Search

This review provides a comprehensive overview of recent advancements in the synthesis, properties, and applications of organic materials in the optoelectronics sector. The study emphasizes the critical role of organic materials in the development of state-of-the-art optoelectronic devices such as organic solar cells, organic thin-film transistors, and OLEDs. The review further examines the structure, operational principles, and performance metrics of organic optoelectronic devices. Organic materials have emerged as promising candidates due to their low-cost production and potential for large-area or flexible substrate applications. Additionally, this review highlights the physical mechanisms governing the optoelectronic properties of high-performance organic materials, particularly photoinduced processes relevant to charge carrier photogeneration. It discusses the unique benefits of organic materials over traditional inorganic materials, including their light weight, simple processing, and flexibility. The report delves into the challenges related to stability, scalability, and performance, while highlighting the wide range of electronic properties exhibited by organic materials, which are critical for their performances in optoelectronic devices. Furthermore, it addresses the need for further research and development in this field to achieve consistent performance across different types of devices.

Abstract The increase in global energy consumption and the related ecological problems have generated a constant demand for alternative energy sources superior to traditional ones. This is why unlimited photon-energy harnessing is important. A notable focus to address this concern is on advancing and producing cost-effective low-loss solar cells. For efficient light energy capture and conversion, we fabricated a ZnPC:PC70BM-based dye-sensitized solar cell (DSSC) and estimated its performance using a solar cell capacitance simulator (SCAPS-1D). We evaluated the output parameters of the ZnPC:PC70BM-based DSSC with different photoactive layer thicknesses, series and shunt resistances, and back-metal work function. Our analyses show that moderate thickness, minimum series resistance, high shunt resistance, and high metal-work function are favorable for better device performance due to low recombination losses, electrical losses, and better transport of charge carriers. In addition, in-depth research for clarifying the impact of factors, such as thickness variation, defect density, and doping density of charge transport layers, has been conducted. The best efficiency value found was 10.30% after tweaking the parameters. It also provides a realistic strategy for efficiently utilizing DSSC cells by altering features that are highly dependent on DSSC performance and output.

Thin films of zinc oxide (ZnO) doped with transition metals have recently gained significant attention due to their potential applications in a wide range of optoelectronic devices. This study focuses on ZnO thin films doped with the transition metals Co, Fe, and Zr, exploring various aspects of their structural, morphological, optical, electrical, and photoluminescence properties. The thin films were produced using RF and DC co-sputtering techniques. The X-ray diffraction (XRD) analysis revealed that all the doped ZnO thin films exhibited a stable wurtzite crystal structure, showcasing a higher structural stability compared to the undoped ZnO, while the atomic force microscopy (AFM) imaging highlighted a distinctive granular arrangement. Energy-dispersive X-ray spectroscopy was employed to confirm the presence of transition metals in the thin films, and Fourier-transform infrared spectroscopy (FTIR) was utilized to investigate the presence of chemical bonding. The optical characterizations indicated that doping induced changes in the optical properties of the thin films. Specifically, the doped ZnO thin film’s bandgap experienced a significant reduction, decreasing from 3.34 to 3.30 eV. The photoluminescence (PL) analysis revealed distinguishable emission peaks within the optical spectrum, attributed to electronic transitions occurring between different bands or between a band and an impurity. Furthermore, the introduction of these transition metals resulted in decreased resistivity and increased conductivity, indicating their positive influence on the electrical conductivity of the thin films. This suggests potential applications in solar cells and light-emitting devices.

The increasing demand for energy and electricity and the depletion of fossil fuels are global problems. In recent years, dye-sensitized solar cell (DSSC) technologies have gained notoriety for their application in solar energy. DSSCs are considered a promising alternative renewable energy source to both inorganic and organic photovoltaic (PV) cells. Many types of dyes are being investigated to enhance the light-harvesting properties of DSSCs, but the actual realization of these absorbers in cell structure requires optimum parameters. The main aim of this study was to simulate proposed zinc phthalocyanine (ZnPC)-based structures to validate their design, assess their performance for commercial implementation, and optimize the cell parameters for optimum efficiency. To that end, Scaps-1D was employed to evaluate the performance of DSSCs to determine their optimum parameters. We found that ZnPC and isopropoxy ZnPC molecules outperform others molecules because of better optoelectronic properties. Several other parametric effects, such as photoactive layer thicknesses, doping densities, trap densities, and charge carrier mobilities, were also evaluated to observe their impact on device performance. The results show that moderate thickness, low defect density, moderate doping, and charge carrier mobility are favorable for better device performance due to low recombination losses, electrical losses, and better transport of charge carriers. The utmost power conversion efficiency values found for ZnPC- and ZnPC: PC70BM-based DSSCs after optimization were 9.50% and 9.81%. This paper also suggests a practical method for efficiently using DSSC cells by modifying factors that are significantly reliant on DSSC performance and output.

This work focuses on preparing TiO2, CdS, and composite TiO2:CdS thin films for photovoltaic applications by thermal evaporation. The suggested materials exhibit very good optical and electrical properties and can play a significant role in enhancing the efficiency of the device. Various microscopy and spectroscopy techniques were considered to investigate the optical, morphological, photoluminescence, and electrical properties. FTIR confirms the material identification by displaying some peaks in the fingerprint region. UV Vis spectroscopy yields high transmission (80–90%) and low absorbance (5–10%) within the spectral region from 500 nm to 800 nm for the composite thin films. The optical band gap values for CdS, TiO2, and TiO2:CdS thin films are 2.42 eV, 3.72 eV, and 3.6 eV. XRD was utilized to analyze the amorphous nature of the thin films, while optical and SEM microscopy were employed to examine the morphological changes caused by the addition of CdS to TiO2. The decrease in the bandgap of the composite thin films was determined by the Tauc plot, which is endorsed due to the band tailing effects. Photoluminescence spectroscopy depicts several emission peaks in the visible region when they are excited at different wavelengths, and the electrical measurement enhances the material conductivity. Furthermore, the proposed electron transport materials (TiO2, CdS, TiO2:CdS) were simulated with different perovskite materials to validate their design by employing the SCAPS-1D program and assess their performance in commercial implementation. The observed results suggest that TiO2:CdS is a promising candidate to be used as an ETM in PSC with enhanced productivity.

Aluminum nitride (AlN) is a semiconductor material possessing a hexagonal wurtzite crystal structure with a large band gap of 6.2 eV. AlN thin films have several potential applications and areas for study, particularly in optoelectronics. This research study focused on the preparation of Ni-doped AlN thin films by using DC and RF magnetron sputtering for optoelectronic applications. Additionally, a comparative analysis was also carried out on the as-deposited and annealed thin films. Several spectroscopy and microscopy techniques were considered for the characterization of structural (X-ray diffraction), morphological (SEM), chemical bonding (FTIR), and emission (PL spectroscopy) properties. The XRD results show that the thin films have an oriented c-axis hexagonal structure. SEM analysis validated the granular-like morphology of the deposited sample, and FTIR results confirm the presence of chemical bonding in deposited thin films. The photoluminescence (PL) emission spectra exhibit different peaks in the visible region when excited at different wavelengths. A sharp and intense photoluminescence peak was observed at 426 nm in the violet-blue region, which can be attributed to inter-band transitions due to the incorporation of Ni in AlN. Most of the peaks in the PL spectra occurred due to direct-band recombination and indirect impurity-band recombination. After annealing, the intensity of all observed peaks increases drastically due to the development of new phases, resulting in a decrease in defects and a corresponding increase in the crystallinity of the thin film. The observed structural, morphological, and photoluminescence results suggest that Ni: AlN is a promising candidate to be used in optoelectronics applications, specifically in photovoltaic devices and lasers.

The hole transport layer (HTL) in organic solar cells (OSCs) plays an imperative role in boosting the cell’s performance. PEDOT:PSS is a conventional HTL used in OSCs owing to its high design cost and instability issues. It can be replaced with graphene oxide to increase the cell performance by overcoming instability issues. Graphene oxide (GO) has gained popularity in recent years for its practical use in solar energy due to its remarkable mechanical, electrical, thermal, and optical properties. This work uses SCAPS-1D to examine the results of graphene oxide (GO)-based organic solar cells by giving a comparison between the performance of absorber layers and a GO-based HTL to see which absorber material interacts more strongly with GO. The absorber layer PBDB-T:ITIC paired with GO as HTL outperforms the other absorber layers due to its better optical and electrical characteristics. Numerical simulations are performed within the SCAPS software at various absorber layer thicknesses, defect densities, and doping values to assess the influence on device performance and efficiency. After cell optimization, the best efficiency of an improved OSC is found to be 17.36%, and the outcomes of the simulated OSC are referenced to the results of the experimentally implemented OSC. These results provide a possible future direction for developing GO-based OSCs with higher efficiency.

Background: The optimal amount and timing of protein intake in critically ill patients are unknown. REPLENISH (Replacing Protein via Enteral Nutrition in a Stepwise Approach in Critically Ill Patients) trial evaluates whether supplemental enteral protein added to standard enteral nutrition to achieve a high amount of enteral protein given from ICU day five until ICU discharge or ICU day 90 as compared to no supplemental enteral protein to achieve a moderate amount of enteral protein would reduce all-cause 90-day mortality in adult critically ill mechanically ventilated patients., Methods: In this multicenter randomized trial, critically ill patients will be randomized to receive supplemental enteral protein (1.2 g/kg/day) added to standard enteral nutrition to achieve a high amount of enteral protein (range of 2-2.4 g/kg/day) or no supplemental enteral protein to achieve a moderate amount of enteral protein (0.8-1.2 g/kg/day). The primary outcome is 90-day all-cause mortality; other outcomes include functional and health-related quality-of-life assessments at 90 days. The study sample size of 2502 patients will have 80% power to detect a 5% absolute risk reduction in 90-day mortality from 30 to 25%. Consistent with international guidelines, this statistical analysis plan specifies the methods for evaluating primary and secondary outcomes and subgroups. Applying this statistical analysis plan to the REPLENISH trial will facilitate unbiased analyses of clinical data., Conclusion: Ethics approval was obtained from the institutional review board, Ministry of National Guard Health Affairs, Riyadh, Saudi Arabia (RC19/414/R). Approvals were also obtained from the institutional review boards of each participating institution. Our findings will be disseminated in an international peer-reviewed journal and presented at relevant conferences and meetings., Trial Registration: ClinicalTrials.gov, NCT04475666 . Registered on July 17, 2020., (© 2024. The Author(s).)

Background: The use of urinary sodium to guide diuretics in acute heart failure is recommended by experts and the most recent European Society of Cardiology guidelines. However, there are limited data to support this recommendation. The ENACT-HF study (Efficacy of a Standardized Diuretic Protocol in Acute Heart Failure) investigated the feasibility and efficacy of a standardized natriuresis-guided diuretic protocol in patients with acute heart failure and signs of volume overload., Methods: ENACT-HF was an international, multicenter, open-label, pragmatic, 2-phase study, comparing the current standard of care of each center with a standardized diuretic protocol, including urinary sodium to guide therapy. The primary end point was natriuresis after 1 day. Secondary end points included cumulative natriuresis and diuresis after 2 days of treatment, length of stay, and in-hospital mortality. All end points were adjusted for baseline differences between both treatment arms., Results: Four hundred one patients from 29 centers in 18 countries worldwide were included in the study. The natriuresis after 1 day was significantly higher in the protocol arm compared with the standard of care arm (282 versus 174 mmol; adjusted mean ratio, 1.64; P <0.001). After 2 days, the natriuresis remained higher in the protocol arm (538 versus 365 mmol; adjusted mean ratio, 1.52; P <0.001), with a significantly higher diuresis (5776 versus 4381 mL; adjusted mean ratio, 1.33; P <0.001). The protocol arm had a shorter length of stay (5.8 versus 7.0 days; adjusted mean ratio, 0.87; P =0.036). In-hospital mortality was low and did not significantly differ between the 2 arms (1.4% versus 2.0%; P =0.852)., Conclusions: A standardized natriuresis-guided diuretic protocol to guide decongestion in acute heart failure was feasible, safe, and resulted in higher natriuresis and diuresis, as well as a shorter length of stay., Competing Interests: Disclosures Dr Dauw received speaker fees from AstraZeneca, Boehringer-Ingelheim, and Bayer; Dr Lelonek received speaker and consulting fees from Novartis, Novo Nordisk, Servier, AstraZeneca, Boehringer-Ingelheim, Bausch Health, Bayer, Ewopharma, and Gedeon Richter and was involved in clinical trials from Amgen, Novartis, Novo Nordisk, and Boehringer-Ingelheim; Dr Borbély received speaker fees from Astra Zeneca, Bayer, Boehringer-Ingelheim, and Novartis; Dr Cobo-Marcos received speaker fees from Astra Zeneca, Boehringer-Ingelheim, Novartis, Vifor Pharma, Novo Nordisk, and Bayer; Dr Barge-Caballero received travel grants and speaker fees from Astra Zeneca, Boehringer-Ingelheim, Novartis, Viatris, and Pfizer and received research grants from Pfizer; Dr Barker received speaker fees from AstraZeneca, Novartis, and Medtronic; Dr Doghmi received speaker fees from Novartis, Boehringer-Ingelheim, and Pfizer; Dr Nijst received speaker fees from Novartis, Boehringer-Ingelheim, and Bayer; and Dr Martens received consultancy fees from Novartis and CLS Vifor and is supported by a research grant from the Belgian American Educational Foundation and the Frans Van de Werf Fund. The other authors report no conflicts.

Background: Protein intake is recommended in critically ill patients to mitigate the negative effects of critical illness-induced catabolism and muscle wasting. However, the optimal dose of enteral protein remains unknown. We hypothesize that supplemental enteral protein (1.2 g/kg/day) added to standard enteral nutrition formula to achieve high amount of enteral protein (range 2-2.4 g/kg/day) given from ICU day 5 until ICU discharge or ICU day 90 as compared to no supplemental enteral protein to achieve moderate amount enteral protein (0.8-1.2 g/kg/day) would reduce all-cause 90-day mortality in adult critically ill mechanically ventilated patients., Methods: The REPLENISH (Replacing Protein Via Enteral Nutrition in a Stepwise Approach in Critically Ill Patients) trial is an open-label, multicenter randomized clinical trial. Patients will be randomized to the supplemental protein group or the control group. Patients in both groups will receive the primary enteral formula as per the treating team, which includes a maximum protein 1.2 g/kg/day. The supplemental protein group will receive, in addition, supplemental protein at 1.2 g/kg/day starting the fifth ICU day. The control group will receive the primary formula without supplemental protein. The primary outcome is 90-day all-cause mortality. Other outcomes include functional and quality of life assessments at 90 days. The trial will enroll 2502 patients., Discussion: The study has been initiated in September 2021. Interim analysis is planned at one third and two thirds of the target sample size. The study is expected to be completed by the end of 2025., Trial Registration: ClinicalTrials.gov Identifier: NCT04475666 . Registered on July 17, 2020., (© 2023. The Author(s).)

Aims: Although acute heart failure (AHF) with volume overload is treated with loop diuretics, their dosing and type of administration are mainly based upon expert opinion. A recent position paper from the Heart Failure Association (HFA) proposed a step-wise pharmacologic diuretic strategy to increase the diuretic response and to achieve rapid decongestion. However, no study has evaluated this protocol prospectively., Methods and Results: The Efficacy of a Standardized Diuretic Protocol in Acute Heart Failure (ENACT-HF) study is an international, multicentre, non-randomized, open-label, pragmatic study in AHF patients on chronic loop diuretic therapy, admitted to the hospital for intravenous loop diuretic therapy, aiming to enrol 500 patients. Inclusion criteria are as follows: at least one sign of volume overload (oedema, ascites, or pleural effusion), use ≥ 40 mg of furosemide or equivalent for >1 month, and a BNP > 250 ng/L or an N-terminal pro-B-type natriuretic peptide > 1000 pg/L. The study is designed in two sequential phases. During Phase 1, all centres will treat consecutive patients according to the local standard of care. In the Phase 2 of the study, all centres will implement a standardized diuretic protocol in the next cohort of consecutive patients. The protocol is based upon the recently published HFA algorithm on diuretic use and starts with intravenous administration of two times the oral home dose. It includes early assessment of diuretic response with a spot urinary sodium measurement after 2 h and urine output after 6 h. Diuretics will be tailored further based upon these measurements. The study is powered for its primary endpoint of natriuresis after 1 day and will be able to detect a 15% difference with 80% power. Secondary endpoints are natriuresis and diuresis after 2 days, change in congestion score, change in weight, in-hospital mortality, and length of hospitalization., Conclusions: The ENACT-HF study will investigate whether a step-wise diuretic approach, based upon early assessment of urinary sodium and urine output as proposed by the HFA, is feasible and able to improve decongestion in AHF with volume overload., (© 2021 The Authors. ESC Heart Failure published by John Wiley & Sons Ltd on behalf of European Society of Cardiology.)

The COVID-19 pandemic had significant impact on health care worldwide which has led to a reduction in all elective admissions and management of patients through virtual care. The purpose of this study is to assess changes in STEMI volumes, door to reperfusion, and the time from the onset of symptoms until reperfusion therapy, and in-hospital events between the pre-COVID-19 (PC) and after COVID-19 (AC) period. All acute ST-segment elevation myocardial infarction (STEMI) cases were retrospectively identified from 16 centers in the Kingdom of Saudi Arabia during the COVID-19 period from January 01 to April 30, 2020. These cases were compared to a pre-COVID period from January 01 to April 30, 2018 and 2019. One thousand seven hundred and eighty-five patients with a mean age 56.3 (SD ± 12.4) years, 88.3% were male. During COVID-19 Pandemic the total STEMI volumes was reduced (28%, n = 500), STEMI volumes for those treated with reperfusion therapy was reduced too (27.6%, n= 450). Door to balloon time < 90 minutes was achieved in (73.1%, no = 307) during 2020. Timing from the onset of symptoms to the balloon of more than 12 hours was higher during 2020 comparing to pre-COVID 19 years (17.2% vs <3%, respectively). There were no differences between the AC and PC period with respect to in-hospital events and the length of hospital stay. There was a reduction in the STEMI volumes during 2020. Our data reflected the standard of care for STEMI patients continued during the COVID-19 pandemic while demonstrating patients delayed presenting to the hospital., (Copyright © 2020 Elsevier Inc. All rights reserved.)

Data on spontaneous coronary artery dissection (SCAD) is based on European and North American registries. We assessed the prevalence, epidemiology, and outcomes of patients presenting with SCAD in Arab Gulf countries. Patients (n = 83) were diagnosed with SCAD based on angiographic and intravascular imaging whenever available. Thirty centers in 4 Arab Gulf countries (Kingdom of Saudi Arabia, United Arab Emirates, Kuwait, and Bahrain) were involved from January 2011 to December 2017. In-hospital (myocardial infarction [MI], percutaneous coronary intervention, ventricular tachycardia/fibrillation, cardiogenic shock, death, implantable cardioverter-defibrillator placement, dissection extension) and follow-up (MI, de novo SCAD, death, spontaneous superior mesenteric artery dissection) cardiac events were recorded. Median age was 44 (37-55) years, 42 (51%) were females and 28.5% were pregnancy-associated (21.4% were multiparous). Of the patients, 47% presented with non-ST-elevation acute coronary syndrome, 49% with acute ST-elevation myocardial infarction, 12% had left main involvement, 43% left anterior descending, 21.7% right coronary, 9.6% left circumflex, and 9.6% multivessel; 52% of the SCAD were type 1, 42% type 2, 3.6% type 3, and 2.4% multitype; 40% managed medically, 53% underwent percutaneous coronary intervention, 7% underwent coronary artery bypass grafting. Females were more likely than males to experience overall (in-hospital and follow-up) adverse cardiovascular events ( P = .029).

A gap in the knowledge on the status of heart failure (HF) in Asia versus other regions led to the creation of a working group of Asian experts from 9 countries or regions (Hong Kong, Indonesia, Malaysia, Philippines, Singapore, South Korea, Taiwan, Thailand, and Vietnam). Each expert sought the best available data from local publications, registries, or clinical practice. The prevalence of HF in Asia was generally similar to global values (1% to 3%), but with some outliers. There were substantial variations in healthcare spending, and the average cost of HF hospitalization varied from 813 US$ in Indonesia to nearly 9000 US$ in South Korea. Comorbidities were frequent, particularly hypertension, diabetes mellitus, and dyslipidemia. Modifiable risk factors such as smoking were alarmingly common in some countries. Asian HF patients spent between 5 and 12.5days in hospital, and 3% to 15% were readmitted for HF by 30days. The pharmacological treatment of Asian patients generally followed international guidelines, including renin-angiotensin-aldosterone system inhibitors (61% to 90%), diuretics (76% to 99%), beta-blockers (32% to 78%), and digoxin (19% to 53%), with some room for improvement in terms of life-saving therapies. Our review supports implementation of a more comprehensive and organized approach to HF care in Asia., (Copyright © 2016 The Authors. Published by Elsevier Ireland Ltd.. All rights reserved.)

Introduction: The Malaysian National Cardiovascular Disease Database (NCVD) team presents Percutaneous Coronary Intervention (PCI) Registry report for the year 2007 to 2009. It provides comprehensive information regarding practice and outcome of PCI in Malaysia., Methodology: It was a voluntary, multi-centered, observational, cohort study and included patients of 18 years or above who underwent PCI at eleven participating centers in Malaysia from the year 2007 to 2009., Result: Ten thousand six hundred and two patients underwent 11,498 PCI procedures with 18,116 stents for 15,538 lesions. Mean age of the patients was 57 years and more than 98% of patients had at least one cardiovascular risk factor. A significant number of our patients were diabetic (50%) and had renal impairment (44.7% had ≤ stage 3 chronic kidney disease) at the time of procedure. Fifty eight percent of the lesions were type B2 or type C lesion. Twenty eight percent of the lesions had high risk characteristics. Procedural success rate was about 97% and post-procedural complications were low. Overall in-hospital, all cause mortality was 1%, of which 85% were cardiac related deaths. The poor prognostic factors for in-hospital mortality were acute coronary syndrome cases, higher Killip class and increasing age., Conclusion: Compared to other registries, Malaysian patients undergoing PCI were much younger with high prevalence of risk factors. In spite of complex and high risk lesions, procedural success was high, with overall low mortality rate. NCVD-PCI Registry aims to improve over-all cardiac services in Malaysia through its ongoing journey., (Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.)

Purpose: The objective of this study was to determine the effect of para-aminohippurate (PAH) and tetraethylammonium (TEA) on basolateral cellular accumulation (C(Pt)) and bath-to-lumen transepithelial transport rates (J(B)(-->)(L)) of platinum from cisplatin (cDDP) and a conjugate of cDDP, N-acetyl- L-cysteine-cDDP (NAC-cDDP), in S(1), S(2), and S(3) segments of the rabbit proximal tubule., Methods: Cellular accumulations and transport rates were determined using the isolated perfused tubule technique and samples were analyzed by ICP-MS., Results: First, to establish the control data, each tubular segment was bathed in free cDDP (2 m M) which resulted in no observable toxicity. Next, TEA (4 m M) was added to the bathing solution containing cDDP. This resulted in a reduction in platinum J(B)(-->)(L) by approximately 75% in the S(1) segment and 50% in the S(2) and S(3) segments. C(Pt) was reduced by 80-90% in relation to control values with no observable changes in toxicity. In the next experiment, exposure of the basolateral membrane to NAC-cDDP (2 m M) elicited pronounced toxicity after 20-30 min of perfusion. The J(B)(-->)(L) for NAC-cDDP was similar for each of the three nephron segments. There were no significant differences in the ability of these three segments to accumulate NAC-cDDP, but the conjugate increased uptake of platinum by 200-300% in the S(1) and S(2) segments, with no significant change in the S(3) segments, compared cDDP control values. The presence of PAH (4 m M) in the bathing solution significantly reduced J(B)(-->)(L) (by approximately 90%) for NAC-cDDP in all segments and the C(Pt) by approximately 80%. This also abrogated the NAC-cDDP-induced toxicity., Conclusions: There was axial heterogeneity among the basolateral membranes of the S(1), S(2), and S(3) segments of the proximal tubule in accumulating free cDDP and transport of NAC-cDDP. Generally, the NAC-cDDP molecule was transported more avidly than free cDDP across the basolateral membrane, except in the S(3) segment, where accumulation was similar to that of free cDDP. It is concluded that a PAH-sensitive organic anion transporter is involved in the accumulation of NAC-cDDP at the basolateral membrane and a TEA-sensitive organic cation transport system is involved in the accumulation of free cDDP.

Objective: The purpose of this work was to determine if gallium nitrate placed in human root canals would diffuse across root dentin and reach concentrations high enough to inhibit osteoclasts (approximately 10(-4) M)., Background Data: External root resorption by osteoclasts is a common sequela of dental trauma. If not detected and treated, it can lead to the loss of a tooth. Gallium has recently been reported to inhibit osteoclastic resorption in vitro., Methods: Roots were cleaned and shaped using standard endodontic procedures and the tips sealed with cyanoacrylate cement. The root canal space was filled with an aqueous solution of 1.0 M gallium nitrate chelated with 1.0 M sodium citrate buffer (pH 7.2). The roots were then sectioned longitudinally into two equal halves. Each half was fixed to a translation stage that moved at a constant rate beneath a frequency-quadrupled Nd-YAG laser (266 nm) laser that was used to sample the concentration of 43Ca, 69Ga, and 71Ga by laser ablation across the thickness of root dentin to the periodontal surface. The plume of ablated dentin was swept into an inductively heated plasma chamber by argon gas and hence into a mass spectrometer., Results: Quantitative analyses of the distribution of gallium showed it was highest adjacent to the root canal space and fell as more peripheral sites were sampled but then rose slightly at the external boundary of the root which is covered with a thin layer of atubular cementum., Conclusions: Even the lowest concentrations of gallium found in peripheral root dentin exceeded the 10(-4) M concentration required to inhibit osteoclastic activity. This simple endodontic treatment should undergo clinical trials to determine its efficacy in vivo. The laser ablation, inductively coupled mass spectrometry method is a powerful analytic tool for measuring spatial distribution of materials in mineralized tissues.

The rubella virus (RUB) nonstructural (NS) protein (NSP) ORF encodes a protease that cleaves the NSP precursor (240 kDa) at a single site to produce two products. A cleavage site mutation was introduced into a RUB infectious cDNA clone and found to be lethal, demonstrating that cleavage of the NSP precursor is necessary for RUB replication. Based on computer alignments, the RUB NS protease was predicted to be a papain-like cysteine protease (PCP) with the residues Cys1152 and His1273 as the catalytic dyad; however, the RUB NS protease was recently found to require divalent cations such as Zn, Co, and Cd for activity (X. Liu, S. L. Ropp, R. J. Jackson, and T. K. Frey, J. Virol. 72:4463-4466, 1998). To analyze the function of metal cation binding in protease activity, Zn binding studies were performed using the minimal NS protease domain within the NSP ORF. When expressed as a maltose binding protein (MBP) fusion protein by bacteria, the NS protease exhibited activity both in the bacteria and in vitro following purification when denatured and refolded in the presence of Zn. Atomic absorption analysis detected 1.6 mol of Zn bound per mol of protein refolded in this manner. Expression of individual domains within the protease as MBP fusions and analysis by a Zn(65) binding assay revealed two Zn binding domains: one located at a predicted metal binding motif beginning at Cys1175 and the other one close to the cleavage site. Mutagenesis studies showed that Cys1175 and Cys1178 in the first domain and Cys1227 and His1273, the His in the predicted catalytic site, in the second domain are essential for zinc binding. All of these residues are also necessary for the protease activity, as were several other Cys residues not involved in Zn binding. Far-UV circular dichroism (CD) analysis of the MBP-NS protease fusion protein showed that the protease domain contained a large amount of alpha-helical structure, which is consistent with the results of secondary-structural prediction. Both far-UV-CD and fluorescence studies suggested that Zn did not exert a major effect on the overall structure of the fusion protein. Finally, protease inhibitor assays found that the protease activity can be blocked by both metal ion chelators and the metalloprotease inhibitor captopril. In conjunction with the finding that the previously predicted catalytic site, His1273, is essential for zinc binding, this suggests that the RUB NS protease is actually a novel virus metalloprotease rather than a PCP.

The influence of modified plasma membrane fatty acid composition on cellular strontium accumulation in Saccharomyces cerevisiae was investigated. Growth of S. cerevisiae in the presence of 1 mM linoleate (18:2) (which results in 18:2 incorporation to approximately 70% of total cellular and plasma membrane fatty acids, with no effect on growth rate) yielded cells that accumulated Sr2+ intracellularly at approximately twice the rate of S. cerevisiae grown without a fatty acid supplement. This effect was evident over a wide range of external Sr2+ concentrations (25 microM to 5 mM) and increased with the extent of cellular 18:2 incorporation. Stimulation of Sr2+ accumulation was not evident following enrichment of S. cerevisiae with either palmitoleate (16:1), linolenate (18:3) (n-3 and n-6 isomers), or eicosadienoate (20:2) (n-6 and n-9 isomers). Competition experiments revealed that Ca2+- and Mg2+-induced inhibition of Sr2+ accumulation did not differ between unsupplemented and 18:2-supplemented cells. Treatment with trifluoperazine (TFP) (which can act as a calmodulin antagonist and Ca2+-ATPase inhibitor), at a low concentration that precluded nonspecific K+ efflux, increased intracellular Sr2+ accumulation by approximately 3.6- and 1.4-fold in unsupplemented and 18:2-supplemented cells, respectively. Thus, TFP abolished the enhanced Sr2+ accumulation ability of 18:2-supplemented cells. Moreover, the rate of Sr2+ release from Sr2+-loaded fatty acid-unsupplemented cells was found to be at least twice as great as that from Sr2+-loaded 18:2-enriched cells. The influence of enrichment with other fatty acids on Sr2+ efflux was variable. The results reveal an enhanced Sr2+ accumulation ability of S. cerevisiae following 18:2-enrichment, which is attributed to diminished Sr2+ efflux activity in these cells.

A previous analysis of Omaha skeletons dating between A.D. 1780 and 1820 revealed the presence of lead in all skeletons with high concentrations in children and adult males (Reinhard and Ghazi [1992] Am. J. Phys. Anthropol. 89:183-195). Two likely explanations for the high lead levels were presented: 1) metabolic absorption of lead and 2) diagenetic uptake of lead by the bones from postmortem application of pigments to the corpse. Two types of lead were available to the Omaha tribe: 1) Mississippi Valley type, and 2) non-Mississippi Valley type. It has been suggested that red-lead pigment mixed with mercury sulphide (cinnabar) applied to the corpse may have been one of the sources of lead found in bones. Further isotopic analyses of samples of pigment and metallic lead artifacts associated with the skeletons revealed that non-Mississippi Valley type lead is present in the pigment while Mississippi Valley type lead comes from metallic artifacts. Both lead and mercury were found in the pigment samples, verifying that a lead-based pigment mixed with cinnabar-based pigment was used as a cosmetic by the Omaha. Isotopic analysis of lead in skeletons indicates that the pigment contributed most to lead content of bone. This new evidence clarifies the previous study and suggests specific mechanisms by which lead became incorporated into bone.

The analysis of skeletal remains of Omaha Indians buried between AD 1780 and 1820 indicated that lead was incorporated in cortical bone. The diagenetic or biogenetic origin of the lead was evaluated by examination of lead isotope ratios of the bones and artifacts, and comparison of lead concentrations in burial soils with those of the bones. The isotopic values of the lead artifacts demonstrate that the lead was mined in the Missouri region. Although the isotope ratios in the bones are not identical with that from the lead artifacts, there is a strong relationship between them. This finding indicates that the lead in the bone was at least partly derived from the artifacts. Because lead artifacts rarely accompanied the burials but lead was ubiquitous in the bones, we suggest a biogenetic origin for the lead. There is also the possibility that some of the lead may have been derived from pigments applied to the corpse during mortuary ritual.

Some observations from a study of 2,745 patients with psychiatric disorders from the outpatients clinics at the Alexandria University Central Hospital have been presented. There are significantly more neurotics and fewer psychotics among women. Mental disorders were in general most prevalent in the 15 to 30 age group. No definite educational correlates with any group of mental disorders were recognized in this study.