FDA-approved disulfiram as a novel treatment for aggressive leukemia

Acute leukemia continues to be a major cause of death from disease worldwide and current chemotherapeutic agents are associated with significant morbidity in survivors. While better and safer treatments for acute leukemia are urgently needed, standard drug development pipelines are lengthy and drug repurposing therefore provides a promising approach. Our previous evaluation of FDA-approved drugs for their antileukemic activity identified disulfiram, used for the treatment of alcoholism, as a candidate hit compound. This study assessed the biological effects of disulfiram on leukemia cells and evaluated its potential as a treatment strategy. We found that disulfiram inhibits the viability of a diverse panel of acute lymphoblastic and myeloid leukemia cell lines (n = 16) and patient-derived xenograft cells from patients with poor outcome and treatment-resistant disease (n = 15). The drug induced oxidative stress and apoptosis in leukemia cells within hours of treatment and was able to potentiate the effects of daunorubicin, etoposide, topotecan, cytarabine, and mitoxantrone chemotherapy. Upon combining disulfiram with auranofin, a drug approved for the treatment of rheumatoid arthritis that was previously shown to exert antileukemic effects, strong and consistent synergy was observed across a diverse panel of acute leukemia cell lines, the mechanism of which was based on enhanced ROS induction. Acute leukemia cells were more sensitive to the cytotoxic activity of disulfiram than solid cancer cell lines and non-malignant cells. While disulfiram is currently under investigation in clinical trials for solid cancers, this study provides evidence for the potential of disulfiram for acute leukemia treatment. KEY MESSAGES: Disulfiram induces rapid apoptosis in leukemia cells by boosting oxidative stress. Disulfiram inhibits leukemia cell growth more potently than solid cancer cell growth. Disulfiram can enhance the antileukemic efficacy of chemotherapies. Disulfiram strongly synergises with auranofin in killing acute leukemia cells by ROS induction. We propose testing of disulfiram in clinical trial for patients with acute leukemia.

Invasion-Block and S-MARVEL: A high-content screening and image analysis platform identifies ATM kinase as a modulator of melanoma invasion and metastasis

Robust high-throughput assays are crucial for the effective functioning of a drug discovery pipeline. Herein, we report the development of Invasion-Block, an automated high-content screening platform for measuring invadopodia-mediated matrix degradation as a readout for the invasive capacity of cancer cells. Combined with Smoothen-Mask and Reveal, a custom-designed, automated image analysis pipeline, this platform allowed us to evaluate melanoma cell invasion capacity posttreatment with two libraries of compounds comprising 3840 U.S. Food and Drug Administration (FDA)-approved drugs with well-characterized safety and bioavailability profiles in humans as well as a kinase inhibitor library comprising 210 biologically active compounds. We found that Abl/Src, PKC, PI3K, and Ataxia-telangiectasia mutated (ATM) kinase inhibitors significantly reduced melanoma cell invadopodia formation and cell invasion. Abrogation of ATM expression in melanoma cells via CRISPR-mediated gene knockout reduced 3D invasion in vitro as well as spontaneous lymph node metastasis in vivo. Together, this study established a rapid screening assay coupled with a customized image-analysis pipeline for the identification of antimetastatic drugs. Our study implicates that ATM may serve as a potent therapeutic target for the treatment of melanoma cell spread in patients.

Systematic In Vitro Evaluation of a Library of Approved and Pharmacologically Active Compounds for the Identification of Novel Candidate Drugs for KMT2A-Rearranged Leukemia

Patients whose leukemias harbor a rearrangement of the Mixed Lineage Leukemia (MLL/KMT2A) gene have a poor prognosis, especially when the disease strikes in infants. The poor clinical outcome linked to this aggressive disease and the detrimental treatment side-effects, particularly in children, warrant the urgent development of more effective and cancer-selective therapeutics. The aim of this study was to identify novel candidate compounds that selectively target KMT2A-rearranged (KMT2A-r) leukemia cells. A library containing 3707 approved drugs and pharmacologically active compounds was screened for differential activity against KMT2A-r leukemia cell lines versus KMT2A-wild type (KMT2A-wt) leukemia cell lines, solid tumor cells and non-malignant cells by cell-based viability assays. The screen yielded SID7969543, an inhibitor of transcription factor Nuclear Receptor Subfamily 5 Group A Member 1 (NR5A1), that limited the viability of 7 out of 11 KMT2A-r leukemia cell lines including 5 out of 7 lines derived from infants, without affecting KMT2A-wt leukemia cells, solid cancer lines, non-malignant cell lines, or peripheral blood mononuclear cells from healthy controls. The compound also significantly inhibited growth of leukemia cell lines with a CALM-AF10 translocation, which defines a highly aggressive leukemia subtype that shares common underlying leukemogenic mechanisms with KMT2A-r leukemia. SID7969543 decreased KMT2A-r leukemia cell viability by inducing caspase-dependent apoptosis within hours of treatment and demonstrated synergy with established chemotherapeutics used in the treatment of high-risk leukemia. Thus, SID7969543 represents a novel candidate agent with selective activity against CALM-AF10 translocated and KMT2A-r leukemias that warrants further investigation.

Screening and genotyping of Orientia tsutsugamushi from field-collected on-host chiggers (Acari: Prostigmata) recovered from a positive scrub typhus locality in Kelantan, Malaysia

Orientia tsutsugamushi is the causative agent of scrub typhus vectored by larval stages of trombiculid mites (chiggers) that occur in most tropical regions of Southeast Asia. A total of 242 chiggers extracted from eight small mammals captured from a positive scrub typhus locality in Kelantan, Malaysia, were screened for the presence of O. tsutsugamushi. The chiggers were grouped in 16 pools for extraction of DNA prior to screening of O. tsutsugamushi based on the nucleotide sequence of 56-kDa type specific antigen (TSA) gene using nested polymerase chain reaction. Two species of on-host chiggers were identified, the one, Leptotrombidium deliense, much more dominant (94.8%) than the other, Ascoshoengastia sp. (5.2%). The pathogen was detected in two pools (12.5%) of L. deliense recovered from Rattus rattus and Tupaia sp. The 56-kDa TSA gene sequence analysis revealed the O. tsutsugamushi harboured in those chiggers were Karp prototype strain with high similarity (99.3%). Findings of this study strongly supported the existence of scrub typhus infections in certain parts of Malaysia which agrees with previous local reports. Moreover, this study highlighted the pressing need of a large-scale close observation of O. tsutsugamushi DNA sequences from chiggers that can probably be collected from other positive scrub typhus localities to precisely provide the distribution and prevalence of this zoonotic pathogen.

Combination efficacy of ruxolitinib with standard-of-care drugs in CRLF2-rearranged Ph-like acute lymphoblastic leukemia

Philadelphia chromosome-like acute lymphoblastic leukemia (Ph-like ALL) is a high-risk ALL subtype with high rates of relapse and poor patient outcome. Activating mutations affecting components of the JAK-STAT signaling pathway occur in the majority of Ph-like ALL cases. The use of JAK inhibitors represents a potential treatment option for Ph-like ALL, although we and others have shown that CRLF2-rearranged Ph-like ALL responds poorly to single-agent JAK inhibitors in the preclinical setting. Therefore, the aim of this study was to identify effective combination treatments against CRLF2-rearranged Ph-like ALL, and to elucidate the underlying mechanisms of synergy. We carried out a series of high-throughput combination drug screenings and found that ruxolitinib exerted synergy with standard-of-care drugs used in the treatment of ALL. In addition, we investigated the molecular effects of ruxolitinib on Ph-like ALL by combining mass spectrometry phosphoproteomics with gene expression analysis. Based on these findings, we conducted preclinical in vivo drug testing and demonstrated that ruxolitinib enhanced the in vivo efficacy of an induction-type regimen consisting of vincristine, dexamethasone, and L-asparaginase in 2/3 CRLF2-rearranged Ph-like ALL xenografts. Overall, our findings support evaluating the addition of ruxolitinib to conventional induction regimens for the treatment of CRLF2-rearranged Ph-like ALL.

Review of Mites Found on Various Animal Hosts and at Different Localities in Malaysia

Mite biodiversity and distribution in Malaysia is currently understudied. Most previous works on Malaysian Acari have focused on pest organisms of medical, veterinary, and agricultural concern, with a few recent studies centered on mites in forensic contexts. Previous literatures have targeted collection sites in forest reserves and/or mountains in either Peninsular or Malaysian Borneo, though the state of Sarawak had the least publications related to mite species descriptions despite having the highest number of nature parks of any state in the country. Most publications focused on the three states Selangor, Pahang and Sabah. Most of the mite species reported were from mammals (66.3%), with fewer species from birds (21.7%), arthropods (11.2%), and reptiles (0.8%). We believe that further work on the systematic documentation of mite species throughout Malaysia is necessary as it could generate useful tools, such as the use of mites as biogeographical markers or as forensic indicators. Therefore, this review catalogs mite species that have been documented in or on animal hosts in Malaysia and serves as a foundation for future work.

Description and characterization of questing hard tick, Dermacentor steini (Acari: Ixodidae) in Malaysia based on phenotypic and genotypic traits

Identifying certain species of Dermacentor ticks in Malaysia is challenging as there is no comprehensive work on their systematics and lack of specific taxonomic keys. In this study, we described and characterized D. steini ticks collected from a forest reserve in the vicinity of the Forest Research Institute of Malaysia using integrated phenotypic and genotypic traits. In total two males and three females of questing D. steini ticks were morphologically identified using specific illustrated taxonomic keys based on their special characters. Further confirmation and characterization of the tick species were then examined using PCR, followed by sequencing partial mitochondrial 16S rDNA gene (mt-rrs). Clustering analysis based on mt-rrs was carried out by constructing neighbor-joining tree topology to clarify the genetic variation of local D. steini. Based on external morphological characterizations, all ticks were successfully identified down to the species as adult D. steini. The molecular traits based on phylogenetic tree provide very strong support for the monophyletic clade of D. steini including high percentages of similarity (97-100%) with available sequences in GenBank. Furthermore, a low intraspecific variation (4%) among the species of D. steini was observed but it was genetically different from other Dermacentor species with high interspecific value (8-15%). These findings produced the first genotypic data of D. steini using 16S rDNA gene which confirmed the presence of this species in Malaysia. Moreover, this study supports the taxonomic status of local D. steini and adds to the knowledge of accurate identification of ticks.

First report of Histiostoma sp. (Astigmata: Histiostomatidae) phoretic on a forensically important blowfly, Chrysomya villeneuvi (Diptera: Calliphoridae)

This is the first record of phoretic histiostomatid mites found on a forensically important blow fly species, Chrysomya villeneuvi (Diptera: Calliphoridae), collected from decomposing rabbit carcasses placed in Bukit Lagong Forest Reserve, Sungai Buloh and MARDI Cameron Highlands, Malaysia. The blow flies frequenting around the carcasses were first captured using an insect net. After pinning, they were examined under a stereomicroscope and mites phoretic on their body were carefully removed and preserved in 70% ethanol. Mites were cleared in lactic acid before mounting on slides using Hoyer's medium and identified under a compound microscope. The flies and their mites were identified as C. villeneuvi and deutonymphs of Histiostoma spp. (Astigmata: Histiostomatidae), respectively. This insectmite association may be useful to provide insights regarding the minimum post-mortem interval and the location of death in forensic entomological investigations.

PCR identification and phylogenetic analysis of the medically important dust mite Suidasia medanensis (Acari: Suidasiidae) in Malaysia

The occurrence of Suidasia medanensis (= S. pontifica) mites in Malaysian house dust was first reported in 1984. The taxonomy of this storage mite is, however, quite confusing. Therefore, we need an accurate identification to resolve morphological problems due to its minute size and some overlapping characters between species. The purpose of this study was to demonstrate the application of partial mitochondrial cytochrome c oxidase subunit I (COI) sequences for the identification of S. medanensis by PCR. Identity of the mite was first determined by observing morphological characters under a light microscope. Genomic DNA of S. medanensis mites was successfully extracted prior to PCR and DNA sequencing using COI universal primers. The length of the COI sequences obtained was 378 bp. BLAST analysis of amplicon sequences showed that local S. medanensis COI region had 99% maximum identity with S. medanensis nucleotide sequence (AY525568) available in the GenBank. As the phylogenetic tree generated indicated, COI sequences from this study were clustered with S. medanensis from Korea and the UK in one major clade, supported with high bootstrap value (> 85%). Results of the phylogenetic analysis of this COI gene were congruent with the morphological identification and provided strong support for a single clade of local S. medanensis.

Phenotypic and genotypic identification of hard ticks of the genus Haemaphysalis (Acari: Ixodidae) in Peninsular Malaysia

Morphotaxonomy based on phenotypic traits of immature hard ticks (Acari: Ixodidae) is a skill challenge and has prompted many inexperienced acarologists to adopt DNA-based methods for identifying and discriminating the species. The aim of this study is therefore to utilize COI gene for verifying the morphological status of Haemaphysalis ticks in Peninsular Malaysia. A total of 19 on-host ticks collected from four localities were first identified using specific illustrated taxonomic keys that lead to the genus of Haemaphysalis. Genotypic traits of tick species were then verified molecularly based on cytochrome oxidase subunit I (COI) gene using polymerase chain reaction and direct sequencing. Clustering analysis was carried out by constructing a phylogenetic tree to determine the genetic variation and diversity of local Haemaphysalis ticks. Based on external morphological characterizations, all immature ticks were successfully identified down to the genus level only. Molecular analysis of the genotypic using COI gene revealed 16 individuals (84%) as Haemaphysalis hystricis, and three individuals as H. humerosa with sequence homology of 97-99 and 86-87%, respectively. Haemaphysalis hystricis were clustered in their respective monophyletic group in the phylogeny trees with a bootstrap of 100%. Furthermore, a low intraspecific variation (<0.3%) was observed among Malaysian H. hystricis but high interspecific value (>15%) recorded. This study morphologically and molecularly confirms the presence of H. hystricis in Malaysia and the findings will add value to the existing knowledge in identification of ticks in this country.

Laboratory contact and topical evaluations of household disinfectants against house dust mites Dermatophagoides pteronyssinus and Dermatophagoides farinae (Acari: Pyroglyphidae)

The contact and topical activity of two household disinfectants containing chloroxylenol and benzyl chlorophenol against, Dermatophagoides pteronyssinus and Dermatophagoides farinae mites were evaluated in the laboratory. For contact activity, 30 adult mites were placed for 24 hrs on Whatman No. 1 filter paper impregnated with disinfectant. For topical activity, each disinfectant was directly applied to individual body of all 30 dust mites and observed for 24hrs. All treatments were replicated 12 times. Chloroxylenol disinfectant was found to be more effective compared to benzyl chlorophenol disinfectant in killing pyroglyphid mites.

1,8-Naphthalimide derivatives: new leads against dynamin I GTPase activity

Fragment-based in silico screening against dynamin I (dynI) GTPase activity identified the 1,8-naphthalimide framework as a potential scaffold for the design of new inhibitors targeting the GTP binding pocket of dynI. Structure-based design, synthesis and subsequent optimization resulted in the development of a library of 1,8-naphthalimide derivatives, called the Naphthaladyn™ series, with compounds 23 and 29 being the most active (IC50 of 19.1 ± 0.3 and 18.5 ± 1.7 μM respectively). Compound 29 showed effective inhibition of clathrin-mediated endocytosis (IC50(CME) 66 μM). The results introduce 29 as an optimised GTP-competitive lead Naphthaladyn™ compound for the further development of naphthalimide-based dynI GTPase inhibitors.

Acarine ectoparasites of Panti Forest Reserve in Johore, Malaysia

OBJECTIVE

To identify the presence of acarine ectoparasites and determine whether there is any potential public health risk in Panti Forest Reserve, Johore, Malaysia.

METHODS

Trapping of animals and avifauna was conducted simultaneously along 5 expedition trails using 150 wire traps, 10 harp traps and 30 mist nets for 6 consecutive nights. A total of 140 animals consisting of 7 species of birds, 19 species of bats, 6 species of rodents and 1 species of tree-shrew as well as 8 myriapods were examined.

RESULTS

Infestation rates of ticks, mesostigmatid mites and chiggers on animals examined were 24.3%, 28.6% and 27.9%, respectively. Infestation on bats was low (1.5%) and none occurred on birds. Majority of ticks extracted were at immature stages (78.9%). Genera of ticks on animals were Amblyomma, Dermacentor, Haemaphysalis and Ixodes. Ixodes granulatus was the only species of ticks identified from the animals. Examination of ticks under vegetation revealed 54% adults leading to identification of 3 species of ticks. A total of 7 species of mesostigmatid mites were found. 6 species were on rodent, Maxomys surifer and another one species, Laelaps nuttalli was found only on Leopoldamys sabanus. Laelaps sanguisugus was the only mesostigmatid found infesting tree-shrews. Seven genera of chiggers were identified. From this, 5 genera were on rodents, 4 genera on tree-shrews and 1 genus on a bat.

CONCLUSIONS

A total of 16 genera, 2 sub-genus and 14 species of acarine ectoparasites were found in this area. Findings of the survey demonstrate the presence of three spesies of acarine ectoparasites which have potential health risk i.e. Ixodes granulatus, Laelaps nuttalli and Leptotrombidium deliense.

Building a better dynasore: the dyngo compounds potently inhibit dynamin and endocytosis

Dynamin GTPase activity increases when it oligomerizes either into helices in the presence of lipid templates or into rings in the presence of SH3 domain proteins. Dynasore is a dynamin inhibitor of moderate potency (IC₅₀ ~ 15 μM in vitro). We show that dynasore binds stoichiometrically to detergents used for in vitro drug screening, drastically reducing its potency (IC₅₀ = 479 μM) and research tool utility. We synthesized a focused set of dihydroxyl and trihydroxyl dynasore analogs called the Dyngo™ compounds, five of which had improved potency, reduced detergent binding and reduced cytotoxicity, conferred by changes in the position and/or number of hydroxyl substituents. The Dyngo compound 4a was the most potent compound, exhibiting a 37-fold improvement in potency over dynasore for liposome-stimulated helical dynamin activity. In contrast, while dynasore about equally inhibited dynamin assembled in its helical or ring states, 4a and 6a exhibited >36-fold reduced activity against rings, suggesting that they can discriminate between helical or ring oligomerization states. 4a and 6a inhibited dynamin-dependent endocytosis of transferrin in multiple cell types (IC₅₀ of 5.7 and 5.8 μM, respectively), at least sixfold more potently than dynasore, but had no effect on dynamin-independent endocytosis of cholera toxin. 4a also reduced synaptic vesicle endocytosis and activity-dependent bulk endocytosis in cultured neurons and synaptosomes. Overall, 4a and 6a are improved and versatile helical dynamin and endocytosis inhibitors in terms of potency, non-specific binding and cytotoxicity. The data further suggest that the ring oligomerization state of dynamin is not required for clathrin-mediated endocytosis.

A preliminary field survey of ectoparasites of rodents in urban park, Sarawak, Malaysian Borneo

A survey of ectoparasites was carried out during Eco-Zoonoses Expedition in Bukit Aup Jubilee Park (BAJP), Sibu, Sarawak, Malaysian Borneo from 5(th) to 9(th) June 2008. A total of nine individuals comprising two species of rodents were captured. The species of rodents screened for ectoparasites were Sundamys muelleri and Callosciurus notatus. Four genera and six species of ectoparasites were collected, namely, Ixodes granulatus, Ixodes sp., Laelaps sedlaceki, Laelaps nuttalli, Hoplopleura dissicula and Listrophoroides sp. Three species of the ectoparasites are known to have potential health risk. The species were Ixodes granulatus, Laelaps nuttalli and Hoplopleura dissicula. This survey produced the first list of ectoparasites in Bukit Aup Jubilee Park, Sarawak, Malaysia.

Pyrimidyn compounds: dual-action small molecule pyrimidine-based dynamin inhibitors

Dynamin is required for clathrin-mediated endocytosis (CME). Its GTPase activity is stimulated by phospholipid binding to its PH domain, which induces helical oligomerization. We have designed a series of novel pyrimidine-based "Pyrimidyn" compounds that inhibit the lipid-stimulated GTPase activity of full length dynamin I and II with similar potency. The most potent analogue, Pyrimidyn 7, has an IC50 of 1.1 μM for dynamin I and 1.8 μM for dynamin II, making it among the most potent dynamin inhibitors identified to date. We investigated the mechanism of action of the Pyrimidyn compounds in detail by examining the kinetics of Pyrimidyn 7 inhibition of dynamin. The compound competitively inhibits both GTP and phospholipid interactions with dynamin I. While both mechanisms of action have been previously observed separately, this is the first inhibitor series to incorporate both and thereby to target two distinct domains of dynamin. Pyrimidyn 6 and 7 reversibly inhibit CME of both transferrin and EGF in a number of non-neuronal cell lines as well as inhibiting synaptic vesicle endocytosis (SVE) in nerve terminals. Therefore, Pyrimidyn compounds block endocytosis by directly competing with GTP and lipid binding to dynamin, limiting both the recruitment of dynamin to membranes and its activation. This dual mode of action provides an important new tool for molecular dissection of dynamin's role in endocytosis.

Dynamin inhibition blocks botulinum neurotoxin type A endocytosis in neurons and delays botulism

The botulinum neurotoxins (BoNTs) are di-chain bacterial proteins responsible for the paralytic disease botulism. Following binding to the plasma membrane of cholinergic motor nerve terminals, BoNTs are internalized into an endocytic compartment. Although several endocytic pathways have been characterized in neurons, the molecular mechanism underpinning the uptake of BoNTs at the presynaptic nerve terminal is still unclear. Here, a recombinant BoNT/A heavy chain binding domain (Hc) was used to unravel the internalization pathway by fluorescence and electron microscopy. BoNT/A-Hc initially enters cultured hippocampal neurons in an activity-dependent manner into synaptic vesicles and clathrin-coated vesicles before also entering endosomal structures and multivesicular bodies. We found that inhibiting dynamin with the novel potent Dynasore analog, Dyngo-4a(TM), was sufficient to abolish BoNT/A-Hc internalization and BoNT/A-induced SNAP25 cleavage in hippocampal neurons. Dyngo-4a also interfered with BoNT/A-Hc internalization into motor nerve terminals. Furthermore, Dyngo-4a afforded protection against BoNT/A-induced paralysis at the rat hemidiaphragm. A significant delay of >30% in the onset of botulism was observed in mice injected with Dyngo-4a. Dynamin inhibition therefore provides a therapeutic avenue for the treatment of botulism and other diseases caused by pathogens sharing dynamin-dependent uptake mechanisms.

Inhibition of dynamin by dynole 34-2 induces cell death following cytokinesis failure in cancer cells

Inhibitors of mitotic proteins such as Aurora kinase and polo-like kinase have shown promise in preclinical or early clinical development for cancer treatment. We have reported that the MiTMAB class of dynamin small molecule inhibitors are new antimitotic agents with a novel mechanism of action, blocking cytokinesis. Here, we examined 5 of the most potent of a new series of dynamin GTPase inhibitors called dynoles. They all induced cytokinesis failure at the point of abscission, consistent with inhibition of dynamin while not affecting other cell cycle stages. All 5 dynoles inhibited cell proliferation (MTT and colony formation assays) in 11 cancer cell lines. The most potent GTPase inhibitor, dynole 34-2, also induced apoptosis, as revealed by cell blebbing, DNA fragmentation, and PARP cleavage. Cell death was induced specifically following cytokinesis failure, suggesting that dynole 34-2 selectively targets dividing cells. Dividing HeLa cells were more sensitive to the antiproliferative properties of all 5 dynoles compared with nondividing cells, and nontumorigenic fibroblasts were less sensitive to cell death induced by dynole 34-2. Thus, the dynoles are a second class of dynamin GTPase inhibitors, with dynole 34-2 as the lead compound, that are novel antimitotic compounds acting specifically at the abscission stage.

Ectoparasites of small mammals in four localities of wildlife reserves in Peninsular Malaysia

Field surveys of ectoparasites on rodents and scandents were conducted in four localities of wildlife reserves in Peninsular Malaysia from October 2008 to November 2009. A total of 16 animals comprising 5 species of hosts were caught and examined for ectoparasites. The hosts examined were Maxomys rajah, Maxomys whiteheadi, Leopoldamys sabanus, Lariscus insignis and Tupaia glis. Of these hosts, 9 genera, consisting of 14 species of ectoparasites were extracted. Three species of ticks (Ixodidae), 7 species of mesostigmatid mites (Laelaptidae), 3 species of chiggers (Trombiculidae) and 1 species of listrophorid mites (Listrophoriidae) were identified. The infestation rate of ectoparasites observed ranged from 12.5% to 62.5%. Among the ectoparasites found, Ixodes granulatus and Leptotrombidium deliense are of known medical importance.

The pthaladyns: GTP competitive inhibitors of dynamin I and II GTPase derived from virtual screening

We report the development of a homology model for the GTP binding domain of human dynamin I based on the corresponding crystal structure of Dictyostelium discoidum dynamin A. Virtual screening identified 2-[(2-biphenyl-2-yl-1,3-dioxo-2,3-dihydro-1H-isoindole-5-carbonyl)amino]-4-chlorobenzoic acid (1) as a approximately 170 microM potent inhibitor. Homology modeling- and focused library-led synthesis resulted in development of a series of active compounds (the "pthaladyns") with 4-chloro-2-(2-(4-(hydroxymethyl)phenyl)-1,3-dioxoisoindoline-5-carboxamido)benzoic acid (29), a 4.58 +/- 0.06 microM dynamin I GTPase inhibitor. Pthaladyn-29 displays borderline selectivity for dynamin I relative to dynamin II ( approximately 5-10 fold). Only pthaladyn-23 (dynamin I IC(50) 17.4 +/- 5.8 microM) was an effective inhibitor of dynamin I mediated synaptic vesicle endocytosis in brain synaptosomes with an IC(50) of 12.9 +/- 5.9 microM. This compound was also competitive with respect to Mg(2+).GTP. Thus the pthaladyns are the first GTP competitive inhibitors of dynamin I and II GTPase and may be effective new tools for the study of neuronal endocytosis.

The dynamin inhibitors MiTMAB and OcTMAB induce cytokinesis failure and inhibit cell proliferation in human cancer cells

The endocytic protein dynamin II (dynII) participates in cell cycle progression and has roles in centrosome cohesion and cytokinesis. We have described a series of small-molecule inhibitors of dynamin [myristyl trimethyl ammonium bromides (MiTMAB)] that competitively interfere with the ability of dynamin to bind phospholipids and prevent receptor-mediated endocytosis. We now report that dynII functions specifically during the abscission phase of cytokinesis and that MiTMABs exclusively block this step in the cell cycle. Cells treated with MiTMABs (MiTMAB and octadecyltrimethyl ammonium bromide) and dyn-depleted cells remain connected via an intracellular bridge for a prolonged period with an intact midbody ring before membrane regression and binucleate formation. MiTMABs are the first compounds reported to exclusively block cytokinesis without affecting progression through any other stage of the cell cycle. Thus, MiTMABs represent a new class of antimitotic compounds. We show that MiTMABs are potent inhibitors of cancer cell growth and have minimal effect on nontumorigenic fibroblast cells. Thus, MiTMABs have toxicity and antiproliferative properties that preferentially target cancer cells. This suggests that dynII may be a novel target for pharmacologic intervention for the treatment of cancer.

Scanning electron micrographs of two species of Sturnophagoides (Acari: Astigmata: Pyroglyphidae) mites in Malaysia

Scanning electron microscope (SEM) images of two dust mites, Sturnophagoides brasiliensis and Sturnophagoides halterophilus, are presented to provide an improved visualization of the taxonomic characters of these mites. Sturnophagoides halterophilus can be differentiated from S. brasiliensis by their expanded genu and femur of leg I. The differences in morphology of male and female S. brasiliensis are also discussed.

Ticks (Ixodidae) and other ectoparasites in Ulu Muda Forest Reserve, Kedah, Malaysia

A survey of ticks and other ectoparasites was carried out during a national biodiversity scientific expedition at Ulu Muda Forest Reserve, Kedah, Malaysia from 23-29 March 2003. A total of 161 animals comprising 20 species of birds, 16 species of bats, six species of non-volant small mammals and 12 species of reptiles were examined for ticks and other ectoparasites. From these animals, nine species in five genera of ticks, 10 species in two families of Mesostigmatid mites and five species of chiggers were collected. Three of the ectoparasitic species found, Dermacentor auratus, Ixodes granulatus and Leptotrombidium deliense are of known public health importance. This survey produced the first list of ticks and other ectoparasites in the forest reserve and the third study of ectoparasites in Kedah. Fourteen species of these ectoparasites are new locality records.

Scanning electron micrographs of Blomia tropicalis (Acari:Astigmata: Echimyopodidae), a common house dust mite in Malaysia

Many finer taxonomic characters of Blomia tropicalis are not distinctly visible under conventional light microscopy. Scanning electron micrographs of this mite are therefore presented in this paper for better appreciation of the inconspicuous features of the morphology of the species. The differences in morphology of male and female B. tropicalis are also briefly discussed.

A preliminary survey of ectoparasites of small mammals in Kuala Selangor Nature Park

Trapping of small mammals was conducted at 5 study sites in Kuala Selangor Nature Park (KSNP) from 20-24 June 2005. A total of 11 animals comprising 2 species of rodents, Maxomys whiteheadi and Rattus exulans were caught from 3 sites, i.e from an area of mixed secondary forest and mangrove swamp; an area of mangrove swamp, and from an area of lalang fringing mangrove swamp. From these animals, the following 7 species of ectoparasites were found: Laelaps echidninus, Laelaps nuttalli, Ascoschoengastia indica, Leptotrombidium deliense, Hoplopleura pectinata, Hoplopleura pacifica and Polyplax spinulosa. One of the ectoparasites found, L. deliense is a known vector of scrub typhus and thus may pose potential health risks to visitors to KSNP.

A survey of ectoparasites in Gunung Stong Forest Reserve, Kelantan, Malaysia

A survey of ticks and other ectoparasites was carried out during a national biodiversity scientific expedition at Gunung Stong Forest Reserve, Kelantan, Malaysia from 23-29 May 2003. A total of 272 animals comprised of 12 species of birds, 21 species of bats, 7 species of rodents and 2 species of insects were examined for ticks and other ectoparasites. From these animals, 5 species in 4 genera of ticks; 7 species in 2 families of Mesostigmatid mites and 5 species of chiggers were collected. Among the ectoparasites found were Ixodes granulatus and Leptotrombidium deliense, which are of known medical importance. A tick island consisting of 10 nymphal stages of Dermacentor spp was observed feeding on Rattus tiomanicus.

House dust mite fauna in the Klang Valley, Malaysia

Allergy to house dust mites (HDM) is an important cause of asthma and rhinitis in Malaysia. This study was carried out to evaluate the dust mite fauna in the Klang Valley. Dust samples were collected from 20 houses from March 1994 to February 1995. Thirty-three dust samples from mattresses were examined monthly for the occurrence of HDM. A total of 22 species in 9 families of HDM was identified. The most common and densely populated species was Blomia tropicalis with an average density of 8,934 mites/g of dust. Dermatophagoides pteronyssinus was the next in abundance, followed by Malayoglyphus intermedius. All houses surveyed were found to be infested with HDM and every house had at least 6 species of HDM. B. tropicalis and D. pteronyssinus were found in all mattresses. HDM in the Klang Valley were found to be highly prevalent and present in high densities. In this study, counts of D. pteronyssinus was found to exceed the proposed exposure threshold of 500 mites/g dust, for triggering acute asthma. Although counts of B. tropicalis exceeded D. pteronyssinus, no conclusion could be made because there is currently no exposure threshold for triggering acute asthma, for this species. Monthly distribution of B. tropicalis and D. pteronyssinus showed 2 peaks and 4 peaks, respectively. The major peak for D. pteronysinus was in January 1995 whereas for B. tropicalis, the major peak was more variable and occurred between November 1994 to January 1995. Both the species showed minor peak in April 1994.

First report on sensitization to allergens of a house dust mite, Suidasia pontifica (Acari: Saproglyphidae)

A species of house dust mite, Suidasia pontifica, was recently shown to produce allergens affecting man. The species may be as important as other allergen producing mite in sensitization and causing allergic symptoms in Malaysians. Surveys conducted demonstrated that 80% of the houses surveyed were positive for this mite with densities ranged from 2 to 50 mites per gram of dust. Colonies of the species has been successfully established and materials from those colonies have been used to produce extracts for studies on sensitization to the mites. A total of 85 suspected allergic rhinitis patients were tested and 74.1% demonstrated positive reactions. Extract of this mite should be considered for routine diagnostic testing and possible immunotherapy.

Gabexate for the prevention of pancreatic damage related to endoscopic retrograde cholangiopancreatography. Gabexate in digestive endoscopy--Italian Group

BACKGROUND

Endoscopic retrograde cholangiopancreatography (ERCP) is associated with elevated levels of pancreatic enzymes and pancreatitis. Gabexate, a protease inhibitor, has been used to prevent pancreatic damage related to ERCP.

METHODS

We conducted a multicenter, double-blind comparison of gabexate (1 g given by intravenous infusion starting 30 to 90 minutes before endoscopy and continuing for 12 hours afterward) with placebo (mannitol and sodium chloride, administered in the same fashion). A total of 435 adults scheduled to undergo ERCP and, when indicated, endoscopic sphincterotomy underwent randomization; 17 were excluded from the final analysis for various reasons. The remaining 418 patients (mean age, 60.4 years)--208 in the gabexate group and 210 in the placebo group--were analyzed. Acute pancreatitis was considered to be present if serum amylase or lipase levels (or both) were five times greater than the upper limits of normal in association with the onset of pancreatic pain.

RESULTS

After the procedures, 276 patients (66 percent) had elevated pancreatic-enzyme levels; the frequency was similar in the two groups. Mean serum amylase values were higher in the placebo group than in the gabexate group through 24 hours of observation (P=0.03). Twelve patients in the gabexate group and 29 in the placebo group had abdominal pain (6 percent vs. 14 percent, P=0.009). Sixteen patients in the placebo group and five in the gabexate group had acute pancreatitis (8 percent vs. 2 percent, P=0.03). Two patients treated with gabexate and six given placebo had adverse events, all of which resolved. Two patients given placebo died of acute pancreatitis; one was excluded from the evaluation because pancreatitis was present before endoscopy. One patient in the gabexate group died, from a myocardial infarction.

CONCLUSION

Prophylactic treatment with gabexate reduced pancreatic damage related to ERCP, as reflected by reductions in the extent but not the frequency of elevated enzyme levels and in the frequency of pancreatic pain and acute pancreatitis.

Life-cycle, longevity and fecundity of Blomia tropicalis (Acari: Glycyphagidae) in a tropical laboratory

In the present study on the life-cycle of Blomia tropicalis, freshly laid eggs were observed until they developed into adults; the development periods between stages were recorded. The eggs took an average of 22.9 +/- 6.4 days to develop to adults. For longevity experiments, newly emerged adults were kept at 25 degrees C and observed until they died. There was no significant difference in longevities of the different sexes (p = 0.053). Production of eggs by mated females were monitored until egg production stopped and the female died. Mated females and males survived an average of 32.2 +/- 15.4 and 30.9 +/- 17.7 days respectively. The difference in longevity of the mated females, and males was not significant (p = 0.747). Longevity of the mated females was found to be significantly (p < 0.05) shorter than unmated females.