Immune responses to adeno-associated virus and its recombinant vectors

Recombinant adeno-associated virus (rAAV) vectors have emerged as highly promising for use in gene transfer for a variety of reasons, including lack of pathogenicity and wide host range. In addition, all virus-encoded genes have been removed from standard rAAV vectors, resulting in their comparatively low intrinsic immunogenicity. For gene replacement strategies, transgenes encoded by rAAV vectors may induce less robust host immune responses than other vectors in vivo. However, under appropriate conditions, host immune responses can be generated against rAAV-encoded transgenes, raising the potential for their use in vaccine development. In this review, we summarize current understanding of the generation of both undesirable and beneficial host immune responses directed against rAAV and encoded transgenes, and how they might be exploited for optimal use of this promising vector system.

Removal of Cu and Pb by tartaric acid modified rice husk from aqueous solutions

A study on the modification of rice husk by various carboxylic acids showed that tartaric acid modified rice husk (TARH) had the highest binding capacities for Cu and Pb. The carboxyl groups on the surface of the modified rice husk were primarily responsible for the sorption of metal ions. A series of batch experiments using TARH as the sorbent for the removal of Cu and Pb showed that the sorption process was pH dependent, rapid and exothermic. The sorption process conformed to the Langmuir isotherm with maximum sorption capacities of 29 and 108 mg/g at 27 +/- 2 degrees C for Cu and Pb, respectively. The uptake increased with agitation rate. Decrease in sorbent particle size led to an increase in the sorption of metal ions and this could be explained by an increase in surface area and hence binding sites. Metal uptake was reduced in the presence of competitive cations and chelators. The affinity of TARH for Pb is greater than Cu.

A returned traveller with persistent fever due to murine typhus

Murine (endemic) typhus is a notifiable disease in Hong Kong, but its diagnosis can be difficult. We report a case of murine typhus in a middle-aged man who presented with persistent fever, headache, and skin rash 2 weeks after returning from a visit to China. The diagnosis of murine typhus requires a high index of suspicion for a febrile patient with a history of potential exposure to the disease vector (rat flea) in an endemic area. The importance of early recognition lies in the potential for early therapeutic intervention, leading to decreases in morbidity and duration of stay in hospital.

Immunogenic issues concerning recombinant adeno-associated virus vectors for gene therapy

Recombinant adeno-associated virus (rAAV) vectors have emerged as highly promising for use in gene transfer for a variety of reasons, including lack of pathogenicity and wide host range. In addition, all virus-encoded genes have been removed from standard rAAV vectors, resulting in their comparatively low intrinsic immunogenicity. For gene replacement strategies, transgenes encoded by rAAV vectors may induce less robust host immune responses than other vectors in vivo. However, under appropriate conditions, host immune responses can be generated against rAAV encoded transgenes, raising the potential for their use in vaccine development. In this review, we have summarized current understanding of the generation of both undesirable and beneficial host immune responses directed against rAAV and encoded transgenes, and how they might be exploited for optimal use of this promising vector system.

Selective cytotoxicity of gemcitabine in bladder cancer cell lines

We have examined the cytotoxic effect of gemcitabine in intravesical therapy using an in vitro co-cultured spheroid model composed of transitional cell carcinoma (TCC) and fibroblasts from both human and rat species. Immunohistochemistry analysis of the co-cultured spheroids, using cytokeratin-13 and vimentin antibodies against TCC and fibroblasts, respectively, showed the central location of fibroblasts within the spheroid, whereas TCC formed the peripheral layers. Spheroids composed of human TCC and fibroblasts (MGH-U3/CRL-1120 or RT-112/CRL-1120) as well as rat TCC and their corresponding fibroblasts (AY-27/RF-Ed1) displayed the same drug tolerance profile after an exposure of 0, 1, 3, 5, 7 and 14 days. As confirmed by time-lapse photography, MTT essay and vital dye staining, gemcitabine selectively killed the human and rat bladder cancer cell lines, but did not affect un-transformed human and rat fibroblast lines.

Immunogenicity of a p210(BCR-ABL) fusion domain candidate DNA vaccine targeted to dendritic cells by a recombinant adeno-associated virus vector in vitro

Chronic myelogenous leukemia (CML) is characterized by a t(9;22) translocation, which results in the expression of chimeric BCR-ABL fusion oncoproteins that are necessary for oncogenesis, unique to the leukemic clones, and represent enticing targets for immunotherapy. As a strategy for the immunotherapy of CML, we constructed a recombinant adeno-associated virus vector encoding the p210(BCR-ABL) b3a2 variant fusion region with flanking sequences (CWRBA) and used it to express the BCR-ABL fusion region within primary human dendritic cells (DCs), the most potent antigen-presenting cells currently known. Peripheral blood mononuclear cells from healthy donors were primed and restimulated in vitro with autologous DCs transduced with purified CWRBA, CWRAP (negative control), or pulsed with a peptide corresponding to the fusion domain (positive control). No specific responses were generated using DCs transduced with CWRAP. In contrast, CWRBA-transduced DCs primed autologous T cells in an antigen-specific, MHC-restricted fashion to levels comparable with the positive control. CWRBA-transduced DCs elicited both cytotoxic CD4+/Th1 and CD8+ responses, although the former were more readily detected in this system. Cytotoxicity against a tumor cell line endogenously expressing the p210(BCR-ABL) b3a2 variant fusion region was also demonstrable. In addition, HLA-DRB5(*)0101+DRA (DR2a) was identified as a new restriction element capable of presenting the b3a2 BCR-ABL fusion region epitope. Thus, the construct developed herein may serve as a candidate vaccine for gene-based antigen-specific immunotherapy of CML and may serve as a paradigm for the use of DCs transduced with recombinant adeno-associated virus vectors encoding multiepitope immunogens for vaccine development.

Prevalence of snoring and sleep-disordered breathing in a group of commercial bus drivers in Hong Kong

OBJECTIVES

To assess the prevalence of sleep-disordered breathing (SDB) and its associated symptoms in a group of commercial bus drivers in Hong Kong.

METHODS

Two hundred and sixteen of 410 bus drivers from three different shifts were interviewed with the Sleep & Health Questionnaire (SHQ) and the Epworth sleepiness scale (ESS) at a Hong Kong bus depot. Seventeen subjects from each shift were then randomly selected for at-home sleep study using the Mesam IV device (Madaus Medizin-Elektronik, Freiburg, Germany).

RESULTS

There were 207 men and nine women (mean age 42.4 +/- 7.5 years; body mass index (BMI) 25.4 +/- 4.5 kg/m2; ESS 5.3 +/- 4.2). From the SHQ it was discovered that: (i) daytime sleepiness was reported by 87 subjects (40%), (ii) snoring > or = 3 times per week was reported by 80 subjects (37%), (iii) witnessed apnoea was reported by 17 subjects (7.9%) and (iv) 29 subjects (13.4%) reported having fallen asleep during driving. Among the 51 subjects who underwent the at-home sleep study: (i) 31 subjects (61%) had respiratory disturbance index (RDI) > or = 5 per hour of sleep, (ii) 21 subjects (41%) had RDI > or = 10 per hour of sleep, (iii) 12 subjects (24%) had RDI > or = 15 per hour of sleep and (iv) 35 subjects (68.6%) snored objectively > or = 10% of the night. Ten subjects (20%) had RDI > or = 5 and sleepiness at work, while five subjects (9.8%) had RDI > or = 5 and ESS > 10. No significant differences were noted in the SHQ responses, ESS, objective snoring or RDI among the three groups. Multiple regression analysis showed that BMI and witnessed apnoea were the only positive independent predictors of RDI.

CONCLUSIONS

This study showed a high prevalence of objective snoring and SDB in a group of commercial bus drivers. Neither self-reported sleepiness nor the ESS could identify subjects with SDB.

Determinants of continuous positive airway pressure compliance in a group of Chinese patients with obstructive sleep apnea

OBJECTIVE

To assess continuous positive airway pressure (CPAP) compliance and factors associated with CPAP compliance among Chinese patients with obstructive sleep apnea (OSA).

DESIGN

A prospective study of 112 consecutive patients with newly diagnosed OSA commencing CPAP treatment.

SETTING

A university teaching hospital.

MEASUREMENTS AND RESULTS

The following factors were evaluated for any correlation with objective CPAP compliance (effective mask pressure [hours per day]) at 1 month and 3 months: age, baseline apnea-hypopnea index (AHI), common OSA symptoms, minimum arterial oxygen saturation (SaO(2)), mean SaO(2), arousal index (AI), Epworth sleepiness scale (ESS), education level, CPAP levels, satisfaction with CPAP, side effects, and machine cost. There were 101 male and 11 female patients, with a mean (+/- SD) age of 45.6 +/- 1.2 years; body mass index, 29.3 +/- 5.2 kg/m(2); AI, 60 +/- 18/h; AHI, 48 +/- 24/h; minimum SaO(2) of 70 +/- 17%; and mean SaO(2) of 86 +/- 7%. ESS fell from 12.9 +/- 4.0 (baseline) to 5.2 +/- 4.7 at 3 months (p < 0.001). Objective CPAP compliance was 5.4 +/- 1.6 h/d and 5.3 +/- 1.6 h/d, while 75% and 72% of our patients were using CPAP objectively for > or = 4 h/d and at least 70% of the nights per week at 1 month and 3 months, respectively. Following univariate analysis of variance, a high baseline AHI (p = 0.006 and p = 0.004) was associated with higher objective CPAP compliance at 1 month and 3 months, respectively.

CONCLUSION

CPAP usage and compliance were high in this patient population. A high baseline AHI was the only significant independent predictor of better CPAP compliance.

92% pump depletion in a continuous-wave one-pump fiber optical parametric amplifier

Theory shows that near-complete pump depletion can be obtained in uniform fiber-optic parametric amplifiers (OPA's) for a particular phase-matching condition. We have demonstrated 92% pump depletion in a cw fiber OPA, with a 200-mW pump at 1560 nm in an 11-km-long dispersion-shifted fiber.

Inactivation of pyruvate formate-lyase by dioxygen: defining the mechanistic interplay of glycine 734 and cysteine 419 by rapid freeze-quench EPR

Pyruvate formate-lyase from Escherichia coli (EC 2.3.1.54; PFL) catalyzes the reversible anaerobic conversion of pyruvate and CoA into acetyl-CoA and formate. Active PFL contains a novel alpha-carbon centered glycyl radical at G734 that is required for its catalytic activity. Two adjacent cysteine residues, C418 and C419, are essential for PFL activity according to site-directed mutagenesis studies. Upon exposure to air, active PFL loses its activity with the concomitant loss of the glycyl radical. Previous EPR studies of dioxygen inactivation of PFL revealed protein-based peroxyl and sulfinyl radicals during the manual mixing and quenching process [Reddy et al. (1998) Biochemistry 37, 558-563]. To probe the mechanism of this process, we carried out experiments using rapid freeze-quench EPR spectroscopy. Upon mixing of active wild type or C418A PFL with oxygenated solution, a short-lived radical intermediate appears at the earliest time point (10 ms), followed by the appearance of a long-lived sulfinyl radical. The axial EPR spectrum of this short-lived radical (g = 2.034, 2.007) is characteristic of a peroxyl radical. When C419A PFL or the double mutant [C418A/C419A] PFL was mixed with oxygenated solution, the peroxyl radical was also observed at 10 ms but in this case persisted over 12 s. These observations provide compelling evidence to support a proposed mechanism in which dioxygen quenches the glycyl radical in the active enzyme and the resulting peroxyl radical may react further with the sulfhydryl group of the C419 residue to form the sulfinyl radical.

Identification of differentially expressed genes from ovarian cancer cells by MICROMAX cDNA microarray system

Using the MICROMAX cDNA microarray system, we were able to identify genes that are differentially overexpressed in ovarian cancer. A total of 30 putative genes, which are differentially overexpressed in ovarian cancer cell lines, were identified. The differential expression of some of these genes was further confirmed by real-time RT-PCR. Using this strategy, we have identified genes that either overexpress in all cancer cell lines or in only some cancer cell lines. Further characterization of these genes will allow them to be exploited in diagnosis, prognosis, anticancer therapy, and molecular classification of ovarian cancer.

Urea reduction ratio that considers effects of ultrafiltration and intradialytic urea generation

We modified the urea reduction ratio (URR) equation to correct the effects of ultrafiltration and intradialytic urea generation on the delivered dose of hemodialysis: mURR = [1 - (R/1 + 2*UF/BW) + 0.01*t] x 100% where mURR is modified URR, R is postdialysis plasma urea nitrogen (PUN) to predialysis PUN ratio, UF is ultrafiltrate volume in liters, BW is postdialysis body weight in kilograms, and t is dialysis session length in hours. The equation was validated against 145 hemodialysis treatments on 33 stable maintenance dialysis patients. The mURR values obtained closely predicted single-pool Kt/V (spKt/V) values. In contrast to conventional URR, the range of spKt/V values at each mURR value is narrow over a wide range of UF, t, and R values. Based on the mURR equation, mURR values of 64%, 70%, and 76% are mathematically equivalent to spKt/V levels of 1.0, 1.2, and 1.4, respectively. This equation can be a useful bedside tool to quantify hemodialysis dose.

Evaluation of a structural model of Pseudomonas aeruginosa outer membrane protein OprM, an efflux component involved in intrinsic antibiotic resistance

The outer membrane protein OprM of Pseudomonas aeruginosa is involved in intrinsic and mutational multiple-antibiotic resistance as part of two resistance-nodulation-division efflux systems. The crystal structure of TolC, a homologous protein in Escherichia coli, was recently published (V. Koronakis, A. Sharff, E. Koronakis, B. Luisl, and C. Hughes, Nature 405:914-919, 2000), demonstrating a distinctive architecture comprising outer membrane beta-barrel and periplasmic helical-barrel structures, which assemble differently from the common beta-barrel-only conformation of porins. Based on their sequence similarity, a similar content of alpha-helical and beta-sheet structure determined by circular dichroism spectroscopy, and our observation that OprM, like TolC, reconstitutes channels in planar bilayer membranes, OprM and TolC were considered to be structurally homologous, and a model of OprM was constructed by threading its sequence to the TolC crystal structure. Residues thought to be important for the TolC structure were conserved in space in this OprM model. Analyses of deletion mutants and previously isolated insertion mutants of OprM in the context of this model allowed us to propose roles for different protein domains. Our data indicate that the helical barrel of the protein is critical for both the function and the integrity of the protein, while a C-terminal domain localized around the equatorial plane of this helical barrel is dispensable. Extracellular loops appear to play a lesser role in substrate specificity for this efflux protein compared to classical porins, and there appears to be a correlation between the change in antimicrobial activity for OprM mutants and the pore size. Our model and channel formation studies support the "iris" mechanism of action for TolC and permit us now to form more focused hypotheses about the functional domains of OprM and its related family of efflux proteins.

A case of alpha-fetoprotein-producing gastric cancer

INTRODUCTION

A case of alpha-fetoprotein (AFP)-producing gastric cancer is described in a 57-year-old Chinese woman.

CLINICAL PICTURE

She presented with bleeding tendency and bone pain, and was found to have haematological evidence of disseminated intravascular coagulation and spinal metastasis. Her tumour markers, including AFP, Ca 19-9 and carcinoembryonic antigen (CEA) were elevated. In view of the elevated tumour markers, there was an exhaustive search for a primary lesion in the gastrointestinal tract, liver and ovaries. There was no radiological evidence to suggest any lesion in the chest, liver or pelvis. Lectin affinity electrophoresis of the AFP showed AFP-L2 and AFP-L3 bands, which are suggestive of a non-hepatoma malignancy.

MANAGEMENT

Gastroscopy showed a gastric ulcer and she developed bleeding after the gastric biopsy which required urgent surgery. Intraoperatively she was found to have carcinomatous peritone and a malignant ulcer in the greater curve of the stomach. Histology confirmed a linitis plastica like adenocarcinoma which stains for AFP.

OUTCOME

She died from multi-organ failure 3 days after surgery.

CONCLUSION

AFP-producing adenocarcinoma of the stomach is not uncommon. Lectin affinity electrophoresis of AFP is helpful in the differentiation between hepatoma and non-hepatoma malignancies.

Middle ear effusions after radiotherapy: correlation with pre-radiotherapy nasopharyngeal tumor patterns

OBJECTIVE

The purpose of this study was to assess whether pretreatment tumor patterns of nasopharyngeal carcinoma (NPC) can predict the status of the middle ear after radiation treatment.

MATERIALS AND METHODS

Pretreatment and follow-up magnetic resonance imaging (MRI) was performed in 32 patients (64 ears) who had radiation therapy for NPC. For the purpose of analysis, the ears were placed into their pre-radiation therapy tumor pattern groups and the presence of middle ear effusion (MEE) with regard to eustachian tube (ET) invasion or displacement was identified.

RESULTS

MEEs were present in 31 (48.4%) ears after radiation therapy. All of the MEEs that resolved were in the preradiation therapy groups where tumor invasion of the eustachian tube was present irrespective of the amount of ET displacement. There was, however, no significant difference for resolved MEEs between ears with ET invasion or displacement (p = 0.32 and p = 0.71, respectively, Fisher's exact test). The MEEs occurred with significantly greater frequency in ears with minor ET displacement than in those with major ET displacement (p = 0.013, Fisher's exact test) as well as in previously normal ears compared with other groups (p = 0.008, Mann-Whitney U test).

CONCLUSION

A pre-radiation therapy NPC tumor pattern was not found that clearly predicted the outcome of MEE after radiation treatment. The findings, however, suggest that approximately one third of MEEs in patients with invasion of ET or paratubal structures, irrespective of the amount of ET displacement, resolve after therapy. The MEEs that were present in ears with ET displacement and no invasion did not resolve despite reversal of the displacement after treatment, which suggests that ET position plays a less important role than invasion in the resolution of MEE. It is, however, difficult to be certain, because ears with invasion were invariably associated with ET displacement, and the contribution of radiation therapy to the development of MEE further complicates the issue.

Enzymatic treatment of mechanical pulp fibers for improving papermaking properties

Three enzyme preparations (crude cellulase, laccase, and proteinase) were evaluated for their potential to improve the papermaking properties of mechanical pulp. After treating a long fibre-rich fraction of the pulp with enzyme, the fibres were recombined with untreated fines for handsheet making and testing. None of the enzymes altered the retention of fines or the consolidation of the furnish mix during handsheet formation. All three enzymes increased tensile stiffness index, which is a measure of the initial resistance of the handsheets to strain. Only the laccase preparation, an enzyme that modifies pulp lignin, consistently increased fibre bonding to enhance other strength properties of the handsheets.

Prevalence of sleep disturbances in chinese patients with end-stage renal failure on continuous ambulatory peritoneal dialysis

Patients with end-stage renal failure (ESRF) are reported to have a high prevalence of sleep disorders, such as daytime sleepiness, insomnia, restless legs syndrome (RLS), and obstructive sleep apnea syndrome (OSAS). However, there are few published data from Southeast Asia. A sleep questionnaire was administered to 201 patients (103 men) at the continuous ambulatory peritoneal dialysis (CAPD) outpatient clinic to assess sleep problems. Patients had a mean age of 56.7 +/- 12 (SD) years, with a mean body mass index (BMI) of 23.6 +/- 3.5 kg/m(2). Daytime sleepiness was the most frequent symptom (77.1%), and frequent awakening occurred in 69% of the patients. Sleep-onset insomnia and sleep-maintenance insomnia occurred in 73% and 60% of the patients, respectively. Sixty-two percent of the patients reported symptoms of RLS, which significantly correlated with sleep-onset insomnia (odds ratio [OR], 2.9; 95% confidence interval [CI], 1.5 to 5.5; P = 0.001) and sleep-maintenance insomnia (OR, 2.1; 95% CI, 1.2 to 3.8; P = 0.014). The prevalence of OSAS was estimated by the frequency of the following symptoms: extremely loud snoring, 7 patients (3.5%); observed choking, 21 patients (10.5%); witnessed apnea, 11 patients (5.6%); snoring and witnessed apnea, 6 patients (3%); disruptive snoring, 29 patients (14.4%); and disruptive snoring and witnessed apnea, 3 patients (1.5%). This questionnaire survey confirmed a high prevalence of daytime sleepiness, insomnia, and RLS in patients with ESRF undergoing CAPD but showed a relatively low prevalence of OSAS of up to 14.4%, which may be related to the low BMI of these patients with ESRF compared with other populations. Whether this contributes to the overall better survival observed in some Asian patients with ESRF undergoing dialysis needs further investigation.

Substituted 2-aminopyridines as inhibitors of nitric oxide synthases

A series of substituted 2-aminopyridines was prepared and evaluated as inhibitors of human nitric oxide synthases (NOS). 4,6-Disubstitution enhanced both potency and specificity for the inducible NOS with the most potent compound having an IC50 of 28 nM.

Telomere dysfunction impairs DNA repair and enhances sensitivity to ionizing radiation

Telomeres are specialized nucleoprotein complexes that serve as protective caps of linear eukaryotic chromosomes. Loss of telomere function is associated with rampant genetic instability and loss of cellular viability and renewal potential. The telomere also participates in processes of chromosomal repair, as evidenced by the 'capture' or de novo synthesis of telomere repeats at double-stranded breaks and by the capacity of yeast telomeres to serve as repositories of essential components of the DNA repair machinery, particularly those involved in non-homologous end-joining (NHEJ). Here we used the telomerase-deficient mouse, null for the essential telomerase RNA gene (Terc), to assess the role of telomerase and telomere function on the cellular and organismal response to ionizing radiation. Although the loss of telomerase activity per se had no discernable impact on the response to ionizing radiation, the emergence of telomere dysfunction in late-generation Terc-/- mice imparted a radiosensitivity syndrome associated with accelerated mortality. On the cellular level, the gastrointestinal crypt stem cells and primary thymocytes showed increased rates of apoptosis, and mouse embryonic fibroblasts (MEFs) showed diminished dose-dependent clonogenic survival. The radiosensitivity of telomere dysfunctional cells correlated with delayed DNA break repair kinetics, persistent chromosomal breaks and cytogenetic profiles characterized by complex chromosomal aberrations and massive fragmentation. Our findings establish a intimate relationship between functionally intact telomeres and the genomic, cellular and organismal response to ionizing radiation.

Use of a peripherally implanted subcutaneous permanent central venous access device for chemotherapy--the Singapore General Hospital experience

BACKGROUND

Venous access for chemotherapy patients at the Singapore General Hospital has conventionally been via an externalised (Hickman) catheter. A peripherally implanted permanent subcutaneous central venous access device (P.A.S.Port) was introduced in 1996.

AIMS

We review its use, complications and cost competitiveness with other chemotherapy delivery systems.

METHODS

A retrospective study of clinical records was conducted with follow up interviews of patients and nursing staff.

RESULTS

Twelve patients had the P.A.S.Port inserted for administration of chemotherapy as an outpatient procedure. Immediate complications were pain (8%) and bruising (8%). One port-related infection (8%) one week following insertion was reported and one patient complained of interference with elbow movement as a late complication. Cost analysis was favourable for P.A.S.Port over an externalised Hickman catheter or chest-placed port at one year. Patient and nursing staff acceptance was high.

CONCLUSION

P.A.S.Port insertion is a safe outpatient procedure and is an alternative for permanent venous access.

Autologous stem-cell transplantation for poor-risk and relapsed intermediate- and high-grade non-Hodgkin's lymphoma

The primary objective of this study was to evaluate the outcome of patients treated with high-dose chemo-/radiotherapy or high-dose chemotherapy and autologous stem-cell transplant (ASCT) for relapsed, refractory, or poor-risk intermediate-grade (IG) and high-grade (HG) non-Hodgkin's lymphoma (NHL). The secondary objectives were to determine prognostic factors for relapse and survival. Between February 1987 and August 1998, 264 patients, 169 (64%) IG and 95 (36%) HG, underwent high-dose therapy and ASCT at City of Hope National Medical Center (COHNMC). There were 157 (59%) males and 107 (41%) females with a median age of 44 years (range, 5-69 years). The median number of prior chemotherapy regimens was 2 (range, 1-4), and 71 (27%) had received prior radiation as part of induction or as salvage therapy. The median time from diagnosis to ASCT was 10.8 months (range, 3-158 months). Ninety-four patients (36%) underwent transplantation in first complete/partial remission (CR/PR), 40 (15%) in induction failure, and 130 (49%) in relapse or subsequent remission. Two preparative regimens were used: total body irradiation/high-dose etoposide/cyclophosphamide (TBI/VP/CY) in 208 patients (79%) and carmustine/etoposide/cyclophosphamide (BCNU/VP/CY) in 56 patients (21%). One hundred sixty-three patients (62%) received peripheral blood stem cells (PBSC) and 101 (38%) received bone marrow (BM) alone or BM plus PBSC. At a median follow-up of 4.43 years for surviving patients (range, 1-12.8 years), the 5-year Kaplan-Meier estimates of probability of overall survival (OS), progression-free survival (PFS), and relapse for all patients are 55% (95% confidence interval [CI]: 49%-61%), 47% (95% CI: 40%-53%), and 47% (95% CI: 40%-54%), respectively. There were 27 deaths (10%) from nonrelapse mortality, including seven (3%) patients who developed second malignancies (five with myelodysplasia/acute myelogenous leukemia and two with solid tumors). By stepwise Cox regression analysis, disease status at ASCT was the only prognostic factor that predicted for both relapse and survival. The 5-year probability of PFS for patients transplanted in first CR/PR was 73% (95% CI: 62%-81%) as compared to 30% (95% CI: 16%-45%) for induction failure and 34% (95% CI: 26%-42%) for relapsed patients. Our results further support the role of high-dose therapy and ASCT during first CR/PR for patients with poor-risk intermediate- and high-grade NHL. Early transplant is recommended for patients failing initial induction therapy or relapsing after chemotherapy-induced remission. Relapse continues to be the most common cause of treatment failure. An alternative approach to prevent relapse, the incorporation of radioimmunotherapy into the high-dose regimen, is being investigated. The development of a second malignancy is a serious complication of high-dose therapy, which requires close surveillance.

Insertion mutagenesis and membrane topology model of the Pseudomonas aeruginosa outer membrane protein OprM

Pseudomonas aeruginosa OprM is a protein involved in multiple-antibiotic resistance as the outer membrane component for the MexA-MexB-OprM efflux system. Planar lipid bilayer experiments showed that OprM had channel-forming activity with an average single-channel conductance of only about 80 pS in 1 M KCl. The gene encoding OprM was subjected to insertion mutagenesis by cloning of a foreign epitope from the circumsporozoite form of the malarial parasite Plasmodium falciparum into 11 sites. In Escherichia coli, 8 of the 11 insertion mutant genes expressed proteins at levels comparable to those obtained with the wild-type gene and the inserted malarial epitopes were surface accessible as assessed by indirect immunofluorescence. When moved to a P. aeruginosa OprM-deficient strain, seven of the insertion mutant genes expressed proteins at variable levels comparable to that of wild-type OprM and three of these reconstituted MIC profiles resembling those of the wild-type protein, while the other mutant forms showed variable MIC results. Utilizing the data from these experiments, in conjunction with multiple sequence alignments and structure predictions, an OprM topology model with 16 beta strands was proposed.