Ahmed Esmail

Spread spectrum code-division multiple-access (CDMA) systems are currently considered as very attractive alternatives to the more familiar FDMA and TDMA systems, especially in the presence of multipath fading and external interference. The problem of code selection in a CDMA system with a finite number of users is addressed in this paper. A simple and efficient method for the selection of finite code sets with relatively high processing gain from Gold and Kasami code families of relatively large sizes is described in detail. Selected code sets of period 63 are presented along with their overall average performance parameters for different number of users.

In the present study, caspase-3 enzyme activity (apoptotic marker) and heat shock protein-70 (HSP70) expression in male rat liver after aflatoxin B1 (AFB1) treatment and the effect of melatonin (MEL) were investigated. Four groups of 20 rats each were used: controls, MEL-treated rats (MEL dose, 5 mg/kg body wt), AFB1-treated rats (50 microg/kg body wt) and MEL+AFB1-treated rats. After 8 weeks of daily treatment, biochemical assays in liver homogenates were done. The caspase-3 enzyme activity was measured using colorimetric method while the level of HSP70 expression was determined using dot blot analysis. In addition, the tissue levels of lipid peroxides (LPO), nitric oxide (NO), glutathione (GSH) and the enzyme activities of glutathione reductase (GR) and glutathione peroxidase (GSPx) were determined using colorimetric methods. The levels of caspase-3 activities and HSP70 level in AFB1 group were significantly higher than control group. Concomitantly, the levels of oxidative stress indices, LPO and NO, were significantly increased while the levels of antioxidants, GSH, GSPx and GR in AFB1 group were significantly decreased compared to their levels in controls. Caspase-3 activity was positively correlated with LPO while negatively correlated with GSH in rat livers treated with AFB1. The levels of caspase-3 activity, LPO, NO and HSP70 expression were significantly lower while the levels of GSH, GSPx and GR activities were significantly higher in MEL+AFB1 group than AFB1 group. In conclusion, higher levels of caspase-3 activity and HSP70 expression were associated with oxidative stress in rat liver treated with AFB1. The increased HSP70 expression in liver of AFB1 group may be due to a compensatory defense mechanism. MEL may effectively normalize the impaired antioxidants status, which consequently reduce both expression of HSP70 and apoptotic dysregulation in the liver. Thus, clinical application of MEL as therapy may benefit in cases of aflatoxicosis.

Spread spectrum code-division multiple-access (CDMA) systems are currently considered as very attractive alternatives to the more familiar FDMA and TDMA systems, especially in the presence of multipath fading and external interference. The problem of code selection in a CDMA system with a finite number of users is addressed in this paper. A simple and efficient method for the selection of finite code sets with relatively high processing gain from Gold and Kasami code families of relatively large sizes is described in detail. Selected code sets of period 63 are presented along with their overall average performance parameters for different number of users.

The UV and visible fluorescence of Na2 molecules in a heat-pipe, excited by the frequency doubled radiation of a tunable mode-locked cavity-dumped cw dye laser was observed through a monochromator, using time-resolved single-photon counting. The effective lifetimes of the directly excited C 1 ∏ u state and the collisionally populated 23 ∏ g and 21∑{/u +} states have been measured

Hepatic expression of growth hormone (GH)-inducible genes serine protease inhibitor (Spi 2.1) and insulin-like growth factor (IGF)-I are inhibited by interleukin (IL)-1. The current study examines the role of the nuclear factor kappaB (NFkappaB) pathway and suppressor of cytokine signaling (SOCS)-3 expression as potential mechanisms for IL-1-mediated GH resistance. CWSV-1 hepatocytes were cotransfected with Spi 2.1 or IGF-1 promoter luciferase constructs and empty pCMV4 vector or dominant negative inhibitor-kappaBalpha (IkappaBalpha)S/A construct. Cells were treated with or without IL-1 and then stimulated with or without recombinant human GH. Cell extracts were assayed for luciferase activity and protein, normalized and expressed as fold-induction. CWSV-1 cells transfected with pCMV4 or IkappaBalphaS/A were treated with or without IL-1 then SOCS-3 mRNA was measured. Finally, CWSV-1 cells were cotransfected with a SOCS-3 promoter construct with or without pCMV4 or IkappaBalphaS/A and then stimulated with or without IL-1 to investigate SOCS-3 promoter activity. CWSV-1 cells cotransfected with pCMV4 demonstrated a three- to fivefold induction of Spi 2.1 or IGF-1 promoter activity after GH stimulation that was almost completely inhibited by IL-1. Cotransfection with IkappaBalphaS/A increased GH-inducible Spi 2.1 and IGF-1 promoter activity, but the inhibitory effects of IL-1 on both promoters were attenuated by cotransfection with IkappaBalphaS/A. IL-1 stimulated SOCS-3 mRNA expression and promoter activity. Cotransfection with IkappaBalphaS/A increased IL-1-inducible SOCS-3 promoter activity, but not SOCS-3 mRNA or protein. Signaling via the NFkappaB pathway is responsible for the inhibitory effects of IL-1 on GH-inducible gene expression by a mechanism that does not seem to involve increased SOCS-3 expression.

Injury of articular cartilage due to trauma or pathological conditions is the major cause of disability worldwide, especially in North America. The increasing number of patients suffering from joint-related conditions leads to a concomitant increase in the economic burden. In this review article, we focus on strategies to repair and replace knee joint cartilage, since knee-associated disabilities are more prevalent than any other joint. Because of inadequacies associated with widely used approaches, the orthopedic community has an increasing tendency to develop biological strategies, which include transplantation of autologous (i.e., mosaicplasty) or allogeneic osteochondral grafts, autologous chondrocytes (autologous chondrocyte transplantation), or tissue-engineered cartilage substitutes. Tissue-engineered cartilage constructs represent a highly promising treatment option for knee injury as they mimic the biomechanical environment of the native cartilage and have superior integration capabilities. Currently, a wide range of tissue-engineering-based strategies are established and investigated clinically as an alternative to the routinely used techniques (i.e., knee replacement and autologous chondrocyte transplantation). Tissue-engineering-based strategies include implantation of autologous chondrocytes in combination with collagen I, collagen I/III (matrix-induced autologous chondrocyte implantation), HYAFF 11 (Hyalograft C), and fibrin glue (Tissucol) or implantation of minced cartilage in combination with copolymers of polyglycolic acid along with polycaprolactone (cartilage autograft implantation system), and fibrin glue (DeNovo NT graft). Tissue-engineered cartilage replacements show better clinical outcomes in the short term, and with advances that have been made in orthopedics they can be introduced arthroscopically in a minimally invasive fashion. Thus, the future is bright for this innovative approach to restore function.

Acrolein is the metabolite of cyclophosphamide (CP) believed to be involved in the bladder toxicity associated with this anticancer drug. The mechanism by which this extremely reactive intermediate is delivered to the bladder is not known. Glutathione (GSH) readily conjugates with acrolein, and the acrolein mercapturate S-(3-hydroxypropyl)-N-acetylcysteine (3-hydroxy-PrMCA) has been found in the urine of animals and man given CP. The objectives of this study were to prepare and characterize synthetic standards of the GSH acrolein adduct (3-oxopropyl)glutathione (3-oxoPrGSH), the acrolein mercapturates S-(3-oxopropyl)-N-acetylcysteine (3-oxoPrMCA) and 3-hydroxyPrMCA, and the S-oxidation product of 3-oxoPrMCA (3-oxoPrMCA S-oxide). In addition, the release of acrolein from, and the bladder toxicity of, these conjugates was determined. 3-OxoPrGSH and 3-oxoPrMCA were prepared with a 99% yield by condensing acrolein with GSH and N-acetylcysteine, respectively. 3-HydroxyPrMCA was prepared with a 63% yield by refluxing 3-chloropropanol and N-acetylcysteine in a basic medium. Oxidation of 3-oxoPrMCA with H2O2 was used to prepare 3-oxoPrMCA S-oxide. By decreasing the reaction time to 1 h, and adjusting the ratio of 3-oxoPrMCA to H2O2, the yield of 3-oxoPrMCA S-oxide was increased to 96%. The anhydrous aldehyde, 3-oxoPrMCA, afforded characteristic aldehydic proton resonances (1H NMR) in deuterated dimethyl sulfoxide. New resonances were observed in deuterated water, indicating a 75% hydration of the aldehyde to the corresponding geminal diol. This phenomenon was enhanced with 3-oxoPrMCA S-oxide where approximately 100% hydration of the aldehyde to the corresponding geminal diol was observed. When incubated at 25 degrees C in 100 mM potassium phosphate buffer containing 1 M KCl, pH 8.0, 3-oxoPrMCA released approximately 6% and 3-oxoPrMCA S-oxide released approximately 16-18% of the theoretical maximum yield of acrolein after 30 min, as indicated by an increase in absorbance at 210 nm and confirmed by trapping this aldehyde as a semicarbazone. There was less than a 2% yield of acrolein from 3-hydroxyPrMCA or 3-oxoPrGSH under similar conditions. At pH 7.4 the release of acrolein from 3-oxoPrMCA and 3-oxoPrMCA S-oxide was decreased by 50%. An assay where aldehydes are reacted with m-aminophenol in acid media produced fluorescence consistent with 72%, 46%, 23%, and 1% yields of acrolein from 3-oxoPrMCA S-oxide, 3-oxoPrMCA, 3-oxoPrGSH, and 3-hydroxyPrMCA, respectively.(ABSTRACT TRUNCATED AT 400 WORDS)

Damage of cartilage due to traumatic or pathological conditions results in disability and severe pain. Regenerative medicine, using tissue engineering-based constructs to enhance cartilage repair by mobilizing chondrogenic cells, is a promising approach for restoration of structure and function. Fresh fibrin (FG) and platelet-rich fibrin (PR-FG) glues produced by the CryoSeal(®) FS System, in combination with human bone marrow-derived mesenchymal stem cells (BM-hMSCs), were evaluated in this study. We additionally tested the incorporation of heparin-based delivery system (HBDS) into these scaffolds to immobilize endogenous growth factors as well as exogenous transforming growth factor-β(2). Strongly, CD90+ and CD105+ hMSCs were encapsulated into FG and PR-FG with and without HBDS. Encapsulation of hMSCs in PR-FG led to increased expression of collagen II gene at 2.5 weeks; however, no difference was observed between FG and PR-FG at 5 weeks. The incorporation of HBDS prevented the enhancement of collagen II gene expression. BM-hMSCs in FG initially displayed enhanced aggrecan gene expression and increased accumulation of Alcian blue-positive extracellular matrix; incorporation of HBDS into these glues did not improve aggrecan gene expression and extracellular matrix accumulation. The most significant effect on cartilage marker gene expression and accumulation was observed after encapsulation of hMSCs in FG. We conclude that FG is more promising than PR-FG as a scaffold for chondrogenic differentiation of hMSCs; however, immobilization of growth factors inside these fibrin scaffolds with the HBDS system has a negative impact on this process. In addition, BM-hMSCs are valid and potentially superior alternatives to chondrocytes for tissue engineering of articular cartilage.

Endothelial dysfunction is of vital importance as it may cause ischemia and dysfunction in various organs, especially the heart and kidneys. Despite this problem being well documented in patients with end-stage renal disease, there are insufficient data considering this issue to demand sirolimus use in renal transplantation. One potential cause of endothelial dysfunction in renal transplantation patients may be the use of the conventional protocols with cyclosporine [CsA]- versus sirolimus-based therapy. We studied 22 renal transplant recipients including on CsA (n = 14; group I, and sirolimus (n = 8; group II). Endothelial functions of the brachial artery were evaluated using high-resolution vascular ultrasound. Endothelium-dependent and-independent vasodilatations were assessed by sublingual nitroglycerine (NTG). Results are presented as percentage from baseline values. Significant endothelial dysfunction was noted among renal transplant patients treated with CsA. Endothelium-dependent vasodilatation was 3.6% ± 2.8% in group I and 14.5% ± 3.2% in group II (P < 0.002). The increase in brachial artery diameter after sublingual NTG measured 9.9% ± 4.7% versus 22.1% ± 5.9% in groups I and group II, respectively. This observation indicated that endothelial vasodilatation was preserved among patients on sirolimus but not CsA therapy. We concluded that endothelial vasodilatation is impaired in renal transplant recipients. Moreover, sirolimus seems to be more useful than CsA to overcome the compromised vasculature as observed in diabetic and elderly patients.

Abstract: The generation of coherent phonons in polycrystalline bismuth film is observed by ultrafast time-resolved electron diffraction. The dynamics of the diffracted intensities from the (110), (202), and (024) lattice planes show pronounced oscillations at 130 150 GHz. The ...

The structural properties of bismuth nanoclusters were investigated with transmission high-energy electron diffraction from room temperature up to 525 ± 6 K. The Bi nanoclusters were fabricated by thermal evaporation at room temperature on transmission electron microscope grids coated with an ultrathin carbon film, followed by thermal and femtosecond laser annealing. The annealed sample had an average cluster size of ˜14 nm along the minor axis and ˜16 nm along the major axis. The Debye temperature of the annealed nanoclusters was found to be 53 ± 6 K along the [012] direction and 86 ± 9 K along the [110] direction. At T = 464 ± 6 K, the diffraction intensity started to deviate from Debye-Waller behavior due to increased lattice anharmonicity. The onset of the melting of the Bi nanoclusters was T ˜ 500 ± 6 K, as measured by the reduction of the nanocluster size through the formation of a liquid shell detected by the width of the diffraction rings. The thermal expansion coefficient of the Bi (012) and (110) planes is positive up to ˜ 499 ± 11 K. However, the expansion coefficient of the Bi (012) planes showed a transition from a positive to a negative value that occurs over the temperature range Tc ˜ 499 ± 11 K to 511 ± 8 K. For the Bi (110) planes, the thermal expansion coefficient is positive up to their melting point, which is 525 ± 6 K.