In Silico Design and Experimental Validation of Novel Oxazole Derivatives Against Varicella zoster virus

Varicella zoster virus (VZV) infection causes severe disease such as chickenpox, shingles, and postherpetic neuralgia, often leading to disability. Reactivation of latent VZV is associated with a decrease in specific cellular immunity in the elderly and in patients with immunodeficiency. However, due to the limited efficacy of existing therapy and the emergence of antiviral resistance, it has become necessary to develop new and effective antiviral drugs for the treatment of diseases caused by VZV, particularly in the setting of opportunistic infections. The goal of this work is to identify potent oxazole derivatives as anti-VZV agents by machine learning, followed by their synthesis and experimental validation. Predictive QSAR models were developed using the Online Chemical Modeling Environment (OCHEM). Data on compounds exhibiting antiviral activity were collected from the ChEMBL and uploaded in the OCHEM database. The predictive ability of the models was tested by cross-validation, giving coefficient of determination q2 = 0.87-0.9. The validation of the models using an external test set proves that the models can be used to predict the antiviral activity of newly designed and known compounds with reasonable accuracy within the applicability domain (q2 = 0.83-0.84). The models were applied to screen a virtual chemical library with expected activity of compounds against VZV. The 7 most promising oxazole derivatives were identified, synthesized, and tested. Two of them showed activity against the VZV Ellen strain upon primary in vitro antiviral screening. The synthesized compounds may represent an interesting starting point for further development of the oxazole derivatives against VZV. The developed models are available online at OCHEM http://ochem.eu/article/145978 and can be used to virtually screen for potential compounds with anti-VZV activity.

NPP-669, a Novel Broad-Spectrum Antiviral Therapeutic with Excellent Cellular Uptake, Antiviral Potency, Oral Bioavailability, Preclinical Efficacy, and a Promising Safety Margin

DNA viruses are responsible for many diseases in humans. Current treatments are often limited by toxicity, as in the case of cidofovir (CDV, Vistide), a compound used against cytomegalovirus (CMV) and adenovirus (AdV) infections. CDV is a polar molecule with poor bioavailability, and its overall clinical utility is limited by the high occurrence of acute nephrotoxicity. To circumvent these disadvantages, we designed nine CDV prodrug analogues. The prodrugs modulate the polarity of CDV with a long sulfonyl alkyl chain attached to one of the phosphono oxygens. We added capping groups to the end of the alkyl chain to minimize β-oxidation and focus the metabolism on the phosphoester hydrolysis, thereby tuning the rate of this reaction by altering the alkyl chain length. With these modifications, the prodrugs have excellent aqueous solubility, optimized metabolic stability, increased cellular permeability, and rapid intracellular conversion to the pharmacologically active diphosphate form (CDV-PP). The prodrugs exhibited significantly enhanced antiviral potency against a wide range of DNA viruses in infected human foreskin fibroblasts. Single-dose intravenous and oral pharmacokinetic experiments showed that the compounds maintained plasma and target tissue levels of CDV well above the EC₅₀ for 24 h. These experiments identified a novel lead candidate, NPP-669. NPP-669 demonstrated efficacy against CMV infections in mice and AdV infections in hamsters following oral (p.o.) dosing at a dose of 1 mg/kg BID and 0.1 mg/kg QD, respectively. We further showed that NPP-669 at 30 mg/kg QD did not exhibit histological signs of toxicity in mice or hamsters. These data suggest that NPP-669 is a promising lead candidate for a broad-spectrum antiviral compound.

A standardized approach to the evaluation of antivirals against DNA viruses: Orthopox-, adeno-, and herpesviruses

The search for new compounds with a broad spectrum of antiviral activity is important and requires the evaluation of many compounds against several distinct viruses. Researchers attempting to develop new antiviral therapies for DNA virus infections currently use a variety of cell lines, assay conditions and measurement methods to determine in vitro drug efficacy, making it difficult to compare results from within the same laboratory as well as between laboratories. In this paper we describe a common assay platform designed to facilitate the parallel evaluation of antiviral activity against herpes simplex virus type 1, herpes simplex virus type 2, varicella-zoster virus, cytomegalovirus, vaccinia virus, cowpox virus, and adenovirus. The automated assays utilize monolayers of primary human foreskin fibroblast cells in 384-well plates as a common cell substrate and cytopathic effects and cytotoxicity are quantified with CellTiter-Glo. Data presented demonstrate that each of the assays is highly robust and yields data that are comparable to those from other traditional assays, such as plaque reduction assays. The assays proved to be both accurate and robust and afford an in depth assessment of antiviral activity against the diverse class of viruses with very small quantities of test compounds. In an accompanying paper, we present a standardized approach to evaluating antivirals against lymphotropic herpesviruses and polyomaviruses and together these studies revealed new activities for reference compounds. This approach has the potential to accelerate the development of broad spectrum therapies for the DNA viruses.

Synthesis and Antiviral Evaluation of Octadecyloxyethyl Benzyl 9-[(2-Phosphonomethoxy)ethyl]guanine (ODE-Bn-PMEG), a Potent Inhibitor of Transient HPV DNA Amplification

Human papillomavirus (HPV) high-risk genotypes such as HPV-16 and HPV-18 cause the majority of anogenital tract carcinomas, including cervical cancer, the second most common malignancy in women worldwide. Currently there are no approved antiviral agents that reduce or eliminate HPV and reverse virus-associated pathology. We synthesized and evaluated several alkoxyalkyl acyclic nucleoside phosphonate diesters and identified octadecyloxyethyl benzyl 9-[(2-phosphonomethoxy)ethyl]guanine (ODE-Bn-PMEG) as an active compound which strongly inhibited transient amplification of HPV-11, -16, and -18 origin-containing plasmid DNA in transfected cells at concentrations well below its cytotoxic concentrations. ODE-Bn-PMEG demonstrated increased uptake in human foreskin fibroblast cells and was readily converted in vitro to the active antiviral metabolite, PMEG diphosphate. The P-chiral enantiomers of ODE-Bn-PMEG were obtained and appeared to have equivalent antiviral activities against HPV. ODE-Bn-PMEG is a promising candidate for the local treatment of HPV-16 and HPV-18 and other high-risk types, an important unmet medical need.

Synthesis and antiviral activity of certain second generation methylenecyclopropane nucleosides

A second-generation series of substituted methylenecyclopropane nucleosides (MCPNs) has been synthesized and evaluated for antiviral activity against a panel of human herpesviruses, and for cytotoxicity. Although alkylated 2,6-diaminopurine analogs showed little antiviral activity, the compounds containing ether and thioether substituents at the 6-position of the purine did demonstrate potent and selective antiviral activity against several different human herpesviruses. In the 6-alkoxy series, antiviral activity depended on the length of the ether carbon chain, with the optimum chain length being about four carbon units long. For the corresponding thioethers, compounds containing secondary thioethers were more potent than those with primary thioethers.

Selective phosphorylation of antiviral drugs by vaccinia virus thymidine kinase

The antiviral activity of a new series of thymidine analogs was determined against vaccinia virus (VV), cowpox virus (CV), herpes simplex virus, and varicella-zoster virus. Several compounds were identified that had good activity against each of the viruses, including a set of novel 5-substituted deoxyuridine analogs. To investigate the possibility that these drugs might be phosphorylated preferentially by the viral thymidine kinase (TK) homologs, the antiviral activities of these compounds were also assessed using TK-deficient strains of some of these viruses. Some of these compounds were shown to be much less effective in the absence of a functional TK gene in CV, which was unexpected given the high degree of amino acid identity between this enzyme and its cellular homolog. This unanticipated result suggested that the CV TK was important in the mechanism of action of these compounds and also that it might phosphorylate a wider variety of substrates than other type II enzymes. To confirm these data, we expressed the VV TK and human TK1 in bacteria and isolated the purified enzymes. Enzymatic assays demonstrated that the viral TK could efficiently phosphorylate many of these compounds, whereas most of the compounds were very poor substrates for the cellular kinase, TK1. Thus, the specific phosphorylation of these compounds by the viral kinase may be sufficient to explain the TK dependence. This unexpected result suggests that selective phosphorylation by the viral kinase may be a promising new approach in the discovery of highly selective inhibitors of orthopoxvirus replication.

Distinct thymidine kinases encoded by cowpox virus and herpes simplex virus contribute significantly to the differential antiviral activity of nucleoside analogs

Orthopoxviruses and herpesviruses are both large enveloped DNA viruses, yet these virus families exhibit very different susceptibilities to antiviral drugs. We investigated the activation of nucleoside analogs by the types I and II thymidine kinase (TK) homologs expressed by herpes simplex virus type 1 (HSV-1) and cowpox virus (CV). Antiviral activity against TK(-) and TK(+) strains of HSV-1 and CV was determined, and the ratio of the EC(50) values was used as a measurement of TK dependence. As to HSV-1, most of the selected compounds were markedly less effective against the TK(-) strains, suggesting that this enzyme was required for the activation of these nucleoside analogs. This differs from the results for CV where only idoxuridine and bromodeoxyuridine appeared to be activated, putatively by the type II TK expressed by this virus. These data confirm that the type II TK encoded by CV exhibits a more limited substrate specificity than the type I TK encoded by HSV-1. These data suggest that the inefficient activation of nucleoside analogs by the orthopoxvirus TK significantly limits their activity. Additional screening against orthopoxviruses will be required to identify nucleoside analogs that are efficiently activated by their type II TK.

Comparative activities of lipid esters of cidofovir and cyclic cidofovir against replication of herpesviruses in vitro

Cidofovir (CDV) is an effective therapy for certain human cytomegalovirus (HCMV) infections in immunocompromised patients that are resistant to other antiviral drugs, but the compound is not active orally. To improve oral bioavailability, a series of lipid analogs of CDV and cyclic CDV (cCDV), including hexadecyloxypropyl-CDV and -cCDV and octadecyloxyethyl-CDV and -cCDV, were synthesized and found to have multiple-log-unit enhanced activity against HCMV in vitro. On the basis of the activity observed with these analogs, additional lipid esters were synthesized and evaluated for their activity against herpes simplex virus (HSV) types 1 and 2, human cytomegalovirus, murine cytomegalovirus, varicella-zoster virus (VZV), Epstein-Barr virus (EBV), human herpesvirus 6 (HHV-6), and HHV-8. Using several different in vitro assays, concentrations of drug as low as 0.001 microM reduced herpesvirus replication by 50% (EC50) with the CDV analogs, whereas the cCDV compounds were generally less active. In most of the assays performed, the EC50 values of the lipid esters were at least 100-fold lower than the EC50 values for unmodified CDV or cCDV. The lipid analogs were also active against isolates that were resistant to CDV, ganciclovir, or foscarnet. These results indicate that the lipid ester analogs are considerably more active than CDV itself against HSV, VZV, CMV, EBV, HHV-6, and HHV-8 in vitro, suggesting that they may have potential for the treatment of infections caused by a variety of herpesviruses.

In vitro activity and mechanism of action of methylenecyclopropane analogs of nucleosides against herpesvirus replication

We have reported previously that methylenecyclopropane analogs of nucleosides have excellent activity against certain members of the herpesvirus family. A second generation, the 2,2-bis-hydroxymethyl derivatives, were synthesized, and 18 compounds were tested for activity in vitro against herpes simplex virus types 1 and 2 (HSV-1 and HSV-2), human and murine cytomegalovirus (HCMV and MCMV), varicella-zoster virus (VZV), and Epstein-Barr virus (EBV). Selected analogs were also evaluated against human herpesvirus type 6 (HHV-6) and HHV-8. None of the 18 compounds had activity against HSV-1 or HSV-2, but four were active against VZV by plaque reduction (PR) assay at 50% effective concentration (EC(50)) levels of < or =50 microM. Six of the 18 compounds were active against HCMV by cytopathic effect or PR assays with EC(50)s of 0.5 to 44 microM, and all were active against MCMV by PR (0.3 to 54 microM). Four of the compounds were active against EBV by enzyme-linked immunosorbent assay (<0.3 to 4.4 microM). Four compounds with CMV activity were also active against HHV-6A and HHV-6B (0.7 to 28 microM), and three compounds were active against HHV-8 (5.5 to 16 microM). One of these, ZSM-I-62, had particularly good activity against CMV, HHV-6, and HHV-8, with EC(50)s of 0.7 to 8 microM. Toxicity was evaluated in adherent and nonadherent cells, and minimal cytotoxicity was observed. Mechanism of action studies with HCMV suggested that these compounds are phosphorylated by the ppUL97 phosphotransferase and are potent inhibitors of viral DNA synthesis. These results indicate that at least one of these compounds may have potential for use in treating CMV and other herpesvirus infections in humans.

Inhibition of herpesvirus replication by a series of 4-oxo-dihydroquinolines with viral polymerase activity

Herpesviruses cause a wide variety of human diseases ranging from cold sores and genital herpes to encephalitis, congenital infections and lymphoproliferative diseases. These opportunistic viruses cause major problems in immunocompromised individuals such as transplant recipients, cancer patients, and HIV-infected persons. The current treatment of these infections is not optimal and there is a need for more active, less toxic compounds that might be used in place of or in addition to current therapies. We have evaluated a new series of 4-oxo-dihydroquinolines, which have a different mechanism of action than nucleosides and have activity against multiple herpesviruses. Of the four new compounds evaluated, two (PHA-529311 and PHA-570886) had greater activity than the parent, PHA-183792, against several herpesviruses and one (PHA-568561) was as effective as the parent. A fourth, PHA-243672, was considerably less effective. They had greater efficacy against cytomegalovirus (CMV) than the other herpesviruses tested and also had activity against acyclovir-resistant herpes simplex virus and varicella-zoster virus isolates and ganciclovir or foscarnet-resistant CMV isolates. These results confirm the broad-spectrum efficacy of these compounds against multiple herpesviruses and suggest that members of this class may have a potential role for treatment of a variety of herpesvirus infections.

Efficacy of methylenecyclopropane analogs of nucleosides against herpesvirus replication in vitro

We have reported previously that purine methylenecyclopropane analogs are potent agents against cytomegaloviruses. In an attempt to extend the activity of these compounds, the 2-amino-6-cyclopropylaminopurine analog, QYL-1064, was selected for further study by modifying the purine 6 substituent. A total of 22 analogs were tested against herpes simplex virus types 1 and 2 (HSV-1, HSV-2), varicella zoster virus (VZV), human cytomegalovirus (HCMV), murine cytomegalovirus (MCMV), Epstein-Barr virus (EBV), human herpesvirus type 6 (HHV-6) and human herpesvirus type 8 (HHV-8). Ten of the analogs had activity against at least one of the viruses tested. One compound had moderate activity against HSV-1 and six had activity against VZV. All but one compound was active against HCMV with a mean EC50 of 2.1 +/- 0.6 microM, compared with a mean EC50 of 3.9 +/- 0.8 microM for ganciclovir. Of special interest was the fact that eight of the ten compounds were active against both HHV-6A and HHV-6B with mean EC50 values of 6.0 +/- 5.2 mciroM and <2.4 +/- 1.5 microM, respectively. Only two compounds had activity against EBV, whereas all but one compound was active against HHV-8 with a mean EC50 of 3.1 +/- 1.7 microM. These results indicate that members of this series of methylenecyclopropane analogs are highly active against HCMV, HHV-6, and HHV-8 but are less active against HSV, VZV, and EBV.

In vitro activities of benzimidazole D- and L-ribonucleosides against herpesviruses

Herpes simplex virus types 1 and 2 (HSV-1 and HSV-2), varicella-zoster virus (VZV), cytomegalovirus (CMV), Epstein-Barr virus (EBV), human herpesvirus 6 (HHV-6), and human herpesvirus 8 (HHV-8) are responsible for a number of clinical manifestations in both normal and immunocompromised individuals. The parent benzimidazole ribonucleosides evaluated in this series, 2-bromo-5,6-dichloro-1-(beta-D-ribofuranosyl)benzimidazole (BDCRB) and maribavir (1263W94), are potent and selective inhibitors of human CMV replication. These nucleosides act by two different mechanisms. BDCRB blocks the processing and maturation of viral DNA, whereas 1263W94 inhibits the viral enzyme pUL97 and interferes with DNA synthesis. In the present study, we have evaluated the in vitro antiviral activity of BDCRB, an analog, GW275175X (175X), and 1263W94 against the replication of HSV-1, HSV-2, VZV, CMV, EBV, HHV-6, and HHV-8. By using various methodologies, significant activity was observed against human CMV and EBV but not against HSV-1, HSV-2, VZV, HHV-6, or HHV-8. Plaque reduction assays performed on a variety of laboratory and clinical isolates of human CMV indicated that all strains, including those resistant to ganciclovir (GCV) and foscarnet, were sensitive to all three benzimidazole ribonucleosides, with mean 50% effective concentration values of about 1 to 5 microM compared to that of GCV at 6 microM. The toxicity of these compounds in tissue culture cells appeared to be similar to that observed with GCV. These results demonstrate that the benzimidazole ribonucleosides are active against human CMV and EBV and suggest that they may be useful for the treatment of infections caused by these herpesviruses.

Carmustine, Ara C, cyclophosphamide and etoposide with autologous bone marrow transplantation in relapsed or refractory lymphoma: a dose-finding study

The purpose of this study was to define the dose-limiting non-hematologic toxicity of carmustine, Ara C, cyclophosphamide and etoposide (BACE). Between October 1986 and March 1990, 37 patients with relapsed or refractory lymphoma received escalating doses of combination chemotherapy followed by autologous bone marrow transplant (ABMT). Twenty patients with Hodgkin's disease (HD) and 17 patients with intermediate or high grade non-Hodgkin's lymphoma (NHL) initially received conventional-dose therapy with either a 7 week course of modified MACOP-B or a single dose of cyclophosphamide (CY) at 2 g/m2 depending on prior therapy and response. Regardless of response, patients then received escalating doses of BACE, toxicity permitting. Ten patients obtained complete responses (CR) and 12 patients were partial responders (PR), CR+PR (75%) with modified MACOP-B and 7 (64%) patients obtained PR with CY. The maximum-tolerated dose (MTD) for BACE was determined to be carmustine 700 mg/m2, Ara C 1500 mg/m2, CY 150 mg/kg and etoposide 1500 mg/m2. When Ara C was escalated from 1500 mg/m2 to 3000 mg/m2 holding the other drugs at the prior doses, the next two patients died secondary to diffuse alveolar damage. Overall and event-free survivals are identical with 14 of 37 patients (38%) alive with a median follow-up of 61 months (range 38-79 months). Ten patients were treated at the MTD, none of whom died a toxic death and 3 (30%) are alive with a median follow-up of 42 months (range 38-52 months). We defined the MTD and BACE showing pulmonary toxicity to be the dose-limiting non-hematologic toxicity.(ABSTRACT TRUNCATED AT 250 WORDS)

Reduced renal accumulation and toxicity of cisplatin in experimental galactosemia

The kidneys of streptozotocin (STZ)-diabetic rats are resistant to certain toxic effects of the antineoplastic drug cisplatin. The mechanism is unknown. This study used the galactosemic rat model to test the hypothesis that the apparent diabetes-induced protection is due to changes in the kidney secondary to chronically elevated hexose concentrations. Galactosemic rats are normoinsulinemic and are free from many of the multiple biochemical abnormalities seen in STZ diabetics. The experiments compared renal cortical platinum (Pt) and blood urea nitrogen (BUN) levels after intraperitoneal injection of 5 mg/kg of cisplatin in galactosemic, STZ-diabetic, and age-matched nondiabetic Sprague-Dawley rats. Nephrotoxicity was defined as a BUN concentration ratio (after to before cisplatin) > 2.5. The results demonstrate that the kidneys of both galactosemic and STZ-diabetic rats became resistant to cisplatin-induced elevation of BUN and, further, that the development of the protection was related to the duration of the diabetic state. Although the protective effect developed more slowly in the galactosemic rats, the attenuation of the rise in BUN was ultimately comparable to that seen in STZ diabetics. Renal cortex [Pt] after cisplatin injection was significantly lower in galactosemics and STZ diabetics compared with age-matched nondiabetics, with the order nondiabetics > galactosemics > STZ diabetics. It was noted, however, that renal Pt accumulation was maximally depressed within 4 weeks of experimental diabetes, whereas the BUN ratio continued to decline with increasing duration of both galactosemia and STZ diabetes. Thus, reduced renal Pt accumulation cannot by itself explain the progressive attenuation of the toxicity. The results support the hypothesis and suggest that the galactosemic rat will be a useful model for mechanistic study of diabetes-induced protection from cisplatin nephrotoxicity.

Dose-related cutaneous toxicities with etoposide

BACKGROUND

Cutaneous toxicities are seen frequently in association with administration of high doses, but not standard doses, of agents. With the increasing use of etoposide in dose-intensive regimens, cutaneous toxicities are appearing with increasing frequency.

METHODS

A retrospective analysis of 145 patients treated with various doses of etoposide was conducted.

RESULTS

This analysis revealed a statistically significant increase in the frequency of these toxicities at doses of 2400 mg/m2 and 4200 mg/m2, compared with doses of 1800 mg/m2. Intense, painful palmar erythema accompanied by bullae formation and desquamation occurred at the 4200 mg/m2 dose. Symptoms were controlled by a short course of corticosteroids.

CONCLUSION

Although they are not dose limiting, substantial dose-related skin toxicities can be an important side effect of high-dose etoposide therapy.

Encephalopathy and seizures induced by intravesical alum irrigations

Hemorrhagic cystitis is a significant toxic effect of cyclophosphamide therapy. Continuous bladder irrigation of a 1% alum solution is a simple and generally safe method of chemical cautery to treat the bleeding urothelium. We report four cases of encephalopathy coincident with elevated aluminum levels as well as one patient who developed seizures while receiving continuous bladder irrigations with alum. All patients had significant renal insufficiency. We recommend the cautious use of alum irrigation in patients with renal impairment and monitoring of serum aluminum levels to prevent excessive accumulation and toxicity.

Generalized seizures secondary to high-dose busulfan therapy

Two patients without prior histories of neurologic disorders experienced generalized seizures while receiving high-dose busulfan (total dose 16 mg/kg) as part of a preparative regimen for allogeneic bone marrow transplantation. A review of the literature revealed 14 similar occurrences. Maintenance of therapeutic blood concentrations of phenytoin in subsequent patients at our institution has resulted in no further patients experiencing generalized seizures. Prophylactic anticonvulsant therapy should be considered in patients receiving high doses of busulfan.

High-dose etoposide and cyclophosphamide without bone marrow transplantation for resistant hematologic malignancy

Seventy-five patients with resistant acute leukemia or lymphoma received high-dose cyclophosphamide and etoposide to explore the activity of this combination in resistant hematologic malignancies, and to determine the maximum doses of these drugs that can be combined without bone marrow transplantation. Etoposide was administered over 29 to 69 hours by continuous infusion corresponding to total doses of 1.8 g/m2 to 4.8 g/m2. Cyclophosphamide, 50 mg/kg/d, was administered on 3 or 4 consecutive days total 150 to 200 mg/kg ideal body weight). At all dose levels myelosuppression was severe but reversible. Mucosal toxicity was dose-limiting with the maximum tolerated dose level combining etoposide 4.2 g/m2 with cyclophosphamide 200 mg/kg. Continuous etoposide infusion produced stable plasma levels that were lower than would be achieved after administration by short intravenous infusion, and this could explain our ability to escalate etoposide above the previously reported maximum tolerated dose. There were 28 complete (35%) and 12 partial (16%) responses. Median duration of complete response (CR) was 3.5 months (range 1.1 to 20+). Seventeen of 40 patients (42%) with acute myelogenous leukemia (AML) achieved CR, including 6 of 20 (30%) with high-dose cytosine arabinoside resistance. We conclude that bone marrow transplantation is not required after maximum tolerated doses of etoposide and cyclophosphamide. This regimen is active in resistant hematologic neoplasms, and the occurrence of CR in patients with high-dose cytosine arabinoside-resistant AML indicates a lack of complete cross-resistance between these regimens.

Hodgkin's lymphoma of the uterus presenting as refractory pelvic inflammatory disease. A case report

Lymphoma rarely presents with initial involvement of the uterine corpus, though disseminated disease may well involve the pelvic organs secondarily. We treated a patient for Hodgkin's lymphoma presenting as pelvic serositis found at hysterectomy for refractory pelvic pain. Nodules consistent with Hodgkin's lymphoma were found within the uterine serosa and muscularis as well as throughout the uterine and tubal lymphatics, but no visible or palpable adenopathy was noted in the pelvis or abdomen or peripherally. Following surgery the patient developed signs and symptoms of widespread lymphoma, which developed fulminantly but responded well initially to standard chemotherapy. This is the first reported case of systemic Hodgkin's lymphoma presenting de novo in the uterine corpus and associated with clinical symptoms referable to the female reproductive tract.

Demonstration of phenotypic abnormalities of thymic epithelium in thymoma including two cases with abundant Langerhans cells

A panel of monoclonal antibodies that phenotypically define stages of normal human thymic epithelial (TE) cell maturation was used to compare thymic epithelium of nine thymomas with hyperplastic thymic epithelium in myasthenia gravis (MG) and thymic epithelium of normal thymuses. It has been shown previously that normal thymic epithelial cells express antigens of early TE cell maturation (A2B5, TE-4) throughout thymic ontogeny and acquire antigens 12/1-2, TE8, and TE-15 at 14 to 16 weeks of fetal gestation. Hyperplastic MG thymic epithelial cells expressed TE antigens in phenotypic patterns similar to that seen in normal postnatal thymus, ie, TE in subcapsular cortex and medulla was TE4+, A2B5+, and 12/1 - 2+ and Hassall's bodies were reactive with antibodies TE8 and TE15. In contrast, thymic epithelium in primary mediastinal thymomas was TE4+, A2B5+, TE8-, and greater than 75% of thymoma epithelium was 12/1 - 2-, a thymic epithelial phenotype similar to that seen on normal fetal thymic epithelium at 14 to 16 weeks fetal gestation. In one subject with a mature epithelial histologic pattern, thymoma epithelium was found to be strongly TE8+, a phenotype suggestive of a later stage of TE maturation. Lymphocytes in five of seven thymomas with immature thymic epithelial cells predominantly expressed immature thymocyte phenotype while two thymomas with immature epithelial phenotype showed a predominance of Langerhans cells and surrounding lymphocytes expressing a mature phenotype. Lymphocytes in the thymoma with differentiated epithelial cells expressed a mature thymocyte phenotype. Thus, in thymomas of varying histologic types, phenotypic abnormalities of thymic epithelium are present; these phenotypic abnormalities may reflect abnormal thymic epithelial maturation.

Acute neurologic dysfunction after high-dose etoposide therapy for malignant glioma

Etoposide (VP-16-213) has been used in the treatment of many solid tumors and hematologic malignancies. When used in high doses and in conjunction with autologous bone marrow transplantation, this agent has activity against several treatment-resistant cancers including malignant glioma. In six of eight patients (75%) who we treated for recurrent or resistant glioma, sudden severe neurologic deterioration occurred. This developed a median of 9 days after initiation of high-dose etoposide therapy. Significant clinical manifestations have included confusion, papilledema, somnolence, exacerbation of motor deficits, and sharp increase in seizure activity. These abnormalities resolved rapidly after initiation of high-dose intravenous dexamethasone therapy. In all patients, computerized tomographic (CT) brain scans demonstrated stability in tumor size and peritumor edema when compared with pretransplant scans. This complication appears to represent a significant new toxicity of high-dose etoposide therapy for malignant glioma.

Characteristics of participants in community health promotion programs: four-year results

Four years of participant tracking data (N = 24,995) for community-based programs targeting cardiovascular disease risk factors are presented. Over two-thirds of contacts were female; age segment representation in these programs was comparable to the city's demography. However, the data show that programs of varying formats which target specific risk factors attract different types of participants. Implications for marketing strategy are discussed.

Antibody against T lymphoblastic leukemia-associated antigen (3-40) identifies vimentin and keratin intermediate filaments in normal cells

Antibody 3-40 defines a 35- to 40-kd surface antigen present on T lymphoblastic leukemia (T-ALL) cells that is absent on normal hematopoietic cells (Naito et al, Blood 62:852, 1983). Using immunoblot analysis of cytoskeletal proteins and indirect immunofluorescence of cell lines treated with various cytoskeletal inhibitors, in this report we have demonstrated that antibody 3-40 also identifies vimentin intermediate filaments (IMF) within the HSB-2 (T-ALL) cell line as well as in normal thymocytes, peripheral blood mononuclear cells, and human and rodent fibroblast cell lines. Cross-reactivity with several keratin subclasses was demonstrated in both human and rodent epithelial cell lines, human thymus, and skin. In addition, we have shown that antibody 3-40 defined a 39-kd intracellular IMF-associated protein in HSB-2 cells, epithelial and fibroblast cell lines. This IMF-associated protein may be selectively expressed on the surface of human T cells during malignant transformation.

Expression of antigens by cultured epithelial cells: comparison of epidermis and thymic epithelium

We have established long term in vitro cultures of human thymic epithelium and human epidermis free of contaminating fibroblasts. The cultured cells were examined using a panel of monoclonal antibodies which were raised against human thymic stroma and recognize tissue specific differentiation antigens of human epidermis and thymic epithelium. A subset of cultured epidermal cells (50%) and thymic epithelial cells (18%) expressed the TE-4 antigen characteristic of basal keratinocytes in skin and endocrine epithelium found in the subcapsular cortex and medulla of the thymus. Subpopulations of the cultured cells expressed the antigens detected by antibodies TE-8 and TE-15. In tissue sections antibodies TE-8 and TE-15 bound to the stratum granulosum and stratum corneum of skin and to the Hassall's bodies of thymus, and therefore recognize antigens characteristic of late stages of keratinized epithelial differentiation. In addition, a subset of thymic epithelial cells expressed the antigen detected by antibody TE-3 which is expressed by nonendocrine thymic epithelium found in the thymic cortex. Thus, in vitro cultures of both epidermal and thymic epithelial cells expressed the entire array of differentiation antigens detected by our panel of monoclonal antibodies. This approach can be used to evaluate the role of components of the thymic microenvironment at various stages of differentiation on developing T lymphocytes. In addition, the cultured epidermal cells can be used to evaluate epidermis as a site of extrathymic T cell maturation.

In vitro growth and phenotypic characterization of mesodermal-derived and epithelial components of normal and abnormal human thymus

Long-term in vitro cultures of human thymic tissue were established and phenotypically characterized using monoclonal reagents that define distinct components of the human thymic microenvironment. The epithelial component of the thymus, defined by monoclonal antibodies TE-3, TE-4, BBTECS, and AE1 (anti-keratin) was isolated from the mesodermal component, defined by antibody TE-7, and maintained separately in long-term culture. The epithelial cells were subcultured repeatedly and recovered from storage in liquid nitrogen. The in vitro phenotype of the cultured cells was compared to that of cultured human epidermal cells. A subpopulation of cultured thymic epithelial cells along with a subpopulation of cultured epidermal cells expressed antigens (TE-8, TE-15) characteristic of late stages of keratinized epithelial cell differentiation. Thus, we have established a system whereby components of the human thymic microenvironment can be cultivated in vitro while maintaining the capacity to differentiate. This approach can be used to evaluate the role of components of the thymic microenvironment at various stages of differentiation on developing T lymphocytes. In addition, keratin-containing thymic epithelial cells were successfully cultured from thymuses obtained from patients with myasthenia gravis and thymoma. Cultivation of abnormal thymic epithelium will provide insight into aberrant T lymphocyte-thymic epithelial interaction.

Phenotypic and functional characterization of human malignant T cells

Malignancies of thymus-derived (T) lymphocytes can be divided into two major groups: diseases of T cells expressing immature T cell markers (T-ALL, T cell lymphoblastic lymphoma) and diseases of malignant T cells expressing markers in a pattern similar to normal mature T cells (T cell CLL, ATL, various forms of CTCL, and T-PLL). Until specific pathways of normal cell maturation are known, the relationship of phenotypic expression of various T cell markers by malignant T cells to a particular stage of normal T cell differentiation must remain speculative. However, phenotypic characterization of malignant T cells is an important first step in the study of events that transpire in the development of T cell malignancies. Future parallel study into the mechanisms of normal and aberrant T cell maturation will undoubtedly lead to greater understanding of the pathogenesis of the T cell malignancies, and therefore pave the way for specific therapies for these difficult-to-treat syndromes.

Mitomycin-induced hemolytic-uremic syndrome

Four patients who took the antitumor agent mitomycin manifested microangiopathic hemolytic anemia, thrombocytopenia, and renal failure. At autopsy, kidneys from all four patients had a microangiopathy typical of the hemolytic-uremic syndrome (HUS), with thromboses in glomerular capillaries and arterioles, fibrin deposition in mesangium, and prominent cellular intimal proliferation of the interlobular arteries. Development of the HUS was an important factor contributing to death in all four patients. From a review of the literature and our initial results of a randomized chemotherapy protocol for metastatic adenocarcinoma of the colorectum, it appears that mitomycin was the most likely cause for the development of the HUS in these patients. As more patients are being treated with mitomycin, particular care must be taken to monitor them for development of a drug-induced HUS.

Differentiation of human T lymphocytes. I. Acquisition of a novel human cell surface protein (p80) during normal intrathymic T cell maturation

The thymus is thought to be the primary central lymphoid organ in which T cells mature. Although thymic cortical and medullary compartments are distinct histologically, few antigens have been described that are absolutely acquired during the presumed intrathymic maturation pathway from cortical to medullary thymocytes. In this paper, we describe the acquisition during human intrathymic T cell maturation of a novel protein (p80) defined by a monoclonal antibody (A1G3). Although the p80-A1G3 antigen is distributed throughout the body and is not T cell specific, our study demonstrates that expression of p80-A1G3 antigen in normal human thymus is associated with thymocyte functional maturity and location in the thymus medulla. Moreover, in contrast to other markers of mature human T cells, the p80-A1G3 cell surface protein is not expressed on T6+ cortical thymocytes, and, therefore, is absolutely acquired by medullary thymocytes during T cell maturation. Thus, the p80-A1G3 antigen and the A1G3 antibody provide a heretofore unavailable system for the study of molecular events that transpire during the maturation of thymocytes.

Differentiation of human T lymphocytes. I. Acquisition of a novel human cell surface protein (p80) during normal intrathymic T cell maturation

The thymus is thought to be the primary central lymphoid organ in which T cells mature. Although thymic cortical and medullary compartments are distinct histologically, few antigens have been described that are absolutely acquired during the presumed intrathymic maturation pathway from cortical to medullary thymocytes. In this paper, we describe the acquisition during human intrathymic T cell maturation of a novel protein (p80) defined by a monoclonal antibody (A1G3). Although the p80-A1G3 antigen is distributed throughout the body and is not T cell specific, our study demonstrates that expression of p80-A1G3 antigen in normal human thymus is associated with thymocyte functional maturity and location in the thymus medulla. Moreover, in contrast to other markers of mature human T cells, the p80-A1G3 cell surface protein is not expressed on T6+ cortical thymocytes, and, therefore, is absolutely acquired by medullary thymocytes during T cell maturation. Thus, the p80-A1G3 antigen and the A1G3 antibody provide a heretofore unavailable system for the study of molecular events that transpire during the maturation of thymocytes.

Effect of thymectomy on peripheral lymphocyte subsets in myasthenia gravis: selective effect on T-cells in patients with thymic atrophy

Myasthenia gravis (MG) is an autoimmune disease affecting nicotinic acetylcholine receptors. The clinical improvement that follows thymectomy in some myasthenic patients implicates thymic factors as well in the pathogenesis of MG. We have studied circulating immunoregulatory T cell subsets before and after thymectomy in 11 adult patients with MG. Six patients had thymic hyperplasia and five patients had atrophic thymus at the time of thymectomy. Before thymectomy, patients who subsequently were shown to have an atrophic thymus, had lower lymphocyte counts than either patients later shown to have a hyperplastic thymus (1315 +/- 143 lymphocytes/mm3 vs. 2434 +/- 350 lymphocytes/mm3, p less than 0.01), or age-matched controls (1315 +/- 143 lymphocytes/mm3 vs. 2636 +/- 589 lymphocytes/mm3, p less than 0.02). Moreover, after thymectomy, in MG patients with an atrophic thymus, there was a significant rise in lymphocyte count (from 1315 +/- 143 lymphocytes/mm3 to 2279 +/- 292 lymphocytes/mm3, p less than 0.02) beginning 3 days postthymectomy and persisting for at least 6 weeks thereafter. In comparison, patients with a hyperplastic thymus showed no change in circulating lymphocyte counts (p greater than 0.1). Enumeration of lymphocyte subsets in MG patients with an atrophic thymus demonstrated normal B cell numbers before and after thymectomy (p greater than 0.1), whereas, T cells were significantly decreased before thymectomy compared with age-matched normal subjects (859 +/- 82 T cells/mm3 vs. 2215 +/- 545 T cells/mm3, p less than 0.05), and rose to near normal levels after thymectomy (1796 +/- 294 T cells/mm3, p less than 0.02 compared with prethymectomy levels). Using monoclonal anti-T cell antibodies 3A1, OKT4, and OKT8, we found that, before thymectomy in the atrophic thymus group, 3A 1+ T cells were significantly depressed compared with postthymectomy levels (620 +/- 173 cells/mm3 vs. 1627 +/- 331 cells/mm3, p less than 0.02) as were OKT4+ cells 436 +/- 88 cells/mm3 vs. 1112 +/- 63 cells/mm3, p less than 0.001), In contrast, no significant change was seen after thymectomy in the OKT8+ cell subset (p greater than 0.1). MG patients with an atrophic thymus had decreased plasma cortisol levels postthymectomy compared with prethymectomy levels, whereas thymectomy in MG patients with a hyperplastic thymus effected no change in plasma cortisol levels. These data demonstrate in MG patients with an atrophic thymus that thymectomy has an effect on the number of circulating T cells, and in particular, on those T cells expressing antigens 3A1 and OKT4. This effect may in part be mediated by changes in plasma adrenal corticosteroid levels after thymectomy or may be due to a factor produced by atrophic thymuses in MG.

Effect of thymectomy on peripheral lymphocyte subsets in myasthenia gravis: selective effect on T-cells in patients with thymic atrophy

Myasthenia gravis (MG) is an autoimmune disease affecting nicotinic acetylcholine receptors. The clinical improvement that follows thymectomy in some myasthenic patients implicates thymic factors as well in the pathogenesis of MG. We have studied circulating immunoregulatory T cell subsets before and after thymectomy in 11 adult patients with MG. Six patients had thymic hyperplasia and five patients had atrophic thymus at the time of thymectomy. Before thymectomy, patients who subsequently were shown to have an atrophic thymus, had lower lymphocyte counts than either patients later shown to have a hyperplastic thymus (1315 +/- 143 lymphocytes/mm3 vs. 2434 +/- 350 lymphocytes/mm3, p less than 0.01), or age-matched controls (1315 +/- 143 lymphocytes/mm3 vs. 2636 +/- 589 lymphocytes/mm3, p less than 0.02). Moreover, after thymectomy, in MG patients with an atrophic thymus, there was a significant rise in lymphocyte count (from 1315 +/- 143 lymphocytes/mm3 to 2279 +/- 292 lymphocytes/mm3, p less than 0.02) beginning 3 days postthymectomy and persisting for at least 6 weeks thereafter. In comparison, patients with a hyperplastic thymus showed no change in circulating lymphocyte counts (p greater than 0.1). Enumeration of lymphocyte subsets in MG patients with an atrophic thymus demonstrated normal B cell numbers before and after thymectomy (p greater than 0.1), whereas, T cells were significantly decreased before thymectomy compared with age-matched normal subjects (859 +/- 82 T cells/mm3 vs. 2215 +/- 545 T cells/mm3, p less than 0.05), and rose to near normal levels after thymectomy (1796 +/- 294 T cells/mm3, p less than 0.02 compared with prethymectomy levels). Using monoclonal anti-T cell antibodies 3A1, OKT4, and OKT8, we found that, before thymectomy in the atrophic thymus group, 3A 1+ T cells were significantly depressed compared with postthymectomy levels (620 +/- 173 cells/mm3 vs. 1627 +/- 331 cells/mm3, p less than 0.02) as were OKT4+ cells 436 +/- 88 cells/mm3 vs. 1112 +/- 63 cells/mm3, p less than 0.001), In contrast, no significant change was seen after thymectomy in the OKT8+ cell subset (p greater than 0.1). MG patients with an atrophic thymus had decreased plasma cortisol levels postthymectomy compared with prethymectomy levels, whereas thymectomy in MG patients with a hyperplastic thymus effected no change in plasma cortisol levels. These data demonstrate in MG patients with an atrophic thymus that thymectomy has an effect on the number of circulating T cells, and in particular, on those T cells expressing antigens 3A1 and OKT4. This effect may in part be mediated by changes in plasma adrenal corticosteroid levels after thymectomy or may be due to a factor produced by atrophic thymuses in MG.