Sweet Potato Starch Microparticles as Controlled Drug Release Carriers: Preparation and In Vitro Drug Release

The aim of this study was to investigate the in vitro drug release behavior of sweet potato starch (SPS) microparticles intended for controlled drug delivery applications. Diclofenac sodium (DS) was used as a model drug candidate in the present study. SPS microparticles were prepared using a spray-drying technique by varying the polymer concentration and drug loading. The mean particles size of drug-loaded spray-dried SPS microparticles was between 10.3 and 13.1 µm. The mean particle size increased slightly with increase in the concentration of SPS. The mean particle size of spray-dried SPS microparticles increased from 10.3 to 13.1 µm when the concentration of SPS increased from 2 to 4% w/v. Under the current spray-drying conditions, the percentage yield of spray-dried SPS microparticles did not vary much among the various formulations and it was between 65.2 and 70.1%. The encapsulation efficiencies of SPS microparticles formulations was between 95.1–98.2%, suggesting good encapsulating ability of the SPS polymer by spary drying. Drug release from all the formulations of spray-dried SPS microparticles was controlled over period of 6 h. The cumulative amount of drug release from the spray-dried SPS microparticles decreased with an increase in the concentration of SPS, while it increases as the drug loading is increased. Release of the drug from spray-dried SPS microparticles followed Fick's law of diffusion since a good correlation coefficient (R²) was observed with the Higuchi plots (R² = 0.9928 to 0.9979).     

Chromatin decondensation, pronucleus formation, metaphase entry and chromosome complements of human spermatozoa after intracytoplasmic sperm injection into hamster oocytes

Obtaining karyotypes from human spermatozoa after microinjection into Syrian golden hamster oocytes is difficult and the hitherto reported results are unsatisfactory. This may be related to the injection and culture technique or to the high susceptibility of the hamster oocytes to undergo parthenogenetic activation or both. Therefore, we investigated the hamster oocyte-human sperm microinjection model using the following two approaches: (i) application of contemporary techniques for injection (touching the sperm tail) and culture (hamster embryo culture medium, HECM-3, 10% CO2) and (ii) omission of Ca2+ from the injection medium. Thus, in the first series of experiments, 252 hamster oocytes were injected with human spermatozoa. Among the 219 (87%) oocytes that survived the injection procedure, the mean percentages of male pronucleus formation [two pronuclei (2PN), two polar bodies (PB)], mitotic metaphase entry and sperm chromosome spreads were 41.4, 27.8 and 18.2% respectively. Analysis of the oocytes which failed to develop the male pronucleus following injection revealed that most of them had developed only the hamster female PN while the sperm nuclei were either intact or swollen (partially decondensed), indicating that failure of oocyte activation was not the likely reason for the failure of male PN formation in these oocytes. In the next series of experiments, sibling oocytes were alternately injected with spermatozoa suspended either in the regular (1.9 mM Ca2+) or Ca2+-free injection medium (experiment set 2, n=278). A significant improvement was noted in the mean percentages of oocytes with 2PN, 2PB, metaphase entry and sperm chromosome spreads in the Ca2+-free group versus the regular group (2PN, 2PB: 51 versus 36.6%, metaphase entry: 36.3 versus 26.9% and sperm chromosome spreads: 28 versus 20.4%; all P < 0.04). Thus, parthenogenetic activation appears to be one of the contributing factors for the failure of male PN formation after heterospecific hamster ICSI. From these experiments it can be concluded that application of the advanced injection and culture techniques and omission of Ca2+ from the injection medium are promising for the routine application of the hamster oocyte microinjection for karyotyping of human spermatozoa with poor fertilizing capacity.     

Analysis and optimal design of semi-insulator passivatedhigh-voltage field plate structures and comparison with dielectricpassivated structures

The influences of the field oxide thickness and the junction depth on the breakdown voltage of semi-insulator passivated planar junctions with the field plate are investigated using a 2D simulator. This is done by analyzing the two extreme situations: the planar junction with an infinitely long field plate, and the deep-depleted MOS structure having a finite size. This rather unconventional approach has offered a new physical insight into the role of the metal field plate and has revealed that the severe field crowding associated with a shallow planar junction can be greatly suppressed by using a thin field oxide. The breakdown voltage and the optimal field oxide thickness of the semi-insulator passivated field plate structures remain nearly constant over a wide variation in the junction depth, and therefore such structures are attractive for realizing high-voltages in vertical devices fabricated by low-voltage IC technology. The influences of the field plate width and the inter-electrode spacing are studied by the conventional approach, and a simple and widely applicable design guideline is given for both the nonpunchthrough and the punchthrough type structures. The influence of the surface charge in the range 0 to 10¹² cm^-2 is found to be negligible. The semi-insulator passivated and the dielectric passivated field plate structures are compared under optimal conditions. This suggests that the semi-insulator passivated structures are attractive when thin field oxide and a shallow planar junction are needed and that the dielectric passivated structures are better when compactness is desired     

Esterases as genetic markers in finger millet

Different varieties of finger millet (Eleusine coracana Gaertn.) were screened for esterase activity colorimetrically and electrophoretically using 1-naphthyl acetate and acetylthiocholine chloride as substrates. The Indian brown seed coat variety (Purna), the Indian white seed coat variety (Hamsa), hybrids of these designated as HPB (brown) and HPW (white), African varieties (brown) and Indian-African hybrid varieties (brown) all exhibited 1-naphthyl acetate hydrolysing activity and showed 6,5,6,5,8 and 8 esterolytic bands respectively on gel electrophoresis. The white seed coat varieties, both parental (Hamsa) and hybrid (HPW), did not possess any acetylthiocholine chloride hydrolysing activity while all the brown seed coat varieties did, the African varieties having greater activities than Indian brown seed coat varieties. Thus, the demonstrable variation in esterase isozymic pattern and cholinester hydrolysing activity with the varieties tested provides a useful genetic marker for identifying different varieties of finger millet.     

Trellis-coded CPFSK and soft-decision feedback equalization for micro-cellular wireless applications

In this paper, trellis-codedM-ary CPFSK with noncoherent envelope detection and adaptive channel equalization are investigated to improve the bit error rate (BER) performance of microcellular digital wireless communications systems. For the same spectral efficiency, the trellis-coded modulation (TCM) schemes studied outperform minimum shift keying (MSK) with noncoherent or differentially coherent detection in Rayleigh fading channels. For the case of frequency-selective fading channels, adaptive channel equalization is applied to mitigate the time-variant intersymbol interference (ISI). A new equalizer structure is proposed which, in its feedback path, makes use of fractionally spaced signal samples instead of symbol-spaced hard decisions on transmitted symbols. Computer simulation results indicate that the soft-decision feedback equalizer (SDFE) can significantly improve the system's performance.     

Isolement de bacteries pathogenes contaminant une eau a l'aide d'immunoadsorbants

The potability of water is indicated by the presence or the absence of bacteria from faecal origin. According to the World Health Organization, water is not considered dangerous in the absence of such bacteria. However, only a water free of true pathogenic bacteria is clearly drinkable. In our laboratory, we have elaborated a method allowing direct isolation from water of the main pathogenic bacteria which are common faecal contaminants. These bacteria include Salmonella typhi-murium, Escherichia coli K 88 and K 99 and Vibrio cholerae of the El Tor biotype. Our method consists of filtering contaminated water through small immunoabsorbant columns packed with polyacrylamide-agarose beads coupled to specific antibodies against bacterial antigenic structures.Antisera were obtained from rabbits immunized with antigenic fractions of the bacterial walls, known as Ch 1 + 2 (V. cholerae) Tm 1 + 2 (S. typhi-murium), Ec 1 + 2 K 88 and K 99 (E. coli K 88 and K 99). Antibodies were then isolated and coupled to glutaraldehyde-activated 3% polyacrylamide 4% agarose beads (AcA 34). 500 ml of contaminated water was filtered through the columns. The water consisted either of artificially contaminated samples from the Oise river (France) or of similarly contaminated saline. After filtration, the beads were recovered from the columns, diluted in hypersaline peptone water (V. cholerae) or saline (S. typhi-murium, E. coli K 88 and K 99) and incubated overnight at 37°C. The growth from the hypersaline peptone or saline broth was then removed, placed onto Petri dishes and the colonies were counted.Water samples containing a mixture of 10³ of each of the four bacteria were filtered through beads coated with the different antibodies. Bacteria retained on the beads were only those against which antibodies were directed (Table 1). On the other hand, we have analysed column effluent waters after passing 10³ bacteria through the relevant columns. No bacteria were detected after filtration, which suggest that most of the bacteria were retained on the beads. Bacteria were found in column effluent waters when the water samples contained more than 10⁵ bacteria.This technique is highly specific and allows the filtration of relatively large quantities of water. We believe the method may prove useful for collecting pathogenic bacteria from water directly, without the need for the usual isolation steps.     

Improvement of intermodulation distortion in microwave m.e.s.f.e.t. amplifiers using gate-bias compensation

A simple technique is described for improving the intermodulation distortion performance of microwave m.e.s.f.e.t. amplifiers. The technique utilises transistor gate-bias compensation controlled by the input signal level of the amplifier. For a constant output power of 0 dBm, an improvement in third-order intermodulation distortion product of up to 10 dB has been observed. The advantages and limitations of the technique are discussed.     

Analysis of a Microwave Feedforward Amplifier Using Volterra Series Representation

The use of feedforward correction to reduce nonlinear distortion in a microwave amplifier is investigated, using the Volterra series approach. Expressions are derived for the suppression of main amplifier distortion, in terms of the circuit parameters of the system. It is shown that the gain and phase imbalance in the second interference loop mainly determine the distortion suppression in the feedforward amplifier. An expression is derived for the relationship between amplifier distortion suppression and the degree of gain and phase imbalance in the second interference loop. The effect of the phase imbalance in the second interference loop on the AM-to-AM and AM-to-PM conversion in a feedforward amplifier is discussed; it is shown that the presence of such phase imbalance may cause a substantial difference to exist between the improvement in cross-modulation and that in intermodulation. Further, the gain sensitivity of the feedforward amplifier as a function of gain and phase imbalance is obtained. As an illustrative example, the distortion suppression of a specific IMPATT amplifier with feedforward correction is considered.     

Hilbert quantum image scrambling and graph signal processing-based image steganography

Steganography plays a big role in secret communication by concealing secret information in the carrier. This paper presents a graph signal processing-based robust image steganography technique for posting images over social networks. In the embedding, we first obtained a scrambled version of the secret image using quantum scrambling. Next, we applied graph wavelet transformation on both the cover image and scrambled secret image followed by α (alpha) blending on both image signals (cover image signal and scrambled image signal). Finally, inverse graph wavelet transformation of the resulting image was undertaken to obtain the stego image. In this paper, the use of graph wavelet transformation improved interpixel correlation, which resulted in the excellent visual quality of both the stego image and the extracted secret image. Our experiments show that the picture quality of both the cover image and the stego image is exactly the same.

     

Synthesis and Characterization of an Epidermal Growth Factor Receptor-Selective RuII Polypyridyl–Nanobody Conjugate as a Photosensitizer for Photodynamic Therapy

There is a current surge of interest in the development of novel photosensitizers (PSs) for photodynamic therapy (PDT), as those currently approved are not completely ideal. Among the tested compounds, we have previously investigated the use of Ru^II polypyridyl complexes with a [Ru(bipy)₂(dppz)]²⁺ and [Ru(phen)₂(dppz)]²⁺ scaffold (bipy=2,2′-bipyridine; dppz=dipyrido[3,2-a:2′,3′-c]phenazine; phen=1,10-phenanthroline). These complexes selectively target DNA. However, because DNA is ubiquitous, it would be of great interest to increase the selectivity of our PDT PSs by linking them to a targeting vector in view of targeted PDT. Herein, we present the synthesis, characterization, and in-depth photophysical evaluation of a nanobody-containing Ru^II polypyridyl conjugate selective for the epidermal growth factor receptor (EGFR) in view of targeted PDT. Using ICP-MS and confocal microscopy, we could demonstrate that our conjugate has high selectivity for the EGFR receptor, which is a crucial oncological target because it is overexpressed and/or deregulated in a variety of solid tumors. However, in contrast to expectations, this conjugate was found to not produce reactive oxygen species (ROS) in cancer cells and is therefore not phototoxic.