Analysis of cell-differentiation lineage in human teratomas using new monoclonal antibodies to cytostructural antigens of embryonal carcinoma cells

Human embryonal carcinoma cells sometimes display the developmental potential of early embryonic stem cells. While available data do not clearly identify a counterpart of these tumor cells in normal development, previous comparisons of human embryonal carcinoma and yolk sac carcinomas indicated that these cell types are closely related, and suggested that embryonal carcinoma cells might resemble the progenitors of extraembryonic endoderm. To analyse further cell-differentiation lineage in these tumors, we produced monoclonal antibodies to cytostructurally associated antigens of human embryonal carcinoma cells. Spleen cells from mice immunized with a detergent-insoluble extract of cultured human embryonal carcinoma cells were fused to NS-1 myeloma cells, and hybridoma supernatants were screened by indirect immunofluorescence on the immunizing cell line, then on a panel of cell lines derived from human embryonal carcinomas, yolk sac carcinomas, and a range of neoplastic and normal tissues. Monoclonal antibody GCTM-1 stained the nuclei of all human cells tested and served as a positive control; this antibody immunoprecipitated proteins of 85 and 66 k Da from human embryonal carcinoma cells. GCTM-2 recognized an epitope on a 200-k Da extracellular protein present on the surface of embryonal carcinoma cells, and stained the surface of visceral yolk sac-type carcinoma and colorectal carcinoma cells as well. Enzymatic analysis of carbohydrate residues on the GCTM-2 antigen revealed that it was a keratan sulphate proteoglycan, and suggested that the epitope recognized by the antibody lies on the core protein. In immunoblots, antibody GCTM-3 bound to a 57-k Da cytoskeletal protein expressed in human embryonal carcinoma. This antibody decorated filamentous arrays in cell lines from human embryonal carcinoma, visceral yolk sac carcinoma, parietal yolk sac carcinoma (endodermal sinus tumour), and adenocarcinoma and large cell carcinoma of the lung. Antibody GCTM-4 recognized a determinant present on a 69-k Da polypeptide, associated with a component of the lysosomal compartment, which was expressed in embryonal carcinoma cells, but no other cell type tested. The results with this antibody panel thus allow distinction between human embryonal carcinoma and yolk sac carcinoma, but provide further evidence of a close relationship between these cell types.

The future of antiviral chemotherapy

This article has reviewed the principal antiviral agents and their application in the therapy and prevention of viral diseases. Only acyclovir, amantadine, ribavirin, zidovudine, and vidarabine have received FDA approval for therapy of systemic viral infections. Although ganciclovir, phosphonoformate, the acyclovir prodrugs, disoxaril, and the interferons are now being used only on an investigational basis, it is likely that at least some of these agents will soon be licensed. The search for more effective and safer antivirals continues, and with increasing academic and industrial interest, the prospects for this branch of chemotherapy appear promising.

Failure of antiviral therapy for acquired immunodeficiency syndrome-related cytomegalovirus myelitis

We report the first published case (to our knowledge) of histopathologically documented acquired immunodeficiency syndrome-related cytomegalovirus (CMV) myelitis in which antiviral drug therapy was administered. Despite sensitivity of the patient's CMV isolate to therapy with both ganciclovir and foscarnet, use of neither of these agents halted progression of central nervous system CMV disease. Higher doses of these drugs or combination therapy may be required to treat acquired immunodeficiency syndrome-related CMV myelitis effectively.

Acyclovir prevents reactivation of herpes simplex labialis in skiers

To determine the effectiveness of an antiviral to prevent herpes labialis during a brief, high-risk circumstance, 147 persons with a history of sun-induced recurrences were treated prophylactically with oral acyclovir or matching placebo and were observed during their ski holidays. Five (7%) of 75 acyclovir-treated subjects developed lesions compared with 19 (26%) of 72 persons in the placebo group.

Cytomegalovirus infection

The pathogenic importance of cytomegalovirus (CMV) infection in AIDS-associated pneumonitis is controversial. Uncertainty regarding the significance of CMV isolation from pulmonary secretions of AIDS patients results in part from the difficulty in distinguishing CMV infection from CMV disease and from the high frequency of pulmonary CMV co-infection with other opportunistic pathogens. From our review of the literature to date, we have found only three cases in which AIDS patients with hypoxemia and infiltrates on chest x-ray had lung biopsy or autopsy material reported to demonstrate CMV cytopathic effect in the absence of any other pathogen. However, pulmonary CMV co-infection may be a marker of poor outcome in Pneumocystis carinii pneumonia. In this article, appropriate criteria for instituting specific therapy with the antiviral drug ganciclovir are described.

Effects of long-term acyclovir chemosuppression on serum IgG antibody to herpes simplex virus

Patients with severe or frequent recurrent genital herpes simplex virus (HSV) infection can be managed either by treating each recurrence with acyclovir or by suppressing recurrences with daily administration of the drug. To determine the effects of long-term acyclovir therapy on the immune response to HSV, we studied the change in IgG antibody concentration to HSV in 46 individuals with recurrent genital HSV-2 infection who received acyclovir for 1 year, Twenty-seven subjects received daily acyclovir chemosuppression, while 19 subjects received daily placebo (with acyclovir administered intermittently only during recurrences). Immunoglobulin G (IgG) antibody to HSV was determined before medication began, at completion of 1 year of therapy, and 22 weeks following the first untreated HSV recurrence. Daily acyclovir chemosuppression for 1 year reduced mean IgG antibody concentration by 10% from baseline values (P less than 0.01), whereas in patients receiving intermittent therapy no significant decline was observed. In both groups, however, the first untreated recurrence produced a rise in mean antibody concentrations. We conclude that prolonged daily acyclovir chemosuppression reduces humoral immunity to HSV, but antibody concentrations increase following the first untreated recurrence.

Prolonged continuous versus intermittent oral acyclovir treatment in normal adults with frequently recurring genital herpes simplex virus infection

In Year 1 of this two-year trial, patients with six or more genital herpes recurrences in the past year received suppressive treatment with either acyclovir, 400 mg, or placebo, orally twice daily for one year, and physician-documented recurrences were treated with open-labeled acyclovir, 200 mg, orally five times per day for five days (acute treatment). In Year 2, patients received open-labeled acyclovir treatment either with daily suppressive therapy or intermittent acute therapy. Among 683 patients who completed two years of treatment, 348 received continuous suppressive treatment for two years, 276 received acute treatment in Year 1 and suppressive treatment in Year 2, 24 received suppressive treatment in Year 1 and acute treatment in Year 2, and 35 received acute treatment for two years. Patient groups receiving intermittent acute acyclovir treatment experienced means of 7.0 to 12.6 recurrences/year during treatment as compared with 1.4 to 1.9 recurrences/year among groups receiving continuous suppressive treatment. No patients who received acute treatment remained recurrence-free for two years as compared with 29 percent of patients receiving continuous acyclovir suppression for two years. There was no evidence of cumulative toxicity detected by clinical, hematologic, or blood chemistry evaluations performed monthly in Year 1 and quarterly in Year 2. Suppressive oral acyclovir therapy remained effective and well-tolerated in this two-year trial.

Active site mutagenesis of the AIDS virus protease and its alleviation by trans complementation

Replacement of the putative active site Asp residue of cloned HIV-1 protease with Ala yields a molecule incapable of autocatalytic processing. Similarly, protease/reverse transcriptase and protease/reverse transcriptase/endonuclease polyproteins containing the same mutation accumulate as enzymatically inert polyproteins. Introduction of a second, wild-type, copy of protease in trans alleviates this defect, leading in the case of individually cloned protease to cleavage of the mutant protein, and with the polyprotein mutants to release of the reverse transcriptase and endonuclease polypeptides, the former of which recover enzymatic activity. In related experiments, a similar inhibition and trans-complementation of a genetically engineered gag--protease fusion protein was observed.

Long-term acyclovir suppression of frequently recurring genital herpes simplex virus infection. A multicenter double-blind trial

Normal adults with six or more episodes of genital herpes in the previous year were enrolled in a one-year, multicenter, double-blind trial comparing placebo with 400 mg of acyclovir administered orally twice daily. Patients with episodes during the study were offered 200 mg of acyclovir administered orally five times daily for five days; this allowed comparison of suppressive and episodic treatment. After one year, 227 (44%) of 519 patients receiving suppressive treatment and seven (2%) of 431 receiving placebo (episodic) treatment remained free of recurrences, and the mean numbers of recurrences per year were 1.8 and 11.4, respectively. Among 67 patients who had received suppressive therapy for one year, the mean duration of lesions in the first episode following the discontinuation of treatment was 9.3 days compared with 7.3 days among 45 patients who had received episodic therapy for one year. Treatment was well tolerated, and no changes were noted in the in vitro susceptibility to acyclovir of herpes simplex virus cultured during or after the one-year trial. Continuous or episodic oral acyclovir therapy for one year remained safe and effective.

Randomized prospective trial of ganciclovir maintenance therapy for cytomegalovirus retinitis

We report the first randomized prospective comparative study of long-term maintenance ganciclovir (9-[2-hydroxy-1-(hydroxymethyl)ethoxymethyl]guanine, BW759U, DHPG) therapy for cytomegalovirus retinitis in patients with the acquired immunodeficiency syndrome (AIDS). Eleven retinitis patients who received a 10-day course of ganciclovir induction therapy and then were randomized to receive either immediate daily ganciclovir maintenance therapy or deferred maintenance (eight deferred maintenance, three immediate maintenance) were evaluated for drug efficacy. Median time to retinitis progression was 42 days for the immediate maintenance group compared with 16 days for the deferred maintenance group, (P = 0.07). After crossing over to maintenance therapy, patients in the deferred group had a median time to retinitis progression of 58 days compared to 16 days while not on maintenance therapy (P = 0.13). Only 9% of cultures obtained while patients received maintenance therapy were positive for cytomegalovirus, vs 40% of those obtained off maintenance (P less than 0.001). We can state then that maintenance therapy with ganciclovir delays, but does not halt, progression of cytomegalovirus retinitis and suppresses, but does not eradicate, cytomegalovirus shedding in patients with AIDS.

Dapsone treatment of Pneumocystis carinii pneumonia in the acquired immunodeficiency syndrome

All patients with the acquired immunodeficiency syndrome treated for their first episode of Pneumocystis carinii pneumonia at San Francisco General Hospital between 1 April 1985 and 15 July 1985 were evaluated for their response to treatment with dapsone (100 mg/day) by mouth for 21 days. Of 44 patients evaluated, 18 were eligible for the study. Of these 18 patients, the conditions of 7 of them worsened or failed to improve during treatment with dapsone and they were considered treatment failures. These patients were changed to standard therapy after 4 to 8 days of dapsone therapy. The remaining 11 patients (61%) improved within 3 to 10 days after dapsone therapy was started. Side effects of dapsone therapy were noted in 6 of 11 patients (of these 11 patients, 5 had a rash, 1 had a rash and abnormal liver enzymes, and 1 had abnormal liver enzymes), but in none of the patients were these side effects severe enough to require the cessation of medication. Based on comparison with historical controls, oral dapsone therapy alone appeared to be less effective than standard therapy or the combination of dapsone plus trimethoprim for P. carinii pneumonia in patients with acquired immunodeficiency syndrome.

Treatment of cytomegalovirus retinitis in patients with AIDS

Retinitis is the commonest clinical manifestation of cytomegalovirus (CMV) infection in patients with AIDS. Untreated patients generally experience progressive involvement of the retina, which may result in blindness. Attempts to treat this condition with vidarabine and interferon-alpha have been uniformly unsuccessful. Therapy with ganciclovir (9[(1,3-dihydroxy-2-propoxy)methyl]guanine) (7.5-15 mg/[kg./d] given intravenously in two or three divided doses) has been shown to halt progression of retinitis and may result in limited healing in some cases; viremia and shedding of virus from other sites (such as the urine) are halted or reduced. However, reactivation of infection and retinitis usually occurs when ganciclovir therapy is discontinued. For that reason, most patients have received continued therapy with the drug, most commonly at a dosage of 5-6 mg/(kg.d) administered as a single intravenous infusion 5-7 days per week. Both retrospective and prospective, randomized trials have shown that maintenance therapy delays (but does not prevent) reactivation of infection. Much more limited studies with foscarnet (trisodium phosphonoformate) suggest that this drug will also be useful for treatment of CMV retinitis in AIDS patients. Further research is needed, however, since existing agents have a low therapeutic ratio and cannot be given orally to patients requiring long-term maintenance therapy.

Retinal and gastrointestinal disease due to cytomegalovirus in patients with the acquired immune deficiency syndrome: prevalence, natural history, and response to ganciclovir therapy

Of 760 AIDS patients seen at San Francisco General Hospital in 1986, 5.7 per cent had retinitis and 2.2 per cent had gastrointestinal disease caused by cytomegalovirus. We reviewed the records of 44 patients treated with ganciclovir for culture-confirmed cytomegalovirus retinal (31 patients) or gastrointestinal disease (17 patients) or both (four patients) in 1986. Retinitis stabilized or improved during initial treatment with ganciclovir in 22 of 27 (81.5 per cent) patients. Following a median 10-day induction course, 16 patients with retinitis continued to have serial ophthalmologic assessments: eight patients were maintained on treatment and eight had maintenance treatment deferred. Before treatment, the two groups were comparable in age, Karnofsky scores, hematologic assessment, visual acuity, and history with respect to Pneumocystis carinii pneumonia. Retinitis did not progress for a median 53.8 days in the immediate maintenance group compared to 18.8 days for the deferred maintenance group (p = 0.01). In 17 patients with CMV gastrointestinal disease, nine of 14 (64 per cent) had resolution of pain and eight of 11 (73 per cent) had resolution of diarrhea when treated initially with ganciclovir. In both retinitis and gastrointestinal disease patients, ganciclovir decreased recovery of CMV from urine and blood markedly. Ganciclovir also caused a decrease in mean absolute neutrophil counts to about half of baseline values; decreases in mean platelet count and hemoglobin were also noted but were less than 25 per cent. Neutropenia severe enough to require dose adjustment (less than 800 cells/microliters) occurred in 31 per cent of patients receiving maintenance ganciclovir.

Effects of interleukin 2 and large envelope glycoprotein (gp 120) of human immunodeficiency virus (HIV) on lymphocyte proliferative responses to cytomegalovirus

Lymphocytes from many HIV-infected asymptomatic individuals or patients with AIDS-related conditions (ARC) and from all AIDS patients were unable to proliferate in vitro in response to UV-inactivated cytomegalovirus (CMV). The addition of recombinant IL2 (rIL2) restored proliferative responses of lymphocytes from most HIV-infected asymptomatic individuals and ARC patients to levels similar to those of HIV-seronegative (HIV-) CMV-seropositive (CMV+) individuals. In contrast, rIL2 augmented CMV-specific lymphocyte proliferation of only 33% (6/18) of AIDS patients. Proliferative responses to CMV with or without rIL2 did not correlate well with the levels of CD4+ lymphocytes, HIV antigen levels or ratios of CD4+ and CD8+ lymphocytes. Proliferative responses to CMV were inhibited by relatively high concentrations (greater than or equal to 10 micrograms/ml) of recombinant HIV envelope glycoprotein (rgp120) and this immunosuppression was completely overcome by rIL2. These results indicate that defects in antigen-driven lymphocyte responses of HIV-infected individuals are not simply the result of reduced numbers of CD4+ lymphocytes but are influenced by defects in IL2 pathways and by immunosuppressive effects of HIV gp120.

Serious cytomegalovirus disease in the acquired immunodeficiency syndrome (AIDS). Clinical findings, diagnosis, and treatment

Life-threatening opportunistic cytomegalovirus infection is a complication of the acquired immunodeficiency syndrome (AIDS) that occurs in 7.4% or more of patients with AIDS. Cytomegalovirus retinitis, colitis, esophagitis, and gastritis are the commonest manifestations of severe cytomegalovirus end-organ disease. Extensive trials with intravenous ganciclovir, a nucleoside analogue with myelosuppressive toxicity, have shown that ganciclovir halts the progression of cytomegalovirus retinitis and gastrointestinal disease. Since relapse is common when therapy is discontinued, most patients with AIDS need life-long maintenance therapy. The clinical response to ganciclovir therapy is usually accompanied by diminished shedding of the virus. Based on limited data, foscarnet, a pyrophosphate analogue, also appears to have some efficacy in treating cytomegalovirus infection. Unlike ganciclovir, foscarnet does not cause myelosuppression. An important direction for future clinical research is the development of more effective and less toxic therapy, as well as orally bioavailable drugs for maintenance therapy.

Immunoblot analysis of the humoral immune response in primary cytomegalovirus infection

Cytomegalovirus is a common infection in immunologically normal adults. It may cause an asymptomatic infection or may manifest symptomatically as heterophilic-negative mononucleosis. Studies of CMV infection in immunocompromised patients indicate that humoral immune response plays a role in modulating disease severity; however, the effect of antibodies to CMV in modifying disease expression and transmission in immunologically normal individuals has not been well characterized. Using immunoblot technology, we have demonstrated that immune serum from normal adults contains antibodies to at least 15 CMV-associated proteins and that there is strain-to-strain variation in the expression of these immunogens. The kinetics of the immune response were evaluated by using serial sera collected from normal adults after primary CMV infection; analysis of immunoblots of these sera identified one group of antibodies to CMV proteins that arise early and are stable over time, a second group that appear late after infection, and a third group that are variable among patients and over time.

Inherent sensitivity of cultured human embryonal carcinoma cells to adducts of cis-diamminedichloroplatinum(II) on DNA

Clinical and experimental data indicate that human embryonal carcinoma cells are unusually sensitive to the antitumor drug cis-diamminedichloroplatinum(II) (cisplatin), but the basis of this sensitivity is unknown. Using colony formation assays we measured survival of cultured human embryonal carcinoma cells following cisplatin treatment and related survival to the amount of platinum bound to DNA, determined by isolation of cellular DNA and flameless atomic absorption spectrometry, over a range of drug doses. Similar measurements were carried out on F9 mouse embryonal carcinoma cells and on a fibroblast cell strain from a patient with the genetic disease Fanconi's anemia, a syndrome associated with hypersensitivity to cytotoxic and clastogenic effects of difunctional DNA-binding agents. These results were compared with similar analyses on a variety of cultured cells from previous studies. The embryonal carcinoma cells and the Fanconi's anemia fibroblast strain were among the most sensitive cells on a dose-response basis. Since the amount of platinum bound to DNA after treatment of these cells was similar to values reported for many other cell types, it follows that mouse and human embryonal carcinoma cells are inherently sensitive to DNA-bound platinum adducts, to a degree approaching the sensitivity of fibroblasts from patients with xeroderma pigmentosum and Fanconi's anemia.

Enzymatic modification of glycocalyx in the treatment of experimental endocarditis due to viridans streptococci

The presence of abundant surface polysaccharide, or glycocalyx, on viridans streptococci has been associated with failure to eradicate the organism from experimental cardiac vegetations during penicillin treatment. The role of glycocalyx in retarding sterilization was tested by in vivo administration of dextranase, an endohydrolase that attacks internally situated alpha (1-6) linkages. Dextranase and penicillin, either singly or in combination, were used to treat experimental endocarditis. After two days of therapy, 100% of animals treated with penicillin or dextranase alone had infected vegetations, whereas only 25% treated with penicillin and dextranase had infected vegetations (P less than .01). After five days of therapy, 100% of the animals treated with penicillin had infected vegetations, versus none that were treated with penicillin and dextranase (P less than .01). We conclude that glycocalyx acts to retard antibiotic activity in vegetations and that partial enzymatic digestion of the glycocalyx facilitates penicillin sterilization of the infected valve.

Comparison of nosocomial infections due to Staphylococcus aureus and enterococci in a general hospital

Hospital acquired infections caused by enterococci are increasing in incidence. This increase has been attributed, in part, to widespread use of cephalosporin antibiotics which lack activity against enterococci. To test this hypothesis, we compared patients having nosocomial enterococcal pulmonary and wound infections with those patients having nosocomial staphylococcal infections for antecedant cephalosporin use. In a six month period, we found 14 instances of nosocomial enterococcal wound and respiratory infections; 13 were superinfections (occurring during or up to one week after administration of antimicrobials). Seven had coexisting pathogens noted. In the same six month period, 30 instances of Staphylococcus aureus nosocomial respiratory tract and wound infections were found and only 13 were superinfections (p less than 0.002 compared with enterococcal superinfections). Nine had coexisting pathogens noted. The mean age, gender distribution and underlying illnesses in the Staphylococcus aureus and enterococcal superinfection groups were comparable. Of the 14 instances of enterococcal nosocomial infections, 11 were associated with administration of a cephalosporin compared with seven of 30 for staphylococcal infections (p less than 0.002). Nosocomial enterococcal infections are commonly associated with antimicrobial therapy and the use of cephalosporins may selectively predispose patients to increased risk of enterococcal superinfections.

Cultured stem-cells from human testicular teratomas: the nature of human embryonal carcinoma, and its comparison with two types of yolk-sac carcinoma

The understanding of differentiation in human teratomas requires a better definition of the phenotype and developmental potential of the stem cells in these tumours. We describe the characterization of 6 new cell lines from human testicular teratomas which are representative of 3 distinct cell types. Cell lines GCT 27, GCT 35, and GCT 48, identified as embryonal carcinoma, comprise epithelial cells which express cytokeratin intermediate filaments and desmoplakins, as determined by indirect immunofluorescence microscopy. A minority of the cells also express vimentin. Most cells in these cultures show surface staining with monoclonal antibodies (MAbs) to stage-specific embryonic antigens SSEA 3 and SSEA 4 but not SSEA 1. Staining with MAb W6/32, which recognizes HLA A,B and C chains in the presence of beta-2 microglobulin, is not above background level. When injected into nude mice, GCT 27 cells form tumours consisting of embryonal carcinoma, somatic tissues, and cells positive in immunocytochemical assays for alphafoetoprotein (AFP) and human chorionic gonadotrophin (HCG); GCT 35 cells form embryonal carcinomas with foci of AFP and HCG-positive cells; and GCT 48 cells form embryonal carcinoma only. A second type of cell (GCT 72) displays some properties of rodent visceral endoderm. GCT 72 cells contain cytokeratin intermediate filaments, but not vimentin, and show very strong staining at cell borders with anti-desmoplakin I + II antibody. At the cell surface, GCT 72 cells express the epitopes recognized by antibodies to SSEA 3, SSEA 4, and SSEA 1; staining with W6/32 is negligible. Levels of AFP in supernatants from GCT 72 cultures are in excess of 500 KIU/I. The tumours formed following inoculation of nude mice with GCT 72 cells are solid yolk-sac tumours, with all cells strongly positive for AFP. A third cell type (GCT 44 and GCT 46), resembles in some ways rodent parietal endoderm. These cells uniformly coexpress keratin and vimentin intermediate filaments, but not desmoplakins. The determinants recognized by MAbs to SSEA 3, 4, or 1 are not detected on the majority of cells in these cultures. In striking contrast to the other teratoma lines, these cells can attach to untreated tissue culture plastic in serum-free medium and may be serially cultivated under these conditions. The tumours formed in nude mice by these 2 cell lines are yolk-sac carcinomas with endodermal sinus tumour histology. Thus, human testicular teratomas consist of epithelial cells which may be nullipotent, pluripotent or committed to extraembryonic endodermal differentiation.(ABSTRACT TRUNCATED AT 400 WORDS)

Human pharmacokinetics and tolerance of oral ganciclovir

Ganciclovir is a nucleoside analog which inhibits the replication of herpesviruses in vitro and which has been effective by intravenous administration for the treatment of severe cytomegalovirus infection in immunocompromised patients. Because most patients with acquired immunodeficiency syndrome and severe cytomegalovirus infection have required lifelong daily suppressive ganciclovir therapy to control disease progression, oral therapy appears to have practical advantages. We studied the pharmacokinetics of orally administered ganciclovir in four patients with acquired immunodeficiency syndrome and cytomegalovirus retinitis. Repeated oral ganciclovir doses (10 to 20 mg/kg every 6 h) were well tolerated. With a 20-mg/kg dose given every 6 h, mean steady-state peak and trough levels were 2.96 and 1.05 microM, respectively, and the area under the concentration-time curve from 0 to 24 h was 47 microM X h. Calculated absorption was 3.0%, based on urinary excretion. Because the levels achieved in serum with oral ganciclovir approximated those required to inhibit cytomegalovirus in vitro, a trial of oral maintenance therapy in immunocompromised patients with severe cytomegalovirus infections seems warranted.