Host-Guest Complexation of Oxaliplatin and Para-Sulfonatocalix[n]Arenes for Potential Use in Cancer Therapy

P-sulfonatocalix[n]arenes have demonstrated a great potential for encapsulation of therapeutic drugs via host-guest complexation to improve solubility, stability, and bioavailability of encapsulated drugs. In this work, guest-host complexes of a third-generation anticancer drug (oxaliplatin) and p-4-sulfocalix[n]arenes (n = 4 and 6; p-SC4 and p-SC6, respectively) were prepared and investigated, using ¹H NMR, UV, Job’s plot analysis, and DFT calculations, for use as cancer therapeutics. The peak amplitude of the prepared host-guest complexes was linearly proportional to the concentration of oxaliplatin in the range of 1.0 × 10⁻⁵ M⁻¹ to 2.1 × 10⁻⁴ M⁻¹. The reaction stoichiometry between either p-SC4 or p-SC6 and oxaliplatin in the formed complexes was 1:1. The stability constants for the complexes were 5.07 × 10⁴ M⁻¹ and 6.3 × 10⁴ M⁻¹. These correspond to complexation free energy of −6.39 and −6.52 kcal/mol for p-SC4 and p-SC6, respectively. Complexation between oxaliplatin and p-SC4 or p-SC6 was found to involve hydrogen bonds. Both complexes exhibited enhanced biological and high cytotoxic activities against HT-29 colorectal cells and MCF-7 breast adenocarcinoma compared to free oxaliplatin, which warrants further investigation for cancer therapy.     

On the numerical solution of integral equations of the second kind with weakly singular kernels

The purpose of this paper is to introduce the (Toeplitz) quadrature method for solving Fredholm integral equations of the second kind with mildly singular kernels. We are presented some numerical examples for the computation of the error estimate using the MathCad package.     

Synthesis of Certain Fused Thienopyrimidines of Biological Interest

4‐(4‐Acetylphenylamino)cycloocteno[4,5]thieno[2,3‐d]pyrimidine ( 4 ) was prepared and condensed with certain aldehydes, phenylhydrazine, malononitrile to obtain 5a‐d , 6 and 7 , respectively. 4‐Hydrazino & 4‐substituted amino derivatives of 2‐arylcycloocteno[4,5]thienopyrimidines 10a‐c & 11a‐i were synthesized. Cyclization of the hydrazino compounds 10a‐c with orthoalkanoate esters or the arylidene derivatives 12a‐c with bromine in acetic acid afforded the fused triazolo system 13a‐i . Reaction of the hydrazino compound 10c with acetic anhydride gave 15 while the reaction of 10b,c with acid chlorides gave 16a‐d . Furthermore, the tetrazolothienopyrimidines 17a‐c were synthesized. Some of the newly synthesized compounds were tested for their antimicrobial activity.     

Quantum superarrivals and information transfer through a time-varying boundary

The time-dependent Schrödinger equation is solved numerically for the case of a Gaussian wave packet incident on a time-varying potential barrier. The time evolving reflection and transmission probabilities of the wave packet are computed for several different time-dependent boundary conditions obtained by reducing or increasing the height of the potential barrier. We show that in the case when the barrier height is reduced to zero, a time interval is found during which the reflection probability is larger (superarrivals) compared to the unperturbed case. We further show that the transmission probability exhibits superarrivals when the barrier is raised from zero to a finite value of its height. Superarrivals could be understood by ascribing the features of a real physical field to the Schrödinger wave function which acts as a carrier through which a disturbance, resulting from the boundary condition being perturbed, prpagates from the barrier to the detectors measuring reflected and transmitted probabilities. The speed of propagation of this effect depends upon the rate of reducing or raising the barrier height, thus suggesting an application for secure information transfer using superarrivals.     

DNA-Mediated Stack Formation of Nanodiscs

Membrane-scaffolding proteins (MSPs) derived from apolipoprotein A-1 have become a versatile tool in generating nano-sized discoidal membrane mimetics (nanodiscs) for membrane protein research. Recent efforts have aimed at exploiting their controlled lipid protein ratio and size distribution to arrange membrane proteins in regular supramolecular structures for diffraction studies. Thereby, direct membrane protein crystallization, which has remained the limiting factor in structure determination of membrane proteins, would be circumvented. We describe here the formation of multimers of membrane-scaffolding protein MSP1D1-bounded nanodiscs using the thiol reactivity of engineered cysteines. The mutated positions N42 and K163 in MSP1D1 were chosen to support chemical modification as evidenced by fluorescent labeling with pyrene. Minimal interference with the nanodisc formation and structure was demonstrated by circular dichroism spectroscopy, differential light scattering and size exclusion chromatography. The direct disulphide bond formation of nanodiscs formed by the MSP1D1_N42C variant led to dimers and trimers with low yield. In contrast, transmission electron microscopy revealed that the attachment of oligonucleotides to the engineered cysteines of MSP1D1 allowed the growth of submicron-sized tracts of stacked nanodiscs through the hybridization of nanodisc populations carrying complementary strands and a flexible spacer.     

Thermal stresses in a rotating non-homogeneous orthotropic hollow cylinder

 In this paper the radial deformation and the corresponding stresses in a non-homogeneous hollow elastic cylinder rotating about its axis with a constant angular velocity is investigated. The material of the cylinder is assumed to the non-homogeneous and cylindrically orthotropic. The system of fundamental equations is solved by means of a finite difference method and the numerical calculations are carried out for the temperature, the components of displacement and the components of stress with the time t and through the thickness of the cylinder. The results indicate that the effect of inhomogeneity is very pronounced. Received on 21 December 2000     

New Synthesis of Pyrido[2,3-d] and [3,2-d]Oxazines

N-Hydroxyquinolinimide 1 reacts with each of aromatic amines, hydrazine hydrate and aromatic hydrocarbons to give arylcarbamoyl pyridines 2, pyrrolopyridines 3, pyridopyridazines 4 and pyridooxazinones 5 and 6. The heterocycles 5 and 6 can be transformed to the condensed systems, triazolopyridopyridazines 14 and 15 through series of reactions.     

A semi‐synthetic analog of the cembranoid sarcophine

The title mol­ecule, 2(R)‐[(1E,3E,7S,8S,11E,13R)‐13‐hydroxy‐4,8,12‐tri­methyl‐7,8‐epoxy­cyclo­tetradeca‐1,3,11‐trien‐1‐yl]­propane‐1,2‐diol, C₂₀H₃₂O₄, is a semi‐synthetic analog of sarcophine, the natural cembranoid of marine origin, isolated from the soft coral Sarcophyton glaucum. The conformation of the 14‐membered ring differs substantially from that of sarcophine. The two OH groups of the propane‐1,2‐diol moiety form an unusual weak intramolecular hydrogen bond with an O⋯O distance of 2.788 (2) Å, and the mol­ecules are linked into double chains by intermolecular hydrogen bonds with O⋯O distances of 2.772 (2) and 2.849 (2) Å.     

Effect of air injection method on the performance of an air lift pump

Air lift pump performance was investigated experimentally for different submergence ratios (the ratio between the immersed length of the riser and its total length) using different air injection footpiece designs. For this purpose an air lift pump with a riser 200 cm long and 2.54 cm in diameter, was designed and tested. Nine different air injection footpiece designs were used at four submergence ratios with different air injection pressures (from 0.2 to 0.4 bar). An area of 10 mm² was chosen and divided into nine injection hole arrangements (1, 2, 3, 4, 6, 15, 25, 34 and 48 holes) to cover the whole experimental range. Four submergence ratios were used for this work: 0.75, 0.7, 0.6 and 0.5. The experimental results showed a marked effect on the pump performance when operated with different types of injectors at different submergence ratios. The results indicated that the disk with three holes (D3) gives the highest efficiency at nearly all submergence ratios. Moreover, it is found that there is a suitable disk design for maximum water flow rate at every submergence ratio. Further, the highest efficiency resulted at the largest used submergence ratio, namely 0.75. The pump capacity and efficiency were found to be functions of air flow rate, lift ratio, and injection pressure.     

Monitoring pesticide residues in Egyptian fruits and vegetables in 1995.

Organophosphorus, dithiocarbamates, and some synthetic pyrethroids pesticides, which are commonly used in Egypt for pest control, were monitored, as well as persistent organochlorines, which had been prohibited from use several years ago. Fruit and vegetable samples (397) were collected from 8 local markets and examined for 52 pesticides. Of all analyzed samples, 42.8% contained detectable residues, of which 1.76% exceeded their maximum residue limits (MRLs). The rates of contamination with the different pesticides were 0-86%. However, violation rates among contaminated products were very low, ranging from 0 to 4.6%. In general, organochlorine pesticide residues were not detected in most samples. Dithiocarbamate residues were found in 70.4% of 98 samples analyzed for dithiocarbamates, but only one grape sample had residues exceeding the MRL established by the Codex Committee on Pesticide Residues.