficiency virus (HIV) type 1 nucleocapsid protein by disulfide benzamides with cellular anti-HIV activity

Several disulfide benzamides have been shown to possess wide-spectrum antiretroviral activity in cell culture at low micromolar to submicromolar concentrations, inhibiting human immunodeficiency virus (HIV) type 1 (HIV-1) clinical and drug-resistant strains along with HIV-2 and simian immunodeficiency virus [Rice, W. G., Supko, J. G., Malspeis, L., Buckheit, R. W., Jr., Clanton, D., Bu, M., Graham, L., Schaeffer, C. A., Turpin, J. A., Domagala, J., Gogliotti, R., Bader, J. P., Halliday, S. M., Coren, L., Sowder, R. C., II, Arthur, L. O. & Henderson, L. E. (1995) Science 270, 1194-1197]. Rice and coworkers have proposed that the compounds act by "attacking" the two zinc fingers of HIV nucleocapsid protein. Shown here is evidence that low micromolar concentrations of the anti-HIV disulfide benzamides eject zinc from HIV nucleocapsid protein (NCp7) in vitro, as monitored by the zinc-specific fluorescent probe N-(6-methoxy-8-quinoyl)-p-toluenesulfonamide (TSQ). Structurally similar disulfide benzamides that do not inhibit HIV-1 in culture do not eject zinc, nor do analogs of the antiviral compounds with the disulfide replaced with a methylene sulfide. The kinetics of NCp7 zinc ejection by disulfide benzamides were found to be nonsaturable and biexponential, with the rate of ejection from the C-terminal zinc finger 7-fold faster than that from the N-terminal. The antiviral compounds were found to inhibit the zinc-dependent binding of NCp7 to HIV psi RNA, as studied by gel-shift assays, and the data correlated well with the zinc ejection data. Anti-HIV disulfide benzamides specifically eject NCp7 zinc and abolish the protein's ability to bind psi RNA in vitro, providing evidence for a possible antiretroviral mechanism of action of these compounds. Congeners of this class are under advanced preclinical evaluation as a potential chemotherapy for acquired immunodeficiency syndrome.

A novel basis of capsid stabilization by antiviral compounds

Picornaviruses are inactivated by a family of hydrophobic drugs that bind at an internal site in the viral capsid and inhibit viral uncoating. A basis for the capsid stabilization previously unrecognized is revealed by molecular dynamics simulations of the antiviral drug WIN52084s bound to a hydrophobic pocket of solvated human rhinovirus 14. Isothermal compressibilities of the complex and human rhinovirus 14 without the antiviral drug calculated from density fluctuations show that the presence of WIN52084s increases the compressibility of the viral capsid near the antiviral drug. This counterintuitive result is understandable on the basis of the empirical evidence of thermal melting temperatures and protein-folding entropies of globular proteins. Based on this evidence, we propose that a larger compressibility from drug binding confers greater thermal stability to capsid proteins by increasing the conformational entropy of capsids, thereby diminishing the entropy gain with uncoating. We suggest that compressibility is fundamental to the structural integrity of viral capsids and that examination of compressibility and antiviral activity will provide insights into the disassembly process.

Expression and purification of the mouse mammary tumor virus gag-pro transframe protein p30 and characterization of its dUTPase activity

The mouse mammary tumor virus gag-pro transframe protein (p30) contains the nucleocapsid protein domain derived from the 3' end of gag, fused to 154 residues encoded by the 5' region of the pro open reading frame. The DNA coding for p30 was cloned into the plasmid pALTER-1, and an additional nucleotide was inserted by site-directed mutagenesis to allow the read-through from the gag into the pro open reading frame. The obtained insert was then cloned into pGEX-2T, a plasmid containing the glutathione S-transferase gene of Schistosoma japonicum and a nucleotide sequence encoding for a thrombin cleavage site. The chimeric protein (GST-p30) was isolated by affinity chromatography on a glutathione-Sepharose 4B column, and after thrombin treatment, the excised p30 was further purified on a single-stranded DNA-agarose column. This protein showed dUTPase activity, with only negligible cleavage of dATP, dGTP, dCTP, dTTP, or UTP. Its apparent Km for dUTP was 28 microM. The enzyme was inhibited by EDTA, but its effect could be reversed by Mg2+ and other divalent cations. dUTPase activity was also detected in purified mouse mammary tumor virus, and p30 was the only protein recognized by antibodies directed towards the carboxyl-terminal sequence of the dUTPase coding region.

Protective effect of interferon beta on human T cell leukaemia virus type I infection of CD4+ T cells isolated from human cord blood

The present study shows the effect of human interferon beta (IFN beta) on the susceptibility of highly purified cord blood CD4+ T cells to infection with the human T cell leukaemia virus type I (HTLV-I). Unfractionated cord blood mononuclear cells (CBMC), or a separated CD4+ T cell subpopulation (CBCD4) were exposed to HTLV-I by cocultivation with a chronically infected virus-donor cell line. The results show that presence of proviral DNA as well as virus transcription was markedly reduced by IFN beta in both populations, indicating that this cytokine protects not only unfractionated CBMC but also purified CBCD4 cells from virus infection. Moreover IFN beta treatment caused 60%-80% inhibition of virus expression in CBCD4, assayed as the presence of virus core protein p19. This study demonstrates that IFN beta is able to inhibit HTLV-I infection of CBMC through a mechanism that does not necessarily involve cell-mediated natural or antigen-dependent immunity afforded by CBMC subpopulations distinct from targets of HTLV-I infection. Therefore it is reasonable to conclude that IFN beta has a direct protective effect on CBCD4, through induction of antiviral resistance/activity in target cells.

Identification of a sequence element in the alphavirus core protein which mediates interaction of cores with ribosomes and the disassembly of cores

Early in infection core protein is transferred from alphavirus cores to ribosomes (Wengler and Wengler, 1984, Virology 134, 435-442) and it has been suggested that ribosome binding is a property of alphavirus core protein which is involved in core disassembly. Here we describe in vitro analyses of this transfer. Sindbis virus cores, incubated with ribosomes either in a reticulocyte lysate or in buffer, are disassembled with a concomitant transfer of core protein to the large ribosomal subunit. Preincubation of ribosomes with core protein blocks disassembly. Limited proteolysis of Sindbis virus core releases the carboxy-terminal core protein domain as a soluble fragment (Strong and Harrison, 1990, J. Virol. 64, 3992-3994). Trypsin- or proteinase Lys-C-released fragments contain the amino-terminal residue met (106) or gln (94), respectively. The fragment generated by proteinase Lys-C binds to ribosomes and interferes with core disassembly whereas the slightly shorter tryptic fragment has none of these activities. These and further analyses indicate that a conserved sequence element which surrounds amino acid met (106) of SIN CP, the so-called RBSc element, leads to binding of core protein to ribosomes and thereby to core disassembly. Implications of the experiments for regulation of assembly of alphavirus cores and for the core protein-induced resistance to viral multiplication observed in plant virus systems are discussed.

Characterization of hepatitis B virus capsid particle assembly in Xenopus oocytes

Little is known about the assembly of the 28-nm nucleocapsid or core particle of hepatitis B virus. Here we show that this assembly process can be reconstituted in Xenopus oocytes injected with a synthetic mRNA encoding the hepatitis B virus capsid protein (p21.5). Injected oocytes produce both a nonparticulate p21.5 species (free p21.5) and capsid particles. We describe rapid and simple methods for fractionating these species on a small scale either with step gradients of 10 to 60% (wt/vol) sucrose or by centrifugation to pellet the particles, and we characterize the oocyte core particles. Free p21.5 exhibits chemical and physical properties distinctly different from those of particles. Free p21.5 is partially cleaved by proteinase K, whereas core particles are almost completely resistant to cleavage. This suggests that the carboxyl-terminal protamine region, the main target for proteases within p21.5, is exposed in free p21.5 but faces the interior of the p21.5 core particle. Finally, pulse-chase experiments demonstrated that free p21.5 can be chased almost quantitatively into core particles, establishing that free p21.5 is fully competent to form particles and represents an assembly intermediate on the pathway for core particle formation. However, core particle assembly appears very dependent on p21.5 concentration and is rapidly compromised if the p21.5 concentration is lowered. The advantages of oocytes for studying assembly are discussed.

Carbovir: the (-) enantiomer is a potent and selective antiviral agent against human immunodeficiency virus in vitro

In this paper we describe the in vitro antiviral activity of the (-) enantiomer of carbocyclic 2',3'-deoxydidehydroguanosine, (-) carbovir, a nucleoside analogue that has selective and potent anti-HIV activity in a series of lymphocyte culture systems. The cellular cytotoxicity of this compound has also been evaluated in a number of systems and compared to the saturated dideoxynucleoside analogues AZT and ddC.

Interferon-alpha with zidovudine: safety, tolerance, and clinical and virologic effects in patients with Kaposi sarcoma associated with the acquired immunodeficiency syndrome (AIDS)

OBJECTIVE

To evaluate safety, tolerance, and potential efficacy of interferon-alpha and zidovudine combination therapy in patients with Kaposi sarcoma and the acquired immunodeficiency syndrome (AIDS).

DESIGN

Open, phase-I study with randomization between two preparations of interferon-alpha.

SETTING

Outpatient clinic of a cancer research center.

PATIENTS

Forty-three patients with Kaposi sarcoma associated with AIDS.

INTERVENTIONS

Patients were treated with interferon-alpha, 4.5, 9, or 18 million U/d, and zidovudine, 100 or 200 mg orally every 4 hours.

MEASUREMENTS AND MAIN RESULTS

Neutropenia was the major dose-limiting toxicity. Fatigue, liver enzyme elevation, anemia, and thrombocytopenia were dose-limiting in some patients. Maximum tolerated dosages for interferon-alpha 2a with zidovudine, respectively, were 4.5 million U/d with 200 mg every 4 hours or 18 million U/d with 100 mg every 4 hours. An interferon-alpha n1 [corrected] dosage of 9 million U/d with zidovudine dosages of either 100 or 200 mg every 4 hours induced dose-limiting toxicity in most patients. Of 37 evaluable patients, 17 (46%; 95% CI, 30% to 62%) showed complete or partial tumor regression. Antitumor effects occurred more frequently in patients with baseline CD4 counts above 200 x 10(6) cells/L (65%) than in patients with lower baseline counts (30%, P = 0.05). Effects on CD4 cells were related to both initial CD4 count and interferon dose. Increased skin test reactivity and decreased serum human immunodeficiency virus (HIV) p24 antigen and virus recovery from blood cells were seen.

CONCLUSIONS

Combined therapy with interferon-alpha and zidovudine can be safely administered to patients with AIDS and Kaposi sarcoma. The observed effects on tumor growth, HIV replication, and immune function support further studies of the combination in patients at various stages of HIV infection.

Some physico-chemical properties of the rigid form of the Sendai virus nucleocapsid

The effect of some dissociation agents (SDS, beta-mercaptoethanol, urea, EDTA) on the rigid form of the Sendai virus nucleocapsid was studied. Polyacrylamide gel electrophoresis in the presence of lytic mixture (1% SDS, 2% beta-mercaptoethanol, 5 M urea, for 2 min at 100 degrees C) revealed two types of polypeptide subunits (mol. wts. 46,000 and 14,000), as well as the dissociation in the presence of 0.1% SDS only. The EDTA treatment leads to a disorganization of the protein part (10(-2) M) or of the nucleocapsid structure (5 x 10(-2) M).