Influence of residual stress on bonding strength and fracture of plasma-sprayed hydroxyapatite coatings on Ti-6Al-4V substrate

Six hydroxyapatite coatings (HACs) were plasma sprayed on Ti-6Al-4V substrates by varying the substrate temperatures and the cooling conditions. This study is aimed not only to measure the residual stress of HACs under various conditions, but also to assess the influence of residual stress in HACs on their bonding strength. The residual stress and bonding strength were measured by XRD "sin2 psi" technique and standard adhesion test (ASTM C-633), respectively. The result of the study clearly established the relationship between bonding strength and residual stress. The arguments leading to the above conclusion were discussed in detail. Fractographic analysis indicated that fracture of the system occurred mainly inside the hydroxyapatite coating under lower residual stress; as residual stress increased, fracture tended to occur more easily along the crucial HA-Ti alloy substrate interface. A mechanism was presented for the relationships between residual stress, fracture behaviour and bonding strength for the plasma-sprayed hydroxyapatite coatings on Ti-6Al-4V substrate.

Comparison of plasma-sprayed hydroxyapatite coatings and hydroxyapatite/tricalcium phosphate composite coatings: in vivo study

This study aimed to compare biological properties, including osteoconduction, osseointegration, and shear strength, between plasma-sprayed hydroxyapatite (HA) and HA/tricalcium phosphate (TCP) coatings, using a transcortical implant model in the femora of canines. After 3 and 12 weeks of implantation, the implants with surrounding bone were assessed histologically in undecalcified sections in backscattered electron images (BEIs) under a scanning electron microscope (SEM). After short-term (3 week) follow-up, both coatings conducted new bone formation and revealed direct bone-to-coating contact. The HA/TCP coating could not enhance early host-to-coating responses. At 12 weeks, serious dissolution of the HA/TCP coatings evidently occurred. By the new bone healing index (NBHI) and apposition index (AI), we found no significant difference between HA/TCP-coated implants and HA-coated implants throughout all implant periods. At 12 weeks of implantation, some particles dissociated from the HA/TCP coating were found within the remodeling canal. After push-out measurements, the shear strength and failure mode of HA/TCP-coated implants were similar to those of HA-coated implants, and no statistical differences were found between either coating. Consequently, this study indicates that HA/TCP coatings have excellent biological response and may be considered suitable bioactive ceramic coatings for short-term clinical use.

A self-administered instrument for assessing therapeutic approaches of drug-user treatment counselors

In this article we describe the development and psychometric properties of a self-administered instrument for assessing drug-user treatment counselors' therapeutic approaches such as psychodynamic or interpersonal, cognitive-behavioral, family systems or dynamics, 12-step, and case management. We generated an initial pool of items corresponding to these five approaches and modified them based on expert ratings. We developed three sets of items. The first concerned the beliefs underlying each therapeutic approach. The second and third concerned the practices of each applicable approach within individual and group counseling, respectively. With the exception of case management, an approach that originated within social work and which is only applicable to individual counseling, the other four approaches are applicable, at least theoretically, to both individual and group counseling. Additionally, we included items that describe techniques used exclusively with groups (i.e., group techniques). Finally, we included some items that are not associated with any of the traditional approaches but which reflect the practical approach that drug-user treatment programs often take to both individual and group counseling (i.e., practical counseling). The initial instrument consisted of 17 subscales with a total of 76 items. This instrument was administered to 226 counselors from 45 drug-user treatment programs in Los Angeles County. Based on this data, we further refined these scales using confirmatory factor analysis to ensure both construct validity and discriminant validity. The final instrument consisted of 14 subscales with a total of 48 items.

Computational design of direct-bandgap semiconductors that lattice-match silicon

Crystalline silicon is an indirect-bandgap semiconductor, making it an inefficient emitter of light. The successful integration of silicon-based electronics with optical components will therefore require optically active (for example, direct-bandgap) materials that can be grown on silicon with high-quality interfaces. For well ordered materials, this effectively translates into the requirement that such materials lattice-match silicon: lattice mismatch generally causes cracks and poor interface properties once the mismatched overlayer exceeds a very thin critical thickness. But no direct-bandgap semiconductor has yet been produced that can lattice-match silicon, and previously suggested structures pose formidable challenges for synthesis. Much recent work has therefore focused on introducing compliant transition layers between the mismatched components. Here we propose a more direct solution to integrating silicon electronics with optical components. We have computationally designed two hypothetical direct-bandgap semiconductor alloys, the synthesis of which should be possible through the deposition of specific group-IV precursor molecules and which lattice-match silicon to 0.5-1% along lattice planes with low Miller indices. The calculated bandgaps (and hence the frequency of emitted light) lie in the window of minimal absorption in current optical fibres.

Patients with melanoma metastases at cutaneous and subcutaneous sites are highly susceptible to interleukin-2-based therapy

The authors evaluated the records of 371 patients with metastatic melanoma who received treatment with high-dose bolus interleukin-2. Patients with metastases only at cutaneous or subcutaneous sites had a higher objective response rate (50%) than did patients with metastases at these sites plus visceral sites (14%) or patients with metastases at visceral sites only (13%) (p<0.0001). Five patients with disease at cutaneous or subcutaneous sites plus visceral sites experienced regression only at the cutaneous or subcutaneous sites with progression at the visceral sites. Therefore, in the presence of visceral disease, the response rate at cutaneous or subcutaneous sites was only 17% compared with 50% when disease was at the latter sites only (p<0.001). These data suggest that melanoma lesions at cutaneous or subcutaneous sites are highly susceptible targets to interleukin-2-based therapies, but the presence of visceral disease is associated with a significant inhibition of response at cutaneous or subcutaneous sites.

Pathogenesis of herpes simplex virus type 1-induced corneal inflammation in perforin-deficient mice

Herpetic stromal keratitis (HSK) is an inflammatory disease of the cornea that often results in blindness. It is mediated by a host immune response which is triggered by herpes simplex virus (HSV) infection. Immune effector mechanisms are hypothesized to be important in disease development. We investigated, in a mouse model, whether perforin-dependent cytotoxicity is an important effector mechanism in the production of HSK. Wild-type (C57BL/6) and perforin-deficient (PKO) mice were infected intracorneally with HSV-1 strain F. Clinical disease and histologic lesions of the cornea at 23 days postinfection (p.i.) were significantly less severe in HSV-1-infected PKO mice than in infected wild-type mice. mRNA for the chemokine macrophage inflammatory protein 1alpha (MIP-1alpha) was detected by reverse transcription-PCR in the corneas of infected wild-type mice but not in the corneas of infected PKO mice at 23 days p.i. Adoptive transfer of wild-type HSV-1 immune T-cell-enriched splenocytes into HSV-1-infected PKO mice restored the disease phenotype which was seen in infected wild-type mice. In contrast, mice carrying a null-function mutation in the Fas ligand, which is involved in an alternative cytotoxic mechanism, developed clinical disease and histologic lesions which were comparable to those in wild-type mice. Viral clearance from the eyes of PKO mice was not impaired. There was no significant difference between the infectious viral titers isolated from the eyes of PKO and wild-type mice. Our findings show that perforin is important in the pathogenesis of HSK.

Particle irradiation induces FGF2 expression in normal human lens cells

Particle Irradiation Induces FGF2 Expression in Normal Human Lens Cells. Particle radiations, including both proton and helium-ion beams, have been used to successfully treat choroidal melanoma, but with the complication of radiation-induced cataract. We have investigated a role for radiation-induced changes in the expression of basic fibroblast growth factor (FGF2) gene expression as part of the mechanism(s) underlying lens cell injury associated with cataract. Normal human lens epithelial (HLE) cells were cultured in vitro on extracellular matrix (ECM) originated from bovine corneal endothelial cells. This study reports evidence for rapid but transient induction of FGF2 transcripts, an increase of between 5- and 8-fold, within 0.5 h after exposure to particle radiation, followed by another wave of increased transcription at 2-3 h postirradiation. Immunofluorescence results confirm the enhanced levels of FGF2 protein rapidly after exposure to protons or helium ions, followed by another wave of increased activity unique to helium at 6 h postirradiation. This second wave of increased immunoreactivity was not observed in the proton-irradiated samples. Total FGF2 protein analysis after helium-ion exposures shows induced expression of three FGF2 isoforms, with an increase of up to 2-fold in the 18-kDa low-molecular-weight species. Studies of the effects of protons on individual FGF2 protein isoforms are in progress. Several mechanisms involving a role for FGF2 in radiation-induced cataract are discussed.

Growth and differentiation of human lens epithelial cells in vitro on matrix

PURPOSE

To characterize the growth and maturation of nonimmortalized human lens epithelial (HLE) cells grown in vitro.

METHODS

HLE cells, established from 18-week prenatal lenses, were maintained on bovine corneal endothelial (BCE) extracellular matrix (ECM) in medium supplemented with basic fibroblast growth factor (FGF-2). The identity, growth, and differentiation of the cultures were characterized by karyotyping, cell morphology, and growth kinetics studies, reverse transcription-polymerase chain reaction (RT-PCR), immunofluorescence, and Western blot analysis.

RESULTS

HLE cells had a male, human diploid (2N = 46) karyotype. The population-doubling time of exponentially growing cells was 24 hours. After 15 days in culture, cell morphology changed, and lentoid formation was evident. Reverse transcription-polymerase chain reaction (RT-PCR) indicated expression of alphaA- and betaB2-crystallin, fibroblast growth factor receptor 1 (FGFR1), and major intrinsic protein (MIP26) in exponential growth. Western analyses of protein extracts show positive expression of three immunologically distinct classes of crystallin proteins (alphaA-, alphaB-, and betaB2-crystallin) with time in culture. By Western blot analysis, expression of p57(KIP2), a known marker of terminally differentiated fiber cells, was detectable in exponential cultures, and levels increased after confluence. MIP26 and gamma-crystallin protein expression was detected in confluent cultures, by using immunofluorescence, but not in exponentially growing cells.

CONCLUSIONS

HLE cells can be maintained for up to 4 months on ECM derived from BCE cells in medium containing FGF-2. With time in culture, the cells demonstrate morphologic characteristics of, and express protein markers for, lens fiber cell differentiation. This in vitro model will be useful for investigations of radiation-induced cataractogenesis and other studies of lens toxicity.

Comparison of progenitor cell content in sequential peripheral blood progenitor collections after mobilization with chemotherapy and granulocyte macrophage colony-stimulating factor

Optimal timing of peripheral blood progenitor cell (PBPC) harvest to collect maximal stem cell numbers is unknown. We assessed the progenitor cell content in 128 PBPC harvests from 21 patients primed with chemotherapy and granulocyte macrophage-colony stimulating factor (GM-CSF) in relation to absolute neutrophil count (ANC) at collection time. Samples were obtained by leukapheresis during rebound from chemotherapy-induced neutropenia while receiving GM-CSF, and assayed by flow cytometry for CD34+ and by colony assays for CFU-GM and BFU-E. The CD34+ cell concentrations per sample tended to be greater at an ANC < 1,000 mm3 and decreased with rising ANC (p = 0.001). The CFU-GM and BFU-E concentrations per sample remained relatively constant with rising ANC (p = 0.72, p = 0.90, respectively). Total CD34+ cell number per harvest per kg slightly increased with ANC levels (p = 0.044) whereas the total CFU-GM and the total BFU-E per kilogram increased more modestly with rising ANC (p < 0.001, p < 0.001, respectively). We conclude that after priming with chemotherapy and GM-CSF, PBPC could be collected at different absolute neutrophil counts without greatly affecting total CD34+ cell numbers. The greater concentration of CD34+ progenitor cells at a lower ANC together with the CFU-GM and BFU-E peaking with higher ANC suggest a less mature progenitor cell population at lower ANC levels.

Program factors and treatment outcomes in drug dependence treatment: an examination using meta-analysis

In comparison with studies of client characteristics and treatment processes, limited research has been conducted on how program features of drug dependence treatment programs may affect client outcomes. Of particular interest are those characteristics of programs that may have a clinically significant impact on outcomes and that are amenable to change within programs. This study examines the impact of various program factors on client outcomes using data from a meta-analysis of drug dependence effectiveness studies (n = 143). Because of heterogeneity among studies, the data are analyzed in terms of type of outcome variable (drug use and crime), type of design (single-group and treatment-comparison group), and type of treatment (methadone maintenance, therapeutic communities, outpatient drug free, and detoxification). For the more valid treatment-comparison group studies, the weighted mean effect size was 0.29 for drug use outcomes and 0.17 for crime outcomes. Program factors found to be significantly correlated with effect size in one or more modalities were decade of treatment, researcher involvement in treatment delivery, maturity of the program, counselor/client ratio, treatment implementation, treatment exposure, and methadone dosage.

Gut-derived sepsis occurs when the right pathogen with the right virulence genes meets the right host: evidence for in vivo virulence expression in Pseudomonas aeruginosa

OBJECTIVE

To define the putative role of the PA-I lectin/adhesin, a binding protein of Pseudomonas aeruginosa, on lethal gut-derived sepsis after surgical stress, and to determine if this protein is expressed in vivo in response to physical and chemical changes in the local microenvironment of the intestinal tract after surgical stress.

SUMMARY BACKGROUND DATA

Previous work from the authors' laboratory has established that lethal gut-derived sepsis can be induced after the introduction of P. aeruginosa into the cecum of mice after a 30% hepatectomy. This effect does not occur when P. aeruginosa is introduced into the cecum of sham operated control mice. Previous experiments further established that the mechanism of this effect is due to the presence of the PA-I lectin/adhesin of P. aeruginosa, which induces a permeability defect to a lethal cytotoxin of P. aeruginosa, exotoxin A.

METHODS

Three strains of P. aeruginosa, one lacking functional PA-I, were tested in two complementary systems to assess virulence. Strains were tested for their ability to adhere to and alter the permeability of cultured human colon epithelial cells, and for their ability to induce mortality when injected into the cecum of mice after a 30% hepatectomy. To determine if PA-I is "in vivo expressed" when present in the cecal environment after hepatectomy, strains were retrieved from the cecum of sham-operated and hepatectomy-treated mice 24 and 48 hours after their introduction into the cecum and their PA-I expression was assessed.

RESULTS

Results indicated that PA-I plays a putative role in lethal gut-derived sepsis in the mouse, because strains lacking functional PA-I had an attenuated effect on cultured human epithelial cells, and were nonlethal when injected into the cecum of mice after 30% surgical hepatectomy. Furthermore, surgical stress in the form of hepatectomy significantly altered the intestinal microenvironment, resulting in an increase in luminal norepinephrine associated with an increase in PA-I expression in retrieved strains of P. aeruginosa. Co-incubation of P. aeruginosa with norepinephrine increased PA-I expression in vitro, suggesting that norepinephrine plays a role in the observed response in vivo.

CONCLUSIONS

Lethal gut-derived sepsis may occur when intestinal pathogens express virulence determinants in response to environmental signals indicating host stress. In this regard, the PA-I lectin/adhesin of P. aeruginosa appears to be a specific example of in vivo virulence expression in colonizing pathogens in the intestinal tract in response to surgical stress.

Granulocyte-macrophage colony-stimulating factor priming plus papillomavirus E6 DNA vaccination: effects on papilloma formation and regression in the cottontail rabbit papillomavirus--rabbit model

A cottontail rabbit papillomavirus (CRPV) E6 DNA vaccine that induces significant protection against CRPV challenge was used in a superior vaccination regimen in which the cutaneous sites of vaccination were primed with an expression vector encoding granulocyte-macrophage colony-stimulating factor (GM-CSF), a cytokine that induces differentiation and local recruitment of professional antigen-presenting cells. This treatment induced a massive influx of major histocompatibility complex class II-positive cells. In a vaccination-challenge experiment, rabbit groups were treated by E6 DNA vaccination, GM-CSF DNA inoculation, or a combination of both treatments. After two immunizations, rabbits were challenged with CRPV at low, moderate, and high stringencies and monitored for papilloma formation. As expected, all clinical outcomes were monotonically related to the stringency of the viral challenge. The results demonstrate that GM-CSF priming greatly augmented the effects of CRPV E6 vaccination. First, challenge sites in control rabbits (at the moderate challenge stringency) had a 0% probability of remaining disease free, versus a 50% probability in E6-vaccinated rabbits, and whereas GM-CSF alone had no effect, the interaction between GM-CSF priming and E6 vaccination increased disease-free survival to 67%. Second, the incubation period before papilloma onset was lengthened by E6 DNA vaccination alone or to some extent by GM-CSF DNA inoculation alone, and the combination of treatments induced additive effects. Third, the rate of papilloma growth was reduced by E6 vaccination and, to a lesser extent, by GM-CSF treatment. In addition, the interaction between the E6 and GM-CSF treatments was synergistic and yielded more than a 99% reduction in papilloma volume. Finally, regression occurred among the papillomas that formed in rabbits treated with the E6 vaccine and/or with GM-CSF, with the highest regression frequency occurring in rabbits that received the combination treatment.

Retinoic acid receptor-beta as a prognostic indicator in stage I non-small-cell lung cancer

PURPOSE

Retinoids are pivotal in the growth and differentiation of certain epithelial tissues, interacting with nuclear retinoid receptors (the retinoic acid receptors [RARs] and retinoid X receptors [RXRs]), which function as transcription factors. RAR-beta mRNA is undetectable by in situ hybridization (ISH) in 50% of non-small-cell lung cancers (NSCLC). RAR-beta may suppress tumorigenicity. Therefore, we hypothesized that loss of expression of RAR-beta gene in stage I NSCLC is a prognostic factor of a poor clinical outcome.

PATIENTS AND METHODS

We retrospectively analyzed RAR-beta mRNA levels (by ISH using a digoxigenin-labeled antisense riboprobe) in specimens from 185 consecutive patients with completely resected clinical/radiographic stage I NSCLC for whom clinical follow-up data were available.

RESULTS

One hundred fifty-six patients who met the criteria of pathologic stage I NSCLC and positivity for RXR-alpha mRNA (used as a control to assess RNA degradation) and who had adequate follow-up could be evaluated. RAR-beta mRNA expression was undetectable in 51 patients, weakly positive in 64 patients, and strongly positive in 41 patients. Overall survival of the 41 patients with strongly positive RAR-beta was significantly worse than for the 115 patients with weak or absent RAR-beta (P =.045).

CONCLUSION

Unexpectedly, strong RAR-beta expression was associated with a significantly worse outcome of early-stage NSCLC. The mechanisms underlying this clinically and biologically important finding should be further explored.

A comparison of the surface characteristics and ion release of Ti6Al4V and heat-treated Ti6Al4V

This work seeks to investigate the nanosurface characteristics and ion release for a Ti6Al4V alloy prepared by various methods (as received and heat treated at 1300 degrees C for 2 h) with three different passivation treatments (34% nitric acid passivation, 400 degrees C heating in air, and aging in 100 degrees C deionized water). The surface and nanosurface composition are not related to the surface passivation treatments and experimental materials as evaluated by energy dispersive spectroscopy and X-ray photoelectron spectroscopy (XPS) analyses. After passivation and autoclaving treatments, the specimens were immersed in 8.0 mM ethylenediaminetetraacetic acid (EDTA) in Hank's solution and maintained at 37 degrees C for periods of time up to 16 days. The 400 degrees C treated specimens exhibit a substantial reduction in constituent release, which may be attributed to the thicker thickness and rutile structure of the surface oxides. After soaking in Hank's-EDTA solution, a significant time-related decrease in constituent release rate is observed for all kinds of specimens throughout the 0-16 day experimental period. The thicker oxides may be a factor in the improved dissolution resistance. Upon immersion, nonelemental Ca and P are both detected on the surfaces of all kinds of specimens by XPS analysis, and this could be explained by the existence of two types of hydroxyl groups (acidic and basic OH groups) on the oxide surface of the specimens.

Auricular composite grafting to repair nasal vestibular stenosis

Nasal vestibular stenosis is defined as a narrowing of the nasal inlet resulting in airway obstruction. Causes include nasal trauma, infection, and iatrogenic insults. The objectives of this article are to illustrate nasal vestibular stenosis and to analyze common causes and surgical treatments. The operative technique of the senior author (M.S.K.), will be presented. Donor site morbidity and patient outcomes will be discussed. Sixteen patients were seen during a 5-year period. Eleven women and 5 men were evaluated and found to have nasal vestibular stenosis. Three patients had stenosis as a result of nasal fracture or laceration. Stenosis developed in the remaining 13 as a result of nasal surgery. All patients underwent auricular composite grafting, and grafts took in 100%. Partial skin slough occurred in up to 50%; however, re-epithelialization was seen within 3 weeks. Complications were seen at the donor site. Immediate patient satisfaction was seen and continues during long-term follow-up.

Direct binding and In vivo regulation of the fission yeast p21-activated kinase shk1 by the SH3 domain protein scd2

The Ste20/p21-activated kinase homolog Shk1 is essential for viability and required for normal morphology, mating, and cell cycle control in the fission yeast Schizosaccharomyces pombe. Shk1 is regulated by the p21 G protein Cdc42, which has been shown to form a complex with the SH3 domain protein Scd2 (also called Ral3). In this study, we investigated whether Scd2 plays a role in regulating Shk1 function. We found that recombinant Scd2 and Shk1 interact directly in vitro and that they interact in vivo, as determined by the two-hybrid assay and genetic analyses in fission yeast. The second of two N-terminal SH3 domains of Scd2 is both necessary and sufficient for interaction with Shk1. While full-length Scd2 interacted with only the R1 N-terminal regulatory subdomain of Shk1, a C-terminal deletion mutant of Scd2 interacted with both the R1 and R3 subdomains of Shk1, suggesting that the non-SH3 C-terminal domain of Scd2 may be involved in defining specificity in SH3 binding domain recognition. Overexpression of Scd2 stimulated the autophosphorylation activity of wild-type Shk1 in fission yeast but, consistent with results of genetic analyses, did not stimulate the activity of a Shk1 protein lacking the R1 subdomain. Results of additional two-hybrid experiments suggest that Scd2 may stimulate Shk1 catalytic function, at least in part, by positively modulating protein-protein interaction between Cdc42 and Shk1. We propose that Scd2 functions as an organizing center, or scaffold, for the Cdc42 complex in fission yeast and that it acts in concert with Cdc42 to positively regulate Shk1 function.

Idiopathic polyhydramnios and perinatal outcome

OBJECTIVE

The aim of this study was to determine whether there is any association between idiopathic polyhydramnios and adverse perinatal outcome.

STUDY DESIGN

One hundred fifty-one consecutive women with singleton pregnancies complicated by idiopathic polyhydramnios (amniotic fluid index >24 cm) who were delivered at our institution during an 18-month period (December 1996-May 1998) were studied. Outcome measures studied included preterm delivery (<37 weeks' gestation), low birth weight (<2500 g), macrosomia (>4000 g), malpresentation at delivery, rate of cesarean delivery, Apgar score at 5 minutes <7, admission to the neonatal intensive care unit, and perinatal death. These findings were compared by means of the chi(2) test with those of 302 matched control subjects with normal amniotic fluid volume (<24 cm).

RESULTS

Among pregnancies complicated by idiopathic polyhydramnios we did not observe any increases in preterm deliveries, low birth weight, low Apgar scores at 5 minutes, neonatal intensive care unit admissions, or perinatal mortality rate. However, idiopathic polyhydramnios was associated with significantly higher rates of malpresentation, macrosomia, and primary cesarean delivery.

CONCLUSION

In contrast to previous reports that polyhydramnios related to specific causes (congenital anomalies, diabetes mellitus, isoimmunization) is associated with adverse perinatal outcomes, such as prematurity, low birth weight, and perinatal death, idiopathic polyhydramnios is not associated with higher rates of these traditional measures of poor outcome.

Microstructural characterization of plasma-sprayed hydroxyapatite-10 wt% ZrO2 composite coating on titanium

Previous research showed that the concept of adding ZrO2 as second phase to hydroxyapatite (HA) significantly increased the bonding strength of plasma-sprayed composite material. The present work aimed to investigate the microstructural characteristics of plasma-sprayed hydroxyapatite-10 wt% ZrO2 composite coating on titanium using X-ray diffractometry (XRD) and transmission electron microscopy (TEM). In TEM, phases such as HA, amorphous calcium phosphate, alpha-TCP, ZrO2 and minor transformed CaZrO3 are identified. The cubic phase of ZrO2 in HA-10 wt% ZrO2 powders before coating maintains during plasma spraying, and zirconia particle apparently bonds well to the calcium phosphate matrix with local crystallographic relationship. The transformed CaZrO3 does not exist as interface interphase between calcium phosphate matrix and zirconia particle. Instead, reaction of calcium phosphate and zirconia occurs rapidly to transform ZrO2 into CaZrO3. The toughening mechanism of the material studied and its biological implication of the system are discussed.

Human endothelial cell life extension by telomerase expression

Normal human endothelial cells, like other somatic cells in culture, divide a limited number of times before entering a nondividing state called replicative senescence. Expression of the catalytic component of human telomerase, human telomerase reverse transcriptase (hTERT), extends the life span of human fibroblasts and retinal pigment epithelial cells beyond senescence without causing neoplastic transformation (Bodnar, A. G., Ouellette, M., Frolkis, M., Holt, S. E., Chiu, C. P., Morin, G. B., Harley, C. B., Shay, J. W., Lichtsteiner, S., and Wright, W. E. (1998) Science 279, 349-352; Jiang, X., Jimenez, G., Chang, E., Frolkis, M., Kusler, B., Sage, M., Beeche, M., Bodnar, A., Wahl, G., Tlsty, T., and Chiu, C.-P. (1999) Nat. Genet. 21, 111-114). Here, we show that both human large vessel and microvascular endothelial cells also bypass replicative senescence after introduction of hTERT. For the first time, we report that hTERT expression in these life-extended vascular cells does not affect their differentiated and functional phenotype and that these cells maintain their angiogenic potential in vitro. Furthermore, hTERT(+) microvascular endothelial cells have normal karyotype, and hTERT(+) endothelial cell strains do not exhibit a transformed phenotype. Relative to parental cells at senescence, hTERT-expressing endothelial cells exhibit resistance to induction of apoptosis by a variety of different conditions. Such characteristics are highly desirable for designing vascular transplantation and gene therapy delivery systems in vivo.

Microarray analysis of replicative senescence

BACKGROUND

Limited replicative capacity is a defining characteristic of most normal human cells and culminates in senescence, an arrested state in which cells remain viable but display an altered pattern of gene and protein expression. To survey widely the alterations in gene expression, we have developed a DNA microarray analysis system that contains genes previously reported to be involved in aging, as well as those involved in many of the major biochemical signaling pathways.

RESULTS

Senescence-associated gene expression was assessed in three cell types: dermal fibroblasts, retinal pigment epithelial cells, and vascular endothelial cells. Fibroblasts demonstrated a strong inflammatory-type response, but shared limited overlap in senescent gene expression patterns with the other two cell types. The characteristics of the senescence response were highly cell-type specific. A comparison of early- and late-passage cells stimulated with serum showed specific deficits in the early and mid G1 response of senescent cells. Several genes that are constitutively overexpressed in senescent fibroblasts are regulated during the cell cycle in early-passage cells, suggesting that senescent cells are locked in an activated state that mimics the early remodeling phase of wound repair.

CONCLUSIONS

Replicative senescence triggers mRNA expression patterns that vary widely and cell lineage strongly influences these patterns. In fibroblasts, the senescent state mimics inflammatory wound repair processes and, as such, senescent cells may contribute to chronic wound pathologies.

Effect of passivation on the dissolution behavior of Ti6A14V and vacuum-brazed Ti6A14V in Hank's ethylene diamine tetra-acetic acid solution Part I Ion release

This work aims to investigate the effects of three factors, namely: (1) two differently prepared materials (as-polished Ti6A14V and 2 h brazed Ti6A14V); (2) three different surface passivation treatments (34% nitric acid passivation, 400 degrees C heated in air, and aged in 100 degrees C de-ionized water); and (3) periods of immersion time (up to 32 days), on trace element release in Hank's ethylene diamine tetra-acetic acid (EDTA) solution. After passivation and autoclaving treatment, the specimens were immersed in 8.0 mM EDTA in Hank's solution and maintained at 37 degrees C for periods of time up to 32 days. The 400 degrees C -treated specimens exhibit a substantial reduction in constituent release, which may be attributed to the higher thickness and rutile structure of the surface oxides. For acid-passivated and water-aged treatments, a highly significant decrease in the trace levels of Ti, A1, and V is detected from the brazed Ti6A14V compared to those obtained from the Ti6A14V specimens. It is hypothesized that an anatase-rutile transformation of surface TiO_2 is likely to occur, accelerated by the elements of copper and nickel in the brazed specimens. In addition, a significant time-related decrease in constituent release rate is observed for all kinds of specimens throughout the 0-8 day experimental period. The implication of the results is discussed.

An evaluation of the nurse practitioner role in a major rural emergency department

The purpose of this pilot study was to investigate whether nurse practitioners are able to provide a level of primary health service applicable to remote/isolated settings in wound management and treatment of blunt limb trauma. It was hypothesized that there would be no significant difference in the quality of care, or the level of client satisfaction, provided by the medical officers and the nurse practitioners in the study. Two groups participated in the study, nurse practitioners and medical officers. The study used a randomized trial design. Data were collected using quantitative and qualitative methods. Two hundred and thirty-two clients participated in the study. Of this number 63 were supervised cases in the pilot trial. In the randomized trial participants were distributed between nurse practitioners and medical officers (n = 169), of which 91 were randomized to medical officers and 78 to nurse practitioners. Telephone interviews were conducted to evaluate client satisfaction. The majority of study participants were surveyed for client satisfaction (n = 132). This represents approximately 78% of the randomized sample and multivariate analysis was carried out on the data. Study results indicate that there were no significant differences between the two groups in relation to client satisfaction. Very positive outcomes of treatment were consistent across groups in the study. The study also found that there was strong support for the role of the nurse practitioner in the rural emergency setting. Recommendations include further research to measure the efficacy of nurse practitioners utilizing the selected competencies in remote/isolated settings.

An immunochemical study on tau glycation in paired helical filaments

Glycation is a non-enzymatic posttranslational modification that involves a covalent linkage between a sugar and an amino group of protein molecule forming ketoamine. Subsequent oxidation, fragmentation and/or crosslinking of ketoamine leads to the production of advanced glycation endproducts (AGEs). Formation of AGEs causes detrimental effects on the structure and function of affected proteins. Accumulation of AGEs has been implicated in normal aging and in the pathogenesis of diabetes-associated complications and Alzheimer's disease (AD). Of all AGEs, Nepsilon-(carboxymethyl)lysine (CML) is a major glycoxidation product known to be stable and accumulate progressively in vivo. In order to determine if tau is glycated in AD, we raised a rabbit antibody to CML that demonstrated its usefulness in detecting glycation of different proteins in vitro, including BSA, ribonuclease, lysozyme and recombinant tau. Immunochemical analyses indicated that ribose and glucose-6-phosphate are more effective than glucose in generating CML formation in these proteins. We used this antibody to probe for glycation in the following human tau preparations: tau of normal brains and preparations of soluble PHF-tau as well as insoluble PHF from AD brains. All three principal tau components resolved from PHF-tau on Western blots showed CML immunoreactivity indicating that tau is glycated in PHF-tau; and insoluble PHF exhibited prominent CML immunoreactivity on top of the stacking gel. Moreover, immunoelectron microscopic analyses indicate that the anti-CML antibody labels predominantly PHF in aggregates. Taken together, these results suggest that tau becomes glycated in PHF-tau and glycation may play a role in stabilizing PHF aggregation leading to tangle formation in AD.

Molecular genetic alterations in radiation-induced astrocytomas

Astrocytic tumors occasionally arise in the central nervous system following radiotherapy. It is not clear if these gliomas represent a unique molecular genetic subset. We identified nine cases in which an astrocytoma arose within ports of previous radiation therapy, with total doses ranging from 2400 to 5500 cGy. Irradiated primary lesions included craniopharyngioma, pituitary adenoma, Hodgkin's lymphoma, ependymoma, pineal neoplasm, rhabdomyosarcoma, and three cases of lymphoblastic malignancies. Patients ranged from 9 to 60 years of age and developed secondary tumors 5 to 23 years after radiotherapy. The 9 postradiation neoplasms presented as either anaplastic astrocytoma (3 cases) or glioblastoma multiforme (6 cases). Two of the latter contained malignant mesenchymal components. We performed DNA sequence analysis, differential polymerase chain reaction (PCR), and quantitative PCR on DNA from formalin-fixed, paraffin-embedded tumors to evaluate possible alterations of p53, PTEN, K-ras, EGFR, MTAP, and p16 (MTS1/CDKN2) genes. By quantitative PCR, we found EGFR gene amplification in 2 of 8 tumors. One of these demonstrated strong immunoreactivity for EGFR. Quantitative PCR showed chromosome 9p deletions including p16 tumor suppressor gene (2 of 7 tumors) and MTAP gene (3 of 7). Five of 9 tumors demonstrated diffuse nuclear immunoreactivity for p53 protein. Sequencing of the p53 gene in these 9 cases revealed a mutation in only one of these cases, a G-to-A substitution in codon 285 (exon 8). Somewhat unexpectedly, no mutations were identified in PTEN, a commonly altered tumor suppressor gene in de novo glioblastoma multiformes. Unlike some radiation-induced tumors, no activating point mutations of the K-ras proto-oncogene or base pair deletions of tumor suppressor genes were noted. These radiation-induced tumors are distinctive in their high histological grade at clinical presentation. The spectrum of molecular genetic alterations appears to be similar to that described in spontaneous high grade astrocytomas, especially those of the de novo type.

Identification of the block in targeted retroviral-mediated gene transfer

A chimeric retroviral vector (33E67) containing a CD33-specific single-chain antibody was generated in an attempt to target cells displaying the CD33 surface antigen. The chimeric envelope protein was translated, processed, and incorporated into viral particles as efficiently as wild-type envelope protein. The viral particles carrying the 33E67 envelope protein could bind efficiently to the CD33 receptor on target cells and were internalized, but no gene transfer occurred. A unique experimental approach was used to examine the basis for this postbinding block. Our data indicate that the chimeric envelope protein itself cannot participate in the fusion process, the most reasonable explanation being that this chimeric protein cannot undergo the appropriate conformational change that is thought to be triggered by receptor binding, a suggested prerequisite to subsequent fusion and core entry. These results indicate that the block to gene transfer in this system, and probably in most of the current chimeric retroviral vectors to date, is the inability of the chimeric envelope protein to undergo this obligatory conformational change.

Telomerase expression in human somatic cells does not induce changes associated with a transformed phenotype

Expression of the human telomerase catalytic component, hTERT, in normal human somatic cells can reconstitute telomerase activity and extend their replicative lifespan. We report here that at twice the normal number of population doublings, telomerase-expressing human skin fibroblasts (BJ-hTERT) and retinal pigment epithelial cells (RPE-hTERT) retain normal growth control in response to serum deprivation, high cell density, G1 or G2 phase blockers and spindle inhibitors. In addition, we observed no cell growth in soft agar and detected no tumour formation in vivo. Thus, we find that telomerase expression in normal cells does not appear to induce changes associated with a malignant phenotype.

Priority areas for clinical research in palliative care nursing

This report highlights a number of current research issues and concerns in palliative care nursing. The aim of the study was to identify high clinical nursing research priorities in palliative care, drawing on the expertise of nine (n = 9) clinical nurse consultants currently working in this specialty. The Delphi method was used to collect and process data in the study. Thirteen high research priorities emerged which have relevance for nursing practice, patient and family care in the hospice and community care setting. In the context of this study, the concept of high priority relates to research participant consensus on the most pressing nursing research problems which require investigation to improve clinical practice. Study findings provide direction for clinical research and continuing education in palliative care which may benefit expert nurses and their patients.

Membrane-limited expression and regulation of Na+-H+ exchanger isoforms by P2 receptors in the rat submandibular gland duct

1. Cell-specific reverse transcriptase-polymerase chain reaction (RT-PCR), immunolocalization and microspectrofluorometry were used to identify and localize the Na+-H+ exchanger (NHE) isoforms expressed in the submandibular gland (SMG) acinar and duct cells and their regulation by basolateral and luminal P2 receptors in the duct. 2. The molecular and immunofluorescence analysis showed that SMG acinar and duct cells expressed NHE1 in the basolateral membrane (BLM). Duct cells also expressed NHE2 and NHE3 in the luminal membrane (LM). 3. Expression of NHE3 was unequivocally established by the absence of staining in SMG from NHE3 knockout mice. NHE3 was expressed in the LM and in subluminal regions of the duct. 4. Measurement of the inhibition of NHE activity by the amiloride analogue HOE 694 (HOE) suggested expression of NHE1-like activity in the BLM and NHE2-like activity in the LM of the SMG duct. Several acute and chronic treatments tested failed to activate NHE activity with low affinity for HOE as expected for NHE3. Hence, the physiological function and role of NHE3 in the SMG duct is not clear at present. 5. Activation of P2 receptors resulted in activation of an NHE-independent, luminal H+ transport pathway that markedly and rapidly acidified the cells. This pathway could be blocked by luminal but not basolateral Ba2+. 6. Stimulation of P2U receptors expressed in the BLM activated largely NHE1-like activity, and stimulation of P2Z receptors expressed in the LM activated largely NHE2-like activity. 7. The interrelation between basolateral and luminal NHE activities and their respective regulation by P2U and P2Z receptors can be used to co-ordinate membrane transport events in the LM and BLM during active Na+ reabsorption by the SMG duct.

The reduction half cell in biomaterials corrosion: oxygen diffusion profiles near and cell response to polarized titanium surfaces

Mechanically assisted corrosion processes can greatly increase the oxidation currents generated in passivating alloy systems like Co-Cr and titanium due to oxide film disruption. When oxide films are abraded, repassivation and ionic dissolution both occur at rates that are orders of magnitude higher than undisrupted surfaces. The excess electrons generated by these anodic processes must be consumed in corresponding reduction reactions that include the reduction of oxygen. If large enough, these reduction reactions may locally deplete the concentration of solution-dissolved oxygen and, in turn, affect cell behavior in the vicinity of the implant surface. To date, this hypothesis has not been tested. In the present study, a scanning electrochemical microscope was used to measure oxygen concentration profiles in vitro near a planar titanium electrode polarized to different voltages representative of those attainable by titanium undergoing mechanically assisted corrosion. The potentials investigated ranged from 0 mV to -1000 mV (AgCl). The oxygen concentration as a function of distance from the titanium surface was measured using a platinum-iridium microelectrode and an amperometric technique. Also, preliminary experiments were performed to assess the response of rat calvarial osteoblast-rich cells cultured for 2 h on titanium samples polarized to two different potentials (0 mV and -1000 mV versus AgCl). The results of this study indicate that oxygen concentrations near titanium surfaces are affected by sample potentials out to probe-sample distances as great as 500 microm. Within 2 microm of the surface, oxygen concentrations decreased by 15 to 25% for sample potentials between -100 and -500 mV. At potentials more negative than -600 mV, the oxygen concentration dropped rapidly to near zero by -900 mV. The cell experiments showed a statistically significant difference in the amount of cell spreading, as measured by projected cell area, between the two groups (p < 0.03), with the cells cultured at -1000 mV undergoing much less spreading. This implies that -1000 mV inhibits normal cell behavior at the titanium surface and that this is most likely due, at least in part, to a diminished oxygen supply.

Persistence of herpes simplex virus type 1 DNA in chronic conjunctival and eyelid lesions of mice

Herpes simplex virus type 1 (HSV-1) causes chronic blepharitis and conjunctivitis as well as keratitis in humans. The pathogenesis of these inflammatory ocular and dermal lesions is not well understood. We have examined the persistence of HSV-1 DNA and its relationship to inflammatory lesions in the conjunctiva and eyelid skin of mice which were inoculated with HSV-1 by the corneal route. Viral DNA was detected by in situ PCR in the conjunctiva and eyelid tissue of infected mice at 5, 11, 23, and 37 days postinfection (p.i.). This DNA was localized in the epithelial cells of the conjunctiva and hair follicles and in the epidermal cells of the eyelid skin. Viral proteins were not detected in the conjunctiva or the eyelid skin after 5 days p.i., even though histopathological lesions were found at 23 and 37 days p.i. in both tissues. The DNA-containing cells were adjacent to sites of inflammation in the chronic lesions in both the conjunctiva and the eyelid skin. A similar temporal and spatial relationship between HSV-1 DNA and inflammatory lesions has been previously reported for the cornea. Our data suggest that the lesions in the cornea, conjunctiva, and eyelid skin progress similarly. Further studies are required to determine whether the long-term presence of HSV-1 is involved in the mechanism by which these chronic inflammatory lesions develop. The presence of HSV-1 DNA in these extraocular tissues for extended periods may constitute persistent viral infection of nonneuronal cells.

BK virus as a potential co-factor in human cancer

BK virus (BKV) is a member of the polyomavirus family that persistently infects 75-80% of the human population. BKV encodes a large T antigen which is responsible for the transforming functions of the virus. Recent studies have shown an association of BKV DNA with a variety of human tumours including pancreatic islet, brain, urinary tract and Kaposi's sarcoma. Despite the detection of BKV DNA in several human tumours, there is no clear evidence for a causative role in tumour formation. We have sought to characterize the interactions of BKV TAg with cellular tumour suppressor proteins including p53, pRb, p107, and p130 in an attempt to further understand the molecular mechanisms of transformation by BKV. We have shown that BKV TAg can bind to and functionally inhibit p53 and the p53-mediated response to DNA damage. Additionally, we have shown that low levels of BKV TAg are sufficient to induce free E2F and a serum-independent phenotype despite the absence of detectable interactions with pRb family members. Taken together, these results suggest that BKV TAg can both inhibit the cellular response to DNA damage and induce proliferation, allowing for potential accumulation of mutations in cellular growth control genes. These results suggest a possible role for BKV TAg in cellular transformation and tumour formation in the human host.

Myxoid leiomyosarcoma of the uterus: a case report and review of the literature

A case report of myxoid leiomyosarcoma of the uterus in a 54-year-old woman is presented as a rare variant of uterine sarcoma. Only 14 cases have been described in the literature. These tumors have a striking myxoid appearance and exhibit highly malignant behavior despite their low mitotic index. Although it is difficult to establish the nature of the neoplastic cells in the myxoid areas, both light microscopical and immunohistochemical characteristics showed features of smooth muscle cells in some of the cellular areas. Our patient had a tumor which arose in association with hyalinized benign leiomyomatous lesion. Like other reported cases of myxoid leiomyosarcoma, the tumor behaved aggressively.

Identification and cloning of a sequence homologue of dopamine beta-hydroxylase

We have identified and cloned a cDNA encoding a new member of the monooxygenase family of enzymes. This novel enzyme, which we call MOX (monooxygenase X; unknown substrate) is a clear sequence homologue of the enzyme dopamine beta-hydroxylase (DBH). MOX maintains many of the structural features of DBH, as evidenced by the retention of most of the disulfide linkages and all of the peptidyl ligands to the active site copper atoms. Unlike DBH, MOX lacks a signal peptide sequence and therefore is unlikely to be a secreted molecule. The steady-state mRNA levels of MOX are highest in the kidney, lung, and adrenal gland, indicating that the tissue distribution of MOX is broader than that of DBH. Antisera raised to a fusion protein of MOX identifies a single band of the expected mobility by Western blot analysis. MOX mRNA levels are elevated in some fibroblast cell strains at replicative senescence, through this regulation is not apparent in all primary cell strains. The gene for MOX resides on the q arm of chromosome 6 and the corresponding mouse homolog has been identified.

[Myasthenia gravis in Santo Tomás Hospital 1990-1997]

Myasthenia Gravis is an infrequent disease. Diagnosis and treatment must be done early to avoid high morbidity that can compromise patients lives. Nine cases were identified during the eight year 1990-1997 at the Santo Tomas Hospital of Panama city but one had to be excluded because he refused treatment. Most of the patients (7/8) had symptoms for more than 3 months. The diagnosis of Myasthenia Gravis requires a high index of suspicion and the clinical impressión must be confirmed by various diagnostic studies that include the edrophonium test, the repetitive stimulation test, the therapeutic test with pyridostigmine, the determination of acetylcholine anti-receptor antibodies and a CT Scan of the thorax. Medical treatment consists mainly of anticholinesterase agents and surgical treatment consists of thymectomy by means of an extended transternal ablation. Operative results were excellent, seven out of eight improved.

Surface characteristics of Ti6Al4V alloy: effect of materials, passivation and autoclaving

The properties of passivated films for Ti6Al4V alloy prepared by various methods (as-polished, brazed at 970 degrees C for 2 h and brazed at 970 degrees C for 8 h) were investigated. Four passivations (non-treated, nitric acid passivation, 400 degrees C-treated in air, and aged in boiling water), with or without autoclaving treatments, were adopted for evaluating the changes of surface properties, including chemical composition, chemical structure, and oxide thickness. From X-ray photoelectron spectroscopic (XPS) analyses, surface elements of copper and nickel in brazed samples were undetected for non-treated, acid-passivated and boiling water-aged specimens, while they were found in the 400 degrees C-treated specimen. The relative contents of Ti2++Ti3+ to Ti4+ were determined by passivation treatments, but were not related to the experimental materials and autoclaving treatment. Passivation and autoclaving decreased the Ti to Ti4+ ratio by virtue of an increase in oxide thickness. Of the four types of passivation treatment, the 400 degrees C thermal treatment exhibited the lowest content of suboxides and metallic elements and the thickest oxide by XPS analysis; however, this treatment may cause a desorption of the basic OH group in the hydration layer on the surface of titanium alloy.

A comparison of the corrosion behaviour and surface characteristics of vacuum-brazed and heat-treated Ti6Al4V alloy

The corrosion characteristics of the brazed Ti6Al4V specimens were analysed and compared with respect to the conventionally heat-treated specimens by an electrochemical corrosion test. The object of this research was to explore the potentiality of the brazed titanium for biomaterials. The characteristics of the 1300 degrees C heat-treated and the 970 degrees C brazed specimens, with passivation and sterilization treatment, were evaluated by measurement of corrosion potential, Ecorr, corrosion current densities, Icorr, polarization resistance of the reacted surface films, Rp, in a potentiodynamic test. The experimental results show that the corrosion rates of the heat-treated and the brazed samples are similar at Ecorr, and the value of Ecorr for the brazed sample is noble to the heat-treated samples. The passive current density of the brazed specimen is either lower or higher than the heat-treated specimen, depending on the polarization potential. By Auger electron spectroscopic and high-resolution X-ray photoelectron spectroscopic analysis on specimens from the potentiostatic test, the elements of copper and nickel in the brazing filler were not detected while less alumina was found in the reacted film of the brazed specimens when compared with the heat-treated specimens. The implication of the results is discussed.

Managing and treating. AIDS-related diarrhea

Diarrhea is a significant problem for most people with AIDS. Its causes are multifactorial, ranging from infectious organisms to malignancies and functional problems. A thorough evaluation will usually determine the etiology and guide treatment. With HAART, dramatic improvements in immune status have caused a decline in opportunistic infections, including those that cause diarrhea. It is a sign of hope for all patients with HIV.

Immunizing against depression and anxiety after spinal cord injury

OBJECTIVE

To further report on the effectiveness of early psychological intervention in reducing anxiety and depressive mood in persons with spinal cord injury 2 years after injury.

DESIGN

A nonrandomized, longitudinal, controlled trial. SETTING, OUTCOME MEASURES, AND INTERVENTION: Twenty-eight spinal cord injured persons participated in group cognitive behavior therapy during hospital rehabilitation. They were assessed for depressive mood and anxiety before, immediately after, and 12 and 24 months after treatment. The intervention group's responses on the measures were compared with a control group of 31 spinal cord injured persons who only received traditional rehabilitation services during their hospitalization.

RESULTS

Subjects in the treatment group with high depression and anxiety scores before treatment were significantly less depressed and reduced their anxiety to a greater extent 2 years after the injury in comparison with similar persons in the control group.

CONCLUSIONS

Group cognitive behavior therapy for spinal cord injured persons who are abnormally depressed and anxious appears to reduce depressive mood and anxiety in the short and long term.

Assessment of prostate cancer volume using endorectal coil magnetic resonance imaging: a new predictor of tumor response to neoadjuvant androgen suppression therapy

OBJECTIVES

A clinical tool that can reliably assess prostate cancer response to androgen suppression is lacking. This pilot study was designed to identify the potential clinical factor(s) that correlate with tumor response after neoadjuvant therapy.

METHODS

Twenty-one patients managed with definitive local therapy and neoadjuvant androgen suppression (median 3 months [range 2 to 7]) between 1995 and 1997 comprise the study population. Fisher's exact test was used to test the significance of the proportion of patients with a given clinical factor and the outcome of pathologic organ-confined disease. The clinical factors tested included preoperative prostate-specific antigen, biopsy Gleason score, clinical stage, months of total androgen suppression, the change in the endorectal magnetic resonance imaging (erMRI)-defined stage, the change in erMRI-defined tumor, and the change in the erMRI-defined prostate volume during neoadjuvant androgen suppression.

RESULTS

All 21 patients had a decrease in the erMRI-determined prostate volume and prostate-specific antigen during androgen suppression, whereas only 10 of 21 (48%) had a reduction in the erMRI-determined tumor volume. There was a statistically significant increased proportion of patients with a decrease in the erMRI-determined tumor volume (P = 0.008) who had pathologic organ-confined disease.

CONCLUSIONS

The results of this pilot study suggest that the changes in the erMRI-determined tumor volume occurring during androgen suppression may be predictive of the tumor response. Validation in a larger prospective study is currently underway.

The effectiveness of group psychological intervention in enhancing perceptions of control following spinal cord injury

OBJECTIVE

This research investigated the effects of a structured psychological intervention, delivered during hospital rehabilitation, on the perceptions of control in people with spinal cord injury (SCI).

METHOD

A longitudinal study was designed to assess perceptions of control (using an objective measure of locus of control) in SCI persons who participated in specialised group cognitive-behavioural therapy (CBT) during hospital rehabilitation. The treatment SCI group's responses on locus of control were compared with a control group of SCI persons who only received traditional rehabilitation services during their hospitalisation.

RESULTS AND CONCLUSIONS

Mean locus of control scores were not high (i.e. external) for both groups and there were no overall group differences on locus of control responses across time in comparison to the control group. However, subjects in both groups who initially perceived life as externally controlled were extracted to form subgroups. The members of the subgroup who received CBT were significantly more likely to feel in control of themselves 2 years post injury compared to similar persons in the control group. Furthermore, an external locus of control was significantly but mildly associated with depressive mood 2 years after the injury. This research suggests that the provision of a structured psychological program in the rehabilitation stage will be beneficial for many SCI persons who feel that they have little control over their lives.

In vitro and in vivo mechanical evaluations of plasma-sprayed hydroxyapatite coatings on titanium implants: the effect of coating characteristics

This study was undertaken to evaluate the effect of coating characteristics on the mechanical strengths of the plasma-sprayed HA-coated Ti-6Al-4V implant system both in vitro and in vivo. Two types of HA coatings (HACs) with quite different microstructures, concentrations of impurity-phases, and indices-of-crystallinity were used. In vitro testings were done by measuring the bonding-strength at the Ti-6Al-4V-HAC interface, with HACs that had and had not been immersed in a pH-buffered, serum-added simulated body fluid (SBF). The shear-strength at the HAC-bone interface was investigated in a canine transcortical femoral model after 12 and 24 weeks of implantation. The results showed a bonding degradation of approximately 32% or higher of the original strength after 4 weeks of immersion in SBF, and this predominantly depended on the constructed microstructure of the HACs. After the push-out measurements, it was demonstrated that the HACs with higher bonding-strength in vitro would correspondingly result in significantly higher shear-strength at each implant period in vivo. Nevertheless, there were no substantial histological variations between the two types of HACs evaluated. The most important point elucidated in this study was that, among coating characteristics, the microstructure was the key factor in influencing the mechanical stability of the HACs both in vitro and in vivo. As a consequence, a denser HAC was needed to ensure mechanical stability at both interfaces.

Promoter attenuation in gene therapy: interferon-gamma and tumor necrosis factor-alpha inhibit transgene expression

One of the major limitations to current gene therapy is the low-level and transient vector gene expression due to poorly defined mechanisms, possibly including promoter attenuation or extinction. Because the application of gene therapy vectors in vivo induces cytokine production through specific or nonspecific immune responses, we hypothesized that cytokine-mediated signals may alter vector gene expression. Our data indicate that the cytokines interferon-gamma (IFN-gamma) and tumor necrosis factor-alpha (TNF-alpha) inhibit transgene expression from certain widely used viral promoters/enhancers (cytomegalovirus, Rous sarcoma virus, simian virus 40, Moloney murine leukemia virus long terminal repeat) delivered by adenoviral, retroviral or plasmid vectors in vitro. A constitutive cellular promoter (beta-actin) is less sensitive to these cytokine effects. Inhibition is at the mRNA level and cytokines do not cause vector DNA degradation, inhibit total cellular protein synthesis, or kill infected/transfected cells. Administration of neutralizing anti-IFN-gamma monoclonal antibody results in enhanced transgene expression in vivo. Thus, standard gene therapy vectors in current use may be improved by altering cytokine-responsive regulatory elements. Determination of the mechanisms involved in cytokine-regulated vector gene expression may improve the understanding of the cellular disposition of vectors for gene transfer and gene therapy.

An allelic association implicates myeloperoxidase in the etiology of acute promyelocytic leukemia

Myeloperoxidase (MPO) catalyzes a reaction between chloride and hydrogen peroxide to generate hypochlorous acid and other reactive compounds that have been linked to DNA damage. The MPO gene is expressed at high levels in normal myeloid precursors and in acute myeloid leukemias (AMLs) which are clonal derivatives of myeloid precursors that have lost the ability to differentiate into mature blood cells. Two MPO alleles differ at -463 G/A within a cluster of nuclear receptor binding sites in an Alu element. The -463 G creates a stronger SP1 binding site and retinoic acid (RA) response element (RARE) in the allele termed Sp. In this study, we investigate potential links between MPO genotype, MPO expression level, and myeloid leukemia. The SpSp MPO genotype is shown to correlate with increased MPO mRNA levels in primary myeloid leukemia cells. This higher-expressing SpSp genotype is further shown to be overrepresented in acute promyelocytic leukemia-M3 (APL-M3) and AML-M4, suggesting that higher levels of MPO are associated with an increased risk for this subset of leukemias.

Comparative gene mapping in the domestic cat (Felis catus)

The genetic map of the domestic cat has been developed as a model for studying both feline analogues of human genetic disease and comparative genome organization of mammals. We present here the results of syntenic mapping of 35 genes based upon concordant occurrence of feline gene homologues with feline chromosomes and previously mapped loci in a panel of 41 rodent x cat somatic cell hybrids. These somatic cell hybrids retain rodent chromosomes and segregate feline chromosomes, but in different combinations in each hybrid cell line. Thirty-three of the 35 new locus assignments extend and reaffirm conserved chromosome segment homologies between the human and cat genomes previously recognized by comparative mapping and zoo-FISH. These results demonstrate the extensive syntenic conservation between the human and feline genomes and extend the feline gene map to include 105 assigned loci.

Association of Grb2 with Sos and Ras with Raf-1 upon gamma irradiation of breast cancer cells

Raf-1 protein serine/threonine kinase has been implicated in growth and damage-responsive signal transduction pathways. Several reports indicate an important role of Ras protein in the growth factor-induced activation of Raf-1. Here we investigated the possible involvement of Ras in ionizing radiation-induced activation of Raf-1. Irradiation of MDA-MB 231 human breast cancer cells caused an increase in GTP-binding and hydrolysis on Ras, and co-immunoprecipitations of endogenous Grb2 with Sos and Raf-1 with Ras. An increase in the level of membrane-bound Raf-1, and tyrosine-phosphorylation of Raf-1 were observed after irradiation. Consistent with these changes, irradiation of cells stimulated the catalytic activity of Raf-1. Finally, radiation treatment of breast cancer cells led to an increase in the phosphorylation and activity of the mitogen-activated protein kinase. Based on these biochemical modifications in vivo, we conclude that Raf-1 functions as an effector of Ras in the radiation-responsive signal transduction pathway leading to the activities of Raf-1 and mitogen-activated protein kinase.

Long-lasting adenovirus transgene expression in mice through neonatal intrathymic tolerance induction without the use of immunosuppression

The major barrier to the clinical application of adenovirus gene therapy for diseases that require stable transgene expression is the immunogenicity of recombinant adenovirus, which ordinarily limits the duration of its effects to a period of about 2 weeks. We postulated that tolerance to adenovirus could be induced and transgene expression could be prolonged if T lymphocytes underwent thymic selection in the presence of adenovirus antigens. Mice were inoculated in the thymus with a recombinant adenovirus containing the lacZ marker gene during the neonatal period at a time before T-cell maturation had occurred. When the virus was administered intravenously to these mice in adulthood, they were found to have an impaired adenovirus-specific cytotoxic T-lymphocyte response which allowed prolonged hepatic lacZ expression, for up to 260 days. The ability to achieve unresponsiveness to a recombinant adenovirus after inoculation of the thymus in neonates extends the paradigm of intrathymic tolerance induction. Furthermore, this model will enable the study of stable adenovirus transgene expression in vivo without the use of immunosuppression and ultimately may have clinical utility.