Elucidating the Mechanism of Tetrahydrofuran-Diol Formation through Os(VI)-Catalyzed Oxidative Cyclization of 5,6-Dihydroxyalkenes Ligated by Citric Acid

A computational study is reported here on the mechanism of tetrahydrofuran (THF)-diol formation from the Os(VI)-catalyzed oxidative cyclization of 5,6-dihydroxyalkene ligated with citric acid and in the presence of Bro̷nsted acid. Initiated by Os(VI) dioxo citrate formation, coordination of co-oxidant pyridine-N-oxide (PNO) and protonation of its oxo group generate the active catalyst. The catalytic cycle commences through successive steps, including dihydroxyalkene addition to the active catalyst in a concerted mechanism to form hexacoordinated alkoxy-protonated PNO-complexed Os(VI) bisglycolate as a turnover-limiting step (TLS), cyclization to Os(IV) THF-diolate, reoxidation to Os(VI) THF-diolate, and hydrolysis via a dissociative mechanism to furnish the THF-diol and regenerate the active species, sustaining the catalytic cycle through an Os(VI)/Os(IV) cycle. Despite the overall exergonic nature of catalytic cycle (ΔGrcycle = -45.0 kcal/mol), the TLS is accelerated by the formation of an open-valence 16-electron Os(VI) intermediate but decelerated by the undesired formation of a saturated/hexacoordinate 18-electron Os(VI) intermediate. Bro̷nsted acid plays crucial roles in the formation of Os(VI) citrate and the active catalyst, impediment of the second cycle, and the cyclization step. Additionally, besides its role as a co-oxidant, and in the presence of acid, PNO is found to assist the insertion of dihydroxyalkene and, importantly, in releasing the THF-diol to regenerate the active intermediate.

Remote Steric and Electronic Effects of N-Heterocyclic Carbene Ligands on Alkene Reactivity and Regioselectivity toward Hydrocupration Reactions: The Role of Expanded-Ring N-Heterocyclic Carbenes

The remote groups in N-heterocyclic carbene (NHC) ligands have a significant influence on metal-catalyzed reactions. We examine how remote bulkiness, electronic groups, and expanded-ring NHCs (ER-NHCs) influence alkene reactivity and regioselectivity toward hydrocupration using density functional theory calculations. The impact of remote steric bulkiness on the Cu-H insertion rate is analyzed, revealing a strong correlation between the steric substituent constant and rate ratio, where a bulky group increases the rate due to reduced steric effects in the transition state (TS). The steric properties of the examined catalysts (with a remote group R2 = CPh3, CHPh2, CH2Ph, CH3, and H) and their corresponding TSs are found to be modulated greatly by the remote steric substitution group and the ring size of the NHC ligand. Enhanced bulkiness enhances the nucleophilic Cu-H moiety. The remote electronic groups have a smaller impact on insertion barrier compared to that of steric hindrance. Furthermore, ER-NHC exploration indicates that NHCs with over five-membered rings have a significantly negative influence on the reaction rate. Finally, with a highly bulky group (R2 = CPh3), anti-Markovnikov insertion preference is attributed to high interaction energy and improved steric properties. Overall, our findings here provide valuable insights for the development of a more effective catalyst in metal-catalyzed reactions.

Partner effect in accelerating pincer-co catalyzed nitrile hydroboration reactions

The pincer-Co catalyzed nitrile hydroboration of nitrile has been presented as an elegant strategy to afford amine synthesis; however, ligand engineering is required. We show here a strategy to tune the catalytic behavior of the organometallic catalyst, as an alternative approach to ligand engineering, by means of computational investigations to understand the effect of partners such as (18-crown-6)K⁺, W(CO)₃ and W(PMe₃)₃ on the reactivity of the pincer-Co catalyzed nitrile hydroboration reaction through π-coordination to the ligand aromatic ring. The extra additives bind the central phenyl ring of the ligand by either dispersion or chemical bonding. The electron-richness of the cobalt center is tuned by the partner, and follows the order (18-crown-6)K⁺ > W(PMe₃)₃ > no partner > W(CO)₃. While the influence of the covalent W-containing partners parallels the electron-richness of the W, the non-covalent partner, (18-crown-6)K⁺, surprisingly increases the donor ability of the pincer ligand through the polarization effect. All the elementary steps involved in the nitrile hydroboration reaction are influenced by the partner, and the overall barrier is lowered by a surprisingly large amount of 4.9 kcal mol^-1 in the presence of (18-crown-6)K⁺, suggesting a notable partner effect to be explored by experimentalists so that the reactivity of a catalyst can be tuned without ligand modification.

Impact of counteranions on N-heterocyclic carbene gold(i)-catalyzed cyclization of propargylic amide

N-Heterocyclic carbene (NHC) Au(i)-catalyzed organic synthesis has recently been receiving increasing attention, especially with the activation of alkynes. In contrast, counteranions, being widely problematic in Au(i)-catalyzed transformations, are commonly considered as innocent partners and are not respectably included in a computational model. Herein, we report density functional theory (DFT) investigations of the Au(i)-catalyzed cyclization of propargylic amides to exploit the mechanistic effect of several counteranions to shed some light for further future developments. Among the counteranions used in this study, NTf₂ ^-, ClO₄ ^-, TsO^-, TFA^-, TfO^-, MsO^-, and SbF₆ ^-, both the cyclization and protodeauration step favor the 5-exo-dig product over the 6-endo-dig product when the alkyne moiety is terminated with hydrogen. These anions reveal a crucial influence on the energy profile through lowering the barriers of the reaction. Mechanistically, the results obtained from all counteranions show that the protodeauration is slower than the cyclization. By using an energetic span model, the results clearly indicate that the rate-determining state is the protodeauration step for all counteranions, and thus protodeauration is the turnover-limiting step. The turnover frequency (TOF) results for the formation of the 5-exo-dig product show cyclization reactivity in the order of MsO^- > TFA^- > ClO₄ ^- > NTf₂ ^- > TfO^- > TsO^- ≫ SbF₆ ^-, whereas an order of TFA^- > MsO^- > NTf₂ ^- > TfO^- ≈ ClO₄ ^- > SbF₆ ^- ⋙ TsO^- is calculated for the protodeauration, suggesting that SbF₆ ^- and TsO^- are disfavored due to their slow protodeauration. In this regard, and for the 6-endo-dig pathway, our conclusions demonstrate an order of TfO^- > TFA^- > MsO^- > NTf₂ ^- > ClO₄ ^- > TsO^- ⋙ SbF₆ ^- for the cyclization and TFA^- > TsO^- > MsO^- > TfO^- > NTf₂ ^- > ClO₄ ^- ⋙ SbF₆ ^- for the protodeauration, advocating that the anions SbF₆ ^-, NTf₂ ^- and ClO₄ ^- are unlikely partners for the 6-endo-dig pathway because of their slow protodeauration. Finally, the findings here advise that any engineering of the counteranion to increase the efficiency of catalytic system would be more effective on the protodeauration step rather than the cyclization step.

Visible Light-Mediated Germanylation of Aryl Fluorides: Synthetic and Mechanistic Insights

We describe herein a metal-free synthesis of aryl germanes from the reaction of triphenyl germane with fluoro-(hetero)-arenes in the presence of a base under blue light irradiation. The reaction proceeds under mild conditions and tolerates a few functionalities. Scope and limitations of this unprecedented approach is analyzed based on preliminary mechanistic studies.

Selective Synthesis of Azoloyl NH-1,2,3-Triazoles and Azolyl Diazoketones: Experimental and Computational Insights

Here, we report that the reaction of enaminones, from a class of azole series, with sulfonyl azides leads to a difficult-to-separate mixture of two pairs of compounds: (1) 4-azoloyl-NH-1,2,3-triazoles with sulfonamides and (2) azolyl diazoketones with N-sulfonamidines, as a result of the implementation of two competing reactions. On one hand, the electron-donating methyl or methoxy group in the aryl para-position of arylsulfonyl azides favors the production of NH-1,2,3-triazoles together with sulfonamides. On the other hand, the use of highly electrophilic 4-nitrophenylsulfonyl azide promotes the formation of diazoketones and sulfonamidines. It is shown that the direction of each reaction is not only controlled by the nature of the initial enaminones and sulfonyl azides but also depends on the tested solvent. The problem of removing sulfonamides and amidines from the desired products was solved for the first time using new water-soluble enaminones. Based on the experimental and computational studies, the factors contributing to the selective course of alternative reactions were identified, and methods for the synthesis of azoloyl-NH-1,2,3-triazoles and azolyl diazoketones were developed. Density functional theory (DFT) results have shown that the 1,3-dipolar cycloaddition is totally driven toward one single regioisomer with a high asynchronous bond formation, and the introduction of an electron-deficient group in sulfonyl azides induces faster cycloaddition. Additionally, DFT calculations were used to gain further mechanistic insights on the reaction studied here.

Predominance of the second cycle in homogeneous Os-catalyzed dihydroxylation: the nature of Os(vi) → Os(viii) reoxidation and unprecedented roles of amine-N-oxides

Our detailed DFT study of Os-catalyzed alkene dihydroxylation revealed that the reaction predominantly proceeds via a second cycle initiated by the formation of a putative Os(viii)trioxoglycolate as a highly reactive intermediate.

A mechanistic study on the gold(i)-catalyzed cyclization of propargylic amide: revealing the impact of expanded-ring N-heterocyclic carbenes

Density functional theory (DFT) was applied to understand the mechanistic pathway of the gold(i)-catalyzed cyclization of propargylic amide, and to reveal the impact of expanded-ring N-heterocyclic carbenes.

Unveiling the origin of the chemoselectivity of bismacycle-mediated C–H arylation of phenols: from mechanism concept to new coupling design

DFT calculations for the bismacycle-catalyzed C–H arylation of phenols explain the origin of high chemoselectivity. The reducive elimination is polar, which allows the design of new coupling modes.

The nature of metal–metal bonding in Re-, Ru- and Os-corrole dimers

Studies of multiple bonding between transition metal complexes offer fundamental insight into the nature of bonding between metal ions and facilitate predictions of the physical properties and the reactivities of metal complexes containing metal–metal multiple bonds. Here we report a computational interrogation on the nature of the metal–metal bonding for neutral, oxidized, and reduced forms of dinuclear rhenium and osmium corrole complexes, [{Re[TpXPC]}₂]^0/1+/1− and [{Os[TpXPC]}₂]^0/1+/1−, using a complete active space self-consistent (CASSCF) methodology and density functional theory (DFT) calculations. For [{Re[TpXPC]}₂]⁰, [{Ru[TpXPC]}₂]⁰, and [{Os[TpXPC]}₂]⁰, CASSCF calculations shows that the effective bond order is 3.29, 2.63, and 2.73, respectively. On their oxidized forms, [{Re[TpXPC]}₂]¹⁺, [{Ru[TpXPC]}₂]¹⁺, and [{Os[TpXPC]}₂]¹⁺ molecules, the results indicate an electron removal from a ligand-based orbital, where [{Re[TpXPC]}₂]¹⁺ gives slightly different geometry from its neutral form due to populating the δ* orbital. In this regard, the CASSCF calculations give an effective bond order of 3.25 which is slightly lower than in the [{Re[TpXPC]}₂]⁰. On their reduced forms, the electron addition appears to be in the metal-based orbital for [{Re[TpXPC]}₂]¹⁻ and [{Ru[TpXPC]}₂]¹⁻ whereas in the ligand-based orbital for the Os-analogue which has no effect on the Os–Os bonding, an effective bond order of 3.18 and 2.17 is presented for the [{Re[TpXPC]}₂]¹⁻ and [{Ru[TpXPC]}₂]¹⁻, respectively, within the CASSCF simulations. These results will further encourage theoreticians and experimentalists to design metalloporphyrin dimers with distinct metal–metal bonding.

Our CASSCF calculations on the first oxidation and reduction processes of the synthesised [{Re[TpXPC]}₂]⁰, [{Ru[TpXPC]}₂]⁰, and [{Os[TpXPC]}₂]⁰ molecules revealed a pronounced effect on the nature of the metal–metal bonding.

OUP accepted manuscript

STUDY QUESTION

What is the scope of literature regarding women’s reproductive span in terms of definitions, trends and determinants?

SUMMARY ANSWER

The scoping review found a wide variation in definitions, trends and determinants of biological, social and effective women’s reproductive span.

WHAT IS KNOWN ALREADY

A woman’s reproductive span refers to her childbearing years. Its span influences a woman’s reproductive decisions.

STUDY DESIGN, SIZE, DURATION

A systematic scoping review was conducted. We searched MEDLINE, PubMed, JSTOR, CINAHL, Web of Science and Scopus electronic databases from inception to January 2021 without imposing language or date restrictions. We searched unpublished sources including the Global Burden of Disease, Demographic and Health Surveys, and National Health and Nutrition Examination Surveys. The list of relevant references was searched by hand. Sixty-seven reports on women’s reproductive span were included in this review.

PARTICIPANTS/MATERIALS, SETTING, METHODS

This scoping systematic review followed an established framework. The reporting of this scoping review followed the reporting requirements provided in the Preferred Reporting Items for Systematic Reviews and Meta-Analyses, Extension for Scoping Reviews. Identified records were independently screened and data were extracted. We performed conceptual synthesis by grouping the studies by available concepts of reproductive span and then summarized definitions, measures used, temporal trends, determinants, and broad findings of implications on population demographics and assisted reproduction. Structured tabulation and graphical synthesis were used to show patterns in the data and convey detailed information efficiently, along with a narrative commentary.

MAIN RESULTS AND THE ROLE OF CHANCE

A total of 67 relevant reports on women’s reproductive span were published between 1980 and 2020 from 74 countries. Most reports (42/67) were cross-sectional in design. Literature on reproductive span was conceptually grouped as biological (the interval between age at menarche and age at menopause), effective (when a woman is both fertile and engaging in sexual activity) and social (period of exposure to sexual activity). We summarized the working definitions, trends and determinants of each concept. Few articles addressed implications on demographics and assisted reproduction.

LIMITATIONS, REASONS FOR CAUTION

A formal assessment of methodological quality of the included studies was not performed because the aim of this review was to provide an overview of the existing evidence base regardless of quality.

WIDER IMPLICATIONS OF THE FINDINGS

The review produced a comprehensive set of possible definitions of women’s reproductive span, trends, and potential determinants. Further advancement of these findings will involve collaboration with relevant stakeholders to rate the importance of each definition in relation to demography and fertility care, outline a set of core definitions, identify implications for policy, practice or research and define future research opportunities to explore linkages between reproductive spans, their determinants, and the need for assisted reproduction.

STUDY FUNDING/COMPETING INTEREST(S)

This work received funding from the UNDP-UNFPA-UNICEF-WHO-World Bank Special Programme of Research, Development and Research Training in Human Reproduction (HRP), a cosponsored programme executed by the World Health Organization (WHO). The authors had no competing interests.

STUDY REGISTRATION NUMBER

N/A.

Boosting Palladium-Catalyzed Aryl-Nitro Bond Activation Reaction by Understanding the Electronic, Electrostatic, and Polarization Effect: A Computational Study from a Basic Understanding to Ligand Design

Although palladium-catalyzed aryl-nitro bond activation reaction has recently gained a lot of interest, it still requires rather harsh conditions. We here systematically explore the substituent effect on oxidative addition steps, known as the rate-determining step, by density functional theory simulations based on a Nakao's nitrogen heterocyclic carbene (NHC) ligand. The key aryl ring on the catalyst, ring A, acts as a π-donor and stabilizes the palladium center of the transition state, and thus an electron-rich ring A is expected to lower the barrier. However, the polarization and electrostatic effects were shown to be more important, although they were often ignored before. These effects originate from through-space interaction with a nitro group in the resting state, and the overall effect is that any polarizable or partly negative group near ortho- or meta-site of ring A is harmful for the reaction. Based on these discoveries, we proposed a list of guidelines for successful ligand developments and designed several new ligands. These ligands exhibit a significantly lower barrier than the reported Nakao's ligand by as large as ∼5 kcal/mol, in both gas phase and solvent with a moderate dipole. These candidates will promote further experimental studies and enhance the ability to improve ligands in a rational and predictive manner.

Photo-assisted bio-fabrication of silver nanoparticles using Annona muricata leaf extract: exploring the antioxidant, anti-diabetic, antimicrobial, and cytotoxic activities

Green synthesis of metal nanoparticles is reputed to have a robust range of biomedical applications. Silver nanoparticles (AgNPs) bio-fabricated using aqueous leaf extract of Annona muricata were characterized and evaluated for in-vitro antioxidant, lipid peroxidation inhibition, anti-diabetic and antimicrobial activities as well as cytotoxicity in human keratinocyte cells (HaCaT). The extract induced colour change of silver salt solution which absorbed at 420 nm and confirmed the formation of AgNPs. FTIR showed that free amide and hydroxyl groups were responsible for the synthesized nanoparticles. Both XRD and SAED confirmed the crystalline nature of the particles with face centered cubic (FCC) phase. The zeta potential revealed -27.2 mV potential and average distribution size of 35 nm. DLS indicated that the majority of the particles were 86.78 nm size and with a polydispersity index (PDI) of 0.329. AgNPs displayed strong activities against DPPH (IC₅₀ = 51.80 μg/ml), ABTS (IC₅₀ = 30.78 μg/ml), α-amylase (IC₅₀ = 0.90 μg/ml) and α-glucosidase (IC₅₀ = 3.32 μg/ml). The particles exhibited a dose-dependent inhibition of Fe²⁺-induced lipid peroxidation with effective antimicrobial activity against a battery of bacterial strains and cytotoxicity in HaCaT cell line. These findings revealed the potential biomedical applications of the particles and further work will be required to establish its molecular mechanism of action.

Novel Approach for Characterizing Propofol Binding Affinities to Serum Albumins from Different Species

The interaction between the main carrier (serum albumin, SA) of endogenous and exogenous compounds in the bloodstream of different species (human, bovine, canine, rat, rabbit, and sheep) and a general anesthetic agent (propofol, PR) was investigated using an experimental technique (high-performance liquid chromatography) and computational methods (molecular docking, molecular dynamics, sequence, and phylogenetic analyses). The obtained results revealed the differences in the PR binding affinity to various homologous forms of this protein with reliable statistics (R ² = 0.9 and p-value < 0.005), correlating with the evolutionary relationships among SAs from different species. Additionally, the protein conformational changes (root-mean-square deviation ≈ 1.0 Å) and amino acid conservation of binding sites in protein domains were detected, contributing to the SA-PR binding modes. Overall, the outcomes from this study might provide a novel methodology to assess protein-ligand interactions and to gain some interesting insights into drug pharmacokinetics and pharmacodynamics to explain its variations among different species.

Revealing the Mechanism and Origin of Reactivity of Au(I)-Catalyzed Functionalized Indenone Formation of Cyclic and Acyclic Acetals of Alkynylaldehydes

A density functional theory study is presented here to offer mechanistic insights and explications of experimentally intriguing observations in the Au(I)-catalyzed cyclization of cyclic and acyclic acetals of alkynylaldehydes that leads to indenone formation. The reactivity of catalytic cycles with and without methoxy migration is clearly defined when the alkyne terminus is phenylated. The reaction mechanism of indenone formation proceeds first with the coordination of Au(I) to alkyne to initiate the reaction with 1,5-H shift as a rate-determining step (RDS), and the fastest 1,5-H shift is achieved when one phenyl ring carries an electron-donating group and the other one is substituted with an electron-withdrawing group. Following the 1,5-H shift, the reaction undergoes feasible steps that are cyclization and 1,2-H shift before elimination to persist the iterative cycle, but the reactivity of both steps is highly affected by the existence of the phenyl group on the alkyne terminus. The unreactivity of the alkyne terminus not bearing a phenyl ring is because the cyclization is thermodynamically disfavorable, subsequently deactivating the 1,2-H shift kinetically and thermodynamically. The absence of a tether in the acetal unit considerably outpaces any 1,5-H shift and instead activates 1,5-methoxy migration, giving methoxy-migrated indenone, with the 1,2-OMe shift being an RDS.

Ru-catalysed oxidative cyclisation of 1,5-dienes: an unprecedented role for the co-oxidant

The Ru-mediated oxidative cyclisation of 1,5-dienes to furnish 2,5-dihydroxyalkyl-substituted tetrahydrofuran-diols (THF-diols) represents a practical approach for the synthesis of many bioactive natural products. In the current study, we reported profound findings obtained by density functional theory (DFT) simulations, and they were consistent with the experimental conditions. The results set out a catalytic cycle within intermediacy of NaIO₄-complexed Ru(vi) species. Importantly, the co-oxidant played a critical role in the cyclisation step and subsequently the release of THF-diols. Following the formation of Ru(vi) glycolate, cyclisation and THF-diol release proceeded through NaIO₄-coordinated Ru(vi) intermediates, outpacing the Ru(viii) glycolate or THF-diolate intermediates and subsequently entering “second cycle” type pathways. The results indicated a cycle involving Ru(viii)/Ru(vi)/Ru(iv)/Ru(vi) rather than Ru(viii)/Ru(vi)/Ru(viii)/Ru(vi)/Ru(viii). Additionally, the existence of an electron-withdrawing group (EWG) on one of the double bonds of 1,5-dienes revealed that the regioselectivity of the Ru-catalysed oxidative cyclisation was predominantly initiated at the electron-rich alkene. Overall, this study offers new insights, which were ignored by earlier experimentalists and theoreticians, into the Ru-catalysed functionalizations of alkenes and 1,5-dienes.

The Ru-mediated oxidative cyclisation of 1,5-dienes to THF-diols proceeds with the intermediacy of NaIO₄-complexed Ru(vi) species and offers new insights into the Ru-catalysed functionalizations of alkenes and 1,5-dienes.

Mechanistic investigations on Pinnick oxidation: a density functional theory study

A computational study on Pinnick oxidation of aldehydes into carboxylic acids using density functional theory (DFT) calculations has been evaluated with the (SMD)-M06-2X/aug-pVDZ level of theory, leading to an important understanding of the reaction mechanism that agrees with the experimental observations and explaining the substantial role of acid in driving the reaction. The DFT results elucidated that the first reaction step (FRS) proceeds in a manner where chlorous acid reacts with the aldehyde group through a distorted six-membered ring transition state to give a hydroxyallyl chlorite intermediate that undergoes a pericyclic fragmentation to release the carboxylic acid as a second reaction step (SRS). 1H NMR experiments and simulations showed that hydrogen bonding between carbonyl and t-butanol is unlikely to occur. Additionally, it was found that the FRS is a rate-determining and thermoneutral step, whereas SRS is highly exergonic with a low energetic barrier due to the Cl(III) → Cl(II) reduction. Frontier molecular orbital analysis, intrinsic reaction coordinate, molecular dynamics and distortion/interaction analysis further supported the proposed mechanism.

Mechanism of Os-Catalyzed Oxidative Cyclization of 1,5-Dienes

The oxidative cyclization of 1,5-dienes by metal-oxo species is a powerful method for stereocontrolled synthesis of tetrahydrofuran diols (THF-diols), structural motifs present in many bioactive natural products. Oxidative cyclization of (2E,6E)-octa-2,6-diene catalyzed by OsO₄/NMO has been studied using density functional theory (DFT) calculations (M06-2X/aug-cc-pVDZ/Hay-Wadt VDZ (n+1) ECP), highlighting the remarkable effect of acid on the fate of the first intermediate, an Os(VI) dioxoglycolate. A strong acid promotes cyclization of the Os(VI) dioxoglycolate, or its NMO complex, through protonation of an oxo ligand to give more electrophilic species. By contrast, in the absence of acid, reoxidation may occur to afford the Os(VIII) trioxoglycolate, which is shown to favor conventional "second cycle" dihydroxylation reactivity rather than cyclization. The results of the calculations are consistent with experimental results for reactions of OsO₄/NMO with 1,5-dienes with acid (oxidative cyclization) and without acid (second cycle osmylation/dihydroxylation). Detailed evaluation of potential catalytic cycles supports oxidation of the cyclized Os(IV) THF-diolate intermediate to the corresponding Os(VI) species followed by slow hydrolysis and, finally, regeneration of OsO₄.

Phytochemical and pharmacological attributes of piperine: A bioactive ingredient of black pepper

Plants are vital for the wellbeing of humankind in a variety of ways. Some plant extracts contain antimicrobial properties that can treat different pathogens. Most of the world's population relies on medicinal plants and natural products for their primary health care needs. Therefore, there is a growing interest in natural products, medicinal plants, and traditional medicine along with a desire to design and develop novel plant-based pharmaceuticals. These plant-based pharmaceuticals may address the concerns of reduced efficacy of synthetic antibiotics due to the emergence of drug-resistant pathogens. In this regard, some plant extracts from black pepper (Piper nigrum) with antimicrobial properties, including piperine, have the potential to be used as natural dietary supplements together with modern therapeutic approaches. This review highlights possible applications of piperine as the active compound in the fields of rational drug design and discovery, pharmaceutical chemistry, and biomedicine. We discuss different extraction methods and pharmacological effects of the analyzed substance to pave the way for further research strategies and perspectives towards the development of novel herbal products for better healthcare solutions.

Computational assessments of diastereoselective [4+2] cycloaddition and 1,3-borotopic shift of a dearomatized tertiary boronic ester intermediate: reactivities explained through transition-state distortion energies

Interception of a dearomatized tertiary boronic ester, formed through a kinetically and thermodynamically favorable 1,2-metalate rearrangement/anti-S_N2′ elimination of an activated ortho-lithiated benzyl amine, in a [4+2] cycloaddition or 1,3-borotopic shift has been investigated by density functional theory (DFT). Although superacitvated “naked” Li⁺ was found to greatly promote 1,3-borotopic shift, the diastereoselective [4+2] cycloaddition was favored. It was revealed that the factor that controls the diastereoselectivity was the steric bulk provided by the diene, which is in agreement with experimental diastereoselectivity. A comparison of unreactive dienophiles such as maleic anhydride, diethyl maleate, and others with 4-phenyl-3H-1,2,4-triazole-3,5(4H)-dione (PTAD) was found to be in an excellent agreement with the experiments; where their lack of reactivity is attributed to the high deformation energies of the interacting components to achieve the transition state structure which was pronounced with the high energy of LUMO orbitals.

Interception of dearomatized tertiary boronic ester in a diastereoselective [4+2] cycloaddition or 1,3-borotopic shift in the presence or absence of “naked” Li⁺, understanding reactivities by activation/strain model, were evaluated by DFT calculations.

Characterization of a Laser Surface-Treated Martensitic Stainless Steel

Laser surface treatment was carried out on AISI 416 machinable martensitic stainless steel containing 0.225 wt.% sulfur. Nd:YAG laser with a 2.2-KW continuous wave was used. The aim was to compare the physical and chemical properties achieved by this type of selective surface treatment with those achieved by the conventional treatment. Laser power of different values (700 and 1000 W) with four corresponding different laser scanning speeds (0.5, 1, 2, and 3 m·min⁻¹) was adopted to reach the optimum conditions for impact toughness, wear, and corrosion resistance for laser heat treated (LHT) samples. The 0 °C impact energy of LHT samples indicated higher values compared to the conventionally heat treated (CHT) samples. This was accompanied by the formation of a hard surface layer and a soft interior base metal. Microhardness was studied to determine the variation of hardness values with respect to the depth under the treated surface. The wear resistance at the surface was enhanced considerably. Microstructure examination was characterized using optical and scanning electron microscopes. The corrosion behavior of the LHT samples was also studied and its correlation with the microstructures was determined. The corrosion data was obtained in 3.5% NaCl solution at room temperature by means of a potentiodynamic polarization technique.

First report of pediatric hematopoietic stem cell transplantation activities in the eastern mediterranean region from 1984 to 2011: on behalf of the pediatric cancer working committee of the eastern mediterranean blood and marrow transplantation group

To describe the hematopoietic stem cell transplantation (HSCT) activities for children in the Eastern Mediterranean (EM) region, data on transplants performed for children less than 18 years of age between 1984 and 2011 in eight EM countries (Egypt, Iran, Jordan, Lebanon, Oman, Pakistan, Saudi Arabia and Tunisia) were collected. A total of 5187 transplants were performed, of which 4513 (87%) were allogeneic and 674 (13%) were autologous. Overall, the indications for transplantation were malignant diseases in 1736 (38.5%) and non-malignant in 2777 (61.5%) patients. A myeloablative conditioning regimen was used in 88% of the allografts. Bone marrow (BM) was the most frequent source of stem cells (56.2%), although an increasing use of PBSC was observed in the last decade. The stem cell source of autologous HSCT has shifted over time from BM to PBSC, and 80.9% of autologous HSCTs were from PBSCs. The donors for allogeneic transplants were matched-related in 94.5% of the cases, and unrelated transplants, mainly cord blood (99%) in 239 (5.5%) cases. This is the first report to describe the pediatric HSCT activities in EM countries. Non-malignant disorders are the main indication for allogeneic transplantation. Frequency of alternate donor transplantation is low.

Use of holmium laser for urethral strictures in pediatrics: A prospective study

INTRODUCTION

The management of urethral strictures is very challenging and requires the wide expertise of different treatment modalities ranging from endoscopic procedures to open surgical interventions.

OBJECTIVE

To assess the effectiveness and complications of retrograde endoscopic holmium: yttrium-aluminum-garnet laser (Ho: YAG) urethrotomy (HLU) for the treatment of pediatric urethral strictures.

PATIENTS AND METHODS

From January 2010 to January 2013, 29 male pediatric patients with a mean age of 5.9 years and primary urethral strictures 0.5-2 cm long were treated using HLU. The stricture length was <1 cm in 16 (55%) patients and >1 cm in 13 (45%). Fifteen (51.7%) patients had an anterior urethral stricture, while 14 (48.3%) had a posterior urethral stricture. No positive history was found in 14 (48.3%) patients for the stricture disease, while six (20.7%) had straddle trauma and nine (31%) had an iatrogenic stricture. All of the patients were pre-operatively investigated and at 3 and 6 months postoperation by uroflowmetry and voiding cystourethrography (VCUG). If there were suspicious voiding symptoms, selective uroflowmetry and VCUG were performed at 12 months postoperation.

RESULTS

The mean operation time was 31.7 min (20-45 min). Twenty-three (79.3%) and 18 (62.1%) patients showed normal urethra on VCUG with improvement of symptoms at 3 and 6 months, respectively. Thus, recurrence was 37.9% after 6 months of follow-up. The mean pre-operative peak urinary flow rate (Qmax) was 6.47 ml/s. The mean postoperative Qmax at 3 and 6 months was 17.17 ml/s and 15.35 ml/s, respectively. The success rate and flowmetry results did not show any statistical significance in relation to site, length and cause of the strictures. The other 11 patients who failed to improve underwent repeated HLU sessions: 4/11 (36.3%) achieved successful outcomes. Among the seven patients with failed HLU for the second time, a third session was conducted. However, only one patient (14.2%) was cured, while open repair was needed for the remaining six.

DISCUSSION

One study has previously been published on the management of pediatric urethral strictures using HLU. The present results are similar to short-term studies after a single session of visual internal urethrotomy using cold knife (VIU). In the present study, the length, location and cause of strictures did not significantly affect the results. However, the outcomes with strictures <1 cm were better than strictures >1 cm, although patients with strictures >2 cm were excluded. In the present study, the success rates among patients with second and third sessions of HLU were 36.3% and 14.2%, respectively. This was similar to other studies, which reported low success rate with the second session of VIU. The present study was limited by the relatively short period of follow-up and the small number of patients. However, it was the first prospective study evaluating HLU for pediatric strictures. The use of flowmetry and VCUG for evaluation of all patients added to the strength of the study.

CONCLUSION

HLU can be safely used with good success rates for the treatment of primary urethral strictures (<2 cm) in children. Repeat HLU (more than twice) adds little to success.

Hemopoietic stem cell transplantation in thalassemia: a report from the European Society for Blood and Bone Marrow Transplantation Hemoglobinopathy Registry, 2000-2010

Allogeneic hemopoietic stem cell transplantation (HSCT) is the only method currently available to cure transfusion-dependent thalassemia major that has been widely used worldwide. To verify transplantation distribution, demography, activity, policies and outcomes inside the European Group for Blood and Marrow Transplantation (EBMT), we performed a retrospective non-interventional study, extracting data from the EBMT hemoglobinopathy prospective registry database. We included 1493 consecutive patients with thalassemia major transplanted between 1 January 2000 and 31 December 2010. In total, 1359 (91%) transplants were performed on patients <18 years old, 1061 were from a human leukocyte Ag-identical sibling donor. After a median observation time of 2 years, the 2-year overall survival (OS) and event-free survival (EFS; that is, thalassemia-free survival) were 88 ± 1% and 81 ± 1%, respectively. Transplantation from a human leukocyte Ag-identical sibling offered the best results, with OS and EFS of 91 ± 1% and 83 ± 1%, respectively. No significant differences in survival were reported between countries. The threshold age for optimal transplant outcomes was around 14 years, with an OS of 90-96% and an EFS of 83-93% when transplants were performed before this age. Allogeneic HSCT for thalassemia is a curative approach that is employed internationally and produces excellent results.

Untreated Gleason Grade Progression on Serial Biopsies during Prostate Cancer Active Surveillance: Clinical Course and Pathological Outcomes

PURPOSE

We describe the outcomes of patients with low risk localized prostate cancer who were upgraded on a surveillance biopsy while on active surveillance and evaluated whether delayed treatment was associated with adverse outcome.

MATERIALS AND METHODS

We included men in the study with lower risk disease managed initially with active surveillance and upgraded to Gleason score 3+4 or greater. Patient demographics and disease characteristics were compared. Kaplan-Meier curve was used to estimate the treatment-free probability stratified by initial upgrade (3+4 vs 4+3 or greater), Cox regression analysis was used to examine factors associated with treatment and multivariate logistic regression analysis was used to evaluate the factors associated with adverse outcome at surgery.

RESULTS

The final cohort comprised 219 men, with 150 (68%) upgraded to 3+4 and 69 (32%) to 4+3 or greater. Median time to upgrade was 23 months (IQR 11-49). A total of 163 men (74%) sought treatment, the majority (69%) with radical prostatectomy. The treatment-free survival rate at 5 years was 22% for 3+4 and 10% for 4+3 or greater upgrade. Upgrade to 4+3 or greater, higher prostate specific antigen density at diagnosis and shorter time to initial upgrade were associated with treatment. At surgical pathology 34% of cancers were downgraded while 6% were upgraded. Cancer volume at initial upgrade was associated with adverse pathological outcome at surgery (OR 3.33, 95% CI 1.19-9.29, p=0.02).

CONCLUSIONS

After Gleason score upgrade most patients elected treatment with radical prostatectomy. Among men who deferred definitive intervention, few experienced additional upgrading. At radical prostatectomy only 6% of cases were upgraded further and only tumor volume at initial upgrade was significantly associated with adverse pathological outcome.

Association of azoospermia factor region deletions in infertile male subjects among Malaysians

Azoospermia factor region (AZF) deletions (AZFa, AZFb, AZFc and AZFd) in the Y chromosome were analysed in male infertility subjects in various populations with conflicting results. This study comprised of 54 infertile males and 63 fertile controls, and the frequency of AZFa, AZFb, AZFc and AZFd deletions were determined using conventional polymerase chain reaction (PCR) as well as real-time PCR-high resolution melting analysis-based methods. The results of this study showed that, three of 54 cases (5.55%) had AZF (a, b and c) deletions (two had AZFc and one had AZFa deletions). Four cases were found to have AZFd deletions (7.4%) with two of them being associated with AZFc deletions (P = 0.028). The frequency of AZF (a, b and c) deletions in Malaysian infertile male subjects was found to be comparable with other populations. AZFd deletions were found to be significant (P < 0.05) in male infertility and it may be associated with other types of AZF deletions.

Oxidative stress on land snail Helix aspersa as a sentinel organism for ecotoxicological effects of urban pollution with heavy metals

The oxidative stress in the digestive gland of the land snail Helix aspersa was considered as a bioindicator for atmospheric pollution with heavy metals from several industries and vehicular traffic in Kafr El-Zayat city. Regional means of heavy metals concentration of all sites were 0.71, 7.09, 0.71, 2.68, 41.44 and 18.01 mg kg(-1) wet mass for Cd, Mn, Ni, Pb, Zn and Cu, respectively. In addition, the highest values of Cd concentrations were found 1.22 and 1.73 mg kg(-1) wet mass in S1 (Potato International Center) and S4 (The Nile bank), respectively. Lactate dehydrogenase (D-LDH(and recorded lipid peroxidation (LPO) levels were significantly high in S1 and S2 (Traffic station). On the other hand, the highest activity of catalase (CAT) was found in S2 (194.04% of control), while the activity of glutathione peroxidase (GPx) reached the highest significant value in S1. As a matter of fact, glutathione-S-transferase (GST) and glutathione reductase (GR) activities were significantly higher in polluted sites than in reference zone. In contrast, the glutathione (GSH) concentration of exposed animals showed significant decrease in all sites, with the lowest value in S1 (57.61% of control). However, metallothioneins concentration (MT) showed no significant difference in all sites except in S1 which accounted for 127.81% of control. Therefore, the overall results of this study showed the importance of H. aspersa as a sentinel organism for biomonitoring the biologic impact of atmospheric pollution in urban areas.

Barriers affecting utilization of family planning services among rural Egyptian women

Access to family planning (FP), quality of care and exploring barriers to utilization of services are key factors in the adoption and continuation of contraception in Egypt. We conducted this study to explore the barriers affecting utilization of FP as well as the characteristics of women who discontinue using FP and nonusers of the FP services. A descriptive cross-sectional research design was used. A multistage random selection of 8 family health centres in Menufia Governorate, Egypt was done. We selected a purposive sample of 500 married, rural women of reproductive age who fulfilled the required criteria (109 non-users, 391 discontinued). Cognitive barriers were cited by more than 55% of the participants in both groups and cultural barriers by 40% of both groups. Barriers related to the method were cited by 35.8% of the women who had discontinued, and demographic barriers by 39.4% of the non-users.

The 5q31 region in two African populations as a facet of natural selection by infectious diseases

Cases of extreme natural selection could lead either to rapid fixation or extinction of alleles depending on the population structure and size. It may also manifest in excess of heterozygosity and the locus concerned will be displaying such drastic features of allele change. We suspect the 5q31 in chromosome 5 to mirror situation of such extreme natural selection particularly that the region encompasses genes of type 2 cytokine known to associate with a number of infectious and non-infectious diseases. We typed two sets of single nucleotide polymorphisms (SNPS) in two populations: an initial limited set of only 4 SNP within the genes of IL-4, IL-13, IL-5 and IL-9 in 108 unrelated individuals and a replicating set of 14 SN P in 924 individuals from the same populations with disregard to relatedness. The results suggest the 5q31 area to be under intense selective pressure as indicated by marked heterozygosity independent of Linkage Disequilibrium (LD); difference in heterozygosity, allele, and haplotype frequencies between generations and departure from Hardy-Weinberg expectations (DHWE). The study area is endemic for several infectious diseases including malaria and visceral leishmaniasis (VL). Malaria caused by Plasmodiumfalciparum, however, occurs mostly with mild clinical symptoms in all ages, which makes it unlikely to account for these indices. The strong selection signals seems to emanate from recent outbreaks of VL which affected both populations to varying extent.

Tyrosinase activity of Greyia flanaganii (Bolus) constituents

Hyper-pigmentation of the skin is a common problem that is prevalent in middle aged and elderly people. It is caused by over production of melanin. Tyrosinase is known to be the key enzyme in melanin production. Ethanolic extract of Greyia flanaganii leaves showed significant (P<0.05) antityrosinase activity exhibiting the IC₅₀ of 32.62 μg/ml. The total extract was further investigated for its toxicity and effect on melanin production by melanocytes cells, and showed significant inhibition (P<0.05) (20%) of melanin production at 6.25 μg/ml and low levels of cytotoxicity (IC₅₀<400 μg/ml). The amount of antioxidants necessary to decrease the initial DPPH absorbance by 50% (EC₅₀) by the total ethanolic extract was found to be 22.01 μg/ml. The effect of G. flanaganii against acne causing bacteria, Propionibacterium acnes, was investigated using microdilution assay. The MIC of the extract of G. flanaganii was found to be 250 μg/ml. Bioassay-guided fractionation led to the isolation of (3S)-4-hydroxyphenethyl 3-hydroxy-5-phenylpentanoate (1), 2',4',6'-trihydroxydihydrochalcone (2), 2',6',4-trihydroxy-4'-methoxydihydrochalcone (3), 2',6'-dihydroxy-4'-methoxydihydrochalcone (4), 5,7-dihydroxyflavanone [(2S)-pinocembrin] (5), 2',6'-dihydroxy-4',4-dimethoxy dihydrochalcone (6) and (2R,3R)-3,5,7-trihydroxy-3-O-acetylflavanone (7). The isolated compounds were tested for their antioxidant, cytotoxicity, tyrosinase inhibition and antibacterial activities. Compound 2 exhibited significant (P<0.05) antityrosinase activity exhibiting the IC₅₀ of 69.15 μM. The isolated compounds showed low toxicity of the cells with reduction of melanin content of the cells. All compounds tested showed good radical scavenging activity. These data indicates that G. flanaganii extract and its isolated phenolic constituents could be possible skin lightening agents.

Hypoglycemic evaluation of a new triterpene and other compounds isolated from Euclea undulata Thunb. var. myrtina (Ebenaceae) root bark

AIM OF THE STUDY

Investigate the hypoglycaemic activity of the four isolated compounds from a crude acetone extract of the root bark of Euclea undulata var. myrtina, which is used by traditional healers in the Venda area, Limpopo Province in the treatment of diabetes.

MATERIAL AND METHODS

The hypoglycaemic activity of the four compounds isolated from Euclea undulata was determined by in vitro screening of glucose utilization by C2C12 myocytes at a concentration of 25 μg/ml or 50 μg/ml. The inhibition of α-glucosidase was also tested at concentrations ranging from 0.02 to 200.00 μg/ml.

RESULTS

Assay-guided isolation of the crude acetone extract of the root bark of Euclea undulata var. myrtina afforded a new triterpene, α-amyrin-3O-β-(5-hydroxy) ferulic acid (1), in addition to three known compounds; betulin (2), lupeol (3) and epicatechin (4). The in vitro results on C2C12 myocytes suggest that compound 4 may have some effect to lowers blood glucose levels, whereas compound 1 has the ability to inhibit α-glucosidase at a concentration of 200.0 μg/ml with an IC₅₀ value of 4.79 that correlates with that of the positive control acarbose IC₅₀ value 4.75.

CONCLUSION

The results suggest that 4 may have some ability to lower blood glucose levels, whereas 1 has the ability to inhibit α-glucosidase.

ETHNOPHARMACOLOGICAL RELEVANCE

These findings corroborate the ethnomedicinal use of Euclea undulata by traditional healers for the treatment of diabetes as two substances was isolated from the acetone plant extract that exhibit hypoglycaemic activity.

Extraction and phytochemical investigation of Calotropis procera: effect of plant extracts on the activity of diverse muscles

CONTEXT

Calotropis procera (Ait.) R.Br. (Asclepiadaceae) is a shrub or small tree that grows wild in Egypt. Calotropis acts as a purgative, anthelmintic, anticoagulant, palliative (in problems with respiration, blood pressure), antipyretic, and analgesic, and induces neuromuscular blocking activity. Little research has been done to study the electrophysiological effects of this plant's extracts on cardiac, smooth, and skeletal muscle activities.

OBJECTIVE

The present study was conducted to determine the phytochemical composition and the effect of the total alcohol extract of the shoot of the plant, which contains almost all of C. procera's cardiac glycosides, flavonoids, and saponins. Also, this study attempted to throw more light on the electrophysiological effects of the plant extracts on cardiac, smooth, and skeletal muscle activities and to clarify the mechanism(s) of their observed action(s).

MATERIALS AND METHODS

The aerial parts of the plant were air dried and their ethanol extracts partitioned with successive solvents. Cardiac, smooth, and skeletal muscles were used in this study to investigate the physiological and pharmacological effects of the plant extracts from different solvents. The data were analyzed by paired t-test.

RESULTS

The phytochemical investigation of Calotropis procera revealed the presence of cardenolides, flavonoids, and saponins. The effects of ethanol, n-butanol, and ethyl acetate (EtOAc) extracts were each evaluated on isolated toad heart and their mechanisms of action determined. Perfusion with 2 μg/mL ethanol, 0.2 μg/mL butanol, and 0.2 μg/mL EtOAc extracts caused a significant decrease in heart rate (bradycardia), significant increase in the force of ventricular contraction, and increase in T-wave amplitude. In addition, the effects of different extracts of the studied plant on smooth muscle and skeletal muscle were investigated in this study. The different extracts and latex of C. procera induced a negative chronotropic effect and decreased the heart rate (HR) of isolated toad heart. The different extracts increased the power of contraction of the duodenum (trace a). Pretreatment with atropine sulfate as a muscarinic receptor blocker abolished the stimulatory effect of the different plant extracts and latex of C. procera (trace b).

DISCUSSION

The present data suggest that ethanol, butanol, and EtOAc extracts of Calotropis procera have negative chronotropism and positive inotropism. Verapamil could abolish the inotropic effect of ethanol as well as that of butanol and EtOAc extracts. Meanwhile, atropine did not abolish the observed negative chronotropic effect. The ethanol extract increased the power of contraction of rabbit duodenum, but atropine abolished this effect. It also decreased the skeletal muscle contraction; this effect could be through blocking of the nicotinic receptors. Butanol and EtOAc extract data for smooth and skeletal muscles are very close to those for the corresponding ethanol extract of the studied plant. The present data for C. procera indicate its direct action on the myocardium, its increase of smooth muscle motility, and its relaxation of skeletal muscle contraction. The chemical constituents could directly affect the cell membrane probably through receptors coupling to G proteins. They regulate the ion channel physiology as in the myocardium.

CONCLUSION

The present data on the extracts of C. procera indicate a direct action on the myocardium, stimulatory effect on smooth muscle motility, and relaxant action on skeletal muscle contraction. Chemical constituents could directly affect the cell membrane probably through receptors coupling to G proteins. They regulate the ion channel physiology as in the myocardium.

Novel xanthones from Securidaca longepedunculata with activity against erectile dysfunction

AIM OF STUDY

Securidaca longepedunculata is used in the treatment of erectile dysfunction in South Africa. The aim of the study was to isolate and identify the active constituents and to determine their activity in the relaxation of corpus cavernosal smooth muscle.

MATERIALS AND METHODS

Bioassay guided isolation of the bioactive compounds using a smooth muscle relaxation bioassay and structural elucidation was carried out using different spectroscopic techniques including 2D NMR.

RESULTS

Two new xanthones were isolated; one of them showed potent activity to relax the corpus cavernosal smooth muscle by 97 % in comparison to sildenafil (Viagra) at 1.8 x 10(-5) mg/ml.

CONCLUSIONS

S. longepedunculata's xanthones stimulate the relaxation of corpus cavenosum smooth muscle, which supports the traditional use of its root bark.

Antiviral and antituberculous activity of Helichrysum melanacme constituents

Bioassay guided fractionation of the acetonic extract of Helichrysum melanacme using human Influenza virus type A and a drug-sensitive strain of Mycobacterium tuberculosis in vitro resulted in the isolation of 2 4',6'-trihydroxy-3'-prenylchalcone (1) and 4',6',5''-trihydroxy-6'',6''-dimethyldihydropyrano[2'',3''-2',3'] chalcone (2) as active constituents. 3-O-methylquercetin and quercetin were also isolated but were inactive against the microorganisms tested in this study.

Intraspinal lumbar synovial cysts: diagnosis and surgical management

BACKGROUND

Lumbar synovial cysts are a common association of facet joint degenerative disease. However, it is relatively rare for these cysts to cause symptoms of radiculopathy and nerve root compression.

PATIENTS AND METHODS

We report a series of eight cases which were treated over a period of 20 months. There were five female and three male patients with a mean age of 66 years, and an average follow-up of seventeen months. All patients had pre-operative flexion/extension radiographs and MRI scans. Two patients had failed non-surgical treatment, two were associated with a Grade 1 spondylolisthesis, and all were associated with facet joint arthropathy. There were five cases occurring at L4/5 and three at L5/S1.

RESULTS

All patients underwent identical procedures, which involved exploration, hemi-laminotomy, flavectomy and minimal facet joint excision. No patient required posterior lumbar interbody fusion and at follow-up five patients had excellent and three had good results.

Antimicrobial activity, toxicity and the isolation of a bioactive compound from plants used to treat sexually transmitted diseases

Extracts of six ethnobotanically selected medicinal plants (Anredera cordifolia, Elaeodendron transvaalense, Elephantorrhiza burkei, Senna petersiana, Terminalia sericea and Rauvolfia caffra) used traditionally to treat sexually transmitted diseases (STD's) were investigated for antibacterial activity using the agar dilution method. Of the six collected, Terminalia sericea, Senna petersiana and Anredera cordifolia were also investigated for cytotoxicity. The phytochemical studies on Senna petersiana resulted in the isolation of luteolin, which also showed antimicrobial activity. Only the Senna petersiana extract and luteolin isolated from it were tested for antiviral activity and showed some activity at the highest non-toxic concentration of 24 and 500 microg/ml, respectively. The results of the antimicrobial screening support the ethnomedicinal uses of these plants to some extent.

Melatonin reduces oxidative stress induced by ochratoxin A in rat liver and kidney

Melatonin (MEL) displays antioxidant and free radical scavenger properties. In the present study, the effect of MEL on the oxidative stress induced by ochratoxin A (OTA) administration in rats was investigated. Four groups of 15 rats each were used: controls, MEL-treated rats (5 mg/kg body mass), OTA-treated rats (250 microg/kg) and MEL+OTA-treated rats. After 4 weeks of treatment, the levels of malondialdehyde (MDA), a lipid peroxidation product (LPO) were measured in serum and homogenates of liver and kidney. Also, the levels of glutathione (GSH), and activities of glutathione reductase (GR), glutathione peroxidase (GSPx), superoxide dismutase (SOD), catalase (CAT) and glutathione-S-transferase (GST) in liver and kidney were determined. In OTA-treated rats, the levels of LPO in serum and in both liver and kidney were significantly increased compared to levels in controls. Concomitantly, the levels of GSH and enzyme activities of SOD, CAT, GSPx and GR in both liver and kidney were significantly decreased in comparison with controls. In rats received MEL+OTA, the changes in the levels of LPO in serum and in liver and kidney were not statistically significant compared to controls. Concomitantly, the levels of GSPx, GR and GST activities in both liver and kidney tissues were significantly increased in comparison with controls. Similar increases in GSPx, GR and GST activities were also observed in MEL-treated rats when compared with controls. In conclusion, the oxidative stress may be a major mechanism for the toxicity of OTA. MEL has a protective effect against OTA toxicity through an inhibition of the oxidative damage and stimulation of GST activities. Thus, clinical application of melatonin as therapy should be considered in cases of ochratoxicosis.

Comparative study of the venoms from three species of bees: effects on heart activity and blood

Crude venoms from three highly evolved aculeate species: Apis mellifera (highly social bees), Bombus morrisoni (eusocial bees), and Anthophora pauperata (solitary bees), were used for conducting this study to compare the effects of honey bee, bumble bee, and solitary bee venom on toad cardiac muscle activity. In addition, these venoms were tested on rat whole blood in order to determine their ability to induce red blood cell haemolysis. The main toxic effects on isolated toad heart were monitored by ECG after perfusion with different concentrations of each bee venom, and are represented as a decrease in the heart rate (HR) accompanied by an elongation in the P-R interval. A gradual and progressive increase in R-wave amplitude was also noted. Several electrocardiographic changes were noted 5-30 min after envenomation with any of the bee venoms. The mechanism of action of the three bee venoms was determined by direct application of atropine, nicotine, or verapamil to the isolated toad hearts. Comparison of the three venoms revealed that Anthophora pauperata venom is the most effective venom in inducing bradycardia, and it has the strongest negative dromotropic effect. Apis mellifera venom demonstrates the most positive inotropic effect of the three venoms. The effects of bee venom on the blood indices of erythrocyte osmotic fragility (EOF) and plasma albumin levels were studied after incubation of rat blood with each venom. It was noticed that RBCs decreased while Hb content, HCT, MCV, MCH, and MCHC increased, although this change did fluctuate and was not significant. A nonsignificant decrease in EOF was noted after 60 min with any of the venoms used. Incubation of rat whole blood with 1 microg/ml of any of the bee venom solutions revealed a highly significant decrease in plasma albumin levels. It can be concluded that venoms from the three species of bees we tested have negative chronotropic and dromotropic effects on isolated toad heart, with Anthophora pauperata being the most potent. In addition, the venoms have positive inotropic effects withApis mellifera being the most potent. The nonsignificant effects of venom on blood profiles and erythrocyte osmotic fragility, combined with the significant decrease in plasma albumin level suggest a protective effect of plasma albumin against bee venom induced toxicity to erythrocytes.

Reconstructive surgery in spinal tumours

AIMS

This study reports 21 patients who underwent reconstructive surgery for destructive spinal tumours.

MATERIALS AND METHODS

The mean age was 49 years (range: 39-71 years). Primary lesions were met in two cases. Secondary spinal tumours were diagnosed in 19 cases. Thirteen were breast carcinoma metastases (61.9%). The cervical spine was involved in four cases, thoracic spine in six cases, and the lumbar spine in 11 cases. One patient underwent decompression laminectomy and posterior pedicle screw stabilization. The others underwent tumour tissue excision, with spinal reconstruction with autogenous bone grafting, with or without vertebral body replacement prosthesis. Anterior and posterior stabilization of the vertebral column was also used.

RESULTS

The objectives of surgery were achieved, in that early ambulation, easier nursing care, pain relief and neurological recovery were reported in all cases. No surgery-related complications were encountered.

CONCLUSIONS

We recommend surgical intervention for such lesions where reasonable longevity is anticipated.

[The value of selected imaging techniques in evaluation of bone regeneration during limb lengthening]

The paper presents the value of different imaging techniques, including X-rays, ultrasonography, computed tomography and densitometry in the evaluation of bone regenerates during limb lengthening. Material consisted of 60 children, age ranging from 4 to 18 years who underwent surgery using the Ilizarov technique because of limb inequality. During of limb lengthening different imaging techniques were employed for monitoring regenerate growth and remodeling. The study showed that all the employed imaging techniques play an important role in monitoring bone regenerate remodeling at different stages of limb lengthening.

Isopimarane diterpenoids from Lycopus europaeus

A reinvestigation of the diterpene metabolites of Lycopus europaeus allowed the isolation of five new compounds, namely, four isopimarane derivatives (1-4) and 5,9-dihydroxygeranyllinalool (5). The structures of these substances were established by chemical and spectroscopic means.