Feasibility and Workflow Efficiency in MRI-Based HDR Brachytherapy for Cervical Cancer at a Community-Based Practice

PURPOSE/OBJECTIVE(S)

Image-guided brachytherapy (IGBT) has seen widespread use in high-volume centers around the country in the last ten years. GEC-ESTRO recommendations stipulate that the dose be prescribed to the high-risk clinical target volume, which includes the residual tumor present at the time of brachytherapy. This practice has resulted in lesser normal tissue toxicity and improved local control. We introduced MRI volumetric planning at our center three years ago to confer this advantage to our patients. Based on a practice pattern survey by the American brachytherapy society in 2014, IGBT with MRI-based planning was grossly underutilized due to challenges associated with the work stream and availability of MRI. The combined mean procedure time for MR imaging and planning reported at a high-volume brachytherapy center was 63.2 minutes. Our study aimed to identify the time required for MRI-based IGBT for the first HDR fraction for cervical cancer patients at our institution. We aim to understand how we differ from a typical high-volume center and how we may improve our efficiency and workflow.

MATERIALS/METHODS

Between 2020 and 2023, 14 patients were treated with HDR brachytherapy for a diagnosis of cervical cancer. Of these individuals, 7 patients were treated with MRI-guided IGBT during the first HDR fraction. The following time intervals were recorded: 1. Time from applicator insertion to completion of MRI imaging 2. Time from completion of MRI imaging to start of CT simulation 3. Time from start of CT simulation to completion of treatment delivery Materials and methods: Between 2020 and 2023, 14 patients were treated with HDR brachytherapy for a diagnosis of cervical cancer. Of these individuals, 7 patients were treated with MRI-guided IGBT during the First HDR fraction. The following time intervals were recorded: 1. Time from applicator insertion to completion of MRI imaging 2. Time from completion of MRI imaging to start of CT simulation 3. Time from start of CT simulation to completion of treatment delivery.

RESULTS

The mean total procedure time was 582 minutes (Range 494- 665). The mean time and ranges for each phase were as follows. The mean time from the implant insertion to MRI completion was 157.7 minutes (Range 70-307), and the time from MRI completion to the start of CT simulation was 114.7 minutes (Range 17-173), and the time from the start of CT simulation to the treatment delivery was 310 minutes (Range 251-476).

CONCLUSION

Our study demonstrates that MRI-based HDR brachytherapy with a skilled multidisciplinary team in a small community-based practice with an MRI imaging facility is a feasible approach similar to a high-volume center but differs in the total treatment time. Considering high treatment time in the community-based practice, the department is taking a team approach to improve efficiency. This includes establishing a dedicated brachytherapy suite closer to the MRI imaging and incorporating artificial intelligence to assist planning.

Multidisciplinary Consensus Document on the Management of Uncontrolled Hypertension in India

Cardiovascular disease is predicted to be the largest cause of death and disability in India by 2020. Hypertension (HT), one of the main contributing factors, presents a significant public health burden. Inability to achieve adequate blood pressure (BP) control results in uncontrolled hypertension (UHT). The prevalence of UHT is high in India, with only about 9-20% of patients achieving target BP goals. Presently, there are no guidelines specific to UHT, which if left uncontrolled can lead to resistant HT, chronic kidney disease and other complications of HT. A multidisciplinary panel, comprising of specialists in cardiology, nephrology and internal medicine, was convened to address the diagnosis and management of UHT in the Indian population. The panel identified key points concerning UHT and discussed management recommendations in the Indian clinical setting.

Synthesis, Structural, Optical and Dielectric Properties of Nanostructured 0-3 PZT/PVDF Composite Films

Nanostructured PbZr0.52Ti0.48O3 (PZT) powder was synthesized at 500 °C-800 °C using sol-gel route. X-ray diffraction and Rietveld analysis confirmed the formation of perovskite structure. The sample heat treated at 800 °C alone showed the formation of morphotropic phase boundary with coexistence of tetragonal and rhombohedral phase. The PZT powder and PVDF were used in 0-3 connectivity to form the PZT/PVDF composite film using solvent casting method. The composite films containing 10%, 50%, 70% and 80% volume fraction of PZT in PVDF were fabricated. The XRD spectra validated that the PZT structure remains unaltered in the composites and was not affected by the presence of PVDF. The scanning electron microscopy images show good degree of dispersion of PZT in PVDF matrix and the formation of pores at higher PZT loading. The quantitative analysis of elements and their composition were confirmed from energy dispersive X-ray analysis. The optical band gap of the PVDF film is 3.3 eV and the band gap decreased with increase in volume fraction of PZT fillers. The FTIR spectra showed the bands corresponding to different phases of PVDF (α, β, γ) and perovskite phase of PZT. The thermogravimetric analysis showed that PZT/PVDF composite films showed better thermal stability than the pure PVDF film and hydrophobicity. The dielectric constant was measured at frequency ranging from 1 Hz to 6 MHz and for temperature ranging from room temperature to 150 °C. The composite with 50% PZT filler loading shows the maximum dielectric constant at the studied frequency and temperature range with flexibility.

Ameliorative effects of supplemental folinic acid on Lamotrigine-induced fetal malformations in the mouse

Data from our previous work indicate that Lamotrigine (LTG) is teratogenic in the mouse. In the present study, we attempted to determine the possible protective effects of exogenous folate on LTG-induced fetal anomalies in TO mouse. Experiment I entailed administering 4 mg/kg of folinic acid (FA) and (25 mg/kg) of LTG intraperitoneally three times on gestation day (GD) 8 to a group of mice; other groups were a group that received similar volumes of saline, a group that received LTG and Saline, a group that received FA and saline. Experiment 2 involved administering groups of mice with daily 3 doses FA (or proportionate volume of saline) on GD 5 through 10 and either 3 doses of saline on GD8, or 3 doses of LTG on GD8. Maternal plasma concentrations of FA, vitamin B12 and homocysteine were determined an hour after the last injection from one-half of all animals. The other half were allowed to go to term (GD18) when they were euthanized and their fetuses were examined for visceral and skeletal malformations. A high incidence of resorption, abortion, embryolethality, congenital malformations, and intrauterine growth restriction (IUGR), was observed in the LTG-treated group. Folic acid and B12 levels were decreased and homocysteine concentration increased significantly in LTG groups. Mice receiving LTG with FA had normal levels of folate, Vitamin B12 and homocysteine levels, and the fetuses had fewer birth defects similar to the controls which were given saline only. Supplemental FA ameliorated to a great extent the LTG-induced embryonic resorption and malformations and restored the FA status.

Optical control of capacitance in a metal-insulator-semiconductor diode with embedded metal nanoparticles

This paper describes a metal-insulator-semiconductor (MIS) capacitor with flat capacitance voltage characteristics and a small quadratic voltage capacitance coefficient. The device characteristics resemble a metal-insulator-metal diode except that here the capacitance depends on illumination and exhibits a strong frequency dispersion. The device incorporates Fe nanoparticles (NPs), mixed with SrF₂, which are embedded in an insulator stack of SiO₂ and HfO₂. Positively charged Fe ions induce dipole type traps with an electronic polarization that is enhanced by photogenerated carriers injected from the substrate and/or by inter nanoparticle exchange of carriers. The obtained characteristics are compared with those of five other MIS structures: two based on Fe NPs, one with and the other without SrF₂ sublayers. Additionally, devices contain Co NPs embedded in SrF₂ sublayers, and finally, two structures have no NPs, with one based on a stack of SiO₂ and HfO₂ and the other which also includes SrF₂. Only structures containing Fe NPs, which are incorporated into SrF₂, yield a voltage independent capacitance, the level of which can be changed by illumination. These properties are essential in radio frequency/analog mixed signal applications.

Inhibitors of Dengue virus and West Nile virus proteases based on the aminobenzamide scaffold

Dengue and West Nile viruses (WNV) are mosquito-borne members of flaviviruses that cause significant morbidity and mortality. There is no approved vaccine or antiviral drugs for human use to date. In this study, a series of functionalized meta and para aminobenzamide derivatives were synthesized and subsequently screened in vitro against Dengue virus and West Nile virus proteases. Four active compounds were identified which showed comparable activity toward the two proteases and shared in common a meta or para(phenoxy)phenyl group. The inhibition constants (K(i)) for the most potent compound 7n against Dengue and West Nile virus proteases were 8.77 and 5.55 μM, respectively. The kinetics data support a competitive mode of inhibition of both proteases by compound 7n. This conclusion is further supported by molecular modeling. This study reveals a new chemical scaffold which is amenable to further optimization to yield potent inhibitors of the viral proteases via the combined utilization of iterative medicinal chemistry/structure-activity relationship studies and in vitro screening.

Inhibition of Dengue virus and West Nile virus proteases by click chemistry-derived benz[d]isothiazol-3(2H)-one derivatives

Two click chemistry-derived focused libraries based on the benz[d]isothiazol-3(2H)-one scaffold were synthesized and screened against Dengue virus and West Nile virus NS2B-NS3 proteases. Several compounds (4l, 7j-n) displayed noteworthy inhibitory activity toward Dengue virus NS2B-NS3 protease in the absence and presence of added detergent. These compounds could potentially serve as a launching pad for a hit-to-lead optimization campaign.

Design, synthesis, and in vitro evaluation of potential West Nile virus protease inhibitors based on the 1-oxo-1,2,3,4-tetrahydroisoquinoline and 1-oxo-1,2-dihydroisoquinoline scaffolds

The 1-oxo-1, 2, 3, 4-tetrahydroisoquinoline and 1-Oxo-1, 2-dihydroisoquinoline scaffolds were utilized in the design and solution phase synthesis of focused libraries of compounds for screening against West Nile Virus (WNV) protease. Exploratory studies have led to the identification of a WNV protease inhibitor (a 1-oxo-1, 2-dihydroisoquinoline-based derivative, 12j) which could potentially serve as a launching pad for a hit-to-lead optimization campaign. The identified hit was devoid of any inhibitory activity toward a panel of mammalian serine proteases.

Construction of a dengue virus type 4 reporter replicon and analysis of temperature-sensitive mutations in non-structural proteins 3 and 5

Replicon systems have been useful to study mechanisms of translation and replication of flavivirus RNAs. In this study, we constructed a dengue virus 4 replicon encoding a Renilla luciferase (R_luc) reporter, and six single-residue substitution mutants were generated: L128F and S158P in the non-structural protein (NS) 3 protease domain gene, and N96I, N390A, K437R and M805I in the NS5 gene. The effects of these substitutions on viral RNA translation and/or replication were examined by measuring R_luc activities in wild-type and mutant replicon RNA-transfected Vero cells incubated at 35, 37 and 39 °C. Our results show that none of the mutations affected translation of replicon RNAs; however, L128F and S158P of NS3 at 39 °C, and N96I of NS5 at 37 and 39 °C, presented temperature-sensitive (ts) phenotypes for replication. Furthermore, using in vitro methyltransferase assays, we identified that the N96I mutation in NS5 exhibited a ts phenotype for N7-methylation, but not for 2′-O-methylation.

Vigabatrin (VGB) administered during late gestation lowers maternal folate concentration and causes pregnancy loss, fetal growth restriction and skeletal hypoplasia in the mouse

Vigabatrin (VGB) has several therapeutic advantages over older antiepileptic drugs (AED), but there is a lack of information about its potential reproductive toxicologic effects. Our aim was to evaluate the consequences of VGB administered during late gestation on fetal growth and development in the mouse. Based on the results of our previous study, we administered groups of mice a single dose of 450 mg/kg VGB on one of gestation days (GD) 15, 16 or 17. Fetuses were collected on GD 18. VGB groups had a significant incidence of fetal death, abortion, intrauterine growth restriction (IUGR), and hypoplasia of the axial skeleton, metacarpals, metatarsal and phalanges. Abortion was characterized by visible hemorrhagic expulsion of the embryos with their membranes. Maternal plasma folate (FA) and vitamin B12 concentrations were found to be markedly reduced within 12h of VGB treatment. Mice were supplemented with FA from GD 12 through GD 17 with or without a single dose of VGB on GD 15. This group had no abortions. Their fetuses had better body weight and lower frequency of IUGR than those of the non-supplemented VGB group. These data suggest that reductions in maternal FA and vitamin B12 concentrations play an important role in fetal loss, IUGR and skeletal hypoplasia induced by VGB during late gestation in the mouse. In view of the finding that a significant maternal toxicity is associated with this dose regimen, additional groups of mice were treated with 350 mg/kg VGB during embryogenesis and late gestation. This treatment was found to be maternally nontoxic. However, this low dose also resulted in significant fetal loss and IUGR when treatment occurred during late gestation. These data support the hypothesis that late gestation is particularly susceptible to VGB-induced fetal loss and IUGR in the mouse.

Polypyrimidine tract-binding protein is relocated to the cytoplasm and is required during dengue virus infection in Vero cells

The 3' untranslated region (3'UTR) of the dengue virus (DENV) genome contain several sequences required for translation, replication and cyclization processes. This region also binds cellular proteins such as La, polypyrimidine tract-binding protein (PTB), Y box-binding protein 1, poly(A)-binding protein and the translation initiation factor eEF-1 alpha. PTB is a cellular protein that interacts with the regulatory sequences of positive-strand RNA viruses such as several picornaviruses and hepatitis C virus. In the present report, it was demonstrated that PTB translocates from the nucleus to the cytoplasm during DENV infection. At 48 h post-infection, PTB, as well as the DENV proteins NS1 and NS3, were found to co-localize with the endoplasmic reticulum marker calnexin. Silencing of PTB expression inhibited virus translation and replication, whilst overexpression of PTB augmented these processes. Thus, these results provide evidence that, during infection, PTB moves from the nucleus to the cytoplasm and plays an important role in the DENV replicative cycle.

Effects of detergents on the West Nile virus protease activity

Detergents such as Triton X-100 are often used in drug discovery research to weed out small molecule promiscuous and non-specific inhibitors which act by aggregation in solution and undesirable precipitation in aqueous assay buffers. We evaluated the effects of commonly used detergents, Triton X-100, Tween-20, Nonidet-40 (NP-40), Brij-35, and CHAPS, on the enzymatic activity of West Nile virus (WNV) protease. Unexpectedly, Triton X-100, Tween-20, and NP-40 showed an enhancement of in vitro WNV protease activity from 2 to 2.5-fold depending on the detergent and its concentration. On the other hand, Brij-35, at 0.001% enhanced the protease activity by 1.5-fold and CHAPS had the least enhancing effect. The kinetic analysis showed that the increase in protease activity by Triton X-100 was dose-dependent. Furthermore, at Triton X-100 and Tween-20 concentrations higher than 0.001%, the inhibition of compound B, one of the lead compounds against WNV protease identified in a high throughput screen (IC(50) value of 5.7+/-2.5 microM), was reversed. However, in the presence of CHAPS, compound B still showed good inhibition of WNV protease. Our results, taken together, indicate that nonionic detergents, Triton X-100, Tween, and NP-40 are unsuitable for the purpose of discrimination of true versus promiscuous inhibitors of WNV protease in high throughput assays.

Molecular targets for flavivirus drug discovery

Flaviviruses are a major cause of infectious disease in humans. Dengue virus causes an estimated 50 million cases of febrile illness each year, including an increasing number of cases of hemorrhagic fever. West Nile virus, which recently spread from the Mediterranean basin to the Western Hemisphere, now causes thousands of sporadic cases of encephalitis annually. Despite the existence of licensed vaccines, yellow fever, Japanese encephalitis and tick-borne encephalitis also claim many thousands of victims each year across their vast endemic areas. Antiviral therapy could potentially reduce morbidity and mortality from flavivirus infections, but no effective drugs are currently available. This article introduces a collection of papers in Antiviral Research on molecular targets for flavivirus antiviral drug design and murine models of dengue virus disease that aims to encourage drug development efforts. After reviewing the flavivirus replication cycle, we discuss the envelope glycoprotein, NS3 protease, NS3 helicase, NS5 methyltransferase and NS5 RNA-dependent RNA polymerase as potential drug targets, with special attention being given to the viral protease. The other viral proteins are the subject of individual articles in the journal. Together, these papers highlight current status of drug discovery efforts for flavivirus diseases and suggest promising areas for further research.

Specific requirements for elements of the 5' and 3' terminal regions in flavivirus RNA synthesis and viral replication

We initially studied requirements for 5' and 3' terminal regions (TRs) in flavivirus negative strand synthesis in vitro. Purified West Nile (WNV) and dengue-2 (DV2) RNA polymerases were both active with all-WNV or all-DV2 subgenomic RNAs containing the 5'- and 3'TRs of the respective genomes. However, subgenomic RNAs in which the 5'-noncoding region (5'NCR) or the 5'ORF (nts 100-230) in the 5'TR were substituted by analogous sequences derived from the heterologous genome were modestly to severely defective as templates for either polymerase. We also evaluated the infectivity of substitution mutant WNV genome-length RNAs. All WNV RNAs containing the DV2 3'SL were unable to replicate. However, WNV RNAs containing substitutions of the 5'NCR, the capsid gene, and/or 3'NCR nt sequences upstream from the WNV 3'SL, by the analogous DV2 nt sequences, were infectious. Combined results suggested that replication was not dependent upon species homology between the 3'SL and NS5.

Multiple enzyme activities of flavivirus proteins

Dengue viruses (DENV) have 5'-capped RNA genomes of (+) polarity and encode a single polyprotein precursor that is processed into mature viral proteins. NS2B, NS3 and NS5 proteins catalyse/activate enzyme activities that are required for key processes in the virus life cycle. The heterodimeric NS2B/NS3 is a serine protease required for processing. Using a high-throughput protease assay, we screened a small molecule chemical library and identified -200 compounds having > or = 50% inhibition. Moreover, NS3 exhibits RNA-stimulated NTPase, RNA helicase and the 5'-RNA triphosphatase activities. The NTPase and the 5'-RTPase activities of NS3 are stimulated by interaction with NS5. Moreover, the conserved, positively charged motif in DENV-2 NS3, 184RKRK, is required for RNA binding and modulates the RNA-dependent enzyme activities of NS3. To study viral replication, a variety of methods are used such as the in vitro RNA-dependent RNA polymerase assays that utilize lysates from DENV-2-infected mosquito or mammalian cells or the purified NS5 along with exogenous short subgenomic viral RNAs or the replicative intracellular membrane-bound viral RNAs as templates. In addition, a cell-based DENV-2 replicon RNA encoding a luciferase reporter is also used to examine the role of cis-acting elements within the 3' UTR and the RKRK motif in viral replication.

Restricted replication and lysosomal trafficking of yellow fever 17D vaccine virus in human dendritic cells

The yellow fever virus attenuated 17D vaccine strain is a safe and effective vaccine and a valuable model system for evaluating immune responses against attenuated viral variants. This study compared the in vitro interactions of the commercially available yellow fever vaccine (YF-VAX), Dengue virus and the live-attenuated dengue vaccine PDK50 with dendritic cells (DCs), the main antigen-presenting cells at the initiation of immune responses. Similar to PDK50, infection with YF-VAX generated activated DCs; however, for YF-VAX, activation occurred with limited intracellular virus replication. The majority of internalized virus co-localized with endolysosomal markers within 90 min, suggesting that YF-VAX is processed rapidly in DCs. These results indicate that restricted virus replication and lysosomal compartmentalization may be important contributing factors to the success of the YF-VAX vaccine.

Characterization of the West Nile virus protease substrate specificity and inhibitors

West Nile virus (WNV), a mosquito-borne member of Flaviviridae, is a human pathogen causing widespread disease for which there is no vaccine or chemotherapy. The two-component viral serine protease consists of a heterodimeric complex between the hydrophilic domain of the cofactor, NS2B (NS2BH) and the protease domain (NS3-pro). The protease is essential for polyprotein processing followed by assembly of viral replicase and genome replication. Therefore, the protease is an excellent target for development of antiviral therapeutics. Here, we report the expression in Escherichia coli, purification, and characterization of biochemical and kinetic properties of the WNV protease. Furthermore, we show that the WNV and the dengue virus type 2 (DENV-2) proteases are inhibited by aprotinin with inhibitor constants of 0.16 and 0.026 microM, respectively. Molecular modeling of the WNV protease/aprotinin complex, based on the known crystal structures of the WNV NS2BH-N3pro and aprotinin, suggest a potentially strong interaction between the P2 Lys and the protease activator peptide, NS2BH. This conclusion based on molecular modeling is in agreement with our data of a higher k(cat)/Km value with the substrate, Boc-Gly-Lys-Arg-MCA than the Boc-Gly-Arg-Arg-MCA and is also consistent with the results of an earlier study that were based on substrate-based inhibitor peptides.

Antiviral action of nitric oxide on dengue virus type 2 replication

Recently, nitric oxide (NO) has been shown to suppress dengue virus (DENV) RNA and protein accumulation in infected cells. In this report, the potential target of the inhibitory effect of NO was studied at the molecular level. The NO donor, S-nitroso-N-acetylpenicillamine (SNAP), showed an inhibitory effect on RNA accumulation at around 8-14 h post-infection, which corresponded to the step of viral RNA synthesis in the DENV life cycle. The activity of the viral replicase isolated from SNAP-treated DENV-2-infected cells was suppressed significantly compared with that of the negative-control N-acetyl-DL-penicillamine (NAP)-treated cells. Further investigations on the molecular target of NO action showed that the activity of recombinant DENV-2 NS5 in negative-strand RNA synthesis was affected in the presence of 5 mM SNAP in in vitro RNA-dependent RNA polymerase (RdRp) assays, whereas the RNA helicase activity of DENV-2 NS3 was not inhibited up to a concentration of 15 mM SNAP. These results suggest that the inhibitory effect of NO on DENV infection is partly via inhibition of the RdRp activity, which then downregulates viral RNA synthesis.

Mosquito La protein binds to the 3' untranslated region of the positive and negative polarity dengue virus RNAs and relocates to the cytoplasm of infected cells

The untranslated regions (UTRs) of the positive and negative strand RNAs of several viruses are major binding sites for cellular and viral proteins. Human La autoantigen is one of the cellular proteins that interacts with various positive strand RNA viral genomes including that of dengue virus (DEN) within the 5'- and 3'-UTRs of positive (+) and the 3'-UTR of negative strand (-) RNA, and with the nonstructural proteins NS3 and NS5, that form DEN replicase complex. Since DEN replicates in human and mosquito cells, some functional interactions have to be conserved in both hosts. In the present report, we demonstrate that mosquito La protein interacts with the 3'-UTRs of (+) and (-) polarity viral RNAs. The localization of La protein, examined by confocal microscopy, indicates that La protein is redistributed in DEN-infected cells. Furthermore, the presence of La protein in an in vitro replication system inhibited RNA synthesis in a dose-dependent manner, suggesting that La protein plays an important role in dengue virus replicative cycle.

Relative efficacy of various 5- hydroxytryptamine receptor antagonists in the prevention and control of acute nausea and vomiting associated with platinum-based chemotherapy

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Background: The introduction of 5-Hydroxytryptamine-3 receptor (5-HT3) antagonists has represented a significant clinical advance in the prevention and treatment of chemotherapy-induced nausea and vomiting (CINV), particularly for patients receiving highly emetogenic platinum-based regimens. However no study to date has compared the relative efficacy of Dolasetron, Granisetron, Ondansetron and Palonosetron with Dexamethasone in the prevention and control of acute CINV in patients undergoing platinum-based therapy. Methods: Retrospective data were reviewed for 207 consecutive patients receiving Platinum-based chemotherapy in our infusion center between November 1999 and August 2005. Patients receiving 5-HT3 antagonists without Dexamethasone (n=11) were not eligible for the study. Further 15 patients were excluded because of no documentation of CINV. The remaining 181 patients constitute the subject of this study. Patient characteristics including age, sex, race, diagnosis, history of heavy alcohol intake, chemotherapy regimen administered, number of cycles, and performance status at the start of therapy were noted. Primary outcome measure was complete control of acute CINV. National Cancer Institute Common Toxicity Criteria version 2.0 was used to assess toxicity. Results: The 181 patients received 572 cycles of platinum-based therapy. Dolasetron (n=157), Granisetron (n=81), Ondansetron (n=131) and Palonosetron (n=203) (each given with Dexamethasone) achieved complete control of vomiting in 89.8%, 95.5%, 92.3% and 88.1% (ρ=0.86) of cycles respectively. Respectively, complete nausea control was observed in 68.1%, 75.3%, 69.4% and 73.3% (ρ=0.35). DEX 20 mg was not superior to 10mg in complete control of nausea and vomiting (ρ=0.06 and ρ=0.67 respectively). Similarly complete control of nausea and vomiting (ρ=0.12 and ρ=0.10 respectively) was not significantly different in patients getting cisplatin compared to carboplatin based regimens. Conclusion: This study does not demonstrate a significant difference in the efficacy of the four 5-HT3 antagonists in controlling acute CINV. The higher dose of Dexamethasone confers no added benefit over the lower 10mg dose.

No significant financial relationships to disclose.

Effect of maternal exposure to homocystine on sodium valproate-induced neural tube defects in the mouse embryos

BACKGROUND

Neural tube defects (NTD) are mainly of multifactorial origin. Maternal treatment with valproic acid (VPA) during pregnancy induces NTD in susceptible fetuses. Elevated levels of homocysteine are observed in pregnancies with NTD. The mechanism by which homocysteine might cause NTD is unknown.

AIM OF THE STUDY

The aim of this study was to determine if homocystine would augment VPA-induced exencephaly in an experimental model.

METHODS

Groups of mice were injected (IP) on gestational day 8 (GD) with a single dose of 75 mg/kg of L: -Homocystine (HC) or a proportionate volume of saline, followed by a single dose of 600 mg/kg of VPA or an equal volume of saline. In a second experiment, mice were treated with a daily dose of 75 mg/kg of HC or an equal volume of saline (IP) from GD 5 and continued through GD 10. These animals had a single exposure to 600 mg/kg of VPA or saline (IP) on GD 8. All animals were killed by cervical dislocation on GD 18. Plasma homocysteine, folate and vitamin B12 were determined on GD 8 and GD 10 from single and multiple dose groups of mice, respectively, from additional experiments.

RESULTS

The VPA and HC+VPA induced significantly higher rates of embryonic resorption and intrauterine growth retardation (IUGR) than HC or saline alone. HC + VPA groups had significantly more numerous fetuses with severe IUGR than HC alone or VPA alone groups. Both single and multiple doses of HC augmented VPA-induced reduction in fetal body weight. Successive doses of HC did not augment the rate of IUGR more significantly than a single dose of HC. Incidence of exencephaly was significantly enhanced in the HC + VPA groups compared to that in the HC or VPA alone groups. HC alone was not teratogenic. Plasma homocysteine levels increased several fold both in HC and HC + VPA groups and the increase was not particularly more marked in multiple dose groups than in the single dose groups. VPA did not elevate homocysteine concentration. Both FA and vitamin B12 concentrations were reduced by VPA, HC and HC + VPA, but HC and VPA when combined did not produce an additive effect on vitamin levels.

CONCLUSION

These data indicate that HC and VPA interact in neurulation stage embryos, affect fundamental processes of closure of the neural tube and lead to enhanced incidence of NTD.

A prospective, randomised controlled trial comparing the efficacy of pre-oxygenation in the 20° head-upvssupine position*

We investigated whether positioning patients undergoing general anaesthesia for cholecystectomy in a 20 degrees head-up position, as opposed to supine, improved the efficacy of 3 min of standard pre-oxygenation via a circle breathing system. Following pre-oxygenation, patients received a standard induction of anaesthesia and the apnoea time (from administration of rocuronium to the arterial oxygen saturation to fall to 95%) was recorded. Mean (95% CI) apnoea time was 386 (343-429) s in the 20 degrees head-up position (n = 17) vs 283 (243-322) s in the supine position (n = 18; p = 0.002). Pre-oxygenation is significantly more efficacious and by inference more efficient in the 20 degrees head-up position than in the supine position.

A prospective, randomised, controlled study examining binaural beat audio and pre-operative anxiety in patients undergoing general anaesthesia for day case surgery

Pre-operative anxiety is common and often significant. Ambulatory surgery challenges our pre-operative goal of an anxiety-free patient by requiring people to be 'street ready' within a brief period of time after surgery. Recently, it has been demonstrated that music can be used successfully to relieve patient anxiety before operations, and that audio embedded with tones that create binaural beats within the brain of the listener decreases subjective levels of anxiety in patients with chronic anxiety states. We measured anxiety with the State-Trait Anxiety Inventory questionnaire and compared binaural beat audio (Binaural Group) with an identical soundtrack but without these added tones (Audio Group) and with a third group who received no specific intervention (No Intervention Group). Mean [95% confidence intervals] decreases in anxiety scores were 26.3%[19-33%] in the Binaural Group (p = 0.001 vs. Audio Group, p < 0.0001 vs. No Intervention Group), 11.1%[6-16%] in the Audio Group (p = 0.15 vs. No Intervention Group) and 3.8%[0-7%] in the No Intervention Group. Binaural beat audio has the potential to decrease acute pre-operative anxiety significantly.

Effect of maternal administration of vigabatrin during late gestation on fetoplacental amino acid profile in the mouse

The objectives were to determine if vigabatrin in late gestation affects fetal growth and causes alterations in amino acid concentrations in the mouse. A single dose of 450 mg/kg VGB in saline or a proportionate volume of saline was administered intraperitoneally (IP) to Theiler outbred (TO) mice on gestation day 15 and maternal plasma, placentae and fetuses were collected at different time intervals after treatment. VGB attained peak concentration in the maternal plasma and the fetus at 2 h after treatment and in the placenta at 4 h. At 12 h significantly lower concentrations of several amino acid including methionine were found in the placentae and fetuses in the treated group. After 24 h, no difference was seen in the plasma amino acid concentrations but in the placentae and fetuses a significant decrease occurred in some amino acids in the treated group. At 48 and 72 h, a generalized increase in most amino acid levels occurred in the fetus and placenta but not in maternal plasma of the treated group although the fetal and placental weights were significantly reduced. VGB during late gestation causes fetal growth retardation accompanied by an initial disruption of amino acid supply followed by an increase in amino acid concentrations for the next 2 days. This increase did not help restore growth suggesting that early fetal period is particularly vulnerable to VGB-induced intrauterine growth retardation in the mouse.

Modulation of the nucleoside triphosphatase/RNA helicase and 5'-RNA triphosphatase activities of Dengue virus type 2 nonstructural protein 3 (NS3) by interaction with NS5, the RNA-dependent RNA polymerase

Dengue virus type 2 (DEN2), a member of the Flaviviridae family, is a re-emerging human pathogen of global significance. DEN2 nonstructural protein 3 (NS3) has a serine protease domain (NS3-pro) and requires the hydrophilic domain of NS2B (NS2BH) for activation. NS3 is also an RNA-stimulated nucleoside triphosphatase (NTPase)/RNA helicase and a 5'-RNA triphosphatase (RTPase). In this study the first biochemical and kinetic properties of full-length NS3 (NS3FL)-associated NTPase, RTPase, and RNA helicase are presented. The NS3FL showed an enhanced RNA helicase activity compared with the NS3-pro-minus NS3, which was further enhanced by the presence of the NS2BH (NS2BH-NS3FL). An active protease catalytic triad is not required for the stimulatory effect, suggesting that the overall folding of the N-terminal protease domain contributes to this enhancement. In DEN2-infected mammalian cells, NS3 and NS5, the viral 5'-RNA methyltransferase/polymerase, exist as a complex. Therefore, the effect of NS5 on the NS3 NTPase activity was examined. The results show that NS5 stimulated the NS3 NTPase and RTPase activities. The NS5 stimulation of NS3 NTPase was dose-dependent until an equimolar ratio was reached. Moreover, the conserved motif, 184RKRK, of NS3 played a crucial role in binding to RNA substrate and modulating the NTPase/RNA helicase and RTPase activities of NS3.

Histological, histochemical and electron microscopic changes of the placenta induced by maternal exposure to hyperthermia in the rat

Both clinical and experimental investigations have shown that maternal hyperthermia during critical stages of embryo development can induce malformations in the offspring. Studies of the effect of heat stress on the placental functions are limited to the ewes, but that on microscopic structure is unknown. In the present study, rats were exposed to 41 or 42 degrees C for 1 h on gestation day (GD) 9. The controls were sham treated. Fetuses and placentas were collected on GD 20. Intrauterine growth retardation (IUGR) and several craniofacial malformations were observed in the fetuses of the heat-treated group. The placentas of the 42 degrees C group were significantly lighter in weight than those of the control. Light microscopy (LM) revealed thickening, hyalinization and occasional lymphocytic infiltration of the decidua basalis. Giant cells were prominent and glycogen cells had degenerated, leaving behind large cysts in the basal (spongy) zone. Best's carmine stain with or without diastase indicated the reduction in number and degeneration of glycogen cells and cyst formation. The labyrinthine zone was relatively thin in comparison to that of the controls. Perivascular fibrosis and paucity of vascularization were other features of the placentas of the hyperthermia group. Electron microscopy (EM) revealed lipid droplet accumulation in the trophoblast, the presence of myelin bodies and an increased production of collagen in the basal zone. Perivascular fibrosis appeared to have contributed to placental barrier thickening. EM also revealed accumulation of glycogen and lipid droplets in the trophoblasts and fibrin secretion into the extracellular space of the labyrinthine zone. These data suggest that placental pathology possibly contributes to fetal growth retardation in maternally heat-stressed rat fetuses.

Effect of maternal diabetes and ethanol interactions on embryo development in the mouse

The aim of this study was to determine the possible fetal effects of interaction between maternal diabetes and acute doses of alcohol. Pregnant TO mice were made diabetic by a single injection of streptozotocin (STZ) on gestation day (GD) 2. Single dose of 0.003 or 0.03 ml/g body weight of fresh ethanol (25% v/v of absolute alcohol in normal saline) was injected into groups of diabetic and nondiabetic animals on GD 7 or 8. One group of diabetic animals had a daily dose of 6-8 IU of insulin subcutaneously. Fetuses were collected on GD 18. There was a significant increase in the incidence of implantation failure in the diabetes plus ethanol groups and insulin control group. Ethanol injection on GD 7 accentuated diabetes-related embryonic resorption and intrauterine growth retardation (IUGR). This effect was less marked in the diabetic group treated with ethanol on GD 8. Diabetes alone produced a greater incidence of IUGR than ethanol alone. Midfacial hypoplasia and minor anomalies were found more frequently in the combination treatment groups. Holoprosencephaly and thymus hypoplasia observed in diabetic groups were found to be reduced in frequency in the diabetes plus ethanol groups, suggesting an antagonistic type of ethanol-diabetes interaction, stage-dependently. Since severely malformed embryos are known to be resorbed/killed in utero in mice, this reduction might reflect the magnitude of early death of severely malformed embryos. These data suggest that the interaction effects are possibly related to alterations in fundamental developmental processes of early embryos.

Effects of alpha-lipoic acid supplementation on maternal diabetes-induced growth retardation and congenital anomalies in rat fetuses

The mechanism of diabetic embryopathy is not known. Excessive reactive oxygen species (ROS) produced in diabetes may be causally related to foetal anomalies. The objective of this study was to determine whether supplementation with the antioxidant lipoic acid (LA) could prevent maternal diabetes-related foetal malformations and intrauterine growth retardation (IUGR) in rats. Pregnant rats were non-treated (Group I) or made diabetic on gestation day (GD) 2 by injecting streptozotocin (Group II). Group III was injected with 20 mg kg(-1) of LA daily starting on GD 6 and continued through GD 19. Group IV was administered only Tris buffer on the corresponding days. Group V was a set of STZ-treated animals, which were supplemented with a daily dose of 20 mg kg(-1) of LA from GD 6 through GD 19. All fetuses were collected on GD 20. Lipoic acid did not affect the blood sugar levels of diabetic animals significantly but improved their body weight gain and reduced food and water consumption. Diabetic group had a high incidence of embryonic resorption, IUGR, craniofacial malformations, supernumerary ribs and skeletal hypoplasia. Lipoic acid significantly reduced these abnormalities. These data support the hypothesis that ROS are causally related to fetal maldevelopment and IUGR associated with maternal diabetes in the rat. They also highlight the possible role of antioxidants in the normal processes of embryo survival, growth and development.

Experimental studies on reproductive toxicologic effects of lamotrigine in mice

BACKGROUND

Virtually all antiepileptic drugs (AED) tested so far have been found to be teratogenic. The second generation AED possess a number of therapeutic advantages over the older ones. There are, however, very little data on their effects on embryonic development. A recent report suggests that lamotrigine (LTG) can be teratogenic to human fetuses. With only a few cases of prenatal exposure to LTG in the record, however, it has not been possible to establish a recognizable pattern of malformations in the infants of LTG-treated mothers.

OBJECTIVES

The objectives of the present study were to evaluate the reproductive toxic effects of LTG .

RESULTS

Single (50-200 mg/kg) or multiple doses (25, 50, 75 mg/kg) of LTG were administered by intraperitoneal (i.p.) injection (note that the therapeutic administration is oral) to groups of TO mice on gestation day (GD) 7 or 8. Fetuses were collected on GD 18. Maternal toxic effects including a dose-related mortality, a high incidence of abortion, embryo lethality, congenital malformations and intrauterine growth retardation (IUGR) were observed in the LTG-treated group. Administration of LTG in multiple low doses resulted in a better maternal survival and increased incidence of embryonic resorption and malformations with increasing dose; IUGR was significant but not dose-dependent. The malformations characteristic of the LTG multiple low dose group fetuses included maxillary-mandibular hypoplasia, exencephaly, cleft palate, median facial cleft, urogenital anomalies and varying degrees of caudal regression. Skeletal malformations and developmental delay of the skeleton were observed both in single and multiple dose groups.

CONCLUSIONS

The results of this study indicate that LTG administered i.p. at high doses can induce intrauterine growth retardation and at low multiple doses causes a dose-dependent increase in embryonic resorption, craniofacial and caudal malformations as well as maternal toxicity in the mouse. Previous studies in other laboratories have used oral route of exposure and concluded that there are no teratogenic effects of LTG at dose levels that are not maternally toxic.

Further delineation of Hennekam syndrome

We report four children from four inbred Arab families with varying manifestations of Hennekam syndrome and additional features that have not been previously reported. These include abnormalities of the middle ear, anomalous pulmonary venous drainage, interrupted inferior vena cava, polysplenia, crossed renal ectopia, median position of the liver and multiple cavernous haemangiomas. In addition, in one case lymphoedema was absent and oedema due to hypoproteinaemia appeared at 6 years of age. Since anomalies of the veins and the consequent developmental abnormalities of the lymphatics might lead to alterations in the fluid balance of the embryo, we hypothesize that altered fluid dynamics due to defective vascular and lymphatic development might disrupt critical events in craniofacial morphogenesis resulting in Hennekam syndrome.

Requirements for West Nile virus (-)- and (+)-strand subgenomic RNA synthesis in vitro by the viral RNA-dependent RNA polymerase expressed in Escherichia coli

RNA-dependent RNA polymerases (RdRPs) of the Flaviviridae family catalyze replication of positive (+)- strand viral RNA through synthesis of minus (-)-and progeny (+)-strand RNAs. West Nile virus (WNV), a mosquito-borne member, is a rapidly re-emerging human pathogen in the United States since its first outbreak in 1999. To study the replication of the WNV RNA in vitro, an assay is described here that utilizes the WNV RdRP and subgenomic (-)- and (+)-strand template RNAs containing 5'- and 3'-terminal regions (TR) with the conserved sequence elements. Our results show that both 5'- and 3'-TRs of the (+)-strand RNA template including the wild type cyclization (CYC) motifs are important for RNA synthesis. However, the 3'-TR of the (-)-strand RNA template alone is sufficient for RNA synthesis. Mutational analysis of the CYC motifs revealed that the (+)-strand 5'-CYC motif is critical for (-)-strand RNA synthesis but neither the (-)-strand 5'- nor 3'-CYC motif is important for the (+)-strand RNA synthesis. Moreover, the 5'-cap inhibits the (-)-strand RNA synthesis from the 3' fold-back structure of (+)-strand RNA template without affecting the de novo synthesis of RNA. These results support a model that "cyclization" of the viral RNA play a role for (-)-strand RNA synthesis but not for (+)-strand RNA synthesis.

De novo synthesis of negative-strand RNA by Dengue virus RNA-dependent RNA polymerase in vitro: nucleotide, primer, and template parameters

By using a purified dengue virus RNA-dependent RNA polymerase and a subgenomic 770-nucleotide RNA template, it was shown previously that the ratio of the de novo synthesis product to hairpin product formed was inversely proportional to increments of assay temperatures (20 to 40 degrees C). In this study, the components of the de novo preinitiation complex are defined as ATP, a high concentration of GTP (500 micro M), the polymerase, and the template RNA. Even when the 3'-terminal sequence of template RNA was mutated from -GGUUCU-3' to -GGUUUU-3', a high GTP concentration was required for de novo initiation, suggesting that high GTP concentration plays a conformational role. Furthermore, utilization of synthetic primers by the polymerase indicated that AGAA is the optimal primer whereas AG, AGA, and AGAACC were inefficient primers. Moreover, mutational analysis of the highly conserved 3'-terminal dinucleotide CU of the template RNA indicated that change of the 3'-terminal nucleotide from U to C reduced the efficiency about fivefold. The order of preference for the 3'-terminal nucleotide, from highest to lowest, is U, A - G, and C. However, change of the penultimate nucleotide from C to U did not affect the template activity. A model consistent with these results is that the active site of the polymerase switches from a "closed" form, catalyzing de novo initiation through synthesis of short primers, to an "open" form for elongation of a double-stranded template-primer.

Transactivation of human cdc2 promoter by adenovirus E1A

Expression of the adenovirus oncoprotein E1A 12S induces the heterotrimeric transcription factor, NF-Y. NF-Y binds to the two CCAAT motifs upstream of the transcriptional start site of the human cdc2 promoter and is required for activation of the promoter by E1A 12S in cycling cells. The observations that a number of eukaryotic cell cycle regulatory genes also contain the CCAAT motifs and NF-Y binds to them support the notion that E1A 12S could play an important role in deregulated expression of these genes through activation of NF-Y gene in cycling cells.

Amelioration of sodium valproate-induced neural tube defects in mouse fetuses by maternal folic acid supplementation during gestation

Infants of epileptic women treated with valproic acid (VPA) during pregnancy have a higher risk of developing spina bifida than those of the general population. VPA induces exencephaly in experimental animal embryos. But the pathogenetic mechanism remains rather elusive. Antiepileptic drugs (AED) in general accentuate pregnancy-imposed fall in maternal folate levels. Periconceptional folic acid supplementation is reported to protect embryos from developing neural tube defects (NTD). Conflicting results have been reported by experimental studies that attempted to alleviate VPA-induced NTD by folic acid. Our objectives were to determine the critical developmental stages and an effective dose of folic acid for the prevention of VPA-induced exencephaly in mouse fetuses. A single teratogenic dose of 400 mg/kg of VPA was administered to TO mice on gestation day (GD) 7 or 8. It was followed by (1) a single dose of 12 mg/kg of FA (folinic acid) or (2) 3 doses of FA 4 mg/kg each. In experiment (3), FA (4 mg/kg) was administered thrice daily starting on GD 5 and continued through GD 10. These animals received VPA on GD 7 or 8. VPA and B12 concentrations were determined by radioimmunoassay. The single heavy dose of FA had no rescue effect on NTD. Three divided doses of FA on GD 7 and continuous dosing of FA from GD 5 through GD 10 substantially reduced the VPA-induced exencephaly in the fetuses. In the later experiments, the neural folds elevated faster than the non-supplemented group. VPA considerably reduced maternal plasma folate and B12 concentrations. The heavy dose of FA only moderately improved vitamin levels. Three divided doses of FA elevated the vitamin levels slightly better but it was the prolonged dosing of FA that was associated with sustained elevation of plasma levels higher than the control levels and acceleration of neural tube closure thus accounting for the pronounced protection against VPA-induced NTD development. These data suggest that plasma levels of FA and B12 have to be kept substantially elevated and maintained high throughout organogenesis period to protect embryos against VPA-induced NTD in this mouse model.

Folic acid awareness and intake survey in the United Arab Emirates

OBJECTIVE

The aim of this study was to determine the level of knowledge and use of periconceptional folic acid supplementation in a sample of postpartum women recruited from three hospitals.

DESIGN

Cross-sectional survey in which a structured questionnaire was used in a face-to-face encounter between the subject and a trained nurse.

SETTINGS

Two teaching hospitals associated with Faculty of Medicine and Health Sciences and one private hospital.

SUBJECTS

Postpartum women in the three hospitals were recruited during a 40-day period in November 1999. Women who did not agree to participate, had complicated labor, delivered babies with congenital malformations, or were too exhausted or difficult to examine, were excluded.

RESULTS

Univariate analyses showed that overall 46.4% of the respondents had heard about folic acid and only 8.7% knew that it prevented birth defects. 45.5% of respondents took folic acid in the first trimester. The percentage of women who had ever heard about folic acid was higher in those with higher education, and those who were not UAE nationals. Use of folic acid was associated with non-UAE nationality.

CONCLUSION

Awareness of the value of periconceptional folic acid was very low and use of folic acid was less prevalent among women of UAE nationality.

Expression, purification, and characterization of the RNA 5'-triphosphatase activity of dengue virus type 2 nonstructural protein 3

Dengue virus type 2 (DEN2), a member of the Flaviviridae family of positive-strand RNA viruses, contains a single RNA genome having a type I cap structure at the 5' end. The viral RNA is translated to produce a single polyprotein precursor that is processed to yield three virion proteins and at least seven nonstructural proteins (NS) in the infected host. NS3 is a multifunctional protein having a serine protease catalytic triad within the N-terminal 180 amino acid residues which requires NS2B as a cofactor for activation of protease activity. The C-terminal portion of this catalytic triad has conserved motifs present in several nucleoside triphosphatases (NTPases)/RNA helicases. In addition, subtilisin-treated West Nile (WN) virus NS3 from infected cells was reported to have 5'-RNA triphosphatase activity, suggesting its role in the synthesis of the 5'-cap structure. In this study, full-length DEN2 NS3 was expressed with an N-terminal histidine tag in Escherichia coli and purified in a soluble form. The purified protein has 5'-RNA triphosphatase activity that cleaves the gamma-phosphate moiety of the 5'-triphosphorylated RNA substrate. Biochemical and mutational analyses of the NS3 protein indicate that the nucleoside triphosphatase and 5'-RNA triphosphatase activities of NS3 share a common active site.

Renal dose dopamine--it's myth and the truth

Renal dose dopamine is prescribed worldwide for the prevention and treatment of acute renal failure. It's use is based on selective renal vasodilatation (induced at low doses) observed in animal studies and normal subjects. But most clinical studies have failed to demonstrate convincingly the benefit of low dose dopamine in acute renal failure. Moreover adverse effects of dopamine have been recognised warranting its use only in specific situations where benefit is proved. The available data on renal dose dopamine are either poor or statistically underpowered to draw conclusion. Therefore, a prospective, controlled trial with adequate patient number is required, to confirm the benefits.