A phase I/II study of imatinib plus reinduction therapy for c-kit-positive relapsed/refractory acute myeloid leukemia: inhibition of Akt activation correlates with complete response

This phase I/II study evaluated imatinib as a c-kit inhibitor combined with mitoxantrone, etoposide and cytarabine therapy for patients with primary refractory or relapsed c-kit+ acute myeloid leukemia (AML). Imatinib was escalated through three dose levels in successive six patient cohorts. The combination was well tolerated up to 400 mg/day imatinib. Of 21 patients treated at this dose, 13 (62%) achieved complete response (CR), 7 (33%) were non-responders and one died during induction. The CR rate was 80% in patients with standard-risk karyotype versus 33% in patients with adverse karyotype. The CR rate for primary non-responders was 6/14 (43%) versus 7/7 (100%) for relapsed patients. AML blasts from peripheral blood were assayed for phosphorylated Akt (pAkt) and phosphorylated ERK (pERK) by flow cytometry before to and after imatinib dosing. Of eight patients achieving CR with reinduction, seven demonstrated marked (≥60%) pAkt inhibition with imatinib therapy. In contrast, all the six non-responders to reinduction demonstrated <60% pAkt inhibition (P=0.005). There was no correlation between pERK inhibition and response to therapy. These results indicate that lack of pAkt inhibition in vivo is associated with resistance to reinduction therapy using this regimen. Further studies using agents that are able to inhibit Akt more effectively are warranted.

Permanent genetic resources added to Molecular Ecology Resources Database 1 October 2010-30 November 2010

This article documents the addition of 277 microsatellite marker loci to the Molecular Ecology Resources Database. Loci were developed for the following species: Ascochyta rabiei, Cambarellus chapalanus, Chionodraco hamatus, Coptis omeiensis, Cynoscion nebulosus, Daphnia magna, Gerbillus nigeriae, Isurus oxyrinchus, Lates calcarifer, Metacarcinus magister, Oplegnathus fasciatus, Pachycondyla verenae, Phaethon lepturus, Pimelodus grosskopfii, Rotylenchulus reniformis, Scomberomorus niphonius, Sepia esculenta, Terapon jarbua, Teratosphaeria cryptica and Thunnus obesus. These loci were cross-tested on the following species: Austropotamobius italicus, Cambarellus montezumae, Cambarellus puer, Cambarellus shufeldtii, Cambarellus texanus, Chionodraco myersi, Chionodraco rastrospinosus, Coptis chinensis, Coptis chinensis var. brevisepala, Coptis deltoidea, Coptis teeta, Orconectes virilis, Pacifastacus leniusculus, Pimelodus bochii, Procambarus clarkii, Pseudopimelodus bufonius, Rhamdia quelen, Sepia andreana, Sepiella maindroni, Thunnus alalunga, Thunnus albacares, Thunnus maccoyii, Thunnus orientalis, Thunnus thynnus and Thunnus tonggol.

Results from phase Ib studies of PX-12, a thioredoxin inhibitor in patients with advanced solid malignancies

2571

Background: PX-12, a small-molecule inhibitor of Thioredoxin-1 (Trx-1) stimulates apoptosis, down-regulates HIF- 1α, VEGF in animal models. High levels of Trx-1 have been linked to chemoresistance in lung cancers. The phase 2 dose of PX-12 was 226 mg/m2 given by 3-h infusion IV x 5 days, q 21d (Ramanathan RK et al. CCR 13; 2109; 2007). Two Phase 1b trials of PX-12 in patients with advanced solid tumors have been completed to determine the safety, tolerability and optimal biologic dose when delivered by prolonged infusion. Methods: PX-12 was administered as a 24-h infusion every q7- 14d starting at 150 mg/m2/day (n=18); or a 72-h infusion q 21d, starting at 300 mg/m2/day (n=14) using a portable delivery pump. Results: Both the 24- or 72-h infusion of PX-12 were well tolerated in patients at doses up to 400 mg/m2/day. Common grade 1/2 AE's included fatigue, taste alteration, and odor caused by expired drug metabolite. In the 24 h study the maximal dose evaluated was 450 mg/m2. No DLTs were observed in this study. Since no MTD was reached on 24-h infusion up to 450 mg/m2 dose level, additional higher doses were explored utilizing 72-h infusion. DLT in the 72-h study at the highest dose administered (500 mg/m2/day) included reversible hypoxia with or without pneumonitis. Best response was stable disease in 3 pts (SD): liver cancer and colon cancer (24-h infusion) and rectal cancer (72-h infusion). Pharmacodynamics (PD): PX- 12 lowered circulating Trx-1 levels in patients who had starting Trx-1 levels 3-fold greater than that of the normal population (5.4 ng/mL) including all three SD. Circulating VEGF and FGF-2 levels were also lowered over multiple courses of treatment in these patients. The pharmacokinetics of PX-12 showed a dose dependent increase of Cmax and no accumulation over multiple cycles following a 24 h infusion. Conclusions: Dosing at 400 mg/m2/day appears safe and tolerable as a 24–72-h infusion. Extending the infusion time to 72h appears to decrease the intensity of cough and odor compared to bolus 1–3 h infusion. The PD effect produced by PX-12 was apparent only in those patients with elevated plasma Trx-1 levels. Patients with elevated TRX-1 levels appear to have the best probability of having SD. Supported by ProlX Pharmaceuticals/Oncothyreon through an award from the NCI.

[Table: see text]

Preliminary analysis of length and GC content variation in the ribosomal first internal transcribed spacer (ITS1) of marine animals

Length and guanine-cytosine (GC) content of the ribosomal first internal transcribed spacer (ITS1) were compared across a wide variety of marine animal species, and its phylogenetic utility was investigated. From a total of 773 individuals representing 599 species, we only failed to amplify the ITS1 sequence from 87 individuals by polymerase chain reaction with universal ITS1 primers. No species was found to have an ITS1 region shorter than 100 bp. In general, the ITS1 sequences of vertebrates were longer (318 to 2,318 bp) and richer in GC content (56.8% to 78%) than those of invertebrates (117 to 1,613 bp and 35.8% to 71.3%, respectively). Specifically, gelatinous animals (Cnidaria and Ctenophora) were observed to have short ITS1 sequences (118 to 422 bp) with lower GC content (35.8% to 61.7%) than the other animal taxa. Mollusca and Crustacea were diverse groups with respect to ITS1 length, ranging from 108 to 1,118 and 182 to 1,613 bp, respectively. No universal relationship between length and GC content was observed. Our data indicated that ITS1 has a limited utility for phylogenetic analysis as obtaining confident sequence alignment was often impossible between different genera of the same family and even between congeneric species.

Lack of correlation of the health assessment questionnaire disability index with lung parameters in systemic sclerosis associated pulmonary arterial hypertension

OBJECTIVE

Pulmonary arterial hypertension (PAH) affects the quality of life (QoL) and the ability to perform the activities of daily living (ADLs) in patients with systemic sclerosis (SSc). We determined whether the Health Assessment Questionnaire-Disability Index (HAQ-DI), a self-assessment measure of function, correlates with a patient's PAH status in a population of SSc patients with PAH.

METHODS

Forty-one patients from one centre with systemic scleroderma, dyspnea and PAH were included. All patients filled in a HAQ-DI, and underwent evaluation with pulmonary function tests (PFTs), 6-minute walk distance (6MWD), degree of dyspnea (Borg dyspnea index), NYHA functional class, and expert PAH physician global assessment every 6 months. Change in HAQ DI was studied to determine relationship to changes in PAH.

RESULTS

The HAQ-DI scores had no significant correlation with PAH, including NYHA functional class (r=0.38, p=0.39), Borg dyspnea index (r=0.60, p=0.37), 6MWD (r=-0.04, p=0.86), % predicted DLCO (r=0.31, p=0.25), % predicted FVC (r=0.02, p=0.93), and expert PAH physician global assessment (r=0.06, p=0.97).

CONCLUSION

HAQ-DI is not an adequate measure of PAH status in SSc patients with PAH. Although PAH causes severe morbidity and death, changes in PAH severity were not reflected in an overall functional status change as assessed by the HAQ-DI. Thus, HAQ-DI changes do not reflect PAH status in SSc.

Flow cytometric measurement of intracellular pH

A number of fundamentally important biological processes, such as cell signaling and the initiation of mitosis, are accompanied by a change in intracellular pH. Flow cytometric measurement of pH is a generally straightforward procedure that can be done with any instrument equipped with a 488-nm argon laser. The overall approach is similar to that for calcium: generation of a calibration curve by imparting known changes in pH and interpolation of the test sample pH. This unit presents the traditional calibration method using high-potassium buffers and the proton ionophore nigericin and a more recently developed technique, the pseudo null method, which involves resuspension of cells in defined mixtures of weak acids and weak bases.

Women with Her2 unamplified but chromosome 17 hyperploid metatstatic breast cancer (MBC) respond to traztuzumab

21051

Background: Guidelines for the interpretation of Her2 testing by FISH in determining therapy for Her2 positive metatstatic breast cancer generally suggest that only women with Her2 to chromosome 17 (CEP 17) amplification ratios of greater than 2.0 will benefit from traztuzumab. However, hyperploidy of chromosome 17 may lead to increased Her2 copy number despite a normal HER2/CEP 17 ratio, which may also predict response. We sought to examine hyperploid frequency in a well defined Her2 positive MBC population. We also sought to determine the time to progression (TTP) on first chemotherapy for MBC in such women, as well as their overall survival (OS) with MBC. Methods: A tissue mircoarray (TMA) with 3-fold redundancy was constructed using 0.6mm cores from primary or metatstatic paraffin embedded tumor from 124 cases which were Her2 2+ or 3+ by IHC, or amplified by FISH, on pathology report. Four micron thick TMA sections were used for HER2 IHC and HER2 FISH analysis. HER2/CEP 17 ratios of 2.0 or more was considered as amplification. If the tumor was 2+ or 3+ by IHC, greater than or equal to 3 signals for chromosome 17 were seen in a majority of cell nuclei, and the HER2/CEP17 ratio was less than 2.0, the tumor was considered hyperploid Her2 FISH negative. Results: Tissue blocks from 52 tumors delivered clearly interpretable amplification for Her2 by FISH. An additional 10 tumors (8%) were hyperploid, IHC positive (2+ or 3+), and FISH negative. Median survival (Kaplan-Meier) was 39 months (95% CI, 21–62) for women with hyperploid FISH negative tumors and 41 months (95% CI, 25–53) for women with FISH positive tumors (p=0.63, NS, Wilcoxon). Median time to progression (Kaplan-Meier) on first therapy for metastatic disease was 14 months (95% CI, 8–20) for hyperploid FISH negative tumors and 15 months (95% CI, 12–18) for women with FISH positive tumors (p=0.41, NS, Wilcoxon). Conclusions: In this analysis, women with hyperploid Her2 FISH negative IHC positive tumors had similar TTP and OS as women with Her2 FISH positive tumors. These women, although Her2 FISH negative, appeared to respond well to traztuzumab. These provocative results should be repeated on larger data sets.

No significant financial relationships to disclose.

Topoisomerase II-alpha (TOP2A) gene co-amplification does not predict response to therapy and survival in Her-2 neu positive metastatic breast cancer

21108

Background: Preliminary data from a phase III trial of adjuvant traztuzumab (BCIRG, SABCS 2005, abstract 1045) suggested that co-amplification of the genes for HER2 and topisomerase II alpha (TOP2A) on chromosome 17 resulted in improved disease free survival with chemotherapy regimens containing both and anthracycline and traztuzumab. We sought to determine if co-amplification of HER2 and TOP2A was a predictor of response and benefit (or lack thereof) to herceptin containing chemotherapy in the metastatic setting, since few women receive both therapies concurrently for MBC. Methods: A tissue mircoarray (TMA) with 3-fold redundancy was constructed using 0.6mm cores from primary or metatstatic paraffin embedded tumor from 124 cases from Magee-Women's Hospital which were Her2 2+ or 3+ by IHC, or amplified by FISH, on pathology report. Four micron thick TMA sections were used for HER2 immunohistochemical (CB11 monoclonal antibody, Ventana Medical Systems, Tucson, AZ) and HER2 and TOP2A FISH analysis (HER2/CEP 17 and TOP2A/CEP 17 dual color probes from Vysis Inc. Downers Grove, IL). HER2 (or TOP2A) gene to chromosome 17 ratios of 2.0 or more was considered as amplification. Results: Tissue blocks from 52 tumors delivered clearly interpretable amplification for Her2 by FISH on reanalysis. The remaining 72 tumors are undergoing further reanalysis. Of the 52 tumors with Her2 amplification, 15 (29%) had co- amplification of TOP2A. Median survival was 44 months (95% CI, 31–69) for women with TOP2A coamplified tumors and 35 months (95% CI, 29- 63) for women with non-coamplified tumors (p=0.448, NS). Median time to progression on first therapy was 17 months (95% CI, 14–20) for women with TOP2A coamplified tumors and 15 months (95% CI, 12–17) for women with non-coamplified tumors (p=0.939, NS) Conclusions: In this analysis, TOP2A and HER2 gene co-amplification did not correlate with worse TTP on first metatstatic therapy or worse OS from metatstatic disease.

No significant financial relationships to disclose.

Staging accuracy in mycosis fungoides and sezary syndrome using integrated positron emission tomography and computed tomography

OBJECTIVES

To evaluate the usefulness of integrated positron emission tomography and computed tomography (PET/CT) in staging mycosis fungoides (MF) and Sézary syndrome and to correlate PET/CT data with histopathologic diagnosis of lymph nodes (LNs).

DESIGN

A single-center, prospective cohort analysis.

SETTING

Academic referral center for cutaneous lymphoma.

PATIENTS

Thirteen patients with MF and SS at risk for secondary LN involvement. Interventions Patients were clinically evaluated based on general physical examination, total body skin examination, and laboratory screening. They underwent integrated PET/CT followed by excisional biopsy of LNs.

MAIN OUTCOME MEASURES

We used PET/CT to assess LN size and metabolic activity. Enlarged LNs were defined as axillary or inguinal LNs with a short axis 1.5 cm or larger; or cervical LN, with a short axis 1.0 cm or larger. We classified LN pathologic results according to National Cancer Institute (LN1-4) and World Health Organization (WHO 1-3) criteria. We quantified PET activity using standardized uptake value (SUV) and correlated with LN grade.

RESULTS

Based on CT size criteria alone, only 5 patients had enlarged LNs, whereas PET revealed hypermetabolic LNs in all 13 patients. Six patients had LN1-3, and 7 had effacement of LN architecture by lymphoma cells (LN4). Of the 7 patients with LN4 nodes, 4 had SS, and 3 had tumorous MF. Two patients with LN4 nodes had inguinal LNs smaller than 1.5 cm and would have been assigned an N0 classification without the use of integrated PET/CT. Correlation of SUV with LN grade revealed that LN1-3 nodes were associated with a mean SUV of 2.7 (median SUV, 2.2; range, 2.0-4.7) and LN4 nodes were associated with a mean SUV of 5.4 (median SUV, 3.9; range, 2.1-11.8). Patients with large cell transformation had the highest SUVs.

CONCLUSIONS

For staging MF and SS, PET/CT was more sensitive in detecting LN involved by lymphoma compared with CT data alone and thus may provide more accurate staging and prognostic information. The intensity of PET activity correlated with histologic LN grade.

Direct characterization of human T cells in pemphigus vulgaris reveals elevated autoantigen-specific Th2 activity in association with active disease

Pemphigus vulgaris (PV) is a blistering skin disorder mediated by autoantibodies targeting the epidermal adhesion molecule desmoglein 3 (Dsg3). As Th2-associated cytokines are necessary for directing antibody production, it is hypothesized that Dsg3-specific Th2 activity is associated with active disease. We used cell-surface-matrix technology in combination with flow cytometry to characterize the Dsg3-reactive T-cell population using peripheral blood mononucleocytes sampled from PV patients stratified by active (n = 9) or remittent disease (n = 6), and healthy human leucocyte antigen-matched controls (n = 5). We evaluated interferon-gamma-producing CD4+ cells (Th1) and interleukin (IL)-10- or IL-4-producing CD4+ cells (Th2). The mean frequency of Th2 CD4+ T cells was significantly elevated for five of nine PV patients with active disease. No significant Th2 responses were detected for patients with remittent disease or controls. There was a significant association of Th2 activity with active disease compared with remittent and control groups (P = 0.026 and P =0.012, respectively), and Th2 activity was significantly correlated with anti-Dsg3 IgG titre (P = 0.044). One patient with remittent disease converted from a Th2-negative to a Th2-positive response with the initiation of disease activity. An antigen-specific CD4- lymphocyte response was detected in five PV patients (36%), and was shown to correlate closely with the CD8+ population. These results are consistent with the hypothesis that Th2 response directs autoantibody production and is therefore associated with disease activity in PV.

Highly multiplexed molecular inversion probe genotyping: over 10,000 targeted SNPs genotyped in a single tube assay

Large-scale genetic studies are highly dependent on efficient and scalable multiplex SNP assays. In this study, we report the development of Molecular Inversion Probe technology with four-color, single array detection, applied to large-scale genotyping of up to 12,000 SNPs per reaction. While generating 38,429 SNP assays using this technology in a population of 30 trios from the Centre d'Etude Polymorphisme Humain family panel as part of the International HapMap project, we established SNP conversion rates of approximately 90% with concordance rates >99.6% and completeness levels >98% for assays multiplexed up to 12,000plex levels. Furthermore, these individual metrics can be "traded off" and, by sacrificing a small fraction of the conversion rate, the accuracy can be increased to very high levels. No loss of performance is seen when scaling from 6,000plex to 12,000plex assays, strongly validating the ability of the technology to suppress cross-reactivity at high multiplex levels. The results of this study demonstrate the suitability of this technology for comprehensive association studies that use targeted SNPs in indirect linkage disequilibrium studies or that directly screen for causative mutations.

How to minimize inappropriate utilization of Accident and Emergency Departments: improve the validity of classifying the general practice cases amongst the A&E attendees

Studies have found that one-third to two-thirds of all patients attending Accident and Emergency (A and E) Departments could be managed appropriately by general practitioners (GPs). There is also evidence that referral to GPs can be acceptable to patients. The question of primary concern is screening non-urgent cases with high degrees of sensitivity (S), specificity (SP), and positive predictive value (PPV). This paper reports the findings of the validity (S, SP and PPV) of nurses and patients in triaging A and E visitors. A cross sectional study was conducted over a 1 year period and subjects were randomly selected from four A and E Departments located across the four principle geographic regions of Hong Kong by stratified, two-stage sampling. S, SP and PPVs were computed for both non-weighted and weighted conditions. The gold standard for defining the true urgency status of each selected patient was based on a review of the patient's record 3-21 days (or longer if necessary) following the A and E visit. The record review in each A and E was blinded and done independently by a panel of two (and if disagreement existed, three) senior emergency physicians who did not practice in the same hospital. The greatest weights would be for incorrect decisions with greatest impact on patients' well being. The most accurate unweighted nurses' triage classification had an average sensitivity of 87.8%, specificity of 83.9%, and a PPV of 70.1%. When weighted, the average sensitivity reduced to 75%, specificity to 65.7%, and PPV to 54%. The most accurate unweighted patients' self-triage classification yielded a sensitivity of 62.5%, specificity of 69.2%, and a PPV of 58.1%, and correspondingly reduced to 43.3, 49.2 and 38.6% if weights were applied. Validity of the derived patients' self-classifications was too inaccurate for practical use. Hong Kong's current use of a five-point urgency scale by nurses would be further refined for identifying non-urgent visitors. If a mechanism was put in place for additional screening on visitors with a borderline semi-urgent or non-urgent status, the nurses could safely reassign non-urgent patients to GP care. If implemented, a significant impact on hospital costs could be realized.

Facilitated loading of horizontal gels using a capillary comb loader

Manual loading of samples into horizontal gels, such as the agarose gels commonly used for DNA fragment sizing and quantification, is laborious and prone to errors. Manual-loading times for highthroughput gels can reach 10 min/gel, and human error can result in incorrect identification of samples because of reverse loading or other errors in the loading process. To reduce gel-loading times and to improve reliability, a novel comb has been developed that uses glass capillaries and hydrostatic pressure to simplify sample loading from microplates. Accurate sample metering is ensured by the uniform length and volume of the capillaries. The loaded comb is placed in the gel boat over a pre-cast agarose gel, and buffer is added to a reservoir at the top of the comb. Once the buffer rises over the ends of the capillaries, the samples are pushed into the wells by hydrostatic pressure. This technique was successfully demonstrated for a 24-lane comb. This capillary comb loader reduces loading time, maintains well-to-well uniformity, and retains the same geometry and appearance of manually loaded bands, making this loading method compatible with existing downstream processes and software for subsequent analysis of the gel image.

Cyclic AMP and cyclic GMP activate protein kinase G in cavernosal smooth muscle cells: old age is a negative factor

OBJECTIVE

To investigate protein kinase G-I (PKG-I) expression and activation in cavernosal smooth muscle cells (CSMC) of young and old rats.

MATERIALS AND METHODS

PKG-I expression in rat penis was examined by immunohistochemical staining, reverse transcription-polymerase chain reaction, and Western blot analysis. CSMC isolated from young (16-week-old) and old (28-month-old) rats were grown as monolayer cell cultures and treated with different dosages of cAMP or cGMP for different periods. Their proteins were then analysed for the expression of vasodilator-stimulated phosphoprotein (VASP), phosphorylated VASP (at serine 239), PKG-I, and protein kinase A (PKA).

RESULTS

PKG-I expression was detected in the vascular and CSMC of the rat penis. There was little or no difference in the level of PKG-I expression between young and old rats. Treatment of CSMC with different dosages of cAMP or cGMP did not change the expression levels of VASP throughout the entire test period (up to 24 h). In contrast, the level of VASP phosphorylation at S239, i.e. the level of PKG-I activation, depended on the dosages of cAMP and cGMP and on the duration of treatment. Prolonged treatment (24 h) with either cAMP or cGMP resulted in down-regulation of both PKG-I and PKA. While cAMP and cGMP produced very similar results in nearly every aspect, there was a difference in one test, in which cGMP produced much less activated PKG-I than cAMP in the CSMC of 28-month-old-rats.

CONCLUSIONS

For the first time we provide evidence for PKG-I activation in CSMC. Both cAMP and cGMP were capable of activating PKG-I in CSMC. Age seemed to compromise the ability of PKG-I in response to cGMP.

Human PDE5A gene encodes three PDE5 isoforms from two alternate promoters

Sildenafil improves erectile function by inhibiting the cGMP-catalytic activity of phosphodiesterase type V (PDE5). We used rapid amplification of cDNA Ends-polymerase chain reaction (RACE-PCR) to isolate three PDE5 isoforms from human corpus cavernosum. Semiquantitative reverse transcription-polymerase chain reaction (RT-PCR) analysis on eight human cavernous tissue samples showed that all samples expressed the PDE5A1 at a lower level than the PDE5A2 isoform. Five samples expressed the PDE5A3 isoform at various levels while the other three did not. Analysis on non-penile tissues showed that all tissues expressed the A1 and A2 isoforms while only those that have substantial amounts of smooth muscle expressed the A3 isoform. Cloning and sequencing of the PDE5A gene showed that the isoform-specific 5'-ends of the PDE5 mRNAs are encoded from three alternative first exons arranged in the order of A1-A3-A2. Promoter activities were detected upstream from the A1-specific exon and in the intron preceding the A2-specific exon. The upstream PDE5A promoter is expected to direct the expression of all three PDE5 isoforms while the intronic PDE5A2 promoter only the A2 isoform. Both promoters were upregulated by increasing concentrations of either cAMP or cGMP. Several transcription factor AP2 and Sp1-binding sequences identified in the promoters are likely to be the mediators of cAMP/cGMP-responsiveness.

Age-related decrease of protein kinase G activation in vascular smooth muscle cells

Protein kinase G-I (PKG-I) activation is essential for vascular relaxation; however, its quantitative analysis in intact cells has been difficult. To overcome this difficulty, a monoclonal antibody, VASP-16C2, was recently developed that detects phosphorylated serine residue 239 of vasodilator-stimulated phosphoprotein (VASP), a substrate of PKG-I. In this study, we used this antibody to examine (i) possible functional differences between the alpha and beta isoforms of PKG-I, (ii) ability of cAMP to activate PKG-I, as compared to cGMP, the principal PKG-I-activating cyclic nucleotide, and (iii) time course and levels of PKG-I activation in vascular smooth muscle cells (VSMC) of young and old rats. We created COS-7 cell clones that overexpressed PKG-Ialpha or PKG-Ibeta, treated them with cAMP or cGMP, and analyzed their cell lysates for reactivity with VASP-16C2. The results showed that PKG-Ialpha phosphorylated VASP at a higher level than PKG-Ibeta, and cAMP was slightly weaker than cGMP in PKG-I activation. VSMC of young rats responded to cAMP or cGMP stimulation in a dose-dependent manner with increasing levels of PKG-I activation. The response was detected within 10 min and continued for at least 24 h. In contrast, VSMC of old rats showed no PKG-I activation during the first hour of cAMP or cGMP stimulation and, at 24 h these cells showed only low-level PKG-I activation. We propose that the reduced PKG-I activation may explain why vascular relaxation is decreased in older individuals.

The BH3 domain of BAD fused to the Antennapedia peptide induces apoptosis via its alpha helical structure and independent of Bcl-2

Since the over-expression of Bcl-2 is a common cause of multi-drug resistance, cytotoxic peptides that overcome the effects of Bcl-2 may be clinically useful. We harnessed the death-promoting alpha helical properties of the BH3 domain of BAD by fusing it to the Antennapedia (ANT) domain, which allows for cell entry (ANTBH3BAD). Treatment of 32D cells with the ANTBH3BAD peptide results in a 99% inhibition of colony formation. No significant toxicity is observed after treatment with ANT or BH3BAD alone. A mutant fusion peptide unable to bind Bcl-2 induces cell death as effectively as the wild-type ANTBH3BAD. Furthermore, 32D cells over-expressing Bcl-2 show no resistance to the ANTBH3BAD peptide. Therefore, the toxicity of the peptide was independent of the Bcl-2 pathway. We demonstrate that the toxicity of the peptide is due to its alpha helicity that disrupts mitochondrial function. Since this peptide overcomes major forms of drug resistance, it may be therapeutically useful if appropriately targeted to malignant cells.