Autocrine signaling through Ras prevents apoptosis in vascular smooth muscle cells in vitro

Vascular smooth muscle cell (SMC) apoptosis contributes to physiological and pathological vascular remodeling. Autocrine fibroblast growth factor (FGF) signaling promotes survival in SMC in vitro. Interruption of autocrine FGF signaling results in apoptosis that can be rescued by other growth factors such as PDGF (platelet-derived growth factor) or EGF (epidermal growth factor). Such heterologous growth factor rescue is prevented by pharmacological inhibition of MAPK, implicating signaling through Ras in mediating survival. This study was designed to test the hypothesis that signaling through Ras is both necessary and sufficient to mediate SMC survival in vitro. Recombinant adenoviruses encoding dominant-negative (Ras(N17)) and constitutively active (Ras(L61)) mutants of Ras were used. Ras(N17) blocks growth factor-mediated MAPK activation and can itself induce SMC apoptosis. Ras(N17) is synergistic with inhibition of autocrine FGF signaling in triggering apoptosis and prevents heterologous growth factor rescue. Conversely, Ras(L61) prevents apoptosis resulting from inhibition of autocrine FGF signaling. Rescue by Ras(L61) can be partially prevented by pharmacological inhibition of MEK or phosphatidylinositol 3-kinase, two downstream effectors of Ras. These results suggest that Ras signaling is both necessary and sufficient to mediate survival in SMC in vitro. Further work is required to determine how these signaling events are regulated in the context of vascular remodeling in vivo.

Improvement of western blot test specificity for detecting equine serum antibodies to Sarcocystis neurona

Equine protozoal myeloencephalitis (EPM) is a neurological disease of horses and ponies caused by the apicomplexan protozoan parasite Sarcocystis neurona. The purposes of this study were to develop the most stringent criteria possible for a positive test result, to estimate the sensitivity and specificity of the EPM Western blot antibody test, and to assess the ability of bovine antibodies to Sarcocystis cruzi to act as a blocking agent to minimize false-positive results in the western blot test for S. neurona. Sarcocystis neurona merozoites harvested from equine dermal cell culture were heat denatured, and the proteins were separated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis in a 12-20% linear gradient gel. Separated proteins were electrophoretically transferred to polyvinylidene fluoride membranes and blocked in 1% bovine serum albumin and 0.5% Tween-Tris-buffered saline. Serum samples from 6 horses with S. neurona infections (confirmed by culture from neural tissue) and 57 horses without infections (horses from the Eastern Hemisphere, where S. neurona does not exist) were tested by Western blot. Horses from both groups had reactivity to the 62-, 30-, 16-, 13-, 11-, 10.5-, and 10-kD bands. Testing was repeated with another step. Blots were treated with bovine S. cruzi antibodies prior to loading the equine samples. After this modification of the Western blot test, positive infection status was significantly associated with reactivity to the 30- and 16-kD bands (P<0.001, Fisher's exact test). The S. cruzi antibody-blocked Western blot had a sample sensitivity of 100% and sample specificity of 98%. It is concluded that the specificity of the Western blot test is improved by blocking proteins not specific to S. neurona and using reactivity to the 30- and 16-kD bands as the criterion for a positive test.

Coordinate regulation of matrix metalloproteinase-1 and tissue inhibitor of metalloproteinase-1 expression in human vascular smooth muscle cells

The expression of matrix metalloproteinases (MMPs) and their inhibitors (TIMPs) by human vascular smooth muscle cells (SMC) was monitored as a function of the phenotypic modulation in vitro. Cell phenotype was manipulated by varying serum concentration and cell density. Synthetic phenotype was characterized by a minimum expression of the contractile proteins and a maximal proliferation rate. Contractile phenotype was quiescent and expressed a maximal level of contractile proteins. Synthetic cells expressed the highest levels of both MMP-1 and TIMP-1 and displayed maximal collagenolytic activity. No significant change was detected in MMP-2 expression or catalytic activity. Enzyme immunoassays revealed that MMP-1 expression fell by 77+/-2.4-95+/-0.5%, and that of TIMP-1 by 34+/-0.5-59+/-1.9%, as the cells acquired a contractile phenotype. The level of the MMP-1/TIMP-1 complex was similarly reduced by 78+/-2.9-85+/-1.6%. These data demonstrate that the expression of MMP-1 and TIMP-1 are coordinately regulated with SMC phenotype.

Mental disorders and help seeking in a rural impoverished population

OBJECTIVE

This study examined the impact of an in-home screening and educational intervention on help seeking among rural impoverished individuals with untreated mental disorders. The effect of including a significant other in the intervention and reasons for not seeking help were explored.

METHOD

The sample was randomly selected from households in nine rural counties in Virginia. The short form of the CIDI was used to screen 646 adult residents. Respondents who screened positive were randomly assigned to one of three groups: 1) no intervention, 2) an educational intervention, or 3) the educational intervention with a significant other. A list of local sources of health and mental health care was distributed. At one-month post interview, respondents were telephoned to inquire about help seeking.

RESULTS

Almost one-third (32.4%) of these respondents screened positive for at least one disorder. Five hundred and sixty-six (87.6%) were successfully followed up, and thirty-three of the 566 (5.8%) reported that they had sought professional help since the interview. Eighty-four subjects who screened positive and received the educational intervention reported in follow up that they had discussed the interview with a friend or family member, but only eleven (13.1%) received encouragement to seek treatment. The predominant reason endorsed for not seeking help was "felt there was no need," even among respondents who were informed that they had a disorder.

CONCLUSIONS

A significant proportion of this rural impoverished sample screened positive for a mental disorder. Few individuals sought professional help and significant others did not encourage them to seek treatment. The implication of these results for investigators and service providers is that motivating individuals to seek mental health services is a complex process; more attention must be devoted to the development of culturally relevant methods for facilitating help seeking.

Adenoviral-mediated expression of antisense RNA to fibroblast growth factors disrupts murine vascular development

Fibroblast growth factors (FGFs) are expressed in the developing embryo and are postulated to regulate embryonic and vascular growth. The goal of this study was to elucidate the role of basic fibroblast growth factor (FGF-2) in early murine embryonic cardiovascular development in the mouse embryo. Gestation day 7.5 embryos were harvested and placed in culture, and 12 hr later replication-defective adenovirus (0.5 x 10(6) plaque forming units) encoding either beta-galactosidase or antisense FGF-2 RNA was injected into the sinus venosus of the cultured embryos. Embryos receiving only replication-defective adenovirus expressing the beta-galactosidase gene continued to develop normally over the next 12 hr. In contrast, those receiving adenovirus encoding antisense FGF-2 RNA displayed marked morphogenetic abnormalities, including cessation of growth and abnormal yolk sac vascular development, even though the embryonic hearts continued to beat. Abnormal development of the yolk sac vasculature was confirmed by microangiography and by histologic examination. Coinjection of virus carrying FGF-2 cDNA in the sense orientation reversed the effects of antisense FGF-2 RNA expression. These results confirm the efficacy of the replication-defective adenovirus for targeting gene expression to the developing vasculature and provide evidence for a critical role of FGF in the normal vascular assembly in the early embryo. Cessation of embryonic growth on expression of antisense FGF-2 RNA was most likely attributable to failure of efficient circulation of the early embryonic blood cells from the yolk sac into the embryo.

A molecular and serologic survey of Ehrlichia canis, E. chaffeensis, and E. ewingii in dogs and ticks from Oklahoma

Polymerase chain reaction and Southern hybridization were used to survey for the presence of Ehrlichia canis, Ehrlichia chaffeensis, and Ehrlichia ewingii in blood samples of 65 dogs that harbored ticks from northcentral and northeastern Oklahoma. Dog blood samples were also examined for antibodies against E. canis and E. chaffeensis, using an immunofluorescent antibody test. Ten of 65 dogs (15.4%) examined were positive for Ehrlichia spp. by PCR. Four (6.2%) were positive for E. ewingii, 2 (3.1%) for E. canis, and 4 (6.2%) for E. chaffeensis. Seven dogs (10.8%) were seropositive for E. canis or E. chaffeensis. Ticks collected from PCR-positive dogs were examined by PCR for the presence of Ehrlichia DNA. Several groups of ticks were PCR-positive for E. ewingii or E. canis. E. canis was detected in Rhipicephalus sanguineus, which is considered the major vector for that organism. E. ewingii was detected in a larger variety of ticks, including the only known vector Amblyomma americanum, as well as in Dermacentor variabilis and R. sanguineus. Results suggest that Ehrlichia spp. which are canine and human pathogens circulate in dogs in Oklahoma and in several tick species that feed on dogs.

Amplification refractory mutation system linear extension: a novel, gel-free, enzyme-linked immunoassay method for DNA genotyping

A single synthesis cycle of the amplification refractory mutation system (ARMS) was applied to the analysis of K-ras alleles amplified by polymerase chain reaction and immobilized in streptavidin-coated microtiter plates. The ARMS cycle provided the specificity and molecular switch characteristics of a conventional ARMS assay. This allowed linear extension from an allele-specific primer and the incorporation of digoxigenin-labeled deoxyuridine monophosphate from digoxigenin-11-deoxyuridine triphosphate in the presence of the appropriate K-ras allele. Any digoxigenin-labeled deoxyuridine monophosphate substitution was then demonstrated by enzyme-linked immunoassay with colorimetric endpoint. This method is capable of detecting underrepresented acquired mutations, and this has been shown by the unambiguous detection of specific K-ras mutations in cell line DNA/normal human genomic DNA admixtures. The characterization of K-ras mutations in frozen colorectal tumor samples and histologic material is also described.

Autocrine FGF signaling is required for vascular smooth muscle cell survival in vitro

Expression of both basic fibroblast growth factor (bFGF) and FGF receptors (FGFR) by vascular smooth muscle cells suggests that autocrine FGF signaling mechanisms may have important functions. Inhibition of smooth muscle cell bFGF expression provokes apoptosis, suggesting that endogenous bFGF generates an anti-apoptotic signal. The purpose of this study was to determine whether the survival function of endogenous bFGF requires signaling through FGFR. A recombinant adenovirus encoding a truncated murine FGFR-1 lacking the kinase domain (DN-FGFR) efficiently expressed the transgene in cultured rat aortic smooth muscle cells. The truncated receptor acted in a dominant negative fashion to effectively prevent receptor-mediated signaling, assessed by phosphorylation of p42/p44 MAP kinase. Expression of DN-FGFR provoked apoptosis of SMC in a dose-dependent fashion that was insensitive to recombinant bFGF but could be rescued by platelet derived growth factor or epidermal growth factor. Heterologous growth factor rescue was inhibited by PD98059, an inhibitor of MEK (MAP kinase-kinase). These data demonstrate that inhibition of FGF receptor activation results in apoptosis and suggest that an intact autocrine FGF signaling loop is required for vascular smooth muscle cell survival in vitro. These findings also implicate the Ras/Raf/MEK/MAP kinase cascade in generating or sustaining the survival signal. The functional significance of an autocrine FGF signaling loop in non-transformed cells has important implications for cardiovascular development, remodeling and disease.

Observations on tissue stages of Hepatozoon americanum in 19 naturally infected dogs

Lesions and associated tissue stages of Hepatozoon americanum in 19 naturally infected dogs are described. Schizogony takes place in an unidentified host cell which, during the early stages of the asexual cycle, is contained within a broad, multilamellar mucopolysaccharide 'cyst.' Material forming the cyst appears to be host-derived. An intense inflammatory response follows rupture of the schizont and disintegration of the cyst wall. There is unusually intense angiogenesis associated with the resulting granulomatous inflammation initiated by the freed merozoites. Phagocytized zoites enter the canine circulatory system through the walls of these vessels. Evidence is presented that suggests a single infecting episode can cause prolonged (> or = 9 months) infection, and further, that infection is perpetuated by repeated asexual cycles. Parasites in peripheral blood leukocytes include both those with and without a visible nucleus.

Schizophrenia

Psychiatric nursing research has historically focused on psychosocial phenomena characteristic of personal experience or symptomatology associated with mental illness. The current climate of the mental health service system and basic science knowledge proliferation require nurse researchers to develop and evaluate interventions based on biological understanding of symptoms. This review examines psychiatric nursing and the broader psychiatric literature from 1990 to 1996 to provide a synthesis of the current research knowledge about important components of the field of schizophrenia research including causal processes, course and outcome, symptoms, treatment, relapse prevention, and consumer providers, followed by a discussion of directions for future research.

The detection of K-ras mutations in colorectal cancer using the amplification-refractory mutation system

A total of 301 colorectal carcinoma (CRC) archival samples were analysed using the amplification-refractory mutation system (ARMS). Each sample was examined to determine the mutation status of codons 12 and 13 of the K-ras oncogene. The results from direct DNA sequence analysis carried out on 30 of the samples differed from the ARMS result in almost 50% of the cases as a result of the relative excess of wild-type to mutated DNA sequences. To assess the validity of the ARMS data, the polymerase chain reaction (PCR) was used to generate an amplicon from K-ras exon 1 from 23 of the samples. The PCR amplicons were cloned and sequenced, and the DNA sequence analysis of the cloned material was in agreement with the ARMS results in all but one case. This case represented a tumour that exhibited a five-nucleotide reversed inversion. The cloned sequence data confirm the sensitivity and specificity of the individual ARMS reactions and that it is possible in certain cases to detect additional, more complex, sequence variations.

Basic fibroblast growth factor regulates extracellular matrix and contractile protein expression independent of proliferation in vascular smooth muscle cells

Basic fibroblast growth factor (bFGF) can influence proliferation and differentiation in vascular smooth muscle cells. Basic FGF promotes some features of the synthetic phenotype (proliferation) but is known to inhibit others (collagen synthesis). Whether bFGF availability influences smooth muscle cell phenotype independent of proliferation is not known. The purpose of this study was to determine if the effects of bFGF on extracellular matrix and contractile protein expression are dependent on changes in proliferation. Basic FGF availability was manipulated by adding bFGF to cultured cells or by inhibiting bFGF expression using antisense RNA, and adjusting culture conditions such that proliferation was held constant. Compared to cells cultured in serum alone, smooth muscle alpha-actin and myosin heavy chain expression was markedly reduced by added bFGF, but was not influenced by antisense inhibition of bFGF expression. Under the same conditions, collagen synthesis was inhibited by added bFGF, and was stimulated by reduced bFGF expression. These consequences of altering bFGF availability were not associated with changes in FGF receptor expression. These findings demonstrate that alterations in bFGF availability can regulate smooth muscle cell phenotype independent of proliferation, which may be related to the regulation of smooth muscle cell phenotype in vivo.

Interleukin-12 and interleukin-18 synergistically induce murine tumor regression which involves inhibition of angiogenesis

The antitumor effect and mechanisms activated by murine IL-12 and IL-18, cytokines that induce IFN-gamma production, were studied using engineered SCK murine mammary carcinoma cells. In syngeneic A/J mice, SCK cells expressing mIL-12 or mIL-18 were less tumorigenic and formed tumors more slowly than control cells. Neither SCK.12 nor SCK.18 cells protected significantly against tumorigenesis by distant SCK cells. However, inoculation of the two cell types together synergistically protected 70% of mice from concurrently injected distant SCK cells and 30% of mice from SCK cells established 3 d earlier. Antibody neutralization studies revealed that the antitumor effects of secreted mIL-12 and mIL-18 required IFN-gamma. Interestingly, half the survivors of SCK.12 and/or SCK.18 cells developed protective immunity suggesting that anti-SCK immunity is unlikely to be responsible for protection. Instead, angiogenesis inhibition, assayed by Matrigel implants, appeared to be a property of both SCK.12 and SCK.18 cells and the two cell types together produced significantly greater systemic inhibition of angiogenesis. This suggests that inhibition of tumor angiogenesis is an important part of the systemic antitumor effect produced by mIL-12 and mIL-18.

Experimental transmission of Ehrlichia canis (Rickettsiales: Ehrlichieae) by Dermacentor variabilis (Acari: Ixodidae)

Four trials were conducted in which laboratory-reared Dermacentor variabilis nymphs were exposed to Ehrlichia canis by feeding on experimentally infected dogs as soon as classical morulae were detected in peripheral blood monocytes. After molting 25, 50 or 90 adult tick pairs were permitted to feed on 7 Ehrlichia-naive dogs. Transmission occurred in trials 1 (1/1 dog), 3 (1/1 dog) and 4 (2/2 dogs) but not in trial 2 (0/3 dogs), with 4 of 7 dogs becoming infected. Successful transstadial transmission was demonstrated by detection of morulae in peripheral blood lymphocytes and by seroconversion to Ehrlichia canis 30 d post-exposure. Incubation periods ranged between 17 and 22 days (mean = 19). Clinical signs, typical of ehrlichiosis, included mucopurulent ocular discharge, lymphadenopathy and malaise with accompanying pyrexia, leukopenia and thrombocytopenia. Pyrexia, thrombocytopenia and erythrophagocytosis and vacuolization of the cytoplasm of monocytic cells were observed 1-4 d prior to detection of morulae. This is the first demonstration that a tick other than Rhipicephalus sanguineus is capable of transstadial transmission of this important pathogen of dogs.

Antisense basic fibroblast growth factor gene transfer reduces early intimal thickening in a rabbit femoral artery balloon injury model

PURPOSE

The purpose of this study was to determine whether endogenous basic fibroblast growth factor (bFGF) production contributes to the intimal hyperplastic response to injury in a model of rabbit femoral artery balloon injury. Inhibition of de novo production of bFGF protein was targeted by intramural adenoviral gene transfer of antisense bFGF (Ad.ASbFGF) RNA. The adenovirus was delivered locally intraluminally at the time of arterial injury.

METHODS

New Zealand White rabbits underwent balloon injury of the superficial femoral artery, followed by intraluminal delivery of an adenoviral vector encoding a rat antisense bFGF (ASbFGF) transcript at a concentration of 1 x 10(10) plaque-forming units per milliliter. Control animals were treated in a similar fashion, using either an adenovirus encoding the lac Z reporter gene (Ad.lacZ) or phosphate-buffered saline solution (PBS; vehicle) alone. Two weeks after balloon injury, rabbits were killed and perfusion fixed. Femoral arteries were harvested for histomorphometric analysis. Intimal and medial wall thickness was measured at eight points around the vessel perimeter, and mean intimal/medial (I/M) thickness ratios were compared by analysis of variance and Student's t test. In addition, medial cell proliferation in Ad.ASbFGF and Ad.lacZ treated arteries was evaluated 4 days and 2 weeks after balloon injury by 5-Bromo-2'-deoxyuridine labeling.

RESULTS

At 14 days (n = 25) after balloon injury, histomorphometric analysis revealed a significant inhibition of intimal thickening in Ad.ASbFGF-treated arteries as compared with Ad.lacZ-treated and PBS-treated controls (I/M thickness ratios +/- SD, 0.43 +/- 0.22 for Ad.ASbFGF vs 1.03 +/- 0.28 for Ad.lacZ and 0.86 +/- 0.19 for PBS; p < 0.0001 and p = 0.004, respectively). There was no significant difference in the I/M thickness ratios of Ad.lacZ-treated and PBS-treated vessels (p = 0.27). Although there was no significant difference in the proliferation index of Ad.ASbFGF-treated and Ad.lacZ-treated vessels 4 days after injury, an increase in apoptosis was noted in the Ad.ASbFGF-treated vessels 4 days after balloon injury.

CONCLUSIONS

The use of ASbFGF RNA gene transfer, designed to inhibit de novo bFGF synthesis after balloon injury, results in a significant inhibition of neointimal formation. This suggests that continued bFGF synthesis contributes to the arterial response to injury in rabbits. ASbFGF gene transfer may be an effective strategy in limiting the intimal hyperplastic response after vascular reconstructive procedures.

Anatomic variation of structural properties of periacetabular bone as a function of age. A quantitative computed tomography study

The shape of the acetabulum, the volume of the periacetabular bone, and its density for 125 patients with a wide age range have been quantified using quantitative computed tomography. The goals were to study the relationship between geometric and densitometric properties and provide normative data for finite-element analysis. Significant correlations were found between acetabular diameter and (1) depth, (2) cancellous periacetabular bone density, and (3) periacetabular total bone volume. Only changes in densitometric properties significantly correlated with age. Sphericity of the acetabulum did not increase with age. Variability in bone morphology and density was found for both male and female groups. Surgeons using purely geometric measures to quantify the integrity of acetabular bone should be aware of their limitations when selecting hardware for total hip arthroplasty.

Antisense basic fibroblast growth factor gene transfer reduces neointimal thickening after arterial injury

PURPOSE

To determine whether synthesis of endogenous basic fibroblast growth factor (bFGF) after arterial injury is critical to the intimal thickening response, intraluminal adenoviral gene transfer of an antisense bFGF (Ad.ASbFGF) transgene was used to inhibit the subsequent synthesis of bFGF protein after injury.

METHODS

Sprague-Dawley rats underwent balloon catheter carotid artery injury and in vivo gene transfer. Isolated segments of rat common carotid artery were infected with an adenoviral vector encoding an antisense bFGF transcript at concentrations of 2 x 10(9), 1 x 10(10), or 1 x 10(11) pfu/ml. Control rats were treated with either a control adenovirus encoding the beta-galactosidase gene, (Ad.lacZ), at 1 x 10(10), or 1 x 10(11) pfu/ml, or phosphate-buffered saline solution (vehicle). Two weeks after injury the rats were killed and perfusion-fixed. Cross-sectional areas of the carotid arterial intima and media were measured by planimetry, and the intima/media ratio (I/M) was calculated for each vessel.

RESULTS

The mean I/M for each Ad.ASbFGF group and controls were compared and the significance assessed by analysis of variance. At two weeks after injury, the highest dose of Ad.ASbFGF, 1 x 10(11) pfu/ml, resulted in a near total inhibition of thickening (I/M = 0.14 +/- 0.04, mean +/- SEM) when compared with phosphate-buffered saline solution alone (I/M = 0.99 +/- 0.07), or Ad.lacZ 1 x 10(10) pfu/ml (I/M = 1.01 +/- 0.10) control treatments (p < 0.01). A tenfold lower dose of Ad.ASbFGF, 1 x 10(10) pfu/ml, also caused significant reduction in intimal thickening (I/M = 0.39 +/- 0.07, p < 0.01). Treatment with 2 x 10(9) pfu/ml Ad.ASbFGF did not significantly limit intimal thickening (I/M = 0.72 +/- 0.12).

CONCLUSIONS

Inhibition of bFGF synthesis in vivo using an antisense RNA strategy significantly inhibits intimal thickening after arterial balloon injury. This study suggests that continued bFGF synthesis contributes to intimal thickening after arterial injury, and that antisense bFGF may represent an effective strategy in limiting restenosis after angioplasty.

Characterization of a new isolate of Ehrlichia platys (Order Rickettsiales) using electron microscopy and polymerase chain reaction

A mixed-breed pup approximately 3 months old obtained in north central Oklahoma by the Laboratory Animal Resources Unit of Oklahoma State University presented with platelet inclusions. The dog developed severe thrombocytopenia (< 10,000 microliters-1) following the appearance of inclusions. Blood films were monitored daily and when about 75% of platelets had inclusions, samples were collected in EDTA and processed for electron microscopic (EM) studies and polymerase chain reaction (PCR). EM studies on glutaraldehyde-fixed buffy coat revealed rickettsia-like inclusions in numerous platelets. Serologic examination, using Ehrlichia platys antigen, showed high titre suggestive of E. platys infection. PCR primers derived from a highly variable region of the 16S rRNA gene sequence of E. platys were used to specifically amplify that region of the parasite's DNA. Sequencing of the PCR product obtained by general Ehrlichia primers showed one nucleotide difference from the published sequence for E. platys which suggests possible strain variation of this intracellular parasite. Our results indicate that PCR may be a useful tool in the diagnosis of E. platys infection and that, like other Ehrlichia spp., E. platys isolates may vary.

Attempted transmission of Ehrlichia canis by Rhipicephalus sanguineus after passage in cell culture

OBJECTIVES

To compare the transmissibility by the brown dog tick, Rhipicephalus sanguineus, of a recent isolate of Ehrlichia canis (Ebony) with that of another isolate (Oklahoma) that had been passaged in cell culture, and to assess the genetic similarity of the 2 isolates as reflected in the nucleotide (NT) sequence of 16S rDNA.

ANIMALS

13 healthy dogs of various ages and breeds.

PROCEDURE

Larval and nymphal ticks were acquisition fed on acutely infected dogs, and, after molting, they were transmission fed as nymphs and adults, respectively, on Ehrlichia-naive dogs. All dogs were monitored daily by blood smear evaluation for evidence of parasitized leukocytes and by physical examination for clinical signs of ehrlichiosis. Serologic and hematologic values were measured weekly. Using a nested polymerase chain reaction, the 16S rDNA was amplified, and the NT sequence of the template DNA was determined.

RESULTS

The Ebony isolate of E canis was successfully transmitted to dogs by nymphal and adult ticks. In contrast, no ticks that fed on dogs harboring the cell-cultured isolate (Oklahoma) transmitted it to dogs. On the basis of 16S rDNA sequence, the 2 isolates were 99.9% similar, with only 1 NT difference.

CONCLUSIONS

These results reconfirm the vector potential of R sanguineus for E canis. Passage of the Oklahoma isolate of E canis in cell culture apparently adversely affected its transmissibility by ticks, raising the possibility that cell-cultured isolates of this rickettsia may lose their affinity for ticks. Determination of 16S rDNA sequence suggests minor strain variation within the species E canis.

Serum stimulation, cell-cell interactions, and extracellular matrix independently influence smooth muscle cell phenotype in vitro

Vascular injury profoundly alters the vessel wall microenvironment, and smooth muscle cells respond with cell cycle re-entry, loss of contractile elements, extracellular matrix remodeling, and altered signaling by endogenous growth factors and their receptors. Environmental cues include stimulation by exogenous mitogens and both cell-cell and cell-matrix interactions. Modeling this process in smooth muscle cells in vitro, these environmental determinants were varied independently and the phenotypic consequences assessed. Mitogenic stimulation with serum promoted the synthesis of collagen and fibronectin and the expression of fibroblast growth factor receptor-1 and suppressed the content of smooth muscle alpha-actin, myosin heavy chain, and basic fibroblast growth factor. Low cell density (reduced cell-cell contact) was also associated with enhanced extracellular matrix protein production, increased fibroblast growth factor receptor-1 expression, and reduced contractile protein and basic fibroblast growth factor content. The influence of serum stimulation and reduced cell-cell contact were independent and additive. Provision of a type I collagen matrix blunted the influence of serum and cell-cell contact on collagen synthesis but had minor effects on other measures of phenotype. Environmental factors thus independently influence smooth muscle cell phenotype, including endogenous growth factor expression and responsiveness, which can in turn influence the microenvironment of the vessel wall after injury.

Cardiovascular gene therapy: current concepts

Gene therapy techniques are under development for many areas of medicine, including cardiovascular disease. Identifying appropriate gene targets will require more detailed knowledge of the molecular pathophysiology of these disorders, and choosing appropriate vectors and delivery systems will contribute significantly to the challenge of developing this approach for clinical use. The concepts of toxicology and therapeutic drug monitoring will need to be broadened to account for the unique chemical, biological, and genetic characteristics of gene therapeutic agents. This review will provide an overview of strategy development, currently available vectors, and examples of their application to cardiovascular gene transfer. Considerations of the potential toxicities associated with particular vectors and delivery systems, as well as the types of genetic modifications possible, will provide some guidelines regarding appropriate monitoring of their clinical application.

Antisense inhibition of basic fibroblast growth factor induces apoptosis in vascular smooth muscle cells

Basic fibroblast growth factor (bFGF), a potent mitogen for many cell types, is expressed by vascular smooth muscle cells and plays a prominent role in the proliferative response to vascular injury. Basic FGF has also been implicated as a survival factor for a variety of quiescent or terminally differentiated cells. Autocrine mechanisms could potentially mediate both proliferation and cell survival. To probe such autocrine pathways, endogenous bFGF production was inhibited in cultured rat vascular smooth muscle cells by the expression of antisense bFGF RNA. Inhibition of endogenous bFGF production induced apoptosis in these cells independent of proliferation, and apoptosis could be prevented by exogenous bFGF but not serum or epidermal growth factor. The induction of apoptosis was associated with an inappropriate entry into S phase. These data demonstrate that interruption of autocrine bFGF signaling results in apoptosis of vascular smooth muscle cells, and that the mechanism involves disruption of normal cell cycle regulation.

Case manager follow-up to failed appointments and subsequent service utilization

Case manager responses to failed appointments were monitored for 83 seriously mentally ill persons in a rural community mental health center. Case manager actions taken were grouped into four categories of follow-up from most intensive to least intensive: home visit, phone call, letter, and no follow-up. On the whole, case managers most frequently did not follow-up missed appointments (56.7%), followed up by letters (21.3%), and telephone calls (18.7%), and home visits (3.3%). Analyses revealed that home visits were most intensive and all clients who were visited following failed appointments did not fail the subsequent appointment. Clients who received telephone calls or letters were about equally likely to fail the subsequent appointment, but were much more likely to attend the subsequent appointment than were clients who received no follow-up to the failed appointment. Interestingly, clients who failed appointments and received no follow-up were much more likely to need emergency services rather than a regular appointment as their next contact with the clinic.