Tumor cell-specific transgene expression prevents liver toxicity of the adeno-HSVtk/GCV approach

Treatment of colorectal liver metastases with the HSVtk/GCV approach and adenoviral vectors is highly toxic. We present a nontoxic alternative using the cell type-specific CEA promoter instead of the widely used hCMV immediate-early promoter to drive tk gene expression in the context of a recombinant adenovirus. Analysis of CEA promoter-dependent tk gene expression showed significant activity of this promoter in several human and rat tumor-derived cell lines but not in rat primary hepatocytes and in mouse liver, whereas the CMV promoter was highly active in all cell types and tissues investigated. CEA promoter-dependent tk gene expression was sufficient to kill 100% of cancer cells in vitro, even if less than 10% were infected by the adenoviral vector, indicating a significant bystander effect. Moreover, treatment of subcutaneous tumors in SCID mice with Ad.CEA-tk led to a several-fold reduction of tumor growth, and tail vein injection of a high dose of Ad.CEA-tk caused no side-effects in the liver. The CMV promoter was more potent than the CEA promoter in mediating GCV sensitivity to cancer cells in vitro and in vivo, but even a 20-fold reduction of the dose of Ad.CMV-tk did not prevent its liver cell toxicity after systemic application to mice and still resulted in the death of all animals within 4 days after the start of GCV treatment. These results indicate that restriction of tk gene expression to tumor cells in the liver prevents systemic toxicity. Moreover, the CEA promoter is a safe and efficient tool for tumor cell-specific expression of suicide genes in the liver.

Treatment of anogenital warts

The treatment of anogenital warts has long been unsatisfactory, with high treatment failure rates and relapse rates. It would seem that a good cell-mediated immune response is important for successful treatment, and the development of immune response modifiers such as Imiquimod give hope for an improved outcome for many patients.

Expression of a retrovirally transduced gene under control of an internal housekeeping gene promoter does not persist due to methylation and is restored partially by 5-azacytidine treatment

Although expression of transgenes under the control of a retroviral long terminal repeat (LTR) promoter has been shown not to persist due to methylation, it has been observed that internal promoter may be active even if expression from the LTR promoter is silent. We constructed a retroviral vector carrying the herpes simplex virus thymidine kinase (HSVtk) gene under the control of the albumin gene promoter and transduced the HSVtk gene into hepatocellular carcinoma cells. Three of 14 mice, however, could not eradicate HSVtk-transduced grafts completely despite ganciclovir (GCV) treatment. These GCV-refractory cell lines exhibited resistance to GCV after recultivation. Subsequent Southern blot analysis revealed that the HSVtk gene was not deleted but extensively or completely methylated in GCV-refractory lines. Treatment with 5-azacytidine, a demethylating agent, partially restored the sensitivity of GCV-refractory lines to GCV. These results indicate that expression of retrovirally transduced gene may not persist in vivo due to methylation even when the gene is directed by an internal housekeeping gene promoter. These observations may also have important implications for future clinical applications of retrovirus-mediated gene therapy.

Effect of mitomycin C on aqueous humor flow, flare and intraocular pressure in eyes with glaucoma 2 years after trabeculectomy

BACKGROUND

The purpose of this study was to determine the intraocular pressure (IOP), aqueous humor flow, flare and ocular side effects in eyes with a history of hypotony after trabeculectomy with adjunctive mitomycin C (MMC).

METHODS

Thirty-six eyes with primary or secondary open-angle glaucoma and IOP < or = 8 mmHg during the postoperative period were studied 745 +/- 315 days after surgery. MMC (0.2 or 0.5 mg/ml) was applied to the episclera with a cellular sponge. Flare was studied with the Kowa Laser Flare Meter 500. Aqueous humor flow was measured in the afternoon (Fluorotron Master II). IOP, visual fields and best corrected visual acuity were also examined. Twenty-two contralateral eyes without surgical intervention served as controls.

RESULTS

The mean age of patients was 44.5 +/- 16.8 years. The mean IOP was significantly lower in the MMC group than in the control group: 9.6 +/- 6.4 mmHg vs 18.0 +/- 13.6 mmHg at 2 years (P < 0.001). Aqueous flow was significantly lower in subjects treated with MMC than in controls (P < 0.001). The flare values were significantly higher in the MMC-treated group, with a mean of 12.0 +/- 7.7 photon counts/ms, than in the control group, mean 7.9 +/- 4.6 photon counts/ms (P < 0.019).

CONCLUSION

Our data suggest that MMC is a useful ocular hypotensive agent which seems to participate in a change in aqueous humor dynamics when applied topically as an aqueous solution.

Long-term connexin-mediated bystander effect in highly tumorigenic human cells in vivo in herpes simplex virus thymidine kinase/ganciclovir gene therapy

Gene therapy via the herpes simplex virus thymidine kinase (tk) gene and ganciclovir (GCV) treatment eliminates experimental tumors. In this approach, cells expressing the tk gene (tk+) and neighboring tumor cells which do not express the gene are killed. We have demonstrated this bystander effect is enhanced in vitro by gap junctional intercellular communication (GJIC). In order to extend our in vitro results into in vivo situations, we injected into nude mice different ratios of tk+/tk- HeLa cells, either lacking or transfected with connexin43 (Cx43), a gene coding for a gap junction protein. When GCV was administered before tumors were palpable, fewer animals developed tumors, even after a longer period, if the injected cells were mixtures of Cx43(+)-tk+ and Cx43(+)-tk- while tumor growth was not prevented with mixtures of HeLa cells not expressing Cx43, i.e. Cx43(+)-tk+/Cx43(-)-tk-. When GCV was given after the appearance of tumors, the size of the tumors from Cx43- cells was 30% reduced for 3 weeks if 50% of the injected cells were tk+. However, for cells expressing Cx43, the tumor size was 66% reduced if 10% of the cells were tk+. Such a reduction demonstrates a long-term bystander effect which is dependent on Cx43 expression.

The use of azathioprine in severe adult atopic eczema

AIM

To evaluate the use of azathioprine in the treatment of severe adult atopic eczema and review the relevant literature.

BACKGROUND

Effective treatment of severe adult atopic eczema may necessitate the use of agents such as systemic steroids, PUVA or cyclosporin, which are associated with significant morbidity. Azathioprine is an effective alternative which can induce disease remission and may be less toxic.

METHODS

Ten patients treated with azathioprine 0.7-2.5 mg/kg per day for a minimum period of 12 months were evaluated in a retrospective follow-up study.

RESULTS

Clearance or marked improvement was noted in eight patients; three of these later became refractory to the drug. Side-effects were few and were well-tolerated. One patient was found to have lymphoma 8 months after stopping treatment.

CONCLUSION

Azathioprine is an effective and cheaper alternative to cyclosporin in the treatment of severe adult atopic eczema. Its long-term toxicity remains unclear.

Cancer gene therapy using a replication-competent herpes simplex virus type 1 vector

OBJECTIVE

The authors investigate the efficacy of hrR3, a viral vector derived from herpes simplex virus type 1 (HSV 1), in destroying colon carcinoma cells in vitro and in vivo. The effect of adding the prodrug ganciclovir in combination with hrR3 infection also is assessed.

SUMMARY BACKGROUND DATA

Most cancer gene therapy strategies use viral vectors that are incapable of replication. The HSV 1 vector hrR3 is capable of replication, and its replication is cytotoxic to cells. hrR3 also possesses the HSV-thymidine kinase gene, which converts ganciclovir into a toxic metabolite. Thus, the addition of ganciclovir to hrR3-infected cells may enhance the ability of hrR3 to destroy tumor cells. To increase specificity for tumor cells, hrR3 has a mutated ribonucleotide reductase gene and replicates selectively in cells with high levels of endogenous rbonucleotide reductase. Actively dividing cells such as tumor cells have high levels of endogenous ribonucleotide reductase for synthesis of DNA precursors. The authors are interested in the use of HSV 1 vectors to treat liver metastases from colorectal cancer.

METHODS

Ribonucleotide reductase expression in several colon carcinoma cell lines and in primary cultures of human hepatocytes was determined by Western blot analysis. hrR3-mediated cytotoxicity in the colon carcinoma cell lines was determined using an in vitro assay. The human colon carcinoma cell line HT29 was injected into the flanks of nude mice followed by intratumoral injection of hrR3. Tumor growth rate was assessed with and without the addition of intraperitoneal ganciclovir.

RESULTS

Ribonucleotide reductase levels in colon carcinoma cell lines are much higher than in primary cultures of human hepatocytes. hrR3 efficiently destroys colon carcinoma cell lines in vitro. A single intratumoral injection of hrR3 into HT29 flank tumors significantly reduces tumor growth rate, and the administration of ganciclovir has no additive effect.

CONCLUSIONS

The inherent cytotoxicity of hrR3 replication effectively destroys colon carcinoma cells in vitro and in vivo. This cytotoxicity is not enhanced in vivo by the addition of ganciclovir. In the future, more efficacious and selective HSV 1 vectors may be useful in the treatment of cancer.

Understanding and controlling the scarring response: the contribution of histology and microscopy

In response to injury, the body usually initiates a full and swift wound healing response resulting in reconstructed, repaired tissue. In certain instances, due to a variety of factors, this may not happen, an example being chronic granulating venous leg ulcers. At the other extreme, the wound may heal excessively, producing disabling hypertrophic scarring such as can occur following large, deep burn injuries. Our group is interested in the surgical treatment of the eye disease glaucoma. As will be explained, the successful surgical treatment of this disease depends on a reduced scarring response at the end of wound healing. The purpose of this article is to give an overview of our microscopic and histological experimental work which has furthered our understanding of tissue repair, particularly the scarring response and its potential modification for successful glaucoma surgery.

Suicide gene therapy of chemically induced mammary tumor in rat: efficacy and distant bystander effect

We examined the efficacy of suicide gene therapy for nitrosomethylurea-induced mammary tumors in rats. Individual tumors were directly injected with a retrovirus-producing cell line that releases retroviral vectors that transduce the herpes simplex virus type 1 thymidine kinase (HSV1-TK) gene. HSV1-TK specifically converts the nucleoside analogue ganciclovir (GCV) into a toxic metabolite. Compared to control rats receiving saline, we observed a significant tumor regression of the injected tumors following GCV administration, accompanied by a stromal inflammation and an extensive lymphocyte infiltration invading the tumor epithelium. It is noteworthy that the neighboring uninjected tumors also regressed, demonstrating the occurrence of a distant bystander effect. This is the first demonstration that HSV1-TK/GCV can efficiently treat multiple solid tumors directly generated from an epithelial tissue.

Bronchiolitis obliterans organising pneumonia and primary biliary cirrhosis-like lung involvement in a patient with primary biliary cirrhosis

A 55-year-old woman with a 6-year history of primary biliary cirrhosis presented with an acute onset of fever, dyspnoea, crackles over both lower lung fields, and diffuse interstitial and bibasilar patchy pulmonary opacities. After exclusion of an infectious aetiology, an open lung biopsy was performed which revealed two histopathological features: (1) bronchiolitis obliterans organising pneumonia and (2) lympho-histiocytic interstitial pneumonitis and destructive bronchiolitis. Treatment response to corticosteroids and azathioprine followed a bimodal pattern with immediate resolution of her initial presenting symptoms and late resolution of residual gas exchange defects.

Adenovirus-mediated GM-CSF gene and cytosine deaminase gene transfer followed by 5-fluorocytosine administration elicit more potent antitumor response in tumor-bearing mice

Antitumor effects of combined transfer of suicide and cytokine genes were investigated in this study. Adenovirus harboring E. coli cytosine deaminase gene (AdCD) and adenovirus harboring murine granulocyte-macrophage colony-stimulating factor gene (AdGMCSF) were used simultaneously for in vivo gene transfer in melanoma-bearing mice. Growth inhibition of established tumors and prolongation of survival period were observed more significantly in tumor-bearing mice after transfection with AdGMCSF and AdCD followed by continuous injection of prodrug 5-fluorocytosine (5FC) when compared with mice treated with control adenovirus AdlacZ/5FC, AdCD/5FC or AdGMCSF alone (P < 0.01). After combined therapy the expression of MHC-I (H-2Db) and B7-1 molecules on freshly isolated tumor cells increased greatly and more dendritic cells and CD8+ T cells infiltrated into the tumor mass. The activity of specific cytotoxic T lymphocytes was also found to be induced more significantly after the combined therapy. Further experiments showed that apoptosis of tumor cells and induction of antitumor immune response might be involved in the mechanisms of the tumor cell killing by the combined therapy. Our results demonstrated that combined transfer of the GM-CSF and CD suicide genes, being able to inhibit the growth of melanoma synergistically and induce specific antitumor immune response efficiently, thus addressing the drawbacks of suicide gene therapy or cytokine gene therapy which were proved to be not satisfactory when used alone, might be of therapeutic potential for gene therapy of cancer.

Delayed corneal epitheliopathy after antimetabolite-augmented trabeculectomy

PURPOSE

The authors describe the first case of delayed antimetabolite-related corneal epithelial toxicity after trabeculectomy and its successful treatment with limbal stem cell transplantation.

METHODS

A 73-year-old woman underwent trabeculectomy with intraoperative mitomycin C. After surgery she received six 5-mg injections of subconjunctival 5-fluorouracil (5-FU) adjacent to the bleb.

RESULTS

The patient had a functioning trabeculectomy and clear cornea until 30 months after surgery, at which time she developed a nonhealing superior corneal epithelial defect. After 4 months of conservative medical management, an autologous limbal stem cell transplantation was performed. The epithelial defect resolved completely within 1 week of limbal stem cell transplantation.

CONCLUSIONS

Delayed corneal epithelial toxicity may be a late complication of antimetabolite-augmented trabeculectomy.

Uncoupling of 2-fluoro-2-deoxyglucose transport and phosphorylation in rat hepatoma during gene therapy with HSV thymidine kinase

This animal study investigates the application of positron emission tomography (PET) with tracers of tumour metabolism for monitoring suicide gene therapy with herpes simplex virus thymidine kinase (HSVtk). After transplantation of HSVtk-expressing Morris hepatoma cells into ACI rats, dynamic PET measurements of 18F-labeled 2-fluoro-2-deoxyglucose (FDG) uptake were performed in animals 2 days (n = 7) and 4 days (n = 5) after the onset of therapy with 100 mg ganciclovir (GCV)/kg body weight as well as after administration of sodium chloride (n = 8). The arterial FDG plasma concentration was measured dynamically in an extracorporeal loop and the rate constants for FDG transport (K1, k2) and FDG phosphorylation (k3) were calculated using a three-compartment model modified for heterogeneous tissues. Also, quantification using the metabolic rate of FDG turnover and the standardized uptake value (SUV) was done. Furthermore, the thymidine incorporation into the tumour DNA was determined after i.v. administration of 3H-thymidine. An uncoupling of FDG transport and phosphorylation was found with enhanced K1 and k2 values and a normal k3 after 2 days of GCV treatment. The increase in FDG transport normalized after 4 days whereas the phosphorylation rate k3 increased. Quantification using the metabolic rate or the SUV showed congruent but less sensitive results compared with the modeling approach. The thymidine incorporation into the DNA of the tumours declined to 10.5% of the controls after 4 days of GCV treatment. The data indicate that PET with 18FDG and 11C-thymidine may be applied for monitoring of gene therapy with the HSVtk/GCV suicide system. Increased transport rates are evidence of stress reactions early after therapy. The measurement of thymidine incorporation into the tumour DNA can be used as an indicator of therapy efficacy.

Treatment of chronic Chagas' disease with itraconazole and allopurinol

Four hundred four patients with chronic Chagas' disease were treated with itraconazole (6 mg/kg of body weight/day for 120 days), allopurinol (8.5 mg/kg of body weight/day for 60 days), or with a placebo of pure starch. Patients were monitored over a period of four years by clinical examination, serology, xenodiagnosis, hemoculture, and electrocardiogram. Drug tolerance was good, with only four treatments discontinued due to side effects that subsided after suspension of treatment. Parasitologic cure was evident in 44% of the those treated with allopurinol and 53% of those treated with itraconazole, and the electrocardiographic evaluation showed normalization in 36.5% and 48.2%, respectively, of patients with chronic or recent cardiopathy.

Rapid adenoviral transduction of freshly resected tumour explants with therapeutically useful genes provides a rationale for genetic immunotherapy for colorectal cancer

To develop protocols for the molecular immunotherapy of colorectal cancer, we compared the efficacy of three separate classes of therapeutic genes to induce antitumour responses in a murine colorectal cell model. Thus, the effects of two cytokines (IL-2 and GM-CSF) were compared with those of a costimulatory gene (B7.1) and a suicide gene (HSVtk). The rank order of efficacy against primary tumour growth was HSVtk[GCV], B7.1 > puro, IL-2 > GM-CSF, neo whereas the order of efficacy in inducing antitumour immunity was GM-CSF, IL-2, > B7.1, HSVtk[GCV] > puro, neo in a prophylactic vaccination model. To exploit these data in a clinically relevant and realistic way, we also demonstrated that colorectal tumours can reproducibly be explanted and established in short-term culture. Finally, a rapid transduction protocol has been developed by which, using adenoviral vectors, as many as 90% of the cells in these fresh tumour explants can be engineered to express high levels of the clinically relevant genes (GM-CSF or IL-2) within 1-2 weeks of surgery. Adenovirus-mediated gene delivery was reproducibly and significantly more efficient than retroviral transduction using the MFG-beta-Gal retroviral vector over the time-frame of importance for vaccination. Hence, combination of the animal model data with the ex vivo modification protocol suggests that vaccination of colorectal patients of the appropriate stage will be possible and effective.

Transcriptional activation of NF-kappa B activity by Epstein-Barr virus (EBV) LMP1 as a selective therapeutic strategy for EBV-associated diseases

Epstein-Barr virus (EBV) has been known to be associated with many malignant tumors, including nasopharyngeal carcinoma (NPC). Previous studies have indicated that an EBV-encoded oncoprotein, latent membrane protein 1 (LMP1), is expressed in many NPC tissues. LMP1 has been shown to stimulate HIV LTR through the two NF-kappa B binding sites within this promoter. In this study, we examined the feasibility of using this property of LMP1 as a therapeutic strategy for the treatment of NPC. This therapy consists of the preferential killing of the LMP1-expressing cells by gene transfer using the NF-kappa B-mediated herpes simplex virus thymidine kinase (HSVtk)/ganciclovir (GCV) system. The 800-bp HIV-LTR, which contains two NF-kappa B binding sites, was used to drive the HSVtk gene. Stable C33A cell clones expressing the LMP1 and the HSVtk genes were subjected to the GCV sensitivity test. Results showed that cells expressing both the LMP1 and the HSVtk genes were highly sensitive to GCV treatment. These cells were introduced into nude mice subcutaneously and tumors became palpable within 2 weeks. GCV was then introduced intraperitoneally to these mice and the sizes of the tumors were measured daily. Results showed that the tumors regressed in the group of mice carrying cells that stably expressed both the LMP1 and the HSVtk genes, but not in mice carrying cells containing LMP1 or HSVtk alone. Our data indicate that the HSVtk gene expressed from a NF-kappa B-binding motif-containing promoter that is regulated by LMP1 may be used as an in vivo gene therapy strategy of EBV LMP1-expressing cancers such as NPC.

The treatment of encapsulated trabeculectomy blebs in an out-patient setting using a needling technique and subconjunctival 5-fluorouracil injection

PURPOSE

Encapsulation of the trabeculectomy bleb is a common cause of drainage failure in the early post-operative period. The primary management of bleb encapsulation has previously been to restart medical therapy, but recent advances in the technique of needle manipulation and the introduction of adjunctive 5-fluorouracil (5-FU) have increased the popularity of early surgical bleb management. By reporting the results of bleb needling in a series of patients, we aim to illustrate its safety and efficacy.

METHODS

We have reviewed a series of 32 eyes in which needling and 5-FU injection was performed for bleb encapsulation, and analysed the results over a follow-up period of 10.7 +/- 2.9 months.

RESULTS

In 14 (43.7%) cases, primary needling was performed; in the other 18, needling was performed after conservative treatment had proved inadequate. The mean intraocular pressure (IOP) of the group decreased from 29.2 +/- 10.5 mmHg prior to needling to 15.9 +/- 4.0 mmHg at the most recent attendance (paired t-test p = 1.3 X 10(-7), with all eyes having a final IOP measurement of 22 mmHg or less. Twenty-three (71.9%) of the cases maintained a target IOP of 18 mmHg or less without additional treatment; 5 (15.6%) were qualified successes with an untreated IOP between 19 and 21 mmHg. The remaining 4 (12.5%) patients, whose IOPs ranged between 20 and 22 mmHg with one hypotensive agent, were considered needling failures. Choroidal detachment complicated the procedure in 2 cases; in each this resolved with conservative management and without long-term visual consequence.

CONCLUSION

This technique is recommended as a safe and effective method of treating bleb encapsulation.

Use of allopurinol for maintenance of remission in dogs with leishmaniasis

Current treatments for infected dogs with leishmaniasis do not always provide long-term control of the disease and clinical relapses are common. In this study, the usefulness of long-term allopurinol administration in the maintenance of clinical remission in canine leishmaniasis was evaluated. Fifteen dogs with natural leishmania infection were subjected to an initial treatment based on the simultaneous administration of meglumine antimoniate (100 mg/kg/day) and allopurinol (30 mg/kg/day). Once clinical remission was achieved, a maintenance treatment with allopurinol (20 mg/kg/day) administered for one week a month was instituted. Results were compared with those of a retrospective control group comprising 15 infected dogs which only followed the induction treatment. Relapses occurred in 86 per cent of control dogs within 14 months of discontinuing treatment. In contrast, those dogs on intermittent oral allopurinol administration were successfully maintained in clinical remission for a follow-up period of 10 to 44 months. In this latter group, specific antibody titres decreased or were unchanged, no side effects directly attributable to allopurinol were seen and treatment was well accepted by the owners. It is concluded that long-term intermittent administration of allopurinol is an effective way of maintaining clinical remission in dogs with leishmaniasis.

Medical management of ectopic pregnancy

In selected patients who are hemodynamically stable with an unruptured tubal pregnancy, systemic methotrexate has success rates comparable to laparoscopic salpingostomy. Larger randomized studies are necessary to adequately assess subsequent fertility. Local injection of methotrexate or other agents requires a sonographically visible ectopic as well as technical skills, and has less consistent success rates than that of systemic MTX therapy.

The response of pulmonary vascular endothelial cells to monocrotaline pyrrole: cell proliferation and DNA synthesis in vitro and in vivo

Monocrotaline pyrrole (MCTP) causes pulmonary vascular endothelial cell (EC) injury followed by progressive pulmonary vascular leak in vivo and the inhibition of EC proliferation in vitro. It was hypothesized that MCTP inhibits cell proliferation in vitro by interfering with cell cycle progression in a cycle phase-specific manner. Furthermore, it was proposed that early alterations in MCTP-induced lung injury leading to hypertension were associated with a similar inhibition of EC proliferation. Subconfluent cultures of bovine pulmonary artery endothelial cells (BECs) were synchronized with aphidicolin (APH), a reversible G1-S phase inhibitor. Upon removal of APH, BECs were exposed to MCTP (5 micrograms/ml) or its vehicle for a 4-h interval corresponding to either the G1-S, S-G2, or G2 through mitosis (M) phases of the cell cycle. Fluorescence-activated cell sorting (FACS) was used to identify MCTP-induced changes in cell cycle progression in BECs, and the transit of S phase cells through the cycle was characterized through the incorporation of bromodeoxyuridine (BrdU). Synchronized BECs exposed to MCTP between mid-S-G2 or G2 through M were briefly delayed in G2-M at 12 h but underwent cell division by 24 h. By contrast, BECs treated with MCTP immediately after release from APH block became arrested in G2-M at 24 h and showed evidence of continued DNA synthesis and hypertetraploidy, but they did not divide. In vivo, MCTP (3.5 mg/kg i.v.) administration caused an increase in arterial EC BrdU incorporation between Days 3 and 7, but no increase in EC density. During this same interval, pulmonary vascular permeability increased and persisted. In summary, MCTP inhibits cell proliferation in a cell cycle phase-dependent manner in vitro. The results suggest that a similar mechanism could occur in vivo and may be associated with delayed EC repair, a process that could contribute to persistent pulmonary vascular leak.

Nonviral vector-mediated thymidine kinase gene transfer and ganciclovir treatment in leiomyoma cells

OBJECTIVE

To test the hypotheses that ganciclovir is cytotoxic to leiomyoma cells transfected with herpes simplex virus thymidine kinase and that estrogen modulates the responsiveness of tumor cells to this gene therapy approach.

METHODS

Human and rat cultured uterine leiomyoma cells were transfected with plasmids encoding the beta-galactosidase gene, thymidine kinase gene, or a control plasmid. Transfection efficiency was monitored by measuring beta-galactosidase enzyme activity. Ganciclovir cytotoxicity in thymidine kinase-transfected cells was assessed by monitoring cell viability using trypan blue exclusion. The "bystander effect," a phenomenon in which thymidine kinase-expressing cells exposed to ganciclovir are toxic to adjacent thymidine kinase-nonexpressing cells, was assessed when thymidine kinase vector-transfected cells were cocultured with control plasmid-transfected cells at various percentages before exposure to ganciclovir. The effect of estradiol on ganciclovir-thymidine kinase-mediated cytotoxicity was assessed in estrogen-responsive rat leiomyoma cells.

RESULTS

A thymidine kinase-ganciclovir-mediated "bystander effect" was demonstrated, with 48.6% (human) and 65.6% (rat) cell death when 5% of the leiomyoma cells were transfected with the pNGVL1-tk vector, with 0.84% and 1.9% of the cells expected to express thymidine kinase as based on the 16.7% and 39.8% transfection efficiency determined by the reporter gene assay in human and rat leiomyoma cells, respectively. Estradiol promoted cell growth and enhanced the "bystander effect" in rat leiomyoma cells.

CONCLUSION

These findings demonstrate the feasibility of using thymidine kinase gene therapy as a novel treatment for uterine leiomyomas. The effect of estrogen may provide a mechanism to enhance the tumor-suppressive effect of this approach.

Bullous systemic lupus erythematosus: detection of antibodies against noncollagenous domain of type VII collagen

A 9-year-old girl with systemic lupus erythematosus developed bullous eruption. Histopathologic examination showed subepidermal blistering and immunoglobulins (IgG, IgM, IgA) and complement components (C1q, C3) deposited linearly at the basement membrane zone. IgG in this patient's serum bound to the dermal side of 1 mol/L sodium chloride-split normal human skin, and a 290 kd protein was identified in the dermal extract. The patient's serum recognized various epitopes on the noncollagenous domain as demonstrated by the use of fusion proteins of type VII collagen. Resolution of the bullous eruption occurred after treatment with dapsone.