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C Crumpacker

Publications and source records attributed to C Crumpacker.

33 records · Page 2Linked to original sources
PubMed1987

Functional expression of a cloned herpes simplex virus type 1 DNA polymerase gene.

A vector which expresses the herpes simplex virus type 1 (HSV-1) (strain 17) DNA polymerase gene was constructed by ligating two separately cloned HSV DNA restriction fragments into an intermediate plasmid and then mobilizing the intact polymerase gene-encoding sequence into a pSV2 derivative. The expression vector (pD7) contains a functional simian virus 40 replication origin and early enhancer-promoter upstream from the HSV DNA polymerase-encoding sequence. COS-1 cells transfected with pD7 contained an RNA species, shown by Northern blot analysis to hybridize specifically with an HSV DNA pol probe and to be the same size (4.3 kilobases) as the pol mRNA found in HSV-1-infected COS-1 cells. A genetic complementation test was used to establish that pD7 expresses a functional pol gene product. COS-1 cells transfected with pD7 were able to partially complement the growth defect of an HSV-1 (KOS) temperature-sensitive mutant, tsC7, in the DNA polymerase gene at the nonpermissive temperature.

Animals↗
PubMed1987

Ribavirin treatment of the acquired immunodeficiency syndrome (AIDS) and the acquired-immunodeficiency-syndrome-related complex (ARC). A phase 1 study shows transient clinical improvement associated with suppression of the human immunodeficiency virus and enhanced lymphocyte proliferation.

STUDY OBJECTIVE: To assess safety, tolerance, and the clinical and laboratory effects of oral ribavirin in patients with the acquired immunodeficiency syndrome (AIDS) and the AIDS-related complex. DESIGN: Three uncontrolled phase I trials of increasing duration: 14 days, 8 weeks, and 12 months. SETTING: Outpatient clinic of a university-referral hospital. PATIENTS: All patients were antibody-positive for the human immunodeficiency virus (HIV) by radioimmunoprecipitation assay, all had recovered from Pneumocystis carinii pneumonia, and none had Kaposi sarcoma at entry. Nine of ten patients with AIDS had less than 100 CD4+ lymphocytes/mm3 at entry and all patients with the AIDS-related complex had fewer than 200 CD4+ lymphocytes/mm3. Five patients with AIDS and five with the AIDS-related complex entered the 14-day trial. All but two patients with AIDS went on to the 8-week trial, along with seven additional patients with AIDS. Five surviving patients with AIDS and 3 patients with the AIDS-related complex went on to the 1-year study. INTERVENTIONS: Oral ribavirin, 1200 mg twice daily for 3 days was given, followed by 300 mg twice daily for 11 days. During an 8-week trial, a loading dose of oral ribavirin was administered for 3 days, followed by a dose of 300 mg twice daily for 8 weeks. Prolonged regimen of a 3-day loading dose was given, followed by a dose of 300 mg twice daily for 1 year. MEASUREMENTS AND MAIN RESULTS: Ribavirin treatment was well tolerated, with anemia requiring transfusion in one of the ten patients with AIDS receiving the drug for 8 weeks; no other significant toxicity occurred. Six of nine patients initially positive for HIV-1 in blood became negative during ribavirin treatment. Six of nine patients with AIDS had a twofold improvement in lymphoproliferative response to at least one lectin with ribavirin treatment. Mean survival from first episode of P. carinii pneumonia was 17.3 months in patients with AIDS receiving 8 weeks of ribavirin and 21.2 months in patients with AIDS receiving prolonged treatment. CONCLUSIONS: Oral ribavirin, 600 mg daily, was well tolerated and safe in the patients with severe AIDS and the AIDS-related complex. Ribavirin therapy merits extensive evaluation in a multicenter controlled trial to assess its efficacy.

AIDS-Related Complex↗
PubMed1985

2'-Nor-cGMP: a seco-cyclic nucleotide with powerful anti-DNA-viral activity.

As part of our study of antiherpetic acyclonucleosides, we synthesized a cyclic GMP analog, 9-[(2-hydroxy-1,3,2-dioxaphosphorinan-5-yl)oxymethyl]guanine P-oxide, sodium salt (2'-nor-cGMP), and discovered its potent and broad spectrum anti-DNA-viral activities. 2'-Nor-cGMP inhibits the replication of many DNA viruses, including herpes simplex virus, human cytomegalovirus, vaccinia, SV40, and adenovirus, but does not inhibit RNA viruses. In plaque reduction studies this potent antiviral agent is also approximately 10-fold more potent than 9-(1,3-dihydroxy-2-propoxymethyl)guanine (2'NDG) against varicella-zoster virus and inhibits cell transformation by bovine papilloma virus. Unlike 2'NDG, the potent activity of 2'-nor-cGMP against herpes virus is not dependent upon the action of virus-specified thymidine kinase. Intercellular metabolism of 2'-nor-cGMP produced small amounts of 2'NDG triphosphate which were insufficient to account for the antiviral activity observed, implying that this potent anti-DNA-viral agent operates by a mechanism different from that of known acyclonucleosides.

Acyclovir↗
PubMed1985

Inhibition of HSV-transformed murine cells by nucleoside analogs, 2'-NDG and 2'-nor-cGMP: mechanisms of inhibition and reversal by exogenous nucleosides.

A murine cell line transformed with HSV TK (LH-1) exhibits a greatly enhanced cytotoxicity to the nucleoside analog 9-[(2-hydroxy-1-(hydroxymethyl)ethoxy) methyl]guanine (2'-NDG) as compared to the parental LM cell line (I50 LH-1 = 0.4 microM; I50 LM = 44.4 microM). Toxicity of 2'-NDG for LH-1 and LM is reversed only by the addition of 100 microM thymidine (dThd), indicating that 2'-NDG is a substrate for the viral and cellular TK. In LM(TK-) cells--murine cells expressing no TK activity, 2'-NDG cytotoxicity is partially reversed only with dGuo. A cyclic phosphate derivative of 2'-NDG, 2'-nor-cGMP, contains a phosphodiester bond, is also taken up by cells, and does not depend on viral TK for activation. LH-1 cells and LM(TK-) cells are inhibited by similar concentrations of this analog (5.1 and 4.1 microM, respectively). In all three cell lines (LM, LH-1, LM(TK-], the toxicity of 2'-nor-cGMP is significantly reversed with dGuo or cyclic dGMP. This pattern of reversal differs significantly from that observed with 2'-NDG, suggesting that 2'-nor-cGMP is metabolized as a guanosine analog, similar to acyclovir, in LM and LM(TK-) cells. These results indicate that a cyclic monophosphate analog of 2'-NDG can be activated independently of viral TK expression and that cellular metabolic pathways resulting in elevated dGTP concentrations are important for reversal of toxicity induced by guanosine-like nucleoside analogs.

Acyclovir↗
PubMed1984

Nosocomial endocarditis.

We analyzed 14 cases of nosocomial infective endocarditis which occurred over a seven-year period at the Beth Israel Hospital in Boston, and compared them with 90 cases of community-acquired endocarditis. Patients with nosocomial endocarditis were older, more often female, and had a greater incidence of underlying valvular heart disease and bacteremia precipitating invasive procedures (93% v 50%, p less than .05). Forty-three percent of patients had infection at the site of prosthetic valves or intracardiac prosthetic material. The disease carried a significantly higher mortality than community-acquired endocarditis (43% v 11%, p less than .01). The clinical presentation was acute and the infecting organisms reflected the site of origin of bacteremia, with staphylococci from skin and enterococci from urinary sources. Half of the cases in this series may have been prevented by the application of currently recommended preventive and therapeutic practices. Nosocomial endocarditis occurs in a definable sub-population of hospitalized patients and is potentially preventable.

Catheters, Indwelling↗
PubMed1984

A multivariate analysis of risk factors for hepatitis B virus infection among hospital employees screened for vaccination.

Previous studies of risk factors for hepatitis B virus infection among hospital employees have been based on surveys in single institutions or have been analyzed with univariate techniques. From November 1980 through August 1981, the authors performed a multi-institutional seroepidemiologic survey of hospital employees screened for entrance into a hepatitis B vaccine trial who represented groups at high risk for hepatitis B infection. Using a logistic regression model for the analysis of risk factors, the investigators determined the relative odds and 95% confidence intervals for risk of hepatitis B infection to be as follows: race (nonwhite/white: 3.4; 2.4-4.8) (p less than 0.001); history of acute viral hepatitis of an unspecified type (3.6; 2.2-5.9) (p less than 0.001); and employment at hospitals 1 through 5 as compared with hospital 6 (1.8; 1.1-2.9) (p = 0.015). In addition, certain job categories and the duration of employment within some of these categories were associated with increasing risk for hepatitis B infection over time. Laboratory workers (1.4; 1.2-1.7), surgical staff (1.2; 1.1-1.4), and medical staff (1.3; 1.1-1.5) had significant (p less than 0.05) increased risk of prior infection with longer duration of employment. Such time-job interaction was not demonstrable for nursing staff, anesthesiology staff, dental personnel, pathology staff, or ancillary personnel. The logistic regression model also shows that the highest gradient of risk for laboratory workers, surgeons, and medical staff occurs during the first five years of employment. An effective preventive strategy, such as the use of hepatitis B vaccine, should be targeted for these groups at the time of initial employment.

Adult↗
PubMed1984

Incorporation of 1-beta-D-arabinofuranosylcytosine into DNA from herpes simplex virus resistant to 9-beta-D-arabinofuranosyladenine.

We have demonstrated previously that 1-beta-D-arabinofuranosylcytosine (ara-C) incorporates specifically in cellular DNA and that the formation of (ara-C)DNA correlates significantly with inhibition of DNA synthesis and loss of clonogenic survival. Similar results have been obtained with 9-beta-D-arabinofuranosyl-adenine (ara-A). These findings have been extended by studying the incorporation of ara-C in DNA of a wild-type herpes simplex virus (HSV) and a mutant virus resistant to ara-C and ara-A. The results demonstrate that HSV resistance to ara-A is associated with formation of less (ara-C)DNA and less inhibition of DNA synthesis when compared to wild-type virus. This effect on formation of (ara-C)DNA is reversed upon exposure to higher (greater than 10(-6) M) ara-C concentrations, and this pattern of resistance corresponds to drug effect on virus plaque formation. The results also demonstrate a highly significant relationship between incorporation of ara-C in HSV DNA and inhibition of DNA synthesis for both viruses. Further, higher concentrations of ara-C that result in greater inhibition of DNA synthesis are associated with an increasing number of ara-C residues at the 3'-terminus of the DNA strand, thus suggesting that ara-C functions as a poor primer terminus for viral chain elongation. These results also suggest that HSV cross-resistance to ara-A and ara-C may be related to an altered viral DNA polymerase and that incorporation of ara-C in HSV DNA is at least one mechanism responsible for slowing viral synthesis and inducing lethal events.

Animals↗
PubMed1983

Effects of (E)-5-(2-bromovinyl)-2'-deoxyuridine on the proliferation of herpes simplex virus type 1-transformed and thymidine kinase-deficient mouse cells.

(E)-5-(2-Bromovinyl)-2'-deoxyuridine (BVDU) is a highly selective inhibitor of herpes simplex virus-1 (HSV-1). A cell line (LH-1) expressing the HSV thymidine kinase (TK) gene is extremely sensitive to BVDU, whereas the parent line that expresses the cellular TK is resistant to BVDU. A TK-deficient derivative cell line (LMTK(-] which expresses neither the cellular nor viral TK was also extremely sensitive to BVDU. This suggests that the thymidine analog, BVDU, can be phosphorylated in thymidine kinase-deficient cells by pathways other than the cellular or HSV-encoded thymidine kinase.

Animals↗
PubMed1983

Treatment of murine cytomegalovirus pneumonia with acyclovir and interferon.

A murine model of lethal cytomegalovirus pneumonia following intratracheal inoculation of normal mice was used to study the effects of antiviral therapy with acyclovir (ACV) and interferon (IF), alone and in combination. Five hundred units of fibroblast IF administered intraperitoneally the day prior to infection and 100 mg/kg/day ACV administered intraperitoneally for 7 days beginning within 3 h of infection were both highly effective in preventing mortality. Compared to the condition of untreated animals, each drug reduced viral titers in lung homogenates of the treated animals 7 days after infection. However ACV, unlike IF, diminished viral growth in the lung at 14 days, prevented viral dissemination to spleens and salivary glands in some animals, and significantly protected animals from reactivation of virus during immunosuppression 2 months after infection. The combination of ACV + IF offered no increased antiviral activity compared to ACV alone and failed to protect animals from reactivation. In these experiments the overall antiviral activity of ACV alone was greater than IF and the combination of ACV + IF.

Acyclovir↗
PubMed1982

Murine cytomegalovirus pneumonia. Description of a model and investigation of pathogenesis.

Pneumonitis was produced in CD-1 mice by intratracheal instillation of murine cytomegalovirus. Lethal pneumonia occurred after instillation of virus derived from partially purified salivary gland homogenates, whereas virus attenuated by serial passage in cell culture caused mild disease and no mortality, even though both virulent and attenuated strains achieved comparable peak titers in lung homogenates. Virulence was characterized by rapid association of virus with pulmonary macrophages and early spread of virus from macrophages to susceptible parenchymal cells. This resulted in enhanced viral growth and cellular destruction during the first 5 days of infection. Delay in the early growth of murine cytomegalovirus in pulmonary parenchyma may diminish the destructive effects of virus on the lung and prevent mortality.

Animals↗
PubMed1981

Physical mapping of drug resistance mutations defines an active center of the herpes simplex virus DNA polymerase enzyme.

The genome structures of herpes simplex virus type 1 (HSV-1)/HSV-2 intertypic recombinants have been previously determined by restriction endonuclease analysis, and these recombinants and their parental strains have been employed to demonstrate that mutations within the HSV DNA polymerase locus induce an altered HSV DNA polymerase activity, exhibiting resistance to three inhibitors of DNA polymerase. The viral DNA polymerases induced by two recombinants and their parental strains were purified and shown to possess similar molecular weights (142,000 to 144,000) and similar sensitivity to compounds which distinguish viral and cellular DNA polymerases. The HSV DNA polymerases induced by the resistant recombinant and the resistant parental strain were resistant to inhibition by phosphonoacetic acid, acycloguanosine triphosphate, and the 2',3'-dideoxynucleoside triphosphates. The resistant recombinant (R6-34) induced as much acycloguanosine triphosphate as did the sensitive recombinant (R6-26), but viral DNA synthesis in infected cells and the viral DNA polymerase activity were not inhibited. The 2',3'-dideoxynucleoside-triphosphates were effective competitive inhibitors for the HSV DNA polymerase, and the Ki values for the four 2',3'-dideoxynucleoside triphosphates were determined for the four viral DNA polymerases. The polymerases of the resistant recombinant and the resistant parent possessed a much higher Ki for the 2',3'-dideoxynucleoside triphosphates and for phosphonoacetic acid than did the sensitive strains. A 1.3-kilobase-pair region of HSV-1 DNA within the HSV DNA polymerase locus contained mutations which conferred resistance to three DNA polymerase inhibitors. This region of DNA sequences encoded for an amino acid sequence of 42,000 molecular weight and defined an active center of the HSV DNA polymerase enzyme.

Acyclovir↗
PubMedDate not supplied

Treatment of cytomegalovirus pneumonia.

In a multicenter uncontrolled trial of ganciclovir therapy for well-documented cytomegalovirus (CMV) pneumonia in 21 patients following bone marrow transplantation, eight (38%) of 21 survived for more than 90 days. Two additional patients responded to ganciclovir therapy; one survived for 60 days before relapsing with fatal CMV pneumonia, and the other survived 79 days before dying with disseminated aspergillosis. No CMV disease was found in this latter patient at autopsy. The improved survival of patients in this trial may be due to a small number of patients (23%) who developed significant neutropenia during ganciclovir therapy, to the concurrent use of CMV immune globulin in three of the survivors, or to other variables affecting a positive outcome. Data on the use of CMV DNA-DNA hybridization assays to detect CMV DNA directly in patients' blood suggest that this method may be useful in following the clearance of CMV viremia in patients receiving ganciclovir. The results of treatment of CMV pneumonia in bone marrow transplant recipients are compared with those of previous studies, of CMV pneumonia in renal transplant recipients, and of CMV pneumonia in patients with AIDS. Suggestions for further, more definitive, studies of CMV pneumonia are presented.

Acyclovir↗
PubMedDate not supplied

Increased sensitivity of thymidine kinase-deficient (TK-) tumor cell lines to the cell growth inhibitory effects of (E)-5-(2-bromovinyl)-2'-deoxyuridine (BVDU) and related compounds.

Various established antiherpetic drugs, including 1-beta-D-arabinofuranosylthymine (araT), acyclovir (ACV), 9-(1,3-dihydroxy-2-propoxymethyl) guanine (DHPG), 5-(2-chloroethyl)-2'-deoxyuridine (CEDU), (E)-5-(2-bromovinyl)-2'-deoxyuridine (BVDU), and structurally related analogues thereof, i.e. (E)-5-(2-iodovinyl)-2'-deoxyuridine (IVDU), (E)-5-(2-bromovinyl)-2'-deoxycytidine (BVDC), (E)-5-(2-bromovinyl)-1-beta-D-arabinofuranosyluracil (BVaraU), and the carbocyclic analogues of BVDU (C-BVDU), IVDU (C-IVDU) and BVDC (C-BVDC), were evaluated for their inhibitory effects on the growth of murine mammary carcinoma (FM3A/0), murine leukemia (L1210/0) and murine fibroblast (LM/0) cells and the thymidine kinase-deficient (TK-) sublines derived from the FM3A/0, L1210/0 and LM/0 cells. BVDU, IVDU and BVDC showed a markedly increased cytostatic activity against the TK- cell lines. To determine the biochemical mechanism of the increased cytostatic action of these compounds toward TK- cell lines, BVDU and IVDU were further evaluated for their inhibitory effects on pyrimidine nucleotide metabolism, in particular thymidylate synthetase activity, their incorporation into DNA and into trichloroacetic acid (TCA)-insoluble material, and their effects on DNA, RNA and protein synthesis in both TK+ and TK- cells. No marked differences were noted in the interaction of BVDU and IVDU with these potential targets between TK+ and TK- cell lines. Furthermore, neither FM3A/0 nor FM3A/TK- cells expressed a significant phosphorylating activity for (125I) IVDU. However, BVDU and IVDU specifically inhibited the incorporation of (1-14C) mannose and (1-14C) glucose into glycoproteins of FM3A/TK- and L1210/TK- cells. To what extent the inhibition of the incorporation of these monosaccharides into glycoproteins may contribute to the increased cytostatic effects of BVDU and IVDU on TK- cells remains to be determined.

Animals↗