Optical and electronic properties of MgPc-Ch-diisoQ blend organic thin film as an active layer for photovoltaic cells

Organic photovoltaic cells are a promising technology for generating renewable energy from sunlight. These cells are made from organic materials, such as polymers or small molecules, and can be lightweight, flexible, and low-cost. Here, we have created a novel mixture of magnesium phthalocyanine (MgPc) and chlorophenyl ethyl diisoquinoline (Ch-diisoQ). A coating unit has been utilized in preparing MgPc, Ch-diisoQ, and MgPc-Ch-diisoQ films onto to FTO substrate. The MgPc-Ch-diisoQ film has a spherical and homogeneous surface morphology with a grain size of 15.9 nm. The optical absorption of the MgPc-Ch-diisoQ film was measured, and three distinct bands were observed at 800-600 nm, 600-400 nm, and 400-250 nm, with a band gap energy of 1.58 eV. The current density-voltage and capacitance-voltage measurements were performed to analyze the photoelectric properties of the three tested cells. The forward current density obtained from our investigated blend cell is more significant than that for each material by about 22%. The photovoltaic parameters (Voc, Isc, and FF) of the MgPc-Ch-diisoQ cell were found to be 0.45 V, 2.12 μA, and 0.4, respectively. We believe that our investigated MgPc-Ch-diisoQ film will be a promising active layer in organic solar cells.

Abstract 1820: N,N-diethylaminobenzaldehyde-based small molecules to probe aldehyde dehydrogenase as target in prostate cancer

The human aldehyde dehydrogenases (ALDHs) play a major role in the metabolism of endogenous compounds and xenobiotics. Deregulation of ALDHs have implications in a number of cancers and their elevated expression in cancer stem cells (CSCs) have been used as (1) markers for the identification and isolation of these rare cell types and (2) as potential targets for therapeutic intervention. The elevated ALDH expression in tumors is also known to lead to chemotherapy-resistance including taxanes resistance. Although the exact role of ALDHs is not fully understood, emerging information indicates that several isoforms including ALDH1A1, 1A3, 3A1 and 7A1 play a key role in prostate cancer. To unravel ALDH isoform significance, more selective chemical tool compounds are required to probe their role in tumor growth, drug-resistance and CSC protection. To further elucidate the role of ALDHs in prostate cancer, we here report on the perturbation of ALDH expression and function using new chemical probes. N,N-diethylaminobenzaldehyde (DEAB) is a well-known pan ALDH inhibitor, widely used to interrogate ALDH activity. However, its nonselective nature and reported ability to act as a substrate complicates its use for biological readouts, which we wanted to explore further. In this study, a new library of compounds were synthesized and evaluated in cell free and cell-based assays; particular focus was on understanding its interaction with the three key ALDH isoforms ALDH1A1, ALDH1A3 and ALDH3A1. Kinetic inhibitory studies using the human recombinant ALDH isoforms were performed for the whole library of DEAB analogues against ALDH1A1, 1A3 and 3A1. Among all results, compound 14 yielded selective results against ALDH1A3 (Ki of 0.46µM), while compound 18 showed promising results against ALDH3A1 (Ki of 0.30µM). Significantly, sixteen analogues displayed increased cytotoxicity (IC50 = 10-200 µM) compared with DEAB (> 200 µM) against three different prostate cancer cell lines (PC-3, LNCaP, DU145). In addition, 3 of the DEAB-derivatives ALDH-affinic probe compounds (9, 14 and 18) were tested against 5 patient samples of primary prostate epithelial cultures at two doses (50 and 200 µM) in order to investigate their effect on cell viability. All four compounds showed reduction in cell viability at the highest concentration, while 14 and 18 showed a synergistic effect in combination treatment with docetaxel. Similar observations were also evident in the PC-3 prostate cancer cell line. Our investigation demonstrates the importance of ALDHs in prostate cancer while new compounds warrant further studies to understand their potential in inhibiting prostate CSCs.

Citation Format: Elisabet Batlle Rocafort, Ali I. Ibrahim, Maria Sadiq, Sneha Smarakan, Vibhu Jha, Tiziano Tuccinardi, Fiona Frame, Norman Maitland, Rafael Jiménez Aguilar, Raquel Pequerul Pavón, Xavier Parés Casampera, Goreti Ribeiro Morais, Jaume Farrés Vicen, Klaus Pors. N,N-diethylaminobenzaldehyde-based small molecules to probe aldehyde dehydrogenase as target in prostate cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 1820.

Expansion of the 4-(Diethylamino)benzaldehyde Scaffold to Explore the Impact on Aldehyde Dehydrogenase Activity and Antiproliferative Activity in Prostate Cancer

Aldehyde dehydrogenases (ALDHs) are overexpressed in various tumor types including prostate cancer and considered a potential target for therapeutic intervention. 4-(Diethylamino)benzaldehyde (DEAB) has been extensively reported as a pan-inhibitor of ALDH isoforms, and here, we report on the synthesis, ALDH isoform selectivity, and cellular potencies in prostate cancer cells of 40 DEAB analogues; three analogues (14, 15, and 16) showed potent inhibitory activity against ALDH1A3, and two analogues (18 and 19) showed potent inhibitory activity against ALDH3A1. Significantly, 16 analogues displayed increased cytotoxicity (IC₅₀ = 10–200 μM) compared with DEAB (>200 μM) against three different prostate cancer cell lines. Analogues 14 and 18 were more potent than DEAB against patient-derived primary prostate tumor epithelial cells, as single agents or in combination treatment with docetaxel. In conclusion, our study supports the use of DEAB as an ALDH inhibitor but also reveals closely related analogues with increased selectivity and potency.

Cytochrome P450 isoforms 1A1, 1B1 AND 2W1 as targets for therapeutic intervention in head and neck cancer

Epidemiological studies have shown that head and neck cancer (HNC) is a complex multistage process that in part involves exposure to a combination of carcinogens and the capacity of certain drug-metabolising enzymes including cytochrome P450 (CYP) to detoxify or activate such carcinogens. In this study, CYP1A1, CYP1B1 and CYP2W1 expression in HNC was correlated with potential as target for duocarmycin prodrug activation and selective therapy. In the HNC cell lines, elevated expression was shown at the gene level for CYP1A1 and CYP1B1 whereas CYP2W1 was hardly detected. However, CYP2W1 was expressed in FaDu and Detroit-562 xenografts and in a cohort of human HNC samples. Functional activity was measured in Fadu and Detroit-562 cells using P450-Glo™ assay. Antiproliferative results of duocarmycin prodrugs ICT2700 and ICT2706 revealed FaDu and Detroit-562 as the most sensitive HNC cell lines. Administration of ICT2700 in vivo using a single dose of ICT2700 (150 mg/kg) showed preferential inhibition of small tumour growth (mean size of 60 mm³) in mice bearing FaDu xenografts. Significantly, our findings suggest a potential targeted therapeutic approach to manage HNCs by exploiting intratumoural CYP expression for metabolic activation of duocarmycin-based prodrugs such as ICT2700.

Improvement in Infection Prevention and Control Measures at The Children Hospital, Lahore. A My Child Matters Collaborative Project

Background: Overcrowding, lack of operational funds, and healthcare associated infections are major challenges at the Children Hospital Lahore, a public healthcare facility in Pakistan with 900 new pediatric cancer admissions annually. In 2014, a collaboration between My Child Matters (MCM), St. Jude Global Infectious Diseases Program (SJ-GID), and our institution was established to address these issues. Aim: To describe the effect of a collaborative improvement strategy on the infection prevention and control (IPC) standards in a pediatric oncology unit in a resource-limited setting. Methods: Our study was a prospective before-and-after study. We compare the WHO Hand Hygiene Self-Assessment Framework (HHSAF) and 4 modules of the St. Jude modified Infection Control Assessment Tool (ICAT) scores. Our strategy included: (1) creating a multidisciplinary team of pediatric hematology-oncology, infectious disease physicians, nurses, microbiologist, and a data manager, (2) engaging on monthly online IPC mentoring sessions with the SJ-GID and MCM mentors, (3) performing daily inpatient healthcare associated (HAI) surveillance rounds, and (4) providing regular hand hygiene training and compliance audits. Results: Our hand hygiene facility level per WHO scores increased from “Inadequate” during the baseline assessment to “Intermediate/Consolidation” by the end of 3-year implementation (122 vs 352 HHSAF scores). The sink: bed and hand sanitizer: bed ratios improved to 1:6 and 1:1 respectively. Six washrooms were added to our unit. ICAT general infection control module increased by 40% (45 vs 78 ICAT score) and hygiene compliance improved by 20% from baseline. Identification of HAI increased from baseline (4.07 vs 8.7 infections per 1000 patient days). A 25% of the isolates were multidrug-resistant microorganisms. Conclusion: Implementing a collaborative improvement strategy improved the IPC standards in our pediatric cancer center. The increase of HAI might be a result of a better surveillance and laboratory identification. Further targeted interventions should be develop to decrease HAI rates and infection-related morbidity and mortality in our population.

Abstract 1662: Synthesis and biologic evaluation of diethylbenzaldehyde analogues to probe functional activity of aldehyde dehydrogenase activity in cancer

The human aldehyde dehydrogenases (ALDHs) play a major role in detoxifying highly reactive aldehydes into carboxylic acids. Deregulation of ALDHs has implications in a number of cancers. They play an important role as a cancer stem cell (CSC) marker due to high activity found in CSCs, while high expression is also known to lead to resistance to chemotherapeutic drugs. Although the exact roles of ALDHs are not fully understood, emerging information indicates several isoforms from the ALDH1 family, ALDH3A1 and ALDH7A1, play key roles in several cancer types. To probe the role of ALDH functional activity, we here report on the perturbation of ALDH expression and function using diethylbenzaldehyde (DEAB) analogues. The H1299 lung cancer cell line has negligible amount of ALDH activity, and ALDH-expressing variants were used to study the novel DEAB analogues. H1299 wild-type cells (WT) and cells expressing RFP were used as controls. Expression of the proteins was confirmed by Western blots and ALDH enzymatic activity assay. We used cell culture, colorimetric MTT assay, aldefluor assay and in vitro treatment with DEAB analogues. ALDH-expressing lysates were used to obtain biochemical inhibition data of the DEAB analogues using propionaldehyde as substrate with NAD+ as a co-factor. DEAB has been shown to covalently bind to ALDH7A1, and computational modeling was employed to understand how chemical modifications to DEAB affected the binding mode. Selected ALDH-affinic probe compounds were tested in a panel of colon, lung and prostate cancer cell lines including docetaxel-resistant variant and patient samples to investigate if DEAB analogues had an effect on cell viability as single agents or in combination with docetaxel. In conclusion, the novel DEAB analogues aid us to understand ALDH functional activity and provide a platform for discovering more selective ALDH inhibitors

Citation Format: Ali Ibrahim, Maria Sadiq, Daniela Presa, Ioannis Ntafoulis, Ahmad Alkawi, Fiona Frame, Norman J. Maitland, Zoe Cournia, Paul M. Loadman, Jan Moreb, Klaus Pors. Synthesis and biologic evaluation of diethylbenzaldehyde analogues to probe functional activity of aldehyde dehydrogenase activity in cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 1662.

Probing cytochrome P450 bioactivation and fluorescent properties with morpholinyl-tethered anthraquinones

Structural features from the anticancer prodrug nemorubicin (MMDX) and the DNA-binding molecule DRAQ5™ were used to prepare anthraquinone-based compounds, which were assessed for their potential to interrogate cytochrome P450 (CYP) functional activity and localisation. 1,4-disubstituted anthraquinone 8 was shown to be 5-fold more potent in EJ138 bladder cancer cells after CYP1A2 bioactivation. In contrast, 1,5-bis((2-morpholinoethyl)amino) substituted anthraquinone 10 was not CYP-bioactivated but was shown to be fluorescent and subsequently photo-activated by a light pulse (at a bandwidth 532-587 nm), resulting in punctuated foci accumulation in the cytoplasm. It also showed low toxicity in human osteosarcoma cells. These combined properties provide an interesting prospective approach for opto-tagging single or a sub-population of cells and seeking their location without the need for continuous monitoring.

Preclinical anti-cancer activity and multiple mechanisms of action of a cationic silver complex bearing N-heterocyclic carbene ligands

Organometallic complexes offer the prospect of targeting multiple pathways that are important in cancer biology. Here, the preclinical activity and mechanism(s) of action of a silver-bis(N-heterocyclic carbine) complex (Ag8) were evaluated. Ag8 induced DNA damage via several mechanisms including topoisomerase I/II and thioredoxin reductase inhibition and induction of reactive oxygen species. DNA damage induction was consistent with cytotoxicity observed against proliferating cells and Ag8 induced cell death by apoptosis. Ag8 also inhibited DNA repair enzyme PARP1, showed preferential activity against cisplatin resistant A2780 cells and potentiated the activity of temozolomide. Ag8 was substantially less active against non-proliferating non-cancer cells and selectively inhibited glycolysis in cancer cells. Ag8 also induced significant anti-tumour effects against cells implanted intraperitoneally in hollow fibres but lacked activity against hollow fibres implanted subcutaneously. Thus, Ag8 targets multiple pathways of importance in cancer biology, is less active against non-cancer cells and shows activity in vivo in a loco-regional setting.

Abstract 970: Probing the expression and function of aldehyde dehydrogenases in prostate cancer using ALDH-affinic compounds and siRNA

The human aldehyde dehydrogenases (ALDHs) play a major role in detoxifying highly reactive aldehydes into carboxylic acids. Deregulation of ALDHs have implications in a number of cancers including prostate cancer. They play an important role as a cancer stem cell (CSC) marker due to high activity found in CSCs while high expression is also known to lead to resistance to drugs including docetaxel. Although the exact role of ALDHs is not fully understood, emerging information indicates several isoforms including ALDH1A3 and ALDH7A1 play a key role in cancer. To further elucidate the role of ALDHs in prostate cancer, we here report on the perturbation of ALDH expression and function using chemical probes and siRNA.

Primary prostate epithelial cells cultured from patient tissue were used for this study. Cancer samples were obtained from radical prostatectomies and benign samples from transurethral resection of the prostate.

qPCR analysis showed ALDH1A3 to be more highly expressed than ALDH7A1 in the primary prostate epithelial cultures in 18 patient samples. Expression of ALDH1A3 was 3-fold higher in the cancer samples compared to the benign samples. The RNA data correlates with protein expression in 6 patient samples by immunofluorescence. qPCR analysis also showed that knockdown of ALDH7A1 resulted in an increase in the expression of ALDH1A3 suggesting a compensatory mechanism. Trypan blue exclusion assay showed that knockdown of ALDH1A3, ALDH7A1 or a combination of both resulted in a reduction in cell numbers. Flow cytometry was used to study cell differentiation upon knockdown of ALDH1A3, ALDH7A1 or both. In all 7 samples studied there was a reduction in CD49b expression indicating cell differentiation. ALDH7A1 knockdown showed a higher level of cell differentiation in all cases. The colony forming ability of primary cells was also investigated post-transfection of siRNAs against ALDH1A3, ALDH7A1 or both using the colony formation assay which resulted in a lower number of colonies in all 7 samples tested. The effect was more pronounced in benign prostatic hyperplasia (BPH) than in malignant cancer samples and patient variability was observed. ALDH-affinic probe compounds (DEAB and three derivatives, Ali-9, Ali-14 & Ali-18) were tested against 5 patient samples to investigate if they have an effect on cell viability. All four compounds showed reduction in cell viability at the highest concentration while Ali-14 and Ali-18 showed a synergistic effect in combination treatment with docetaxel.

In conclusion, knockdown of ALDH1A3 and ALDH7A1 reduce cell number, induce cells to differentiate and reduce their colony forming ability. Novel ALDH-affinic probe compounds reduced cell viability alone and in combination with docetaxel, therefore these compounds may be of value both as single treatments and to provide a strategy to enhance taxane-based therapy such as docetaxel.

Citation Format: Maria Sadiq, Ali I. Ibrahim, Fiona Frame, Simon J. Allison, Mark Sutherland, Roger M. Phillips, Norman J. Maitland, Klaus Pors. Probing the expression and function of aldehyde dehydrogenases in prostate cancer using ALDH-affinic compounds and siRNA [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 970. doi:10.1158/1538-7445.AM2017-970

Polysialic acid sustains cancer cell survival and migratory capacity in a hypoxic environment

Polysialic acid (polySia) is a unique carbohydrate polymer expressed on the surface of NCAM (neuronal cell adhesion molecule) in a number of cancers where it modulates cell-cell and cell-matrix adhesion, migration, invasion and metastasis and is strongly associated with poor clinical prognosis. We have carried out the first investigation into the effect of polySia expression on the behaviour of cancer cells in hypoxia, a key source of chemoresistance in tumours. The role of polysialylation and associated tumour cell migration and cell adhesion were studied in hypoxia, along with effects on cell survival and the potential role of HIF-1. Our findings provide the first evidence that polySia expression sustains migratory capacity and is associated with tumour cell survival in hypoxia. Initial mechanistic studies indicate a potential role for HIF-1 in sustaining polySia-mediated migratory capacity, but not cell survival. These data add to the growing body of evidence pointing to a crucial role for the polysialyltransferases (polySTs) in neuroendocrine tumour progression and provide the first evidence to suggest that polySia is associated with an aggressive phenotype in tumour hypoxia. These results have significant potential implications for polyST inhibition as an anti-metastatic therapeutic strategy and for targeting hypoxic cancer cells.

Abstract 4093: The impact of the prostate cancer microenvironment on the expression and regulation of aldehyde dehydrogenases

Introduction:

Aldehyde dehydrogenase (ALDH) enzymes are involved in the detoxification of specific endogenous and exogenous aldehyde substrates. High ALDH activity is used to identify stem cells and has also been associated with poor prognosis in cancer. In prostate cancer (PCa) high ALDH activity has been associated with elevated clonogenicity, migratory behaviour, tumor progression and metastasis. Despite these observations there exists a poor understanding of the role of selected ALDH isoforms in PCa. In an attempt to understand if the tumor microenvironment impacts on ALDH function, we investigated their expression under hypoxia.

Methods:

Gene and protein expression analysis of ALDH isoforms -1A1, -1A2, -1A3, -1B1, -2, -3A1 and -7A1 in normal prostate cell line PNT2C2, and a panel of PCa cell lines with different stages of cancer was carried out by quantitative PCR and western blot under normoxic and hypoxic conditions at 24 and 48 hours. Gene expression of the ALDHs in primary prostate cultures was assessed following retinoic acid treatment. siRNA knockdown technology was used to study functional roles of selected ALDH isoforms.

Results:

Gene expression of ALDH1A3 was increased in Bob cells at 24h under hypoxia, at 48h this was less apparent but the expression of most ALDHs in Bob cells including ALDH1A2, -2, -3A1 and -7A1 was reduced at 48h. In SerBob cells, the gene expression of ALDH1A1 and -1B1 was reduced at both time points, whereas the expression of ALDH1A2, -2, and -7A1 was increased under hypoxia. At protein level, the expression of ALDH1A3 appeared low under hypoxia at both time points in SerBob cells while the expression of ALDH3A1 also appeared low after 24h exposure to hypoxia. In DU145 cells, there was an increase in ALDH1A1, -1A2, 1A3, -2, and -3A1 gene expression under hypoxia at 48h. In LNCAP cells, the gene expression of ALDH2 was increased at 48h under hypoxia whereas the expression of ALDH7A1 was reduced at 48h. The protein expression of ALDH7A1 was higher in PC3 cells under hypoxia at 24h. A significant increase was observed in ALDH1A3 and ALDH3A1 expression in response to retinoic acid. ALDH1A3 knockdown showed a significant reduction of cell viability in PC3 cells. Other investigations underway that will be reported at the conference are focused on how prostate cancer stem-like cells expressing ALDHs are responding to hypoxia.

Conclusion:

Our data suggests that the expression of certain ALDHs is affected by hypoxia and ALDH1A3 potentially is involved in cell survival in PCa. Future work will investigate if any of these isoforms can be used as biomarkers to distinguish indolent from malignant PCa.

Citation Format: Maria Sadiq, Simon J. Allison, Fiona Frame, Mark Sutherland, Roger M. Phillips, Norman J. Maitland, Klaus Pors. The impact of the prostate cancer microenvironment on the expression and regulation of aldehyde dehydrogenases. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 4093.

Modelling and characterisation of a ultrasound-actuated needle for improved visibility in ultrasound-guided regional anaesthesia and tissue biopsy

Clear needle visualisation is recognised as an unmet need for ultrasound guided percutaneous needle procedures including regional anaesthesia and tissue biopsy. With inadequate needle visibility, these procedures may result in serious complications or a failed operation. This paper reports analysis of the modal behaviour of a previously proposed ultrasound-actuated needle configuration, which may overcome this problem by improving needle visibility in colour Doppler imaging. It uses a piezoelectric transducer to actuate longitudinal resonant modes in needles (outer diameter 0.8-1.2mm, length>65mm). The factors that affect the needle's vibration mode are identified, including the needle length, the transducer's resonance frequency and the gripping position. Their effects are investigated using finite element modelling, with the conclusions validated experimentally. The actuated needle was inserted into porcine tissue up to 30mm depth and its visibility was observed under colour Doppler imaging. The piezoelectric transducer is able to generate longitudinal vibration with peak-to-peak amplitude up to 4μm at the needle tip with an actuating voltage of 20Vpp. Actuated in longitudinal vibration modes (distal mode at 27.6kHz and transducer mode at 42.2kHz) with a drive amplitude of 12-14Vpp, a 120mm needle is delineated as a coloured line in colour Doppler images, with both needle tip and shaft visualised. The improved needle visibility is maintained while the needle is advanced into the tissue, thus allowing tracking of the needle position in real time. Moreover, the needle tip is highlighted by strong coloured artefacts around the actuated needle generated by its flexural vibration. A limitation of the technique is that the transducer mode requires needles of specific lengths so that the needle's resonance frequency matches the transducer. This may restrict the choice of needle lengths in clinical applications.

Clinical management of dietary induced urolithiasis associated with balanoposthitis in a Boer goat

A Boer-Kajang cross male goat was presented to the Veterinary Hospital, University Malaysia Kelantan with a history of dysuria, hematuria and restlessness. The goat was intensively managed (confined to the pen) and fed with only palm kernel cake for the last three months. Physical examination revealed that the goat was dull, depressed, having an inflamed penis and prepuce with blood stained urine dripping from the penis. The differential diagnoses were obstructive urolithiasis, urinary tract infection and balanoposthitis. Based on the history, clinical signs, physical examination, urinalysis, ultrasonagraphy and feed analysis, the goat was diagnosed with obstructive urolithiasis and balanoposthitis. Treatment was instituted by amputation of the urethral process and retrograde urohydropulsion to relieve the blockade. Sulfadiazine-trimethoprim (Norodine®24) 15mg/kg, I.M; flunixin meglumine 2.2mg/kg, I.M; vitamin B complex 1ml/10kg, I.M and ammonium chloride 300mg/kg orally were administered. The goat responded well to treatment and was recovering well during a follow up visit.

Probing cytochrome P450-mediated activation with a truncated azinomycin analogue

Selective cytochrome P450 bioactivation of truncated azinomycin.

Hypoxia modulates the activity of a series of clinically approved tyrosine kinase inhibitors

BACKGROUND AND PURPOSE

Hypoxia in tumours is known to cause resistance to conventional chemotherapeutic drugs. In contrast, little is known about the effects of hypoxia on targeted anti-cancer drugs. This study evaluated the effect of hypoxia on a series of clinically approved tyrosine kinase inhibitors (TKIs).

EXPERIMENTAL APPROACH

The effect of hypoxia (0.1% oxygen) on the activity of conventional cytotoxic drugs (5-fluorouracil, doxorubicin and vinblastine), the hypoxia-activated prodrug tirapazamine and 9 TKIs was determined in a panel of cell lines. Where hypoxia had a marked effect on chemosensitivity, Western blot analysis was conducted to determine the effect of hypoxia on target expression and the effect of TKIs on cell signalling response under aerobic and hypoxic conditions.

KEY RESULTS

Three patterns of chemosensitivity were observed: resistance under hypoxia, equitoxic activity against hypoxic and aerobic cells, and preferential cytotoxicity to hypoxic cells. Significant hypoxia selectivity (independent of HIF1) was observed in the case of dasatinib and this correlated with the ability of dasatinib to inhibit phosphorylation of Src at tyrosine 530. Sorafenib was significantly less effective under hypoxic conditions but resistance did not correlate with hypoxia-induced changes in Raf/MEK/ERK signalling.

CONCLUSIONS AND IMPLICATIONS

Hypoxia influences the activity of TKIs but in contrast to conventional cytotoxic drugs, preferential activity against hypoxic cells can occur. The search for hypoxia-targeted therapies has been long and fruitless and this study suggests that some clinically approved TKIs could preferentially target the hypoxic fraction of some tumour types.

Investigating the Catalytic Activity of Monoclinic Zirconia; Oxidation of Benzyl Alcohol in Aqueous Medium at Mild Conditions

The oxidation/degradation of benzyl alcohol in artificially contaminated water under atmospheric pressure by molecular oxygen/air over ZrO2(m) catalyst was investigated. Monoclinic phase ZrO2 was synthesized and characterized by modern techniques. Oxidation of benzyl alcohol in aqueous medium was carried out in a typical three necked double walled batch reactor equipped with thermometer and condenser. The rate of oxidation was affected by different reaction parameters such as speed of agitation, catalyst loading, temperature, concentration of substrate solution (46.3 – 185 mmol/L) and partial pressure of oxygen. Major products were detected with GC and UV spectrophotometer. Optimal conditions were setup for better catalytic activity of ZrO2(m). To sum up, catalytic oxidation of benzyl alcohol in aqueous medium by ZrO2(m) is a useful and cheaper method for the conversion of benzyl alcohol to valuable products as well as for the removal of benzyl alcohol from industrial waste water.

Removal of Triphenylmethane Dye from Aqueous Solution by Carbonaceous Adsorbent

Removal of acid blue 1 from aqueous solution on activated carbon produced from Salvadora oleoides was investigated. The samples were characterized by BET surface area, BJH pore volume and pore diameter, XRD, SEM, EDS and FTIR analysis. The surfaces contain functional groups like ketones and hydroxyl which disappeared at high activation temperature; relatively high amount of carbon w.r.t. oxygen was found with the increase in activation temperature; the increase in surface area and development of porous structures showed a positive effect on the adsorption capacity. Adsorption of the dye on carbon at 10 and 45°C showed that the first order, Bangham and Elovich and parabolic diffusion equations apply to the kinetic data. The adsorption rate increased with the temperature and with thermal activation of the sample. Thermodynamic parameters like ΔE≠, ΔH≠, ΔS≠ and ΔG≠ were calculated from the kinetic data. The negative values of ΔS≠ reflect decrease in the disorder of the system at the solid-solution interface during adsorption. Gibbs free energy (ΔG≠), which represents the driving force for the affinity of dye for the carbon, increased with the increase in activation temperature.

Investigating the Activity of Zirconia as a Catalyst and a Support for Noble Metals, in Green Oxidation of Cyclohexane

Green oxidation of cyclohexane by molecular oxygen was carried out over ZrO2 and noble metals (Pd and Pt) supported on zirconia in solvent free conditions. Studies have been carried out in a typical three-necked batch reactor. Reaction products were identified by GC and UV spectrophotometer. Reaction rates were determined as a function of temperature, partial pressure of oxygen, amount of catalyst, volume of reactants, agitation and reaction duration. The agitation effect and activation energy revealed the absence of mass transfer resistance. Experimental results unveiled the effect of morphology of ZrO2 on catalysis. 1.0 wt.% noble metal/ZrO2(m) was found more selective for cyclohexanol production at low temperature, agitation 900rpm and partial pressure of 101.325 KPa while at high temperature cyclohexanol was further oxidized to cyclohexanone. Comparison of Pt/ZrO2 and Pd/ZrO2 catalysts was made on the basis of reactivity and selectivity. Catalysts were characterized by using BET surface area and pore size analyzer, XRD and SEM. To conclude shortly, for the oxidation of cyclohexane, platinum or palladium supported on zirconia are selective, recyclable and could behave as truly heterogeneous catalysts.

Prevalence of rheumatic heart disease in school children of urban Lahore

OBJECTIVE

To determine the prevalence of rheumatic heart disease (RHD) among school children in urban and semiurban areas of Lahore, Pakistan.

METHODS

A cross-sectional survey of school children aged 5-15 years from 70 schools of urban and semiurban Lahore was carried out by a team of cardiologists. Children were screened by clinical examination and diagnosis confirmed by echocardiography. Sociodemographic data were also collected.

RESULTS

Of 24 980 children screened, 986 (3.9%) had a confirmed cardiac lesion; 546 had RHD, 440 had congenital heart disease. The prevalence of RHD was 21.9/1000 children screened (95% CI 20.1 to 23.7). Their mean (SD) age was 10.7 (2.6) years and the female:male ratio was 1.6:1. Most (92.5%) were unaware of the diagnosis and less than 2% were taking rheumatic prophylaxis. All children belonged to a low socioeconomic group and 67% were undernourished.

CONCLUSION

The prevalence of RHD in the urban school population of Lahore is among the highest in the world. The younger age of onset is a special feature and most are unaware of the diagnosis, and hence not receiving life-saving secondary prophylaxis.

Multiple bilateral cannon-ball lung metastases from carcinoma of the prostate: orchiedectomy induced remission

A 56-year-old man presented with lower urinary tract obstructive symptoms, hemoptysis and progressive dyspnoea. Digital rectal examination showed an enlarged nodular prostate and a tru-cut biopsy confirmed carcinoma prostate. Chest x-ray showed multiple bilateral cannon ball opacities suggestive of metastases. He underwent bilateral orchidectomy and follow up assessment showed significant clearing of the cannon-ball lesions in the lungs. He remained asymptomatic at follow up that has extended to 8 years.

Infective endocarditis in children--incidence, pattern, diagnosis and management in a developing country

BACKGROUND

In developing countries, patients with infective endocarditis are referred late, there is low yield of blood cultures and incidence of rheumatic heart disease is still high.

OBJECTIVE

Evaluate clinical pattern, assess diagnostic criteria in our settings and determine outcome.

SETTING

A tertiary referral center for paediatric and adult cardiology.

PATIENTS AND METHODS

All children with infective endocarditis admitted to a single center from April 1997 to March 2000 were analysed. The diagnosis was based on Duke's criteria, which proposed two major and six minor criteria. Minor criteria were expanded to include raised acute phase reactants and presence of newly diagnosed or increasing splenomegally. The patients were stratified as definite, possible and rejected cases.

RESULTS

Of 1402 hospital admissions, 45 patients fulfilled the diagnostic criteria for infective endocarditis giving an incidence of 32 per 1000 hospital admissions. The mean age was 7.9 +/- 4 years (4 months to 16 years) with only two patients under 1 year of age. Rheumatic heart disease was the underlying lesion in 24 patients (53%) while congenital heart lesions occurred in 20 patients (45%). Previous antibiotic treatment was given in 26 patients (58%) definitely. Blood cultures were positive in 21 patients (47%); Streptococcus Viridans being the most common organism, while vegetations on echocardiography were present in 32 patients (71%). Surgery was undertaken in four patients and five patients left against medical advise. Of 10 patients with aortic valve involvement, there were three deaths (30%) and overall mortality was 13% (six patients).

CONCLUSIONS

The incidence of infective endocarditis is 32 per 1000 (3.2%) hospital admissions in a tertiary paediatric cardiology referral center. Rheumatic heart disease is still the most common underlying heart lesion. Blood cultures are positive in less than 50% of cases and echocardiography in expert hands is a more sensitive tool in our set up. Mortality is still high and aortic valve involvement in particular, carried poor prognosis.

Successful occlusion of a coronary arteriovenous fistula using an Amplatzer duct occluder

In an 11-year old boy with a large coronary arteriovenous fistula between the left coronary artery and the right atrium, we achieved successful closure using a 10-8 Amplatzer Duct Occluder introduced from the right internal jugular vein. Angiography 6 weeks later showed complete occlusion of the fistula, with normal opacification of the left coronary arterial system. This technique may be used as an alternative to coils and surgery in selected patients.

Hypotensive action of coumarin glycosides from Daucus carota

Daucus carota (carrot) has been used in traditional medicine to treat hypertension. Activity-directed fractionation of aerial parts of D. carota resulted in the isolation of two cumarin glycosides coded as DC-2 and DC-3. Intravenous administration of these compounds caused a dose-dependent (1-10 mg/kg) fall in arterial blood pressure in normotensive anaesthetised rats. In the in vitro studies, both compounds caused a dose-dependent (10-200 microg/ml) inhibitory effect on spontaneously beating guinea pig atria as well as on the K+ -induced contractions of rabbit aorta at similar concentrations. These results indicate that DC-2 and DC-3 may be acting through blockade of calcium channels and this effect may be responsible for the blood pressure lowering effect of the compounds observed in the in vivo studies.

Management and outcome of infants and children with right atrial isomerism

OBJECTIVES

To assess the current results and outcome of surgery in infants and children with right atrial isomerism and complex congenital heart disease.

SETTING

Tertiary referral centre.

METHODS

20 consecutive children with right atrial isomerism and complex congenital heart disease underwent surgery over a 6 year period between August 1987 and July 1993. The results and outcome were analysed according to age, presentation, and surgical procedures.

RESULTS

Patients were divided into two groups depending on age at presentation and initial surgery: group A comprised 11 patients who required surgical intervention in the first month of life (mean age 5 days); and group B comprised nine patients who required initial surgical intervention after the first month of life (mean age 6.8 months). Seven (64%) of the 11 patients in group A had obstructed pulmonary venous drainage and ten (91%) had pulmonary atresia. There were seven early deaths (64%), including the five patients who required systemic to pulmonary artery shunt and simultaneous repair of obstructed pulmonary veins. The long-term survival rate in this group was 18% (two of 11). Pulmonary venous obstruction was present in two (22%) of the nine patients in group B and four (44%) had pulmonary atresia. There were no early deaths. One patient died after a second palliative procedure. There was one late sudden death. Four patients had a Fontan operation with no deaths. Two of the remaining three patients meet the Fontan criteria. The long-term survival rate in this group was 78% (seven of nine).

CONCLUSIONS

Surgical management of patients with right atrial isomerism who have complex congenital heart disease carries a high mortality and remains palliative. The overall survival rate was 45% (nine of 20); 18% in patients requiring surgery in the first month of life (group A) and 78% in patients requiring surgery after the first month of life (group B) (P < 0.001). Of the total of 20 patients, nine were potential candidates for a Fontan operation. Seven of these have undergone a Fontan procedure with five survivors.

Late systemic desaturation after total cavopulmonary shunt operations

OBJECTIVES

To assess the medium-term results of total cavopulmonary shunt operations in children with left atrial isomerism, interrupted inferior vena cava, and complex congenital heart defects.

BACKGROUND

Creation of a total cavopulmonary shunt provides very good interim palliation for children with interrupted inferior vena cava and complex congenital heart disease; however, longer term results after this operation have not been reported.

METHODS

Detailed follow up of six children who underwent creation of a total cavopulmonary shunt at a tertiary referral centre.

RESULTS

There were no early or late deaths. Oxygen saturations at discharge ranged from 89% to 92% (mean 90%). At last follow up (mean 4.7 years) saturations at rest ranged from 73% to 81% (mean 77%) (P < 0.05). All patients underwent exercise stress testing. At peak exercise oxygen saturations ranged from 62% to 87% (mean 71.5%) and during recovery from 68% to 85% (mean 78%). Cardiac catheterisation was performed in five patients with saturations of less than 80% at rest or peak exercise. No patient had pulmonary arteriovenous fistula. Systemic venous to hepatic venous collaterals were documented in four patients. These were localised below the diaphragm in three and above the diaphragm in one patient. The collateral vessel was successfully embolised in three of these patients, with a rise in resting oxygen saturations from 6 to 10% (mean 7%).

CONCLUSIONS

The development of systemic venous to hepatic venous collaterals is a common complication in patients who undergo a total cavopulmonary shunt operation. This can lead to significant desaturation at rest and during exercise. Detailed angiographic studies of the infradiaphragmatic system veins is required for diagnosis. Transcatheter embolisation of such vessels gives good relief.

Endocarditis with multiple intracardiac shunts: identification and repair

An 8-year-old boy who suffered from Hirschsprung's disease had development of tricuspid valve endocarditis that progressed to aortic root abscess formation, development of a fistulous communication between aorta and right atrium, atrial and ventricular septal defects, and a left ventricle to right atrium defect. Several surgical procedures were required. Operation consisted initially of closure of the septal defects and aortic valve repair. This was followed by homograft replacement of the aortic valve for persistent infection, and further closure of a left ventricle to right atrium fistula.

Influence of ethnic origin on the pattern of congenital heart defects in the first year of life

OBJECTIVE

To assess the prevalence and patterns of congenital heart defects in infants requiring hospital admission in a defined population and to determine the differences in ethnic groups.

DESIGN

A three year retrospective analysis of all hospital admissions for paediatric congenital heart defects in a single centre.

SETTING

Tertiary referral centre for infant cardiac services in the West Midlands region, United Kingdom.

PATIENTS AND METHODS

Indian, Pakistani, Bangladeshi and other individuals from the Indian subcontinent constitute 5.8% of the total population of the West Midlands region. Some 9% of infants, however, are Asian because of a high birth rate. All infants with confirmed congenital heart defects resident in this region who required hospital admission between April 1990 and March 1993 were classified as Asians and non-Asian, mainly white, infants.

RESULTS

Of 1111 infants with congenital heart defects born in the West Midlands and admitted to the hospital, 17.0% were Asian, significantly more than the percentage of Asian infants in the population (P < 0.0001). Asian infants had a higher proportion of complex congenital heart disease (7% v 2.1%, P < 0.001), whereas coarctation of the aorta was more common in non-Asian (3% v 9.1%, P = 0.003). Persistent arterial duct seemed to be more common in Asian children (16% v 10%, NS), but this group included preterm infants admitted for duct ligation. There was no significant difference between the two groups in the other nine categories of congenital heart defects.

CONCLUSIONS

The estimated prevalence of congenital heart defects requiring hospital admission was higher in Asian infants than in non-Asian (9.45 per 1000 v 4.56 per 1000, P < 0.0001). Complex congenital heart defects were more common in Asian infants whereas coarctation of the aorta was more common in non-Asian.

Effectiveness and safety of paediatric interventional cardiac catheterisation in a subregional cardiothoracic unit

OBJECTIVE

To assess the effectiveness and safety of paediatric interventional cardiac catheterization during the development of the service.

SETTING

Sub-regional Paediatric Cardiothoracic Centre.

PATIENTS AND METHODS

All paediatric admissions for cardiac catheterisation between January, 1985 and December, 1992. Data were collected on all patients in whom interventional cardiac catheterisation was performed excluding babies undergoing balloon atrial septostomy. Results were compared with those reported previously by the larger centres.

RESULTS

One hundred and seventy eight interventional procedures were performed in 158 patients, progressing from pulmonary valvuloplasty (1985) and aortic valvuloplasty (1986) to arterial duct occlusion and coil embolisation of shunts (1991). During the study period there was a rise in the number and variety of conditions for which interventional cardiac catheterisation was performed. In terms of morbidity, mortality and technical success, results compared favourably with those published from larger centres.

CONCLUSIONS

Interventional cardiac catheterisation in children can be established effectively and safely in a relatively smaller set up.

Congenitally divided left atrium: diagnostic pitfalls in cross-sectional echocardiography

A 20-month-old patient with a previously diagnosed atrial septal defect presented with acute heart failure. The clinical and echocardiographic features at admission to hospital were of a congenitally partitioned left atrium. At surgery a medially displaced and infolded left atrial appendage together with infolded left atrial wall was found, which gave a false appearance of a left atrial 'membrane'. This unusual arrangement was subsequently correctly identified by transoesophageal echocardiography. It is speculated that the abnormal orientation of the appendage may have produced a physiologic and haemodynamic situation akin to anomalous drainage of the pulmonary veins, which would account for the clinical features in this patient.

False aneurysm of the right ventricular outflow tract after total correction of tetralogy of Fallot: diagnosis by echocardiography and successful repair by neck cannulation for cardiopulmonary bypass

A case of false aneurysm related to the left side of the heart with a connection to the right ventricular outflow tract was found by echocardiography after complete repair of tetralogy of Fallot. Cardiopulmonary bypass was established by cannulating the right internal jugular vein and the ipsilateral common carotid artery. The aneurysm was then excised and the right ventricular outflow tract reconstructed by direct sutures.

Developmental regulation of antisense-mediated gene silencing in Dictyostelium

In Dictyostelium, the expression of antisense transcripts has been successfully used to reduce or eliminate gene expression. In most cases this occurs on the level of RNA stability resulting in a loss of both sense and antisense transcript accumulation. We here show that the antisense effect is regulated during the developmental cycle, i.e., in certain developmental stages and under certain developmental conditions, complementary RNAs appear not to interact with each other, resulting in a failure to abolish expression of the gene of interest. We find that this is not only the case with artificially introduced antisense constructs but also with the endogenous, antisense-regulated PSV-A gene. Our data demonstrate that antisense-mediated gene silencing is conferred by a biochemical machinery that is subject to regulation in vivo. The results provide a basis to better understand this machinery and to dissect the components. They may also explain the failure of some antisense experiments in Dictyostelium and possibly in other organisms.