Effects of microenvironment on morphology and function of the microglial cell line BV-2

Effects of microenvironmental changes were examined in the microglial cell line BV-2. In serum supplemented medium cells were ameboid shaped and exhibited thin cytoplasmatic processes at lower concentration or in absence of serum. High levels of acetylated low-density lipoprotein (LDL) receptor and of phagocytic and proliferative activity were detected. Lipopolysaccharide (LPS) and the neuropeptide substance P (SP) induced secretion of interleukin-6. Low interleukin-3 secretion was detected only occasionally and was not influenced by LPS and SP. In defined medium, "process-bearing" cells were evident. Compared to cultures in serum supplemented medium, the cells expressed lower acetylated LDL-binding and phagocytic activity while actively proliferated, the response to LPS was reduced and to SP absent. Granulocyte/macrophage colony-stimulating factor increased the number of process-bearing cells, of acetylated LDL-binding and of IL-6 secretion induced by LPS. Cell morphology was not influenced by neurotrophins like nerve growth factor and brain-derived neurotrophic factor. The described phenotypical and functional plasticity makes the BV-2 cell line a useful model to investigate mechanisms of microglial activation.

Self-reported nonadherence with antiretroviral drugs predicts persistent condition

PURPOSE

To assess variables predictive of nonadherence persisting over time in HIV-infected people treated with highly active antiretroviral therapy.

METHOD

Prospective study of consecutive HIV-infected patients who were prescribed ritonavir- or indinavir-containing regimens in a university-based HIV clinic in Rome. A patient questionnaire assessing knowledge of treatment regimen, adherence behavior, reasons for taking and missing therapy, factors influencing adherence, and health behaviors was administered at baseline and 1 year later. A predose protease inhibitor plasma level was measured concurrently. Persistent nonadherence was defined as patient self-reported nonadherence both at enrollment and at follow-up questionnaires.

RESULTS

From April 1998 to July 1998, 140 patients were enrolled into the study. At follow-up, 10% remained persistently nonadherent, and 15% of the previously adherent patients became nonadherent. On bivariate analysis, being less than 35 years old (odds ratio [OR] 8.9; 95% CI 1.8-43.1; p =.002), self-reporting nonadherence at enrollment (OR 14.5; 95% CI 3.5-5.8; p <.001), and having experienced "a fair amount" or "a lot" of vomiting (OR 11.1;95% CI 1.6-74.7; p =.02) or pruritus (OR 16.4; 95% CI 2.6-102.8; p =.004) during the 4 weeks before enrollment were significantly correlated to persistent nonadherence.

CONCLUSION

Previous self-reported nonadherence was a strong predictor of persistent nonadherence during follow-up. Moreover, being of younger age and self-reporting vomiting or pruritus were also associated with a higher risk of nonadherence persisting over time.

In vivo demethylation of a MoMuLV retroviral vector expressing the herpes simplex thymidine kinase suicide gene by 5' azacytidine

We constructed a functional MoMuLV-based bicistronic retroviral vector encoding the herpes simplex virus type I thymidine kinase gene, which induces sensitivity to the prodrug ganciclovir (gcv), and the reporter beta-galactosidase gene (MFG-tk-IRES-lacZ). The U937 histiocytic cell line was transduced with this vector, and a clone (VB71) with high-level transgene expression was selected. Severe combined immunodeficient (SCID) mice were injected with VB71 cells to evaluate the role of long terminal repeat methylation in transgene silencing in vivo and to see whether 5-azacytidine (5' aza-C) demethylating agent prevented it. We found 5' aza-C maintained gene expression at high level in vitro. In vivo, time to tumor onset was significantly longer in SCID mice receiving the VB71 cells, 5' aza-C, and gcv compared with animals treated with either 5' aza-C or gcv alone. The number of injected tumor cells influences tumor onset time and the efficacy of 5' aza-C and gcv treatment. The standard gcv treatment schedule (10 mg/kg from d + 1 until the onset of tumor) controlled tumor onset better than short-term treatment with high doses. In conclusion, the results extend our previous findings that transgene methylation in vivo may be prevented with an appropriate schedule of 5' aza-C and gcv.

Group B Streptococcus induces apoptosis in macrophages

Group B Streptococcus (GBS) is a pathogen that has developed some strategies to resist host immune defenses. Because phagocytic killing is an important pathogenetic mechanism for bacteria, we investigated whether GBS induces apoptosis in murine macrophages. GBS type III strain COH31 r/s (GBS-III) first causes a defect in cell membrane permeability, then at 24 h, apoptosis. Apoptosis was confirmed by several techniques based on morphological changes and DNA fragmentation. Cytochalasin D does not affect apoptosis, suggesting that GBS-III needs not be within the macrophage cytoplasm to promote apoptosis. Inhibition of host protein synthesis prevents apoptosis, whereas inhibition of caspase-1 or -3, does not. Therefore, GBS can trigger an apoptotic pathway independent of caspase-1 and -3, but dependent on protein synthesis. Inhibition of apoptosis by EGTA and PMA, and enhancement of apoptosis by calphostin C and GF109203X suggests that an increase in the cytosolic calcium level and protein kinase C activity status are important in GBS-induced apoptosis. Neither alteration of plasma membrane permeability nor apoptosis were induced by GBS grown in conditions impeding hemolysin expression or when we used dipalmitoylphosphatidylcholine, which inhibited GBS beta-hemolytic activity, suggesting that GBS beta-hemolysin could be involved in apoptosis. beta-Hemolysin, by causing membrane permeability defects, could allow calcium influx, which initiates macrophage apoptosis. GBS also induces apoptosis in human monocytes but not in tumor lines demonstrating the specificity of its activity. This study suggests that induction of macrophage apoptosis by GBS is a novel strategy to overcome host immune defenses.

Cytokine therapy in immune-mediated demyelinating diseases of the central nervous system: a novel gene therapy approach

Pro-inflammatory cytokines play a crucial role in the regulatory and effector phase of the immune-mediated mechanism sustaining multiple sclerosis pathogenesis (MS) thus supporting the use of anti-inflammatory cytokines as a therapeutic option. Systemic administration of cytokines shows, however, limited therapeutic efficacy and undesirable/unpredictable side-effects. We have developed a non-toxic system to deliver cytokines within the central nervous system (CNS) based on the intrathecal (i.c.) administration of non-replicative herpes simplex (HSV) type-1-derived viral vectors engineered with heterologous cytokine genes. Compared to controls, mice affected by experimental autoimmune encephalomyelitis (EAE) and i.c. injected with an HSV-1-derived vector containing the gene of the anti-inflammatory cytokine IL-4 showed a significant amelioration of clinical and pathological EAE signs. A decreased mRNA expression of the monocyte chemoattractant protein-1 (MCP-1) by mononuclear CNS-infiltrating cells was also observed. Peripheral T cells from IL-4-treated mice were not affected both in their antigen-specific proliferative response and in the cytokine secretion pattern. Our results indicate that CNS cytokine delivery with HSV-1-derived vectors is a feasible therapeutic strategy and might represent an alternative approach for the treatment of immune-mediated demyelinating diseases. Advantages of this approach over systemic cytokine administration are the high cytokine level reached within the CNS and the absence of side-effects on the peripheral immune system. The short-lasting cytokine production in the CNS after a single vector administration (4 weeks) is the limiting factor of this novel technology which, although promising, has to be improved.

Gene transfer into neurones for the molecular analysis of behaviour: focus on herpes simplex vectors

The use of viral vectors to transfect genes into specific brain-cell populations is a novel approach that can be used to investigate the molecular and cellular basis of brain function. Ideal vectors should be targetable and capable of regulated transgene expression. From the viral vectors developed so far, this article focuses on herpes simplex virus 1 (HSV-1)-based vectors. HSV-1 vectors can be engineered for gene transfer to the brain, which makes them suitable for neuroscience research applications. In particular, genetic manipulations of the virus can almost eliminate toxicity and allow expression of multiple transgenes simultaneously. In some instances, transfection of selected neuronal populations is also possible. Specific alterations in behaviour and in disease models have been described after the viral-vector-mediated expression of specific genes within highly localized brain regions.

In vitro effects of meropenem and imipenem/cilastatin on some functions of human natural effector cells

Meropenem, a new carbapenem antibiotic, was assessed to evaluate its effects on some functional parameters of human polymorphonuclear (PMN) and natural killer (NK) cells in comparison with imipenem/cilastatin. Both drugs significantly inhibited PMN phagocytosis and chemotaxis at concentrations of 2,000 and 4,000 microg/ml. They affected PMN microbicidal activity, evaluated against Candida albicans, only at 4,000 microg/ml. A study of the effects of both drugs on peripheral NK populations and the human NK line (NK-92) showed that even at 4,000 microg/ml there was no effect on antitumor activity. These data indicate that meropenem can reduce some PMN antimicrobial functions only at very high concentrations like imipenem/cilastatin, whereas no concentration influenced NK activity.

Connexin 43-enhanced suicide gene therapy using herpesviral vectors

Tumor cell transduction with the herpes simplex virus (HSV) thymidine kinase (tk) gene and treatment with ganciclovir (GCV) is a widely studied cancer gene therapy. Connexin (Cx)-dependent gap junctions between cells facilitate the intercellular spread of TK-activated GCV, thereby creating a bystander effect that improves tumor cell killing. However, tumor cells often have reduced connexin expression, thus thwarting bystander killing and the effectiveness of TK/GCV gene therapy. To improve the effectiveness of this therapy, we compared an HSV vector (TOCX) expressing Cx43 in addition to TK with an isogenic tk vector (TOZ.1) for their abilities to induce bystander killing of Cx-positive U-87 MG human glioblastoma cells and Cx-negative L929 fibrosarcoma cells in vitro and in vivo. The results showed that low-multiplicity infection of U-87 MG cells with TOCX only minimally increased GCV-mediated cell death compared with infection by TOZ.1, consistent with the endogenous level of Cx in these cells. In contrast, bystander killing of L929 cells was markedly enhanced by vector-mediated expression of Cx. In vivo experiments in which U-87 MG cells were preinfected at low multiplicity and injected into the flanks of nude mice showed complete cures of all animals in the TOCX group following GCV treatment, whereas untreated animals uniformly formed fatal tumors. TOCX injection into U-87 MG intradermal and intracranial tumors resulted in prolonged survival of the host animals in a GCV-dependent manner. Together, these results suggest that the combination of TK and Cx may be beneficial for the treatment of human glioblastoma.

Genetically modified CD34+ cells as cellular vehicles for gene delivery into areas of angiogenesis in a rhesus model

To develop a cellular vehicle able to reach systemically disseminated areas of angiogenesis, we sought to exploit the natural tropism of circulating endothelial progenitor cells (EPCs). Primate CD34+ EPCs were genetically modified with high efficiency and minimal toxicity using a non-replicative herpes virus vector. These EPCs localized in a skin autograft model of angiogenesis in rhesus monkeys, and sustained the expression of a reporter gene for several weeks while circulating in the blood. In animals infused with autologous CD34+ EPCs transduced with a thymidine kinase-encoding herpes virus, skin autografts and subcutaneous Matrigel pellets impregnated with vascular growth factors underwent necrosis or accelerated regression after administration of ganciclovir. Importantly, the whole intervention was perfectly well tolerated. The accessibility, easy manipulation, lack of immunogenicity of the autologous CD34+ cell vehicles, and tropism for areas of angiogenesis render autologous CD34+ circulating endothelial progenitors as ideal candidates for exploration of their use as cellular vehicles when systemic gene delivery to those areas is required. Gene Therapy (2000) 7, 43-52.

Nutritional assessment in head injured patients through the study of rapid turnover visceral proteins

BACKGROUND & AIMS

Nutritional monitoring of rapid turnover visceral protein is important in the recognition of malnutrition in patients admitted to the Intensive Care Unit (ICU). We studied prealbumin and retinol-binding protein in patients who received three different kinds of artificial nutrition in order to evaluate the appropriateness of artificial nutrition.

METHODS

45 consecutive head injury patients received enteral (Group A), parenteral (Group B) or both enteral and parenteral nutrition (Group C) at random. We considered these parameters: prealbumin, retinol binding protein and nitrogen balance before (T1), after 3 (T2), 7 (T3) and 11 (T4) days after the beginning of study. Statistical analysis was performed with Kruskal-Wallis test and Bonferroni's t -test.

RESULTS

Plasma prealbumin and Retinol binding protein (RBP) showed an increasing of basal values during the study period in all groups (<< 0.0001) and more significantly in group A (Enteral nutrition P < 0. 001 vs Total parenteral nutrition (TPN) and Enteral P<< 0.01 vs Enteral and parenteral nutrition).

CONCLUSION

Data obtained in the present study indicate that a laboratory is essential for monitoring nutritional assessment and for checking the appropriateness of nutritional therapy. We found prealbumin to be the most sensitive measure and found it to be the test of choice for early assessment and intervention.

Molecular analysis of behavior by gene transfer into neurons with herpes simplex vectors

One goal of neuroscience is to define the molecular and cellular basis for behavior and neurological diseases. A novel approach to this problem is based on the use of viral vectors to transfect specific genes into specific brain cell populations. This review focuses on herpes simplex-based vectors. Major advances have recently been made to improve the characteristics of these vectors, in particular to reduce their toxicity, to modulate the greatness and the time-course of transgene expression, to precisely target specific cell populations, and to transfer multiple genes. Much remains to be done to obtain robust and prolonged transgene expression. However, specific alterations in the behavior and in disease models have already been described following the herpes simplex vector-mediated expression of specific genes within highly localized brain areas. Therefore, this research strategy is likely to provide new clues on the cellular and molecular basis of behavior and of neurological diseases.

Replication-defective herpes simplex virus vectors for neurotrophic factor gene transfer in vitro and in vivo

We report here the construction and the use of two replication-defective herpes simplex virus vectors, SH FGF-2 and TH FGF-2, which efficiently transfer and express the cDNA for fibroblast-growth-factor-2 (FGF-2) in vitro and in vivo. One mutant was deleted in the immediate-early gene encoding ICP4; the other was deleted in ICP4, ICP22 and ICP27. FGF-2--or the control gene lacZ--were inserted in tk, under control of the human cytomegalovirus immediate-early promoter. Infection of Vero cells with SH FGF-2 induced a dramatic increase in FGF-2 protein levels in the first 2 days after infection, with a rapid return to baseline levels within day 4. In contrast, infection of Vero cells with TH FGF-2 displayed FGF-2 levels progressively increasing up to days 4-5, and slowly returning to baseline. Protein extracts of cells infected with TH FGF-2 induced neuronal differentiation of PC12 cells, indicating that the newly synthesized FGF-2 was biologically active. Robust transient transgene expression was also observed in the rat hippocampus after stereotaxical inoculation of TH FGF-2, but not of TH lacZ or of SH vectors. Enhanced gene expression both in vitro and in vivo by the triple immediate-early gene deletion mutant might be attributed to reduced vector cytotoxicity. The present data suggest that TH FGF-2 is suitable for studies of FGF-2 involvement in neurological disorders.

Nonsustained ventricular tachycardia as a predictor for sudden death in patients with idiopathic dilated cardiomyopathy. The role of amiodarone treatment

BACKGROUND

Sudden death frequently occurs in patients with idiopathic dilated cardiomyopathy. Ventricular arrhythmias are encountered in almost all cases. The prognostic significance of life-threatening arrhythmias such as successfully resuscitated ventricular fibrillation and sustained ventricular tachycardia is well known, while it is controversial for ventricular arrhythmias of a lower degree. Amiodarone has been used widely in these patients but its value in preventing sudden death is still uncertain. The aim of this study was to evaluate the prognostic significance of runs of nonsustained ventricular tachycardia (NSVT) as a hallmark for sudden death and the efficacy of amiodarone in preventing sudden death and reducing overall mortality in a large series of patients with dilated cardiomyopathy.

METHODS

Over the period between 1983 and 1994, a series of 151 consecutive patients with idiopathic dilated cardiomyopathy underwent ambulatory electrocardiographic monitoring for a mean period of 191 hours/patient. Seventy-nine patients (56 male, mean age 50.7 +/- 13.1 years) (group A) had ventricular arrhythmias of Lown class < or = 4A, while 72 (53 male, mean age 48.6 +/- 12.8 years) (group B) had one or more NSVT runs. The two groups were well matched in terms of clinical features. Mean follow-up period was 86.8 +/- 38.7 and 74.7 +/- 39.5 months, respectively. In group A no antiarrhythmic drug was administered, while in group B 54/72 patients were treated with amiodarone (mean dosage 300 mg/day) for a mean period of 69.7 +/- 37.8 months (group B1). The remaining 18 patients received class I antiarrhythmic drugs, mexiletine (12) and propaphenone (6) for a mean period of 46.1 +/- 29.4 months, because amiodarone was contraindicated (3) or serious side-effects occurred during amiodarone treatment (15), which was discontinued after a mean period of 3.8 +/- 3.1 months (group B2).

RESULTS

The cumulative survival probability in the whole population was 86.6% at two years and 65.6% at five years. The rate of sudden death was 6.0% at two years and 18.3% at five years. No statistically significant difference was observed in terms of all-cause mortality or sudden death in the three groups (A, B1, B2). In group B1, amiodarone determined the disappearance of NSVT at Holter monitoring in 50% of patients (27), with no significant difference in the rate of sudden death between the two subgroups.

CONCLUSIONS

In unselected patients with idiopathic dilated cardiomyopathy, cardiovascular mortality does not differ between those with NSVT on chronic amiodarone treatment and those without NSVT who have not undergone antiarrhythmic therapy. There was a trend towards a higher overall and sudden mortality rate in patients with NSVT treated with other antiarrhythmic drugs vs patients with NSVT treated with amiodarone, but due to the small size of the first group no significant difference could be calculated. Assuming NSVT as a potential prognostic marker for sudden death, amiodarone treatment may have exerted a beneficial effect in these patients, but this statement is only a presumption due to the limitations of our study. The disappearance of NSVT during amiodarone treatment is not predictive of a reduced rate in sudden death, so that the potential effect of the drug does not appear to be related to the suppression of NSVT at Holter monitoring.

Enhanced tumor cell killing in the presence of ganciclovir by herpes simplex virus type 1 vector-directed coexpression of human tumor necrosis factor-alpha and herpes simplex virus thymidine kinase

Past studies have documented the promise of herpes simplex virus type 1 (HSV-1) thymidine kinase (TK) suicide gene therapy as a potential antitumor treatment. HSV-TK converts the pro-drug ganciclovir (GCV) into a toxic nucleotide analogue, the incorporation of which into cellular DNA blocks cell proliferation. In this report, we have examined the hypothesis that the effectiveness of HSV-TK suicide gene therapy can be enhanced by coexpression of the antitumor cytokine human tumor necrosis factor-alpha (TNF-alpha) from the same replication-defective HSV-1 vector. In vitro testing demonstrated that TNF-alpha expression from this vector potentiated the killing of both TNF-alpha-sensitive L929 tumor cells and TNF-alpha-resistant U-87 MG cells in the presence of GCV. Furthermore, treatment of established intradermal L929 tumors in vivo with the TNF-alpha/TK vector and GCV resulted in prolonged animal survival compared with treatment with parental HSV-TK vector in the presence or absence of GCV. Treatment of intracerebral U-87 MG tumors showed a clear benefit of TK therapy, but a significant further increase in survival using the TNF-alpha vector could not be demonstrated. We found that potentiation of cell killing in vitro required intracellular TNF-alpha because purified protein added to the culture medium of cells infected with HSV-TK vector failed to have the same effect. Accordingly, potentiation in vivo should depend on efficient infection, but immunohistochemical analysis indicated that virus administration by U-87 MG intratumoral injection was inadequate, resulting in an estimated <1% infection of all tumor cells. Moreover, the majority of infected tumor cells were localized at the tumor margin. Together, these results suggest that TNF-enhanced tk gene therapy should provide a useful treatment for TNF-alpha-sensitive tumors and perhaps also for TNT-alpha-resistant tumors if vector delivery can be improved to increase the percentage of transduced tumor cells.

High-efficacy thymidine kinase gene transfer to ovarian cancer cell lines mediated by herpes simplex virus type 1 vector

In this report, a replication-defective herpes simplex virus type 1 (HSV-1) vector has been employed to deliver the Escherichia coli LacZ and HSV thymidine kinase (HSVtk) genes to six human ovarian carcinoma cell lines and the efficacy of gene transfer compared to that of adenoviral vectors in vitro. The transduction efficiency of the LacZ-containing virus TOZ.1 was evaluated qualitatively and quantitatively following infection of the different ovarian cancer cell lines. The therapeutic ability of the HSV-T3 vector, which contains the HSVtk gene, was additionally investigated in comparison to the AdCMVHSVTK. Our results show that HSV-1-mediated gene transfer is quantitatively superior to adenoviral vector in five of the six ovarian cancer cell lines at a 100-fold lower dose in vitro. Our preliminary studies suggest that HSV-1 may be a promising alternative vector for ovarian cancer gene therapy.

Implications of maturation for viral gene delivery to skeletal muscle

Different viral vectors have been analyzed as gene delivery vehicles to skeletal muscle for potentially therapeutic purposes. In this review, we evaluate the application of retroviral, adenoviral, and herpes simplex viral vectors to deliver genes to skeletal muscle and focus on the dramatic loss of viral transduction detected throughout muscle maturation. Recent results suggested that there are several factors involved in the reduced viral transducibility of mature skeletal muscle: muscle cells become post-mitotic in an early stage, the extracellular matrix develops into a physical barrier, and a loss of myoblast mediation occurs since myoblasts progressively become quiescent. Approaches to improve viral gene delivery to mature skeletal muscle may include the use of particular enzymes to increase the permeability of the extracellular matrix, the pre-treatment of the muscle with a myonecrotic agent to induce myoblast mediation, or the application of the myoblast-mediated ex vivo gene transfer.

Cytokine response to group B streptococcus infection in mice

This study was undertaken to better understand the complex relationship between specific and non-specific host defence mechanisms and group B streptococci (GBS). A comprehensive kinetics analysis of cytokine mRNA expression was performed, by Northern blot assay, in peritoneal exudate cells (PEC) and spleen cells (SC) recovered from CD-1 mice at various times during the course of an intraperitoneal infection with a lethal dose (5 x 10(3) microorganisms/mouse) of type Ia GBS, reference strain 090 (GBS-Ia). Analysis of cytokines involved in the development of a specific TH response shows that GBS-Ia in PEC induce only a weak increase of IL-2 mRNA expression and in SC a cytokine pattern characterized by IL-2, IFN-gamma and IL-12 in the absence of IL-4, IL-5 and IL-10. This selected cytokine pattern could provide appropriate conditions for the development of a TH1 response. Analysis of inflammatory cytokines, which are usually induced early during an in vivo infection, shows that there is a significant expression of mRNA specific for IL-1beta, TNFalpha and IL-6, both in PEC and SC only at 24 h which persists at a high level until 36 h. This delayed cytokine induction, accompanied by the contemporary activation of splenic phagocytic cells, occurs only when the number of GBS-Ia is extremely high. In fact, at 24 h GBS-Ia have heavily colonized all organs. In vitro infection of thioglycollate-elicited peritoneal macrophages confirms that the ability of GBS-Ia to induce a strong inflammatory cytokine response depends strictly on the number of infecting microorganisms. Indeed, macrophages respond to GBS-Ia with a very rapid induction of IL-1beta and TNFalpha mRNA when infected at a ratio of 1:10, but not at 100:1. Two major observations emerged from this study: (1) GBS-Ia, by inducing a cytokine pattern which seems to favour development of a TH1 response, could evade antibody production essential for resistance to GBS; and (2) inflammatory cytokine response is induced when a heavy microbial invasion of the host has already occurred. These novel features of GBS-Ia could contribute to the development and progression of lethal infection in mice.

Group B streptococci persist inside macrophages

Group B streptococci (GBS) are an important cause of neonatal sepsis, pneumonia and meningitis. In the early phase of infection, macrophages and polymorphonuclear cells (PMN) are the first immune cells that interact with GBS. In this in vitro study, to gain insight into GBS-macrophage interaction in the absence of type-specific antibodies, we examined the features of GBS survival in thioglycollate-elicited murine peritoneal macrophages and the effect of GBS on the protein kinase C (PKC)-dependent transduction pathway. Our results demonstrate that type Ia GBS, strain 090 (GBS-Ia) and type III GBS strain COH 31r/s (GBS-III), after in vitro phagocytosis survive and persist intracellularly in macrophages for up to 24 and 48 hr, respectively. However, macrophage activation by interferon-gamma (IFN-gamma) and lipopolysaccharide from Escherichia coli (LPS) caused a significant reduction in the time of intracellular persistence. Macrophage activation by IFN-gamma and LPS seems to be a multifactorial event involving multiple intracellular signal pathways also including PKC. Since PKC is one of the components in the signal network leading to macrophage activation and an important target for several intracellular micro-organisms, we wondered whether PKC could have a role in intracellular GBS survival. Both PKC depletion by treatment with phorbol 12-myristate 13-acetate (PMA) for 18 hr and PKC inhibition by Calphostin C rendered macrophages more permissive for the intracellular GBS survival. Furthermore, GBS-infected macrophages were unable to respond to PMA and LPS, activators of PKC, by inducing antimicrobial activity. The ability of GBS to impair PKC-dependent cell signalling was also demonstrated by the reduced c-fos gene expression in GBS-infected macrophages with respect to control macrophages, after LPS stimulation. In conclusion, our results indicate that GBS survive in macrophages and impairment of PKC signal transduction contributes to their intracellular survival.

Progress in development of herpes simplex virus gene vectors for treatment of rheumatoid arthritis

Arthritis is presently incurable and poorly treatable, but there are good grounds for expecting gene therapy to improve matters considerably. Although local ex vivo delivery of anti-arthritic genes to the synovial lining of joints has shown considerable promise, intraarticular gene delivery may be desirable. Herpes simplex virus (HSV) may be a viable vector for in vivo transfer of anti-arthritic genes to joints. HSV has the advantages of high infectivity, large carrying capacity and high titer. The large packaging capacity would permit the inclusion of multiple anti-arthritic genes and necessary regulatory elements. Recombinant vectors produced by this laboratory infect synovial cells efficiently, permitting prolonged expression of transgenes in vitro and in vivo without evidence of cytotoxicity. Further improvements to this vector system include taking advantage of an endogenous HSV 'stealthing' gene, ICP47, which interferes with formation of antigen-class I complexes. Inclusion of inducible promoters to appropriately regulate expression of anti-arthritic genes should further improve this system.

Risk for atrial fibrillation in patients with hypertrophic cardiomyopathy assessed by signal averaged P wave duration

OBJECTIVE

To assess the relation between P wave duration and the occurrence of atrial fibrillation in hypertrophic cardiomyopathy (HCM).

DESIGN

High resolution signal averaged electrocardiography was used in 110 patients with HCM to determine whether patients at risk for paroxysmal atrial fibrillation could be detected during sinus rhythm by measuring P wave duration. Filtered P wave duration was measured manually, over an average of 300 beats per patient.

RESULTS

During follow up, 18 patients (16%) had at least one one clinical episode of paroxysmal atrial fibrillation, including four patients whose initial episode followed the signal averaged electrocardiogram. The 18 patients with overt atrial fibrillation had greater P wave duration than the 69 patients who did not develop atrial fibrillation: 150 (SD 20) v 126 (14) ms; P < 0.001. Another 23 patients without clinically evident atrial fibrillation had prolonged bursts of the arrhythmia on Holter recording, and showed a P wave duration (138 (15) ms) intermediate between patients with and without clinical atrial fibrillation. In assessing risk for atrial fibrillation, P wave duration > or = 140 ms was associated with sensitivity, specificity, and positive predictive accuracy values of 56%, 83%, and 66%. Multivariate analysis showed that duration of the P wave was the only independent variable associated with occurrence of atrial fibrillation; if P wave duration > or = 140 ms was combined with left atrial enlargement > 40 mm, the specificity and positive predictive accuracy for atrial fibrillation increased to 93% and 78%.

CONCLUSIONS

Measurement of P wave duration in sinus rhythm by high resolution signal averaged electrocardiography may be a useful non-invasive clinical tool for identifying patients with HCM likely to develop electrical instability and atrial fibrillation.

Gene transfer to muscle using herpes simplex virus-based vectors

The main goal of gene therapy for Duchenne muscular dystrophy (DMD) is to restore dystrophin into as many muscle cells as necessary to be therapeutic. Herpes simplex virus type 1 (HSV-1) represents a promising new viral vector capable of efficient transduction of myofibers in vivo. The viral genome is large and can accommodate multiple or large non-viral genes including the full-length dystrophin. Here we report on the use of a replication defective HSV-1 mutant vector (DZ) deleted for the essential immediate early (IE) gene ICP4 for studies of reporter gene transfer and expression following direct inoculation of mouse skeletal muscle. Our initial experiments showed that HSV-1 can efficiently infect and express a foreign reporter gene in myoblasts and myotubes in vitro. Furthermore, the intramuscular inoculation of HSV-1 resulted in transduction of a significant number of muscle fibers in newborn mice and some muscle fibers in adult animals. We have attempted to exploit these features to develop new HSV mutant vectors for dystrophin gene delivery to DMD muscle, however two impediments to using this virus for muscle gene delivery have to be overcome: namely viral cytotoxicity and the differential transducibility with HSV-1 throughout the development of muscle fibers. To solve the first problem, virus mutants deleted for the immediate early (IE) genes (ICP4, ICP22, ICP27 and UL41) were constructed and the multiple deleted virus was greatly reduced in cytotoxicity relative to our first generation HSV vector strains. Current work is aimed at incorporating full-length dystrophin under muscle specific promoter (muscle creatine kinase MCK) into these new viral vectors. To address the second problem we have analysed by immunohistochemistry the spreading of the HSV-1 in newborn versus adult muscles to determine whether mature basal lamina which surrounds the adult muscle fibers blocks the HSV-1 entry into the mature muscle fibers.

Herpes simplex virus vectors for gene transfer to the nervous system

Herpes simplex virus (HSV) represents a candidate gene transfer vector for the treatment of nervous system disease. It has many natural biological features which make it attractive for gene delivery to a variety of tissues. The virus naturally establishes a latency in sensory neurons of the peripheral nervous system, wherein the virus in maintained as an extrachromosomal DNA element in the absence of viral lytic gene expression without altering the metabolism of the host neuron. The virus possesses a neuronal latency-specific promoter system which remains active long-term, while other viral and cellular promoters are repressed. Replication defective virus recombinants have been engineered to delete multiple essential immediate early gene functions rendering these new mutants significantly less cytotoxic to neurons and other cells in culture. Further developments in regulating transgene expression and reducing virus toxicity will continue to aid the design and use of these vectors for therapeutic applications for the nervous system.

Development of replication-defective herpes simplex virus vectors

Numerous diseases of the nervous system result from single gene or multifactorial gene defects such as cancer, immune pathological disorders, metabolic diseases, and common neurodegenerative syndromes (Parkinson's and Alzheimer's diseases). A greater understanding of the molecular, biochemical, and genetic factors involved in the progression of a specific disease state has led to the development of genetic therapies using direct gene transfer to ameliorate the disease condition or correct a genetic defect in situ. Standard gene therapeutic approaches employing retroviruses have not proven feasible for treating disorders of the central nervous system (CNS) since these vectors require dividing cells for integration and expression of the transgene, whereas CNS neurons are postmitotic, terminally differentiated cells. Thus, methods for delivery and expression of therapeutic gene products to treat CNS disease will require new delivery strategies and vehicles including the development of novel vectors for direct gene transfer. These vectors should: efficiently deliver the therapeutic gene(s) to a sufficient number of nondividing neurons; persist long-term in a nonintegrated state within the nerve cell nucleus without disturbing host cell functions; and be able to regulate therapeutic gene expression for diseases that may either require high-level transient transgene expression or continuous low level synthesis of the therapeutic product.