Reperfusion strategy and late clinical outcomes of patients with ST-elevation myocardial infarction (STEMI) in the absence of standard modifiable risk factors (SMuRFs)

Introduction

There is growing evidence that patients presenting with STEMI in the absence of standard modifiable cardiovascular risk factors (SMuRFs; smoking, hypertension, hypercholesterolemia, diabetes) have poorer outcomes compared to those with atleast one SMuRF. It has been hypothesised that this may be in part due to decreased administration of pharmacotherapies in the post-infarct period due to perceived low risk. Long term outcomes of patients without SMuRFs based on reperfusion strategy received during the index admission have not been investigated.

Purpose

We sought to analyse late clinical outcomes of STEMI patients with and without SMuRFs based on reperfusion strategy received during the index admission.

Methods

All patients who underwent PCI between 2003 and 2014 were identified from a PCI centre STEMI database. Late clinical outcomes of patients with and without SMuRFs were analysed overall and based on reperfusion strategy [primary PCI (pPCI) vs pharmaco-invasive PCI (PI-PCI)]. Propensity matching was used to account for differences in baseline characteristics between the groups.

Results

Amongst 2,091 STEMI patients, 531 (25%) had no SMuRFs (51% pPCI, 49% PI-PCI) and 1560 (75%) had ≥1 SMuRF (52% pPCI, 48% PI-PCI). Unadjusted late mortality in SMuRF-less patients was 13.4% (18.8% pPCI, 7.7% PI-PCI) and for those with ≥1 SMuRF was 9.7% (11.0% pPCI, 8.4% PI-PCI). After propensity-matching clinical and angiographic characteristics, 5 year mortality rates were significantly higher for patients without SMuRFs compared to those with SMuRFs [HR 1.36, CI: 1.03–1.81, p=0.031]. This difference was attenuated for patients who underwent pPCI [HR 1.72, CI: 1.22–2.43, p=0.002]. Interestingly, this discrepancy was not observed amongst individuals who underwent pharmaco-invasive PCI [HR 1.13, CI: 0.53–1.48, p=0.638], as SMuRF-less patients had similar mortality rates to their counterparts. Long term rates of reinfarction, stent thrombosis and target vessel revascularisation were similar between the groups. Additionally, there was no significant difference in rates of stroke and major bleeding amongst all 4 subgroups.

Conclusion

Patients presenting with STEMI in the absence of SMuRFs have increased overall late mortality compared to those with at least one SMuRF. However, this difference was not observed in patients who underwent a pharmaco-invasive strategy, whereby patients without SMuRFs had similar outcomes to those with SMuRFs after adjusting for confounders. Our findings suggest the use of a pharmaco-invasive strategy in appropriate SMuRF-less patients presenting with STEMI.

Funding Acknowledgement

Type of funding sources: None.

COVID-19 pandemic and admission rates for and management of acute coronary syndromes in Israel

Background

Since the COVID-19 pandemic outbreak several countries have reported a decrease in the number of patients admitted with non-ST elevation myocardial infarction (NSTEMI).

Purpose

We aimed to evaluate admission trend and outcomes of patients with NSTEMI in the COVID-19 era in a nationwide survey.

Methods

A prospective, multicenter, observational, nationwide study involving 13 medical centers across Israel. All NSTEMI patients admitted to intensive cardiac care units (ICCUs) over an 8-week period during the COVID-19 outbreak were compare them with NSTEMI patients admitted 2 years earlier (control period) during the Acute Coronary Syndrome Israeli Survey (ACSIS) 2018.

Results

There were 624 (43%) NSTEMI patients, of them 349 (56%) hospitalized during the COVID-19 era and 275 (44%) during the control period, representing a 27% increase in NSTEMI admission rate during the COVID-19 era. Approximately 76% were male, median age was 67 years (IQR 58–76). There were no differences in baseline characteristics between the two study periods. During the COVID-19 era, more patients arrived at the hospital via an emergency medical system (EMS) compared with the control period (p for trend = 0.005)

Time from symptom onset to hospital admission was longer in the COVID-19 era [687.00 (IQR147–2805) vs. 178.00 (IQR 102- 407), respectively, p-value <0.001]. Nevertheless, time from hospital admission to reperfusion was similar in both groups. Rate of percutaneous coronary intervention was higher in the COVID-19 era group (91.3% vs. 59.7%, respectively, p<0.001). In-hospital mortality rate was similar in both groups (2.3% vs. 4.7%, respectively, p=0.149) as was the 30-day mortality rate (3.7% vs. 5.1%, respectively, p=0.238).

Conclusions

In contrast to previous reports, in Israel, admission rate of NSTEMI was increased during the COVID-19 era. With longer time from symptoms to admission, but with the same time from hospital admission to reperfusion therapy and with similar in-hospital and 30-day mortality rates.

Funding Acknowledgement

Type of funding sources: None.

Acute myocardial infarction in the Covid-19 era: incidence, clinical characteristics and in-hospital outcomes – a multicenter registry

Background

A reduction in acute myocardial infarction (AMI) hospitalizations during the coronavirus pandemic has been previously documented. We aimed to describe the characteristics and in-hospital outcomes of AMI patients during the Covid-19 era compared to a recent previous registry.

Methods

We conducted a prospective, multicenter, observational study involving 13 intensive cardiac care units (ICCUs) to evaluate consecutive AMI patients admitted throughout an 8-week period during the Covid-19 outbreak. Data were compared to the corresponding period in 2018 using an acute coronary syndrome survey conducted in all ICCUs in Israel. The primary end-point was defined as a composite of sustained ventricular arrhythmia, pulmonary congestion, and/or in-hospital mortality.

Results

The study cohort comprised 1466 patients, of whom 774 (53%) were hospitalized during the Covid-19 outbreak. Overall, 841 patients were diagnosed with ST-elevation MI (STEMI): 424 (50.4%) during the Covid-19 era and 417 (49.6%) during the parallel period in 2018. No differences were detected in the admission rate of patients between the two study periods. STEMI patients admitted during the Covid-19 period tended to have fewer co-morbidities, but a higher Killip class (p value = 0.03). The median time from symptom onset to reperfusion was extended from 180 minutes (IQR 122–292) in 2018 to 290 minutes (IQR 161–1080, p<0.001) in 2020. Hospitalization during the Covid-19 era was independently associated with an increased risk of the combined endpoint of heart failure, malignant arrhythmia, or death in the multivariable logistic regression model (OR 1.63, 95% CI 1.02–2.65, p value = 0.05).

Conclusion

While the admission rate of AMI and STEMI in Israel remained similar during both the Covid-19 era and the corresponding period in 2018, total ischemic time extended significantly during the Covid-19 period, which translated into a more severe disease status upon hospital admission, and a higher rate of in-hospital adverse events.

Funding Acknowledgement

Type of funding sources: Private grant(s) and/or Sponsorship. Main funding source(s): This work was supported by a grant from a Fefer foundation for medical research

Structures of human constitutive nitric oxide synthases

Mammals produce three isoforms of nitric oxide synthase (NOS): neuronal NOS (nNOS), inducible NOS (iNOS) and endothelial NOS (eNOS). The overproduction of NO by nNOS is associated with a number of neurodegenerative disorders; therefore, a desirable therapeutic goal is the design of drugs that target nNOS but not the other isoforms. Crystallography, coupled with computational approaches and medicinal chemistry, has played a critical role in developing highly selective nNOS inhibitors that exhibit exceptional neuroprotective properties. For historic reasons, crystallography has focused on rat nNOS and bovine eNOS because these were available in high quality; thus, their structures have been used in structure-activity-relationship studies. Although these constitutive NOSs share more than 90% sequence identity across mammalian species for each NOS isoform, inhibitor-binding studies revealed that subtle differences near the heme active site in the same NOS isoform across species still impact enzyme-inhibitor interactions. Therefore, structures of the human constitutive NOSs are indispensible. Here, the first structure of human neuronal NOS at 2.03 Å resolution is reported and a different crystal form of human endothelial NOS is reported at 1.73 Å resolution.

The mobility of a conserved tyrosine residue controls isoform-dependent enzyme-inhibitor interactions in nitric oxide synthases

Many pyrrolidine-based inhibitors highly selective for neuronal nitric oxide synthase (nNOS) over endothelial NOS (eNOS) exhibit dramatically different binding modes. In some cases, the inhibitor binds in a 180° flipped orientation in nNOS relative to eNOS. From the several crystal structures we have determined, we know that isoform selectivity correlates with the rotamer position of a conserved tyrosine residue that H-bonds with a heme propionate. In nNOS, this Tyr more readily adopts the out-rotamer conformation, while in eNOS, the Tyr tends to remain fixed in the original in-rotamer conformation. In the out-rotamer conformation, inhibitors are able to form better H-bonds with the protein and heme, thus increasing inhibitor potency. A segment of polypeptide that runs along the surface near the conserved Tyr has long been thought to be the reason for the difference in Tyr mobility. Although this segment is usually disordered in both eNOS and nNOS, sequence comparisons and modeling from a few structures show that this segment is structured quite differently in eNOS and nNOS. In this study, we have probed the importance of this surface segment near the Tyr by making a few mutants in the region followed by crystal structure determinations. In addition, because the segment near the conserved Tyr is highly ordered in iNOS, we also determined the structure of an iNOS–inhibitor complex. This new structure provides further insight into the critical role that mobility plays in isoform selectivity.

Dissecting the kinetics of the NADP(+)-FADH2 charge transfer complex and flavin semiquinones in neuronal nitric oxide synthase

Electron flow within the neuronal nitric oxide synthase reductase domain (nNOSrd) includes hydride transfer from NADPH to FAD followed by two one-electron transfer reactions from FAD to FMN. We have used stopped flow spectrometry to closely monitor these electron transfer steps for both the wild type and the ΔG810 mutant of nNOSrd using a protocol involving both global analyses of the photodiode array spectral scans and curve fittings of single wavelength kinetic traces. The charge transfer complex and interflavin electron transfer events recorded at 750nm and 600nm, respectively, show the kinetics in different time frames. All electron transfer events are slow enough at 4°C to enable measurements of rate constants even for the fast charge transfer event. To our knowledge this is the first time the rate constants for the charge transfer between NADP(+) and FADH2 have been determined for NOS. These procedures allow us to conclude that (1) binding of the second NADPH is necessary to drive the full reduction of FMN and; (2) charge transfer and the subsequent interflavin electron transfer have distinct spectral features that can be monitored separately with stopped flow spectroscopy. These studies also enable us to conclude that interflavin electron transfer reported at 600nm is not limiting in NOS catalysis.

Role of zinc in isoform-selective inhibitor binding to neuronal nitric oxide synthase

In previous studies [Delker, S. L., et al. (2010), J. Am. Chem. Soc. 132, 5437-5442], we determined the crystal structures of neuronal nitric oxide synthase (nNOS) in complex with nNOS-selective chiral pyrrolidine inhibitors, designed to have an aminopyridine group bound over the heme where it can electrostatically interact with the conserved active site Glu residue. However, in addition to the expected binding mode with the (S,S)-cis inhibitors, an unexpected "flipped" orientation was observed for the (R,R)-cis enantiomers. In the flipped mode, the aminopyridine extends out of the active site where it interacts with one heme propionate. This prompted us to design and synthesize symmetric "double-headed" inhibitors with an aminopyridine at each end of a bridging ring structure [Xue, F., Delker, S. L., Li, H., Fang, J., Jamal, J., Martásek, P., Roman, L. J., Poulos, T. L., and Silverman, R. B. Symmetric double-headed aminopyridines, a novel strategy for potent and membrane-permeable inhibitors of neuronal nitric oxide synthase. J. Med. Chem. (submitted for publication)]. One aminopyridine should interact with the active site Glu and the other with the heme propionate. Crystal structures of these double-headed aminopyridine inhibitors in complexes with nNOS show unexpected and significant protein and heme conformational changes induced by inhibitor binding that result in removal of the tetrahydrobiopterin (H(4)B) cofactor and creation of a new Zn(2+) site. These changes are due to binding of a second inhibitor molecule that results in the displacement of H(4)B and the placement of the inhibitor pyridine group in position to serve as a Zn(2+) ligand together with Asp, His, and a chloride ion. Binding of the second inhibitor molecule and generation of the Zn(2+) site do not occur in eNOS. Structural requirements for creation of the new Zn(2+) site in nNOS were analyzed in detail. These observations open the way for the potential design of novel inhibitors selective for nNOS.

Unexpected binding modes of nitric oxide synthase inhibitors effective in the prevention of a cerebral palsy phenotype in an animal model

Selective inhibition of the neuronal isoform of nitric oxide synthase NOS (nNOS) has been shown to prevent brain injury and is important for the treatment of various neurodegenerative disorders. However, given the high active site conservation among all three NOS isoforms, the design of selective inhibitors is an extremely challenging problem. Here we present the structural basis for why novel and potent nNOS inhibitors exhibit the highest level of selectivity over eNOS reported so far (approximately 3,800-fold). By using a combination of crystallography, computational methods, and site-directed mutagenesis, we found that inhibitor chirality and an unanticipated structural change of the target enzyme control both the orientation and selectivity of these novel nNOS inhibitors. A new hot spot generated as a result of enzyme elasticity provides important information for the future fragment-based design of selective NOS inhibitors.

Crystal structures of constitutive nitric oxide synthases in complex with de novo designed inhibitors

New nitric oxide synthase (NOS) inhibitors were designed de novo with knowledge gathered from the studies on the nNOS-selective dipeptide inhibitors. Each of the new inhibitors consists of three fragments: an aminopyridine ring, a pyrrolidine, and a tail of various length and polarity. The in vitro inhibitory assays indicate good potency and isoform selectivity for some of the compounds. Crystal structures of these inhibitors bound to either wild type or mutant nNOS and eNOS have confirmed design expectations. The aminopyridine ring mimics the guanidinium group of L-arginine and functions as an anchor to place the compound in the NOS active site where it hydrogen bonds to a conserved Glu. The rigidity of the pyrrolidine ring places the pyrrolidine ring nitrogen between the same conserved Glu and the selective residue nNOS Asp597/eNOS Asn368, which results in similar interactions observed with the alpha-amino group of dipeptide inhibitors bound to nNOS. These structures provide additional information to help in the design of inhibitors with greater potency, physicochemical properties, and isoform selectivity.

Exploring the electron transfer properties of neuronal nitric-oxide synthase by reversal of the FMN redox potential

In nitric-oxide synthase (NOS) the FMN can exist as the fully oxidized (ox), the one-electron reduced semiquinone (sq), or the two-electron fully reduced hydroquinone (hq). In NOS and microsomal cytochrome P450 reductase the sq/hq redox potential is lower than that of the ox/sq couple, and hence it is the hq form of FMN that delivers electrons to the heme. Like NOS, cytochrome P450BM3 has the FAD/FMN reductase fused to the C-terminal end of the heme domain, but in P450BM3 the ox/sq and sq/hq redox couples are reversed, so it is the sq that transfers electrons to the heme. This difference is due to an extra Gly residue found in the FMN binding loop in NOS compared with P450BM3. We have deleted residue Gly-810 from the FMN binding loop in neuronal NOS (nNOS) to give Delta G810 so that the shorter binding loop mimics that in cytochrome P450BM3. As expected, the ox/sq redox potential now is lower than the sq/hq couple. Delta G810 exhibits lower NO synthase activity but normal levels of cytochrome c reductase activity. However, unlike the wild-type enzyme, the cytochrome c reductase activity of Delta G810 is insensitive to calmodulin binding. In addition, calmodulin binding to Delta G810 does not result in a large increase in FMN fluorescence as in wild-type nNOS. These results indicate that the FMN domain in Delta G810 is locked in a unique conformation that is no longer sensitive to calmodulin binding and resembles the "on" output state of the calmodulin-bound wild-type nNOS with respect to the cytochrome c reduction activity.

Structural studies of constitutive nitric oxide synthases with diatomic ligands bound

Crystal structures are reported for the endothelial nitric oxide synthase (eNOS)-arginine-CO ternary complex as well as the neuronal nitric oxide synthase (nNOS) heme domain complexed with L: -arginine and diatomic ligands, CO or NO, in the presence of the native cofactor, tetrahydrobiopterin, or its oxidized analogs, dihydrobiopterin and 4-aminobiopterin. The nature of the biopterin has no influence on the diatomic ligand binding. The binding geometries of diatomic ligands to nitric oxide synthase (NOS) follow the {MXY}(n) formalism developed from the inorganic diatomic-metal complexes. The structures reveal some subtle structural differences between eNOS and nNOS when CO is bound to the heme which correlate well with the differences in CO stretching frequencies observed by resonance Raman techniques. The detailed hydrogen-bonding geometries depicted in the active site of nNOS structures indicate that it is the ordered active-site water molecule rather than the substrate itself that would most likely serve as a direct proton donor to the diatomic ligands (CO, NO, as well as O(2)) bound to the heme. This has important implications for the oxygen activation mechanism critical to NOS catalysis.

Exploring the binding conformations of bulkier dipeptide amide inhibitors in constitutive nitric oxide synthases

A series of L-nitroarginine-based dipeptide inhibitors are highly selective for neuronal nitric oxide synthase (nNOS) over the endothelial isoform (eNOS). Crystal structures of these dipeptides bound to both isoforms revealed two different conformations, curled in nNOS and extended in eNOS, corresponding to higher and lower binding affinity to the two isoforms, respectively. In previous studies we found that the primary reason for selectivity is that Asp597 in nNOS, which is Asn368 in eNOS, provides greater electrostatic stabilization in the inhibitor complex. While this is the case for smaller dipeptide inhibitors, electrostatic stabilization may no longer be the sole determinant for isoform selectivity with bulkier dipeptide inhibitors. Another residue farther away from the active site, Met336 in nNOS (Val106 in eNOS), is in contact with bulkier dipeptide inhibitors. Double mutants were made to exchange the D597/M336 pair in nNOS with N368/V106 in eNOS. Here we report crystal structures and inhibition constants for bulkier dipeptide inhibitors bound to nNOS and eNOS that illustrate the important role played by residues near the entry to the active site in isoform selective inhibition.

Structures of the Neuronal and Endothelial Nitric Oxide Synthase Heme Domain with d-Nitroarginine-Containing Dipeptide Inhibitors Bound

In a continuing effort to unravel the structural basis for isoform-selective inhibition of nitric oxide synthase (NOS) by various inhibitors, we have determined the crystal structures of the nNOS and eNOS heme domain bound with two D-nitroarginine-containing dipeptide inhibitors, D-Lys-D-Arg(NO)2-NH(2) and D-Phe-D-Arg(NO)2-NH(2). These two dipeptide inhibitors exhibit similar binding modes in the two constitutive NOS isozymes, which is consistent with the similar binding affinities for the two isoforms as determined by K(i) measurements. The D-nitroarginine-containing dipeptide inhibitors are not distinguished by the amino acid difference between nNOS and eNOS (Asp 597 and Asn 368, respectively) which is key in controlling isoform selection for nNOS over eNOS observed for the L-nitroarginine-containing dipeptide inhibitors reported previously [Flinspach, M., et al. (2004) Nat. Struct. Mol. Biol. 11, 54-59]. The lack of a free alpha-amino group on the D-nitroarginine moiety makes the dipeptide inhibitor steer away from the amino acid binding pocket near the active site. This allows the inhibitor to extend into the solvent-accessible channel farther away from the active site, which enables the inhibitors to explore new isoform-specific enzyme-inhibitor interactions. This might be the structural basis for why these D-nitroarginine-containing inhibitors are selective for nNOS (or eNOS) over iNOS.

Structural basis for dipeptide amide isoform-selective inhibition of neuronal nitric oxide synthase

Three nitric oxide synthase (NOS) isoforms, eNOS, nNOS and iNOS, generate nitric oxide (NO) crucial to the cardiovascular, nervous and host defense systems, respectively. Development of isoform-selective NOS inhibitors is of considerable therapeutic importance. Crystal structures of nNOS-selective dipeptide inhibitors in complex with both nNOS and eNOS were solved and the inhibitors were found to adopt a curled conformation in nNOS but an extended conformation in eNOS. We hypothesized that a single-residue difference in the active site, Asp597 (nNOS) versus Asn368 (eNOS), is responsible for the favored binding in nNOS. In the D597N nNOS mutant crystal structure, a bound inhibitor switches to the extended conformation and its inhibition of nNOS decreases >200-fold. Therefore, a single-residue difference is responsible for more than two orders of magnitude selectivity in inhibition of nNOS over eNOS by L-N(omega)-nitroarginine-containing dipeptide inhibitors.

The novel binding mode of N-alkyl-N'-hydroxyguanidine to neuronal nitric oxide synthase provides mechanistic insights into NO biosynthesis

A series of N-alkyl-N'-hydroxyguanidine compounds have recently been characterized as non-amino acid substrates for all three nitric oxide synthase (NOS) isoforms which mimic NO formation from N(omega)-hydroxy-L-arginine. Crystal structures of the nNOS heme domain complexed with either N-isopropyl-N'-hydroxyguanidine or N-butyl-N'-hydroxyguanidine reveal two different binding modes in the substrate binding pocket. The binding mode of the latter is consistent with that observed for the substrate N(omega)-hydroxy-L-arginine bound in the nNOS active site. However, the former binds to nNOS in an unexpected fashion, thus providing new insights into the mechanism on how the hydroxyguanidine moiety leads to NO formation. Structural features of substrate binding support the view that the OH-substituted guanidine nitrogen, instead of the hydroxyl oxygen, is the source of hydrogen supplied to the active ferric-superoxy species for the second step of the NOS catalytic reaction.

Field evaluation of deltamethrin/S-bioallethrin/piperonyl butoxide and cyfluthrin against dengue vectors in Malaysia

Deltacide (S-bioallethrin 0.71% w/v, deltamethrin 0.5% w/v, piperonyl butoxide 8.9% w/v excipients to 100% w/v) and Solfac UL 015 (cyfluthrin 1.5% w/v) were evaluated against the sentinel sugar-fed adults and 4th-instar larvae of Aedes aegypti at 17 storey high-rise apartments in Malaysia using ULV applications. The impact of both insecticides on field populations of Ae. aegypti and Ae. albopictus larvae was monitored weekly using bottle containers. Both Deltacide and Solfac UL 015 showed adulticidal and larvicidal effects. This was the first field trial using Deltacide against dengue vectors in Malaysia and showed its potential for use in dengue vector control programs.

The self-compressing tibial intramedullary nail

Laboratory evaluation of a self-compressing tibial nail demonstrated that significant, initial compression of a simulated fracture or nonunion can be obtained and controlled. However, when this nail was tested in cyclic loading, loss of its initial static compression occurred.

Field efficacy of fipronil 3G, lambda-cyhalothrin 10%CS, and sumithion 50EC against the dengue vector Aedes albopictus in discarded tires

The efficacy of three insecticides, fipronil 3G, lambda-cyhalothrin 10%CS, and sumithion 50EC were evaluated against the dengue vector Aedes albopictus in discarded tires in Kuala Lumpur, Malaysia. The dosage given for each insecticide was 0.01 g of active ingredient/m2. Fipronil 3G was the most effective larvicide with a residual activity of up to two weeks, causing 88% mortality in Aedes albopictus. Lambda-cyhalothrin 10%CS was effective for one week causing 92% larval mortality and two weeks with 63% larval mortality. Sumithion 50EC had a residual efficacy of one week with 79% larval mortality.

Identification of two electron-transfer sites in ascorbate peroxidase using chemical modification, enzyme kinetics, and crystallography

Chemical and mutagenic modification combined with X-ray crystallography has been used to probe the ascorbate binding site in ascorbate peroxidase (APX). Chemical modification of the single Cys residue in APX with Ellman's reagent (DTNB) blocks the ability of APX to oxidize ascorbate but not other small aromatic phenolic substrates. DTNB-modified APX (APX-TNB) exhibits only 1.3% wild-type activity when ascorbate is used as the substrate but full activity when aromatic substrates, guaiacol or pyrogallol, are used. Stopped-flow studies show that APX-TNB reacts normally with peroxide to give compound I but that the rates of reduction of both compounds I and II by ascorbate are dramatically slowed. Conversion of Cys32 to Ser leads to approximately 70% drop in ascorbate peroxidase activity with no effect on guaiacol peroxidase activity. These results indicate that uncharged aromatic substrates and the anionic ascorbate molecule interact with different sites on APX. The 2.0 A X-ray crystal structure of APX-TNB shows clear electron density for the TNB group covalently attached to Cys32 in all four molecules of the asymmetric unit, indicating complete and specific modification. It appears that the ascorbate site is blocked by DTNB modification which is well removed from the exposed delta-heme edge where aromatic substrates are thought to bind. This is the first experimental evidence indicating that ascorbate oxidation does not occur at the exposed heme edge but at an alternate binding site in the vicinity of Cys32 near Arg172 and the heme propionates.

Field evaluation of cyfluthrin and malathion 96 TG ULV spraying at high-rise flats on dengue vectors in Malaysia

Cyfluthrin (Solfac ULO15) and malathion 96 TG were evaluated against sentinel sugar-fed adults and 4th-instar larvae of Aedes aegypti at high-rise flats in Malaysia by ULV spraying. The impact of both insecticides on field populations of Aedes spp. (Ae. aegypti and Ae. albopictus) larvae were monitored weekly using containers. Both cyfluthrin and malathion 96 TG showed adulticidal effects but cyfluthrin showed more significant larvicidal effect than malathion 96 TG (P < 0.05).

Field evaluation of Vectobac G, Vectobac 12AS and Bactimos WP against the dengue vector Aedes albopictus in tires

The efficacy of three formulations of Bacillus thuringiensis var. israelensis was studied against Aedes albopictus in discarded tires. The formulations were: Vectobac G (corn cob formulation), Vectobac 12AS (aqueous suspension), and Bactimos WP (wettable powder formulation). Both Vectobac G and Vectobac 12AS were effective for 24 hr with more than 80% mortality. Both Vectobac formulations were significantly more effective than Bactimos WP for 24 hr after treatment (P < 0.0005). A week after treatment, Vectobac 12AS was significantly different than Bactimos WP (P < 0.05). However, Vectobac G did not differ significantly from Bactimos WP (P > 0.05); two weeks after spraying there was no significant difference among the various formulations (P > 0.05).

The Drosophila schnurri gene acts in the Dpp/TGF beta signaling pathway and encodes a transcription factor homologous to the human MBP family

Decapentaplegic (dpp), a TGF beta-related ligand, plays a key role in Drosophila development. Although dpp receptors have been isolated, the downstream components of the signaling pathway remain to be identified. We have cloned the schnurri (shn) gene and show that it encodes a putative zinc finger transcription factor homologous to the human major histocompatibility complex-binding proteins 1 and 2. Mutations in shn affect multiple events that require dpp signaling as well as the transcription of dpp-responsive genes. Genetic interactions and the strikingly similar phenotypes of mutations in shn and the dpp receptors encoded by thick veins and punt suggest that shn plays a downstream role in dpp signaling.

Drosophila Dpp signaling is mediated by the punt gene product: a dual ligand-binding type II receptor of the TGF beta receptor family

Signaling by TGF beta-related factors requires ligand-induced association between type I and type II transmembrane serine/threonine kinases. In Drosophila, the saxophone (sax) and thick veins (tkv) genes encode type I receptors that mediate signaling by decapentaplegic (dpp), a member of the bone morphogenetic protein (BMP) subgroup of TGF beta-type factors. In this report, we demonstrate that the Drosophila punt gene encodes atr-II, a previously described type II receptor that on its own is able to bind activin but not BMP2, a vertebrate ortholog of dpp. Mutations in punt produce phenotypes similar to those exhibited by tkv, sax, and dpp mutants. Furthermore, punt will bind BMP2 in concert with tkv or sax, forming complexes with these receptors. We suggest that punt functions as a type II receptors for dpp and propose that BMP signaling in vertebrates may also involve sharing of type II receptors by diverse ligands.

Characterization of tolloid-related-1: a BMP-1-like product that is required during larval and pupal stages of Drosophila development

The Drosophila tolloid (tld) gene product belongs to a family of developmentally important proteins that includes bone morphogenetic protein-1 (BMP-1). In Drosophila, tld is required at the blastoderm stage to establish pattern within the dorsal half of the embryo. Genetic analysis suggests that the major function of tld is to augment the activity of the decapentaplegic gene product, a close relative of the TGF-beta superfamily members, BMP-2 and BMP-4. In this report, we describe a new gene called tolloid-related-1 (tlr-1) that maps immediately proximal to tld. Sequence analysis indicates that tlr-1 has a large N-terminal extension relative to tld, but otherwise shows the same general organization of sequence motifs found in tld and other BMP-1 family members. These include a region of similarity to astacin, a crayfish metalloprotease, five copies of a repeat first found in complement proteins C1r and C1s, and two copies of an epidermal growth factor-like sequence. In situ hybridization experiments show that tlr-1 expression partially overlaps tld expression in early embryos, but shows unique transcriptional patterns in late stage embryos that are not seen with tld. In larval stages, both genes are expressed in identical patterns in imaginal discs and in the optic lobes of the brain, but tlr-1 is more abundant than tld. Deletions that eliminate tlr-1 expression cause lethality during larval and pupal stages of development. A small proportion of homozygous mutant flies eclose and show wing veination defects. Transgenic animals in which a tlr-1 cDNA is driven by the tld promoter fail to rescue tld mutations, and extra copies of tld fail to rescue tlr-1 mutations, implying that these genes have evolved functionally distinct features. We propose that tld and tlr-1 arose by gene duplication and that each has evolved independently to acquire distinct tissue specific roles in Drosophila development.

Extrapulmonary tuberculosis: five case reports

Since the 1950s, tuberculosis (TB) morbidity has been decreasing steadily in Israel. However, recent waves of Ethiopian immigrants have brought new cases and have renewed our awareness of the disease. As in other immigrant populations, the incidence of extrapulmonary TB is relatively high, challenging the clinician to make the correct diagnosis at an early stage. Many of the new immigrants settled in the Ashkelon are and were diagnosed and treated in our hospital. We present five cases of TB with extrapulmonary manifestations. Proof of TB infection was found in sites remote from the major clinical manifestation in four of the patients, emphasizing the difficulty in diagnosing the disease. Four of the patients recovered after treatment, but the patient admitted with neurological involvement remained comatose until her death.

The role of Renshaw cells in locomotion: antagonism of their excitation from motor axon collaterals with intravenous mecamylamine

The contribution of Renshaw cell (RC) activity to the production of fictive locomotion in the mesencephalic preparation was examined using the nicotinic antagonist mecamylamine (MEC). After the i.v. administration of 3 doses of MEC (1.0 mg/kg) the following observations were made: 1) ventral root (VR) evoked discharge of RCs was decreased by up to 87.7%, 2) recurrent inhibitory postsynaptic potentials recorded in alpha motoneurons were greatly reduced or abolished, and 3) the rhythmic firing of RCs during the fictive step cycle was abolished in 83% of the cells examined. Locomotor drive potentials (LDPs) in motoneurons persisted during the fictive step cycle after MEC administration. Bursts of motoneuron firing during each fictive step cycle were characterized by increased frequency and number of spikes after MEC, although the burst duration was unaltered for similar step cycle lengths. A greater number and frequency of spikes per burst was also observed in Ia inhibitory interneurons (IaINs), which remained rhythmically active after MEC administration. It is concluded that Renshaw cells are not an integral part of the spinal central pattern generator for locomotion, nor do they control the timing of the motoneuron or IaIN bursts of firing during fictive locomotion. The data are consistent with a role for RCs in limiting the firing rates of motoneurons and IaINs during each burst.