Structured hybrid photodetectors using confined conducting polymer nanochannels

We design and fabricate hybrid organic inorganic perovskite photodetectors that utilize hole transport layer poly(3,4-ethylene dioxythiophene):poly (styrenesulfonate) PEDOT:PSS confined in alumina nanocylinders. This structural asymmetry in the device where the alumina nanopore template is partially filled with PEDOT:PSS provides features that improve certain device characteristics. The leakage component of the current in such devices is considerably suppressed, resulting in enhanced responsivity and detectivity. The funneling aspect of the photogenerated charge carrier transit ultimately leads to fast detectors as compared to conventional perovskite detectors.

The importance of predicting patient responses to monoclonal antibodies for Crohn's disease

INTRODUCTION

Crohn's disease (CD) is a chronic immune-mediated inflammatory bowel disease that results in relapsing and remitting symptoms but progressive transmural bowel damage leading to significant morbidity. CD results from dysregulation of the immune system related to genetic and environmental factors. While the use of monoclonal antibodies targeting cytokines and adhesion molecules has been shown to improve outcomes in CD patients, their widespread use has been limited due to high costs as well as variable access. Here, we summarize the factors that have been shown to correlate with responsiveness to biologic agents for use in practice.

AREAS COVERED

We summarize the current literature regarding factors that have been shown to influence patient response to various biologic agents including: patient-related factors (e.g. age, gender, weight smoking history); disease-specific factors (e.g. disease duration, location/extension, behavior/phenotype, severity); genetic markers; transcription factors, and the gut microbiome. Finally, we review the utility of prediction models and present data supporting the use of recently developed decision support tools.

EXPERT OPINION

Clinical decision support tools developed by machine learning are currently available for the selection of biologic agents in CD patients. We expect these models to become an integral tool for clinicians in the treatment of CD in the coming years.

Dental students' perception of a blended learning approach to clinic orientation

PURPOSE/OBJECTIVES

The pandemic presented a big challenge to dental education: rapid conversion of a hands-on, experiential learning program to a virtual environment. The objectives of this study are to examine the conventional approaches of facilitating the transition from pre-clinic to clinic, to analyze how a blended learning approach including virtual learning modules facilitated this transition, and to assess the benefits of virtual learning in the future of dental school curriculum.

METHODS

Rising third-year dental students in 2020 (n = 134) were engaged in a three-month (from the end of May to the end of August 2020) clinic orientation consisting of virtual didactic and clinic simulated activities. Part I consisted of didactic courses presented virtually. Part II consisted of simulated clinical activities for operative and radiology along with 3-week virtual treatment planning (TP) sessions with quizzes for each week. Part III consisted of clinical assisting and shadowing activities in the clinic on restorative procedures and TP sessions with senior students. Surveys were administered before and after each part of the orientation program.

RESULTS

Data confirmed that 1) virtually-delivered didactic materials increased students' knowledge in learning relevant key topics of clinic transition and 2) virtual TP sessions increased students' perceived confidence and knowledge in assessment and TP.

CONCLUSION

Despite challenges faced during school closure, most dental students positively valued the virtual orientation methods of learning. Integrating a virtual mode of didactic can serve as a new methodology of the dental school curriculum in preparation for the clinic.

2D Position-Sensitive Hybrid-Perovskite Detectors

Hybrid organic-inorganic perovskites (HOIPs) have emerged as a versatile class of semiconductors for numerous optoelectronic applications. Here, we demonstrate light-excitation-dependent two-dimensional (2D) position-sensitive detectors (PSDs) using a mixed-phase perovskite, FA_0.83Cs_0.17Pb(I_0.9Br_0.1)₃, as the active semiconductor, incorporated within a five-terminal device geometry. The light-induced lateral photovoltage, which is initiated by selective charge transfer across the metal-perovskite barrier interface, is utilized to achieve the excitation-position-dependent electric response. The 2D PSD devices exhibit a spatially dependent linear variation of the photosignal with sensitivity >50 μV mm^-1 and a low position detection error (1-2%), making them suitable for applications such as quadrant detectors. Further, it is observed that the device architecture plays a key role in controlling the dynamics and linearity of the HOIP PSDs. The large active area devices (up to ∼2 cm × 2 cm) exhibit a distinct spatial variation of the photosignal. We utilize the functionality of the PSD device for light-tracking applications by implementing a continuous detection scheme.

Microbial contamination and its associations with major ions in shallow groundwater along coastal Tamil Nadu

Microbes in groundwater play a key role in determining the drinking water quality of the water. The study aims to interpret the sources of microbes in groundwater and its relationship to geochemistry. The study was carried out by collecting groundwater samples and analyzed to obtain various cations and anions, where HCO₃^-, Cl^- and NO₃^- found to be higher than permissible limits in few samples. Microbial analysis, like total coliform (TC), total viable counts (TVC), fecal coliforms (FC), Vibrio cholera (V. cholerae) and total Streptococci (T. streptococci) were analyzed, and the observations reveal that most of the samples were found to be above the permissible limits adopted by EU, BIS, WHO and USEPA standards. Correlation analysis shows good correlation between Mg²⁺-HCO₃^-, K⁺-NO₃^-, TVC- V. cholerae and T. streptococci-FC. Major ions like Mg⁺, K⁺, NO₃, Ca²⁺ and PO₄ along with TS and FC were identified to control the geochemical and microbial activities in the region. The magnesium hardness in the groundwater is inferred to influence the TVC and V. cholerae. The mixing of effluents from different sources reflected the association of Cl with TC. Population of microbes T. streptococci and FC was mainly associated with Ca and Cl content in groundwater, depicting the role of electron acceptors and donors. The sources of the microbial population were observed with respect to the land use pattern and the spatial distribution of hydrogeochemical factors in the region. The study inferred that highest microbial activity in the observed in the residential areas, cultivated regions and around the landfill sites due to the leaching of sewage water and fertilizers runoff into groundwater. The concentrations of ions and microbes were found to be above the permissible limits of drinking water quality standards. This may lead to the deterioration in the health of particular coastal region.

Assessment of the radiant emittance of damaged/contaminated dental light-curing tips by spectrophotometric methods

Objectives

This study investigated the effects of physically damaged and resin-contaminated tips on radiant emittance, comparing them with new undamaged, non-contaminated tips using 3 pieces of spectrophotometric laboratory equipment.

Materials and Methods

Nine tips with damage and/or resin contaminants from actual clinical situations were compared with a new tip without damage or contamination (control group). The radiant emittance was recorded using 3 spectrophotometric methods: a laboratory-grade thermopile, a laboratory-grade integrating sphere, and a portable light collector (checkMARC).

Results

A significant difference between the laboratory-grade thermopile and the laboratory-grade integrating sphere was found when the radiant emittance values of the control or damaged/contaminated tips were investigated (p < 0.05), but both methods were comparable to checkMARC (p > 0.05). Regardless of the method used to quantify the light output, the mean radiant emittance values of the damaged/contaminated tips were significantly lower than those of the control (p < 0.05). The beam profile of the damaged/contaminated tips was less homogeneous than that of the control.

Conclusions

Damaged/contaminated tips can reduce the radiant emittance output and the homogeneity of the beam, which may affect the energy delivered to composite restorations. The checkMARC spectrophotometer device can be used in dental offices, as it provided values close to those produced by a laboratory-grade integrated sphere spectrophotometer. Dentists should assess the radiant emittance of their light-curing units to ensure optimal curing in photoactivated, resin-based materials.

Assessing the benefit of reoperations in patients who suffer from fecal incontinence after repair of their anorectal malformation

BACKGROUND AND AIM

Patients with a previously repaired anorectal malformation (ARM) can suffer from complications which lead to incontinence. Reoperation can improve the anatomic result, but its impact on functional outcomes is unclear.

METHODS

We performed a retrospective cohort study of patients with a previously repaired ARM who underwent redo PSARP at our Center and compared results at initial assessment and 12 months after redo.

RESULTS

One hundred fifty-three patients underwent a redo PSARP for anoplasty mislocation (n=93, 61%), stricture (n=55, 36%), remnant of the original fistula (n=28, 18%), or rectal prolapse (n=11, 7%). Post-redo complications included stricture (n=33, 22%) and dehiscence (n=5, 3%). At 1-year post-redo, 75/153 (49%) are on laxatives only, of whom 57 (76%) are continent of stool. Of the remaining 78 (51%) patients, 61 (78%) are clean (≤1 accident per week) on enemas. Interestingly, 16/79 (20%) of patients with expected poor continence potential were continent of stool on laxatives. Overall, 118/153 (77%) are clean after their redo. Quality of life (76.7 vs. 83.8, p=0.05) and Baylor continence (29.2 vs. 17.7, p=<0.0001) scores improved.

CONCLUSION

Patients with fecal incontinence after an ARM repair can, with a reoperation, have their anatomy corrected which can restore continence for many, and improve their quality of life.

LEVEL OF EVIDENCE

IV.

TYPE OF STUDY

Retrospective cohort study.

Estimation tools for reducing the impact of sampling and nonresponse errors in dual-frame RDD telephone surveys

We discuss alternative estimators of the population total given a dual-frame random-digit-dial (RDD) telephone survey in which samples are selected from landline and cell phone sampling frames. The estimators are subject to sampling and nonsampling errors. To reduce sampling variability when an optimum balance of landline and cell phone samples is not feasible, we develop an application of shrinkage estimation. We demonstrate the implications for survey weighting of a differential nonresponse mechanism by telephone status. We illustrate these ideas using data from the National Immunization Survey-Child, a large dual-frame RDD telephone survey sponsored by the Centers for Disease Control and Prevention and conducted to measure the vaccination status of American children aged 19 to 35 months.

Wavelength-Dependent Charge Carrier Dynamics for Single Pixel Color Sensing Using Graded Perovskite Structures

We report smart color-sensing devices of two-dimensional lead halide perovskites that exhibit a graded band gap across the film. We observe that the device short-circuit photocurrent is strongly dependent on excitation wavelength λ, and this arises through photoabsorption at different depths in the sample due to the graded bandgaps present. This λ signature in the response of the device is observed in case of steady-state excitation when incident from the high bandgap side of the film, where a complete reversal in the polarity of the photocurrent I_ph(t) is obtained as the excitation wavelength is spanned across the visible spectrum. The transient photocurrent reveals λ-specific response arrived from a combination of positive and negative I_ph(t) components. The uniqueness of I_ph(t) as a function of incident λ can be utilized to examine spectral purity without dispersive optical elements. An equivalent circuit model description provides a possible glimpse into the physical sources involved in contributing to these features.

Cytoprotection Alternatives for Cancer Treatment: In-vitro Evaluation of Alpinia Zerumbet as a Radioprotective Agent

Cancer radiotherapy and modern synthetic medicine are critical for the treatment of cancer patients, but on the other hand they may have tremendous harmful side effect from the point of view of a weakened immune system. The focus of current research efforts in the industry and academia is not only to find affordable treatment methodologies but also to discover sources that mitigates or prevents the negative impact of these treatments on the patient’s immune system. This review will provide details of optimal methodology involving Invitro application of techniques such as phytochemical analysis, thin layer chromatography, cytogenetic analysis that were adopted to assess the efficacy of Alpinia Zerumbet extracts as a radioprotector. These methodologies provide a holistic evaluation technique for assessing any potential cytoprotective agent, especially if it’s from the herbal domain. As a case study, analytical and inferential results summary of the research conducted to assess radioprotective property of Alpinia Zerumbet, a herbal and readily available derivative, will be presented. The key findings from the research indicate that the Alpinia Zerumbet extract has potential to be an effective radioprotector, with minimal side effects as compared to synthetic chemical cytoprotective agents. Keywords: Radioprotection; cancer; herbal; Alpinia Zerumbet

Electrospun Fibers Containing Emissive Hybrid Perovskite Quantum Dots

We demonstrate a single-step fabrication process of highly stable and luminescent polymer fibers embedded with quantum dots (QDs) of the organic-inorganic hybrid perovskite (OIP) (CH₃NH₃PbBr₃) using the electrospinning process. The fiber (∼2 μm diameter) primarily consists of poly(methyl methacrylate) dispersed with clusters of OIP quantum dots. The OIP clusters are radially distributed, normal to the fiber axis. The photoluminescence quantum yield (PLQY) is high (∼80%) and comparable to that of conventional QDs. The emission maxima are tunable by varying the concentration of OIP precursor in the electrospinning solution. Submicron emission maps show an isotropic and continuous emission along the fiber, suggesting uniform distribution of QD clusters. Temperature-dependent PL response indicates features which are a function of the particle size. For small QDs, the PLQY(T) maxima are close to the ambient temperature, whereas the PLQY(T) maxima shift sizably to T < 50 K for larger QDs. Significant waveguiding of QDs emission and amplified spontaneous emission, a prerequisite for lasing, were observed in the fiber confined OIP system at room temperature.

Self-powered single semiconductor nanowire photodetector

Self-powered photodetectors have been fabricated from a single germanium nanowire (NW) in the metal-semiconductor-metal (MSM) device configuration. The self-powered devices show a high photoresponse (responsivity ∼ 10³-10⁵ A W^-1) in the wavelength range 300-1100 nm. It has been established from I-V characteristics that asymmetry exists in the Schottky barrier height (SBH) at the two MS contacts. We have used simulation to establish that the asymmetric SBH at the metal contacts in an MSM device is a major cause for the 'built-in' axial field that leads to separation of a light generated electron-hole pair in the absence of an applied bias. Thus, even in the absence of external bias, the photogenerated carriers can be separated, which then diffuse to the appropriate electrodes driven by the 'built-in' axial field. We also point out the physical origins that can lead to unequal barrier heights in seemingly identical NW/metal junctions in a MSM device.

Radial Artery Pseudoaneurysm following Cardiac Catheterization: A Nonsurgical Conservative Management Approach

A radial artery pseudoaneurysm represents a rare, potentially catastrophic complication of arterial cannulation that has been reported after cardiac catheterization. Treatment options are limited to chemical, mechanical, and combined approaches to obliterate the radial artery pseudoaneurysm and tract. Manual compression protocols using the TR Band have been variableand anecdotal, without objective measurements of adequate compression, making this technique prone to failure (1). In this report, we present an efficient, safe, and noninvasive management for treatment of radial artery pseudoaneurysms that is cost-effective and efficient and ensures correction without occlusion of the radial artery.

Role of proNGF/p75 signaling in bladder dysfunction after spinal cord injury

Loss of bladder control is a challenging outcome facing patients with spinal cord injury (SCI). We report that systemic blocking of pro-nerve growth factor (proNGF) signaling through p75 with a CNS-penetrating small-molecule p75 inhibitor resulted in significant improvement in bladder function after SCI in rodents. The usual hyperreflexia was attenuated with normal bladder pressure, and automatic micturition was acquired weeks earlier than in the controls. The improvement was associated with increased excitatory input to the spinal cord, in particular onto the tyrosine hydroxylase-positive fibers in the dorsal commissure. The drug also had an effect on the bladder itself, as the urothelial hyperplasia and detrusor hypertrophy that accompany SCI were largely prevented. Urothelial cell loss that precedes hyperplasia was dependent on p75 in response to urinary proNGF that is detected after SCI in rodents and humans. Surprisingly, death of urothelial cells and the ensuing hyperplastic response were beneficial to functional recovery. Deleting p75 from the urothelium prevented urothelial death, but resulted in reduction in overall voiding efficiency after SCI. These results unveil a dual role of proNGF/p75 signaling in bladder function under pathological conditions with a CNS effect overriding the peripheral one.

Technologies for High Power Density Diesel Engines

<p class="p1">The engines used in armoured fighting vehicles have to be compact, light in weight, efficient and reliable. In order to achieve a compact engine design, a complete understanding of all the factors affecting the engine performance is needed. However, it is important to note that the performance of the engine cannot be compromised in the pursuit of compactness. The aim of this paper is to classify systematically various broad areas affecting the engine’s power to weight and power to volume ratio and discuss respective current technologies available. This paper explores the possibility of size and weight reduction and efficiency enhancement of diesel engines by the use of various methods like engine friction reduction, better thermal management, high injection pressure, and turbocharging. Achieving high engine speeds and high BMEP will be the means of achieving high power density. The effects of engine configuration and technologies on compactness are also discussed. Finally, the configuration of a new engine and its design aspects, incorporating all the aforementioned concepts is discussed</p>

Effect of Enhanced External Counter Pulsation Treatment on Aortic Blood Pressure, Arterial Stiffness and Ejection Fraction in Patients with Coronary Artery Disease

INTRODUCTION

Enhanced External Counter Pulsation (EECP) is a non-invasive treatment option for patients with Coronary Artery Disease (CAD). The treatment has shown to augment diastolic pressure and reduce Left Ventricular (LV) after-load by reducing systemic vascular resistance. The effect of EECP in standard brachial blood pressure and central haemodynamic parameters are not known.

AIM

We hypothesized that EECP may have differential effect in CAD patients with low systolic blood pressure when compared to normal systolic pressure and the mechanism underlying this differential effect may be due to improvement in LV function.

MATERIALS AND METHODS

A total of 72 consecutive patients who underwent EECP treatment for symptomatic CAD with LV dysfunction were divided into two groups based on cut-off value of 100mmHg for systolic blood pressure. First group had patients with brachial systolic blood pressure of >100mmHg and second group had patients with brachial systolic blood pressure of ≤100mmHg. We measured central aortic systolic pressure, pulse pressure, augmentation index and augmentation pressure by SphygmoCor device and Ejection Fraction (EF) was measured by echo-cardiography. All these measurements were carried out prior to and after completion of 35 days of EECP sessions.

RESULTS

Central systolic pressure, brachial systolic pressure, aortic pulse pressure, augmentation pressure and augmentation index significantly decreased in patients with normal brachial systolic pressure with baseline moderate LV dysfunction. Brachial systolic, aortic systolic and aortic pulse pressure significantly increased with no change in augmentation index and pressure is observed in patients with baseline severe LV dysfunction associated with low systolic pressure post EECP treatment.

CONCLUSION

EECP treatment has haemodynamically favourable differential effect in normal and low brachial systolic pressure and this is mainly driven by improvement in LV function in patients with symptomatic CAD with LV dysfunction.

Antimelanoma Potential of Eruca sativa Seed Oil and its Bioactive Principles

The present communication reports the comparison of in vivo antioxidant, antimelanoma and antimutagenic activities of Eruca sativa seed oil and its bio principles (allyl isothiocyanate, phenylethyl isothiocyanate and sulphoraphane) against B16F10 melanoma cells induced in C57BL/6 mice model. Among the various treatments considered for the study, isothiocyanates combination (allyl isothiocyanate, phenylethyl isothiocyanate and sulphoraphane; 1:1:1; 10 µM) exhibited optimum antioxidant activity, 51.95±1.14 µM glutathione per mg protein compared to seed oil 25.91±1.26 µM. Lipid peroxidation value was 9.97±1.72 µM malondialdehyde per mg wet weight for isothiocyanates combination against seed oil, 28.45±1.87 µM and rendered significant protection against oxidative stress induced by melanoma in liver tissue. Isothiocyanates combination significantly suppressed various parameters, such as tumor growth, isothiocyanates combination by 36.36% while the seed oil by 15.23%; tumor weight, isothiocyanates combination by 45.9% and seed oil by 19.6%; tumor volume, isothiocyanates combination by 41.7% while the seed oil by 32.3%, measured for antimelanoma activity at a concentration of 10 µM. Isothiocyanates combination has been found to be more cytotoxic bioagent against B16F10 melanoma cells induced in C57BL/6 mice compared to naturally occurring Eruca sativa seed oil.

In vivo antitumor potential of Ipomoea pes-caprae on melanoma cancer

Background:

The incidence of skin cancers is rising gradually. The treatment of melanoma is also necessary to prevent the spread of cancer to other body organs. Scientific literatures have not documented any evidence of the antitumor potential of Ipomoea pes-caprae on melanoma.

Aim of the Study:

Explore in vivo antitumor potential of I. pes-caprae on melanoma cancer.

Materials and Methods:

Petroleum ether (60°C–80°C), methanolic and aqueous extracts, and swaras prepared from the whole herb of I. pes-caprae were assessed for their antitumor activity. The extracts and swaras at doses of 25 and 50 mg/kg b. wt. were administered intraperitoneal along with chemo and radiotherapy for 40 days for exploring antitumor activity against melanoma cancer (B16F10) in male C57BL mice. The results obtained from tumor volume, and histopathological studies were compared with the control and dacarbazine used as a standard.

Results:

Antitumor effect of I. pes-caprae extracts and swaras on melanoma cancer was found to be significant (P < 0.01) compared to normal control. The tumor volume inhibition against tumor-bearing mice, although differed from each other, was concentration dependent. Administration of plant extracts and swaras from the day 1 since tumor inducted. The induction of tumor was found delayed by 10–15 days and the tumor volume on the day 40 was similar to the Dacarbazine treatment used as a standard.

Conclusion:

The results obtained from the tumor volume and histopathological studies clearly revealed the antitumor potential of I. pes-caprae on melanoma cancer.

Nanovesicular carrier-based formulation for skin cancer targeting: evaluation of cytotoxicity, intracellular uptake, and preclinical anticancer activity

CONTEXT

Skin cancer has turned into global epidemic leading to higher incidences among cancer stricken population.

OBJECTIVE

The aim of the present investigation is to evaluate the anticancer potential and intracellular uptake of a novel nanovesicular formulation of 5-FU.

MATERIALS AND METHODS

Detailed intracellular uptake study in conjunction with estimation of intracellular reactive oxygen species was done using skin melanoma cell lines (A375) along with cytotoxicity studies. To further obtain the mechanistic insights into inhibition of tumor cell proliferation, cell-cycle arrest studies were conducted. The preclinical anticancer activity was carried out employing in vivo DMBA-croton oil-induced skin cancer model in mice.

RESULTS AND DISCUSSION

Significant reduction in the number of papillomas was observed in skin cancer-bearing mice on treatment with nanovesicular formulation (51.4 ± 3.2%) in comparison with marketed formulation (21.3 ± 2.1%) of 5-FU. Tumor volume was found to be reduced to 46.3 ± 3.5% with prepared formulation, whereas the marketed formulation-treated group showed the reduction of 18.6 ± 1.8% in comparison with the control (untreated) group.

CONCLUSION

The results of present study demonstrated that nanovesicular formulation of 5-FU possessed the enhanced anticancer activity which could be attributed to better intracellular uptake, cellular retention, and sustained release of drug.

Lenalidomide-based combined therapy induced alterations in serum proteins of multiple myeloma patient: a follow-up case report and overview of the literature

AIM

Multiple myeloma (MM) is a malignant neoplasm of plasma cells (PC) derived from the bone marrow (BM) origin. The present case report was aimed to monitor the efficiency of lenalidomide-based combined therapy (LBCT) induced alterations in serum proteins of 42-year-old female MM patient. Besides, in the context of case report we also present an overview of the literature describing LBCT.

STUDY DESIGN

Serum protein electrophoresis (SPEP) was performed in three visits (V(1)-V(3)) to monitor the disease status of the patient and her treatment response to LBCT. Level of monoclonal protein (M-protein) was measured through cellulose acetate zone electrophoresis and quantified by densitometer in follow-up investigations after therapy intervals.

RESULTS

A significant reduction of M-protein in γ-globulin region was observed (P < 0.007) after receiving LBCT. However, the condition depicted hyper γ-globulinemia. β-globulin (P < 0.002) and α(2)-globulin(P < 0.047) was suppressed from the initial visit and subsequent follow-up also indicated the status of hypoglobulinaemia. Although, serum albumin level was found to be increased after therapy (P < 0.016), hypoalbuminaemia was also noticed before and after LBCT.

CONCLUSION

On the basis of this case report and pertinent literature, we conclude that LBCT is more efficient in the treatment of MM and has significant role in serum protein alterations especially in the reduction of M-protein in the MM patients.

Phytochemical potential of Eruca sativa for inhibition of melanoma tumor growth

Solvent extracts from the aerial and root parts and seed oil from E. sativa (rocket salad) were assayed for anticancer activity against melanoma cells. The seed oil (isothiocyanates rich) significantly (p<0.01) reduced the tumor growth comparable to the control. Remarkably, the seed oil inhibited melanoma growth and angiogenesis in mice without any major toxicity. The findings qualify seed oil for further investigations in the real of cancer prevention and treatment.

In vitro evaluation of genotoxicity of avocado (Persea americana) fruit and leaf extracts in human peripheral lymphocytes

Persea americana is much sought after both for the nutritional value of its fruit and the medicinal values of its various plant parts. A chromosomal aberration assay was undertaken to evaluate the potential genotoxicity of crude extracts from avocado fruits and leaves. Chromosomal aberrations were observed in cultured human peripheral lymphocytes exposed to separately increasing concentrations of 50% methanolic extracts of Persea americana fruit and leaves. The groups exposed to leaf and fruit extracts, respectively, showed a concentration-dependent increase in chromosomal aberrations as compared to that in a control group. The mean percentage total aberrant metaphases at 100 mg/kg, 200 mg/kg, and 300 mg/kg concentrations of leaf extract were found respectively to be 58 ± 7.05, 72 ± 6.41, and 78 ± 5.98, which were significantly higher (p < 0.0001 each) than that in the control group (6 ± 3.39). The mean percentage total aberrant metaphases at 100 mg/kg, 200 mg/kg, and 300 mg/kg concentrations of fruit extract were found to be 18 ± 5.49, 40 ± 10.00, and 52 ± 10.20, respectively, which were significantly higher (p = 0.033, p < 0.0001, and p < 0.0001, respectively) than that for control (6 ± 3.39). Acrocentric associations and premature centromeric separation were the two most common abnormalities observed in both the exposed groups. The group exposed to leaf extracts also showed a significant number of a variety of other structural aberrations, including breaks, fragments, dicentrics, terminal deletion, minutes, and Robertsonian translocations. The group exposed to leaf extract showed higher frequency of all types of aberrations at equal concentrations as compared to the group exposed to fruit extract.

Amoxicillin, clarithromycin, and omeprazole based targeted nanoparticles for the treatment of H. pylori

The aim of the present study was to develop and characterize targeted sustained release nanoparticles of chitosan-glutamic acid conjugates containing triple therapy for Helicobacter pylori to improve its therapeutic effect and reduce its dose-related side effect. The chitosan-glutamate nanoparticles were prepared by using the ionotropic gelation method. The particle sizes of systems ranged between 550 nm and 900 nm. Percent drug entrapment and release profiles of amoxicillin, clarithromycin, and omeprazole in simulated gastric fluid (pH 1.2) were determined using high-performance liquid chromatography. The maximum % drug entrapment and % yield of formulations were about 60-90% and 73-88%, respectively. The stability of the drugs was assessed in simulated gastric fluid (pH 1.2). In vitro antibacterial efficacy of optimized formulations containing monotherapy and triple therapy on isolated culture of H. pylori was assessed. In vivo clearance study and histopathological study were also carried out on Swiss albino mice to evaluate the efficacy of triple therapy containing targeted nanosystem for the treatment of H. pylori. The proposed delivery system holds promise at optimizing the treatment of H. pylori.

Aortic dissection presenting as posterior circulation stroke

Aortic dissection is a rare and life-threatening event. While pain is the most common symptom of aortic dissection, it may be absent in ten percent of patients and present with a myriad of symptoms suggestive of a diverse range of other conditions. A high index of clinical suspicion is mandatory for the accurate and rapid diagnosis of aortic dissection. We report a 25-year-old woman with aortic dissection presenting as a posterior circulation stroke. This combination is very rare.

A multicenter phase II study of gemcitabine, paclitaxel, and cisplatin in chemonaïve advanced ovarian cancer

OBJECTIVES

The objectives of this multicenter phase II study were to evaluate the effects of gemcitabine-paclitaxel-cisplatin combination chemotherapy on response rate, survival, and toxicity in patients with advanced epithelial ovarian cancer (AEOC).

METHODS

Chemonaive AEOC patients with bidimensionally measurable disease or an elevated serum cancer antigen 125 level received cisplatin (70 mg/m(2)) on day 1 and paclitaxel (80 mg/m(2)) and gemcitabine (1000 mg/m(2)) on days 1 and 8, every 3 weeks.

RESULTS

Between October 2000 and September 2001, 46 patients were enrolled. Sixteen patients underwent debulking surgery prior to chemotherapy. In 45 evaluable patients, overall response rate was 64.4% (7 CR and 22 PR). Median time-to-progression was 13.4 months (95% CI, 9.6-17.4 months); median progression-free survival was 12.3 months (95% CI, 8.8-15.6 months); median overall survival was 26.0 months (95% CI, 18 months-not reached); and 1-year survival was 74% (95% CI, 60-88%). The relative dose intensities of gemcitabine, paclitaxel, and cisplatin were 81.4%, 80.2%, and 89.8%, respectively. Grade 3/4 neutropenia was the predominant hematologic toxicity observed (73.9% of patients) followed by grade 3/4 leukopenia (56.5%), anemia (45.7%), thrombocytopenia (23.9%), and febrile neutropenia/neutropenic sepsis (26.1%). The predominant grade 3 nonhematologic toxicities were alopecia (43.5%) and diarrhea (19.6%). Grade 4 nonhematologic toxicities were nausea/vomiting, constipation, and uremia (2.2% each). Two treatment-related deaths occurred (neutropenic sepsis and uremia).

CONCLUSION

Gemcitabine-paclitaxel-cisplatin combination chemotherapy is active with manageable toxicity in chemonaive patients with advanced ovarian cancer and should be explored in larger phase III trials.

Mycobacterium smegmatis RecA protein is structurally similar to but functionally distinct from Mycobacterium tuberculosis RecA

In eubacteria, RecA proteins belong to a large superfamily of evolutionarily conserved, filament-forming, functional homologs of DNA strand exchange proteins. Here, we report the functional characterization of Mycobacterium smegmatis (Ms) and Mycobacterium tuberculosis (Mt) RecA proteins. Although in some respects Ms and Mt RecA proteins are structural and functional homologs of Escherichia coli (Ec) RecA, there are significant differences as well. The single-stranded DNA-binding property of RecA proteins was analyzed by electrophoretic mobility shift assays. We observed that Ms or Mt RecA proteins bound single-stranded DNA in a manner distinct from that of Ec RecA: The former two were able to form protein-DNA complexes in the presence of high salt. Further experiments indicated that Ms or Mt RecA proteins catalyzed adenosine triphosphate hydrolysis at approximately comparable rates across a wide range of pHs. Significantly, DNA strand invasion promoted by Ms or Mt RecA proteins displayed similar kinetics but distinctly different pH profiles. In contrast to MtRecA, MsRecA by itself was unable to form joint molecules across a wide range of pHs. However, regardless of the order in which SSB was added, it was able to stimulate MsRecA to form joint molecules within a narrow pH range, indicating that SSB is a required accessory factor. Together, these results provide a source of sharp contrast between EcRecA and mycobacterial RecAs on the one hand and Mt and Ms RecA proteins on the other.

Crystal structures of Mycobacterium smegmatis RecA and its nucleotide complexes

The crystal structures of Mycobacterium smegmatis RecA (RecA(Ms)) and its complexes with ADP, ATPgammaS, and dATP show that RecA(Ms) has an expanded binding site like that in Mycobacterium tuberculosis RecA, although there are small differences between the proteins in their modes of nucleotide binding. Nucleotide binding is invariably accompanied by the movement of Gln 196, which appears to provide the trigger for transmitting the effect of nucleotide binding to the DNA-binding loops. These observations provide a framework for exploring the known properties of the RecA proteins.

Characterization of DNA strand transfer promoted by Mycobacterium smegmatis RecA reveals functional diversity with Mycobacterium tuberculosis RecA

The RecA-like proteins constitute a group of DNA strand transfer proteins ubiquitous in eubacteria, eukarya, and archaea. However, the functional relationship among RecA proteins is poorly understood. For instance, Mycobacterium tuberculosis RecA is synthesized as a large precursor, which undergoes an unusual protein-splicing reaction to generate an active form. Whereas the precursor was inactive, the active form promoted DNA strand transfer less efficiently compared to EcRecA. Furthermore, gene disruption studies have indicated that the frequencies of allele exchange are relatively lower in Mycobacterium tuberculosis compared to Mycobacterium smegmatis. The mechanistic basis and the factors that contribute to differences in allele exchange remain to be understood. Here, we show that the extent of DNA strand transfer promoted by the M. smegmatis RecA in vitro differs significantly from that of M. tuberculosis RecA. Importantly, M. smegmatis RecA by itself was unable to promote strand transfer, but cognate or noncognate SSBs rendered it efficient even when added prior to RecA. In the presence of SSB, MsRecA or MtRecA catalyzed strand transfer between ssDNA and varying lengths of linear duplex DNA with distinctly different pH profiles. The factors that were able to suppress the formation of DNA networks greatly stimulated strand transfer reactions promoted by MsRecA or MtRecA. Although the rate and pH profiles of dATP hydrolysis catalyzed by MtRecA and MsRecA were similar, only MsRecA was able to couple dATP hydrolysis to DNA strand transfer. Together, these results provide insights into the functional diversity in DNA strand transfer promoted by RecA proteins of pathogenic and nonpathogenic species of mycobacteria.

Structural studies on MtRecA-nucleotide complexes: insights into DNA and nucleotide binding and the structural signature of NTP recognition

RecA protein plays a crucial role in homologous recombination and repair of DNA. Central to all activities of RecA is its binding to Mg(+2)-ATP. The active form of the protein is a helical nucleoprotein filament containing the nucleotide cofactor and single-stranded DNA. The stability and structure of the helical nucleoprotein filament formed by RecA are modulated by nucleotide cofactors. Here we report crystal structures of a MtRecA-ADP complex, complexes with ATPgammaS in the presence and absence of magnesium as well as a complex with dATP and Mg+2. Comparison with the recently solved crystal structures of the apo form as well as a complex with ADP-AlF4 confirms an expansion of the P-loop region in MtRecA, compared to its homologue in Escherichia coli, correlating with the reduced affinity of MtRecA for ATP. The ligand bound structures reveal subtle variations in nucleotide conformations among different nucleotides that serve in maintaining the network of interactions crucial for nucleotide binding. The nucleotide binding site itself, however, remains relatively unchanged. The analysis also reveals that ATPgammaS rather than ADP-AlF4 is structurally a better mimic of ATP. From among the complexed structures, a definition for the two DNA-binding loops L1 and L2 has clearly emerged for the first time and provides a basis to understand DNA binding by RecA. The structural information obtained from these complexes correlates well with the extensive biochemical data on mutants available in the literature, contributing to an understanding of the role of individual residues in the nucleotide binding pocket, at the molecular level. Modeling studies on the mutants again point to the relative rigidity of the nucleotide binding site. Comparison with other NTP binding proteins reveals many commonalties in modes of binding by diverse members in the structural family, contributing to our understanding of the structural signature of NTP recognition.

RecX protein abrogates ATP hydrolysis and strand exchange promoted by RecA: insights into negative regulation of homologous recombination

In many eubacteria, coexpression of recX with recA is essential for attenuation of the deleterious effects of recA overexpression; however, the molecular mechanism has remained enigmatic. Here, we show that Mycobacterium tuberculosis RecX binds directly to M. tuberculosis RecA as well as M. smegmatis and E. coli RecA proteins in vivo and in vitro, but not single-stranded DNA binding protein. The direct association of RecX with RecA failed to regulate the specificity or extent of binding of RecA either to DNA or ATP, ligands that are central to activation of its functions. Significantly, RecX severely impeded ATP hydrolysis and the generation of heteroduplex DNA promoted by homologous, as well as heterologous, RecA proteins. These findings reveal a mode of negative regulation of RecA, and imply that RecX might act as an anti-recombinase to quell inappropriate recombinational repair during normal DNA metabolism.

Model for interacting instabilities and texture dynamics of patterns

A simple model to study interacting instabilities and textures of resulting patterns for thermal convection is presented. The model, consisting of a twelve-mode dynamical system derived for periodic square lattice, describes convective patterns in the form of stripes and patchwork quilt. The interaction between stationary zigzag stripes and standing patchwork quilt pattern leads to spatiotemporal patterns of twisted patchwork quilt. Textures of these patterns, which depend strongly on Prandtl number, are investigated numerically using the model. The model also shows an interesting possibility of a multicritical point, where stability boundaries of four different structures meet.

Crystal structures of Mycobacterium tuberculosis RecA and its complex with ADP-AlF(4): implications for decreased ATPase activity and molecular aggregation

Sequencing of the complete genome of Mycobacterium tuberculosis, combined with the rapidly increasing need to improve tuberculosis management through better drugs and vaccines, has initiated extensive research on several key proteins from the pathogen. RecA, a ubiquitous multifunctional protein, is a key component of the processes of homologous genetic recombination and DNA repair. Structural knowledge of MtRecA is imperative for a full understanding of both these activities and any ensuing application. The crystal structure of MtRecA, presented here, has six molecules in the unit cell forming a 6(1) helical filament with a deep groove capable of binding DNA. The observed weakening in the higher order aggregation of filaments into bundles may have implications for recombination in mycobacteria. The structure of the complex reveals the atomic interactions of ADP-AlF(4), an ATP analogue, with the P-loop-containing binding pocket. The structures explain reduced levels of interactions of MtRecA with ATP, despite sharing the same fold, topology and high sequence similarity with EcRecA. The formation of a helical filament with a deep groove appears to be an inherent property of MtRecA. The histidine in loop L1 appears to be positioned appropriately for DNA interaction.

Prevalence of neurosyphilis at Government Rajaji Hospital, Madurai, India

Forty patients (34 males and 6 females) with neurological complaints/manifestations and with a past history of multiple sexual partners attending the Government Rajaji Hospital, Madurai, India between April 1992 and October 1992 were investigated for neurosyphilis. Metabolic disorders, hypertension, ischaemic heart disease, arrhythmias and trauma were excluded. Seven males (17.5%) were found to have neurosyphilis. The youngest was 26 years old and the oldest was 47. All were married and of low socioeconomic background. Meningovascular syphilis was the predominant presentation (6:1). Associated cardiovascular involvement was noticed in one of the cases. There was no associated HIV infection in these cases. The incidence is higher than previous reports from this centre.