Chitosan/Cellulose Acetate Microspheres Preparation and Ranitidine Release In Vitro

New microspheres containing hydrophilic core and hydrophobic coating as a controlled-release system with no toxic reagents were proposed. Water in oil in water (W/O/W) emulsion and solvent evaporation methods were used to make chitosan/ cellulose acetate (CCA) microspheres sized 200 - 400 microm. Ranitidine hydrochloride, as a model drug, was investigated for its release properties in vitro. The loading efficiency and release rate of ranitidine were affected by chitosan concentration and molecular weight. Higher loadings were obtained at lower concentrations in the interval of 1% to 2%. With chitosan at a 2% concentration microspheres could be obtained with more spherical appearance, smaller size, and higher ranitidine loading efficiency microspheres than at other concentrations. Among the different molecular weight chitosan (47, 145, 308, 499, and 1130 KD) microspheres, the high molecular weight chitosan (1130 KD) microspheres had relatively high loading efficiency (10%). Molecular weight and concentration of chitosan as well as the size of microspheres affected the release of ranitidine. Microspheres smaller than 280 microm released the drug faster than did the bigger by about 10%. The optimal condition for the preparation of the microspheres was chitosan concentration 2%, molecular weight 1130 KD. The ranitidine release from the microspheres was 30% during 48 h in phosphate-buffer saline medium.

[Effect of cerebral mild hypothermia on cerebral mitochondrial ATPase activity in neonatal rats with hypoxic-ischemic brain damage]

OBJECTIVE

To study the effect of cerebral mild hypothermia on cerebral mitochondrial ATPase activities in neonatal rats with hypoxic-ischemic brain damage (HIBD).

METHODS

Eighty-four seven-day-old Wistar rats were randomly assigned into four groups: sham-operated normothermic, sham-operated mild hypothermic, HIBD normothermic and HIBD mild hypothemic. HIBD was induced by left common carotid artery ligation, followed by 8% hypoxia exposure. At each time interval of 2, 6, and 12 hrs post-hypoxia-ischemia (HI), 7 rats were sacrificed and the brain tissues were sampled for detecting the activities of mitochondrial Na+K+ATPase and Ca2+ATPase.

RESULTS

The activities of mitochondrial Ca2+ATPase decreased significantly in the two HIBD groups compared with those of the two sham-operated groups at 2, 6, and 12 hrs post-HI. The HIBD mild hypothemic group had higher mitochondrial Ca2+ATPase activities compared with the HIBD normothermic group at 2, 6, and 12 hrs post-HI (5.25 +/- 0.61 micromol/mgPr.h vs 3.17 +/- 0.81 micromol/mgPr.h 4.59 +/- 0.81 micromol/mgPr.h vs 2.26 +/- 0.53 micromol/mgPr.h4.61 +/- 0.62 micromol/mgPr.h vs 1.31 +/- 0.78 micromol/mgPr.H, respectively) (P < 0.01). The activities of mitochondrial Na+K+ATPase decreased significantly in the two HIBD groups compared with those of the two sham-operated groups at 6 and 12 hrs post-HI. A significant difference was observed in the mitochondrial Na+K+ATPase activities between the HIBD mild hypothemic and HIBD normothermic groups at 6 and 12 hrs post-HI (5.25 +/- 0.66 micromol/mg Pr.h vs 3.76 +/- 0.78 micromol/mgPr.h, 4.74 +/- 0.80 micromol/mgPr.h vs 3.12 +/- 0.53 micromol/mgPr.h; P < 0.01).

CONCLUSIONS

Mild hypothermia following HIBD inhibits the decline in cerebral mitochondrial Ca2+ and Na+K+ ATPase activities in neonatal rats, thus providing protective effects against HIBD.

Immunoassay by capillary electrophoresis with quantum dots

The application of quantum dots in capillary electrophoresis immunoassay was studied for the first time. Quantum dots were conjugated with antibody and subsequently tested by electrophoretic separation of free antibody and antibody-antigen complex. Antibody was fluorescently labeled by quantum dots via conjugation procedures and its electrophoretic characteristics were effectively modified due to the attachment of quantum dots. The determination of human IgM by direct CE based immunoassay could be easily achieved by simply changing the pH value of separation buffer. Polymer additive influenced the separation too but the effect was not as significant as buffer pH adjustment. Satisfactory separation of complex from free antibody could be achieved with 20mM sodium tetraborate as separation buffer, at pH 9.8. The immunoassay application of quantum dots in CE offers considerable advantages and can be readily applied to other large bio-molecules.

[Mild hypothermia attenuates neuronal apoptosis after cerebral hypoxia-ischemia in neonatal rats]

OBJECTIVE

To investigate the effects of mild hypothermia on sequential events of neuronal apoptosis following hypoxic-ischemic brain damage (HIBD) in neonatal rats.

METHODS

A model of HIBD was prepared by ligating the left common carotid artery in 7-day-old rats, followed by 8% hypoxia exposure. HIBD rats were randomly assigned into a hypothermia group (rectal temperature = 33 centi-degrees) and a normothermia group (rectal temperature = 36 centi-degrees). TUNEL, Haematoxylin and Eosin, and Nissl staining were used to detect neuronal apoptosis. Western blotting, RT-PCR and enzyme activity measurement were used to evaluate the changes of plasma and mitochondrial cytochrome c (Cyt c), caspase-3 mRNA expression and caspase-3 enzyme activity, respectively.

RESULTS

The number of apoptotic cells in the ipsilateral hemisphere of the hypothermia group was significantly reduced compared with that of the normothermia group at 72 hrs post-HI (6.4 +/- 1.7% vs 25.3 +/- 1.5%) (P < 0.01). Analysis of Western blotting showed that Cyt c levels increased in the cytosolic fraction, but decreased significantly in the mitochondrial fraction in the ipsilateral hemisphere of the hypothermia group at 24, 48 and 72 hrs of HI insult compared with the normothermia group (P < 0.05). Caspase-3 mRNA increased significantly after 24 hrs post-HI in the normothermia group, and this change became more pronounced with time. Mild hypothermia treatment decreased significantly caspase-3 mRNA expression at 24, 48 and 72 hrs post-HI (P < 0.05). Caspase-3 activity gradually increased 2 hrs after HI insult and peaked at 24 hrs in the normothermia group. Mild hypothermia treatment resulted in a significant reduction in caspase-3 activity in the ipsilateral hemisphere, with an optimal effect produced at 24 hrs post-HI (2.42 +/- 0.5 RFU vs 34.7 +/- 3.2 RFU; P < 0.01).

CONCLUSIONS

Mild hypothermia treatment attenuates neuronal apoptosis following HIBD, possibly through a reduction in Cyt c release from mitochondria and an inhibition of caspase-3 mRNA expression and its enzyme activity.

Isolating Mortierella alpina strains of high yield of arachidonic acid

AIMS

To develop a fast isolation method for arachidonic acid-producing fungi of high yield.

METHODS AND RESULTS

Relation between the staining degree of mycelia of Mortierella alpina stained with triphenyltetrazolium chloride (TTC) and arachidonic acid content in the fungal lipids was investigated. Results showed that staining degree of mycelia stained with TTC increased when arachidonic acid content in mycelia lipids increased. This finding was used to isolate strains of high arachidonic acid yield. Arachidonic acid producing fungi were selectively isolated from soil at a low temperature of 4 degrees C and the mycelia of these isolates were stained with TTC.

CONCLUSIONS

The strain M. alpina M6 that had the highest staining degree had the highest arachidonic acid content (72.3%). The yield of arachidonic acid in this strain reached 4.82 g l(-1).

SIGNIFICANCE AND IMPACT OF THE STUDY

A fast and effective method to isolate strains of high arachidonic acid yield was established according to the finding that staining degree of mycelia of M. alpina was positively correlated with arachidonic acid content in mycelia lipid.

Improved arachidonic acids production from the fungus Mortierella alpina by glutamate supplementation

The effect of various concentrations of glutamate on arachidonic acid (AA) production from Mortierella alpina in shaker flask culture was studied. Glutamate supplementation promoted Mortierella growth, accelerated substrate metabolism, and increased AA production, and a concentration of 0.8 g/l glutamate resulted in the greatest AA yield (1.41 g/l). In 10 l airlift stirred fermenter culture, AA yield in the cultures exposed to 0.8 g/l glutamate was also greater than that in the control (0.56 g/l).

Study on an environmental-friendly and high-efficient fuel cell energy conversion system

The kinds and the distribution of the coal in China are investigated. The results indicated that the 80% coal in China is used by the method of the coal gasification. The possibility of utilization and development of the fuel cell power plant in China is analyzed. A combined cycle generation system is designed. Its net electrical efficiency is about 55% (LHV), which is higher than that of the fire power plant. So it is environmental-friendly and high-efficient generation mode.

Cell death unlikely contributes to taxol production in fungal elicitor-induced cell suspension cultures of Taxus chinensis

Cell suspension cultures of Taxus chinensis, with 20, 40 and 100 mg fungal elicitor l(-1) from Aspergillus niger, underwent rapid cell death after 24 h, which was about 2, 3.7 and 5-fold of that of the control. At the same time, Taxol production was increased, respectively, to about 5, 8 and 3-fold of that of the control. Inhibition of phenolics biosynthesis resulted in a 150% increase in cell death but a 54% decrease in Taxol production compared with 40 mg elicitor l(-1) alone. O2-free N2 inhibited cell death but had little effect on Taxol production as induced by 40 mg fungal elicitor l(-1).

Extraction of lipids from Mortierella alpina and enrichment of arachidonic acid from the fungal lipids

Mortierella alpina is known as an arachidonic acid (AA) producing oleaginous fungus. Extraction of lipids from wet and dry M. alpina biomass was compared. Lipids yield of extraction from dry cells was higher than that of extraction from wet. Wet extraction mainly extracted lipid bodies and lipids in membranes did not extract effectively. Enrichment of AA from the fungal lipids by a urea inclusion method was studied. Most of the saturated and monounsaturated fatty acids, 93.0% and 84.6%, respectively, were removed by forming urea inclusion compounds. AA was concentrated after urea inclusion. Its content in total fatty acids increased 6.2-folds and reached 57.1% with a recovery of 81.9%.

Relationship between Superoxide Anion Radical and Anion Transport Protein of Red Blood Cell Membrane

By using a specific inhibitor of anion transport, DIDS, the dependence on band 3 anion transport protein of superoxide anion radical (O(-)(2).) flux across red blood cell (RBC) membrane into RBC was studied and the effect of superoxide anion radical on anion transport in RBC membrane was also discussed based on the hemolytic t(1/2) in an isotonic solution of NH(4)Cl. The results showed that 40 &mgr;mol/L DIDS could completely inhibit anion transport by band 3 protein in RBC membrane, but had no effect on flux into RBC, proving that the O(-)(2). transport into RBC across RBC membrane was independent of band 3 protein the interaction of O(-)(2). with specific SH-group of membrane protein lowered the anion permeability, and it could be reversed by DTT and mercaptoethanol.

Separation and identification of perchlorinated polycyclic aromatic hydrocarbons and fullerenes (C60, C70) by coupling high-performance liquid chromatography with ultraviolet absorption spectroscopy and atmospheric pressure chemical ionization mass spectrometry

Simultaneous separation and identification of perchlorinated polycyclic aromatic hydrocarbons (PCPAHs) and fullerenes is of practical interest due to the growth mechanism of fullerenes involved with PCPAHs. Non-aqueous reversed-phase high-performance liquid chromatography (HPLC), with an ODS column and a gradient mobile phase of methanol-ethanol-cyclohexane mixtures, was combined with both rapid-scan ultraviolet spectrometry (UV) and atmospheric pressure chemical ionization mass spectrometry (APCI-MS) for the separation and identification of over 80 PCPAHs as well as fullerenes C60 and C70, that were synthesized in the discharge reaction of chloroform. PCPAH retention was found to depend on the number of aromatic rings and the degree of non-planarity of PCPAH structure. Based on the isotopic pattern of molecular ion or/and quasi-molecular ion peaks in corresponding mass spectra, molecular compositions of the PCPAH products were unambiguously determined. The results obtained from the HPLC-UV-MS analysis not only are helpful for the understanding of the fullerenes formation mechanism, but also contribute to the analytical technique capable of separating and identifying the complicated mixture of PCPAHs and fullerenes.

Structure-activity relationship of tubeimosides in anti-inflammatory, antitumor, and antitumor-promoting effects

AIM

To study structure-activity relationship of tubeimosides isolated from Bolbostemma paniculatum for their anti-inflammatory, antitumor, and antitumor-promoting effects.

METHODS

Tubeimosides I, II, and III were isolated from tubers of Bolbostemma paniculatum (Maxim) Franquet (Cucurbitaceae), a Chinese folk medicine,"Tubeimu", and their anti-inflammatory, anti-tumor, anti-tumorigenic activities, and acute toxicity were studied in vivo.

RESULTS

Tubeimosides I, II, and III are all natural analogues of oleanane type of triterpenoid saponins from the same medicinal plant, and all show anti-inflammatory, antitumor, and antitumor-promo ting effects. However, the anti-inflammatory, anti-tumor, and anti-tumorigenic activities of tubeimoside II are stronger than those of tubeimoside I, and the acute toxicity of tubeimoside II is lower than that of tubeimoside I; the anti-inflammatory, anti-tumor, and anti-tumorigenic activities of tubeimoside III are stronger than those of tubeimoside II, and the acute toxicity of tubeimoside III is also stronger than that of tubeimoside II.

CONCLUSION

C-16 hydroxyl group of tubeimoside II plays an important role in enhancing biological activity of tubeimoside II and in decreasing its toxicity. The difference of chemical structure in B and/or C position between tubeimosides III and II plays an important role in enhancing biological activity and toxicity of tubeimoside III. Therefore tubeimosidre II may be the most promising agent for cancer chemoprevention and chemotherapy among tubeimosides I, II, and III.

P450 enzyme expression patterns in the NCI human tumor cell line panel

Cytochrome P450 (P450) enzyme expression patterns were determined for a panel of 60 human tumor cell lines, representing nine tumor tissue types, used by the National Cancer Institute (NCI) Anticancer Drug Screening Program. All 60 tumor cell lines displayed significant P450 activity, as well as P450 reductase activity, as determined using the general P450 substrate 7-benzyloxyresorufin. Cell line-specific P450 enzyme patterns were observed using three other P450 substrates, 7-ethoxycoumarin, coumarin, and 7-ethoxyresorufin, each of which was metabolized at a low rate. Using a pattern-matching computer program, COMPARE, correlative relationships were investigated between the arrays of P450 activities and the patterns of cytotoxicity exhibited by a large group of anticancer agents of proven or potential clinical utility. Significant negative correlations between the patterns of P450-dependent 7-benzyloxyresorufin metabolism activity and cell line chemosensitivity were observed for 10 standard anticancer agents (including 6 alkylating agents) and 55 investigational compounds, suggesting a role for P450 metabolism in the inactivation of these agents. Negative correlations between 7-ethoxycoumarin O-deethylation and cell line chemosensitivity to a group of topoisomerase inhibitors were also seen, again suggesting P450-dependent drug inactivation. P450 enzyme profiling may thus aid in interpreting the patterns of drug sensitivity and resistance in the NCI tumor cell panel, and may facilitate the identification of anticancer agents whose activity can be altered via cytochrome P450 metabolism.

Derivative matrix isopotential synchronous fluorescence spectroscopy for the direct determination of 1-hydroxypyrene as a urinary biomarker of exposure to polycyclic aromatic hydrocarbons

Urinary 1-hydroxypyrene is a biomarker in the measurement of human exposure to polycyclic aromatic hydrocarbons. A rapid and simple derivative isopotential synchronous fluorescence method was developed for the direct determination of 1-hydroxypyrene in urine. A length of iso-intensity route was scanned on the three-dimensional fluorescence spectrum of urine and this result was combined with that from derivative technique. Thus the strong background signals of urine were removed and the 1-hydroxypyrene can be determined directly in urine without tedious pre-separation. The derivative isopotential synchronous fluorescence spectrum was directly obtained from a single scan on a spectrofluorometer, which further simplified isopotential synchronous fluorescence technique. The recoveries of 93% to 115% were obtained for 1-hydroxypyrene added to urine.

The influence of heavy metals on partitioning of PAHs during incineration

The presence of heavy metals (Cr, Cd, Pb and Zn) in feedstock increases the partitioning of polycyclic aromatic hydrocarbons (PAHs) in the solid as well as in the gaseous phases, which has been reported in our previous study. However, the partitioning of PAHs in air-pollution control equipment (APCE) has not been investigated thus far. Hence, the present work was conducted to study the partitioning of PAHs in APCE and the effect of heavy metals on PAHs formation by varying the target heavy metals in the feedstock.A fluidized bed incineration system which includes a primary combustion chamber (sand bed), a secondary combustion chamber (freeboard), and an APCE (cyclone and scrubber) was utilized in this study. The feedstock that contained various heavy metals was fed into the incinerator, and then the PAHs in the cyclone and scrubber were analyzed to determine the effect of heavy metals on PAHs partitioning. The results indicate that the presence of Pb and Zn in feedstock facilitates the formation of PAHs.

Development of a substrate-activity based approach to identify the major human liver P-450 catalysts of cyclophosphamide and ifosfamide activation based on cDNA-expressed activities and liver microsomal P-450 profiles

The contributions of specific human liver cytochrome P-450 (CYP) enzymes to the activation, via 4-hydroxylation, of the oxazaphosphorine anticancer prodrugs cyclophosphamide (CPA) and ifosfamide (IFA) were investigated. Analysis of a panel of 15 human P-450 cDNAs expressed in human lymphoblasts and/or baculovirus-infected insect cells (Supersomes) demonstrated that CYPs 2A6, 2B6, 3A4, 3A5, and three CYP2C enzymes (2C9, 2C18, 2C19) exhibited significant oxazaphosphorine 4-hydroxylase activity, with 2B6 and 3A4 displaying the highest activity toward CPA and IFA, respectively. CYP2B6 metabolized CPA at a approximately 16-fold higher in vitro intrinsic clearance (apparent Vmax/Km) than IFA, whereas 3A4 demonstrated approximately 2-fold higher Vmax/Km toward IFA. A relative substrate-activity factor (RSF)-based method was developed to calculate the contributions of individual P-450s to total human liver microsomal metabolism based on cDNA-expressed P-450 activity data and measurements of the liver microsomal activity of each P-450 form. Using this method, excellent correlations were obtained when comparing measured versus predicted (calculated) microsomal 4-hydroxylase activities for both CPA (r = 0. 96, p <.001) and IFA (r = 0.90, p <.001) in a panel of 17 livers. The RSF method identified CYP2B6 as a major CPA 4-hydroxylase and CYP3A4 as the dominant IFA 4-hydroxylase in the majority of livers, with CYPs 2C9 and 2A6 making more minor contributions. These predicted P-450 enzyme contributions were verified using an inhibitory monoclonal antibody for 2B6 and the P-450 form-specific chemical inhibitors troleandomycin for 3A4 and sulfaphenazole for 2C9, thus validating the RSF approach. Finally, Western blot analysis using anti-2B6 monoclonal antibody demonstrated the presence of 2B6 protein at a readily detectable level in all but one of 17 livers. These data further establish the significance of human liver CYP2B6 for the activation of the clinically important cancer chemotherapeutic prodrug CPA.

In vivo modulation of alternative pathways of P-450-catalyzed cyclophosphamide metabolism: impact on pharmacokinetics and antitumor activity

The widely used anticancer prodrug cyclophosphamide (CPA) is activated in liver by a 4-hydroxylation reaction primarily catalyzed by cytochrome P-4502B and P-4502C enzymes. An alternative metabolic pathway involves CPA N-dechloroethylation to yield chloroacetaldehyde (CA), a P-4503A-catalyzed deactivation/neurotoxication reaction. The in vivo modulation of these alternative, competing pathways of P-450 metabolism was investigated in pharmacokinetic studies carried out in the rat model. Peak plasma concentrations (Cmax) for 4-OH-CPA and CA were increased by 3- to 4-fold, and apparent plasma half-lives of both metabolites were correspondingly shortened in rats pretreated with phenobarbital (PB), an inducer of P-4502B and P-4503A enzymes. However, PB had no net impact on the extent of drug activation or its partitioning between these alternative metabolic pathways, as judged from AUC values (area-under-the-plasma concentration x time curve) for 4-OH-CPA and CA. The P-4503A inhibitor troleandomycin (TAO) decreased plasma Cmax and AUC of CA (80-85% decrease) without changing the Cmax or AUC of 4-OH-CPA in uninduced rats. In PB-induced rats, TAO decreased AUCCA by 73%, whereas it increased AUC4-OH-CPA by 93%. TAO thus selectively suppresses CPA N-dechloroethylation, thereby increasing the availability of drug for P-450 activation via 4-hydroxylation. By contrast, dexamethasone, a P-4503A inducer and antiemetic widely used in patients with cancer, stimulated large, undesirable increases in the Cmax and AUC of CA (8- and 4-fold, respectively) while reducing the AUC of the 4-hydroxylation pathway by approximately 60%. Tumor excision/in vitro colony formation and tumor growth delay assays using an in vivo 9L gliosarcoma solid tumor model revealed that TAO suppression of CPA N-dechloroethylation could be achieved without compromising the antitumor effect of CPA. The combination of PB with TAO did not, however, enhance the antitumor activity of CPA, despite the approximately 2-fold increase in AUC4-OH-CPA, suggesting that other PB-inducible activities, such as aldehyde dehydrogenase, may counter this increase through enhanced deactivation of the 4-hydroxy metabolite. Together, these studies demonstrate that the P-4503A inhibitor TAO can be used to effectively modulate CPA metabolism and pharmacokinetics in vivo in a manner that decreases the formation of toxic metabolites that do not contribute to antitumor activity.

The relationship between the quantity of heavy metal and PAHs in fly ash

Heavy metal and polycyclic aromatic hydrocarbons (PAHs) in flue gas have received considerable attention in recent years due to their mutagenic or carcinogenic properties. The present study is carried out to investigate the influence of the quantity of heavy metals on PAHs formation in fly ash. A fluidized bed incinerator was used in this experiment to obtain fly ash of chemical similarity by incinerating various compositions of waste. The obtained fly ash, both with and without heavy metal, were used to adsorb the PAHs in the flue gas and to investigate the formation of PAHs in fly ash. The results indicate that carbon and heavy metals most greatly influence the formation of PAHs in the fly ash. Carbon is absorptive; heavy metals encourage not only absorption of PAHs but also catalyze PAHs formation.

Modulation of P450-dependent ifosfamide pharmacokinetics: a better understanding of drug activation in vivo

The anti-cancer prodrug ifosfamide (IF) is metabolized by liver P450 enzymes by two alternative pathways. IF is activated to 4-hydroxy IF (4-OH-IF), which ultimately yields the alkylating mustard isophosphoramide, whereas IF N-dechlororethylation inactivates the drug and produces the neurotoxic metabolite chloroacetaldehyde (CA). Both reactions are catalysed by multiple liver P450 enzymes in vitro in isolated rat liver microsomes. The present pharmacokinetic study investigates the potential for modulation of these alternative pathways of IF metabolism in vivo using the adult male Fischer 344 rat model. Rats were treated with IF alone or in conjunction with various P450 inducers and inhibitors in an effort to improve the balance between drug activation and drug inactivation. Plasma concentrations, areas under the curve (AUC) and half-lives were calculated for 4-OH-IF and CA, allowing estimations of the extent of IF activation and deactivation/toxification. Induction of liver P450 2B enzymes by 4-day high-dose phenobarbital (PB) pretreatment significantly decreased the fraction of IF undergoing 4-hydroxylation (AUC(4-OH-IF)/AUC(4-OH-IF)+AUC(CA)), from 37% to 22% of total metabolism (P < 0.05), consistent with in vitro findings that the PB-inducible P450 enzyme 2B1 plays a major role in IF N-dechloroethylation. Pretreatment with the P450 3A inducer dexamethasone proportionally decreased the AUC for both IF metabolites, without any net impact on the fraction of IF undergoing metabolic activation. By contrast, the P450 2B1 inhibitor metyrapone preferentially increased the AUC for the 4-hydroxylation pathway in 3-day low-dose PB-induced rats, thereby increasing the total fraction of IF metabolized via the activation pathway from 36% to 54% (P < 0.05), whereas the P450 inhibitors orphenadrine and troleandomycin had no significant affect on AUC values. These findings demonstrate specific roles for P450 2B and 3A enzymes in catalysing these pathways of IF metabolism in vivo, and demonstrate the potential for modulation of IF's alternative metabolic pathways in a therapeutically useful manner. These studies also highlight several clinically relevant drug interactions that may occur during concomitant administration of IF with drugs and other compounds that modulate hepatic P450 enzyme levels.

Potentiation of cytochrome P450/cyclophosphamide-based cancer gene therapy by coexpression of the P450 reductase gene

Intratumoral expression of cytochrome P450 2B1 sensitizes tumor cells to the cytotoxic action of the alkylating agent prodrug cyclophosphamide (CPA) and provides a novel strategy for cancer gene therapy that may enhance the selectivity and the effectiveness of this class of antitumor drugs [L. Chen and D. J. Waxman, Cancer Res., 55: 581-589, 1995]. P450-catalyzed drug metabolism is obligatorily dependent on electron input from the flavoenzyme NADPH-P450 reductase (RED), which is widely expressed in many cell types, including tumor cells. Here, we investigate the potential utility of combining RED gene transfer with CPA-based P450 gene therapy. Rat 9L gliosarcoma cells stably expressing either basal or elevated (up to 10-fold increase) levels of RED, in the presence or absence of P450 2B1, were selected and characterized. RED overexpression substantially increased the sensitivity of these cells to CPA, but only when combined with P450 2B1 expression. An enhanced cytotoxic response was also obtained when recombinant adenovirus encoding P450 2B1 was used to deliver the P450 gene to RED-overexpressing tumor cells. CPA cytotoxicity was substantially decreased by the RED inhibitor diphenyleneiodonium chloride or by the P450 inhibitor metyrapone, providing evidence of its dependence on the catalytic contributions of both protein components of the P450 metabolic pathway. Conditioned media from P450 2B1-expressing and RED-overexpressing tumor cells treated with CPA exhibited increased formation of the primary 4-hydroxy metabolite and greater cell contact-independent bystander cytotoxic potential compared to tumor cells containing P450 2B1 and basal levels of RED. Evaluation of the impact of P450/RED combination gene therapy using a s.c. solid tumor model/tumor excision assay revealed a dramatic 50-100-fold increase in tumor cell kill in vivo over that provided by liver drug activation alone. These findings establish the importance of endogenous RED levels as a determinant of the sensitivity of tumor cells to CPA/P450 gene therapy and demonstrate the striking therapeutic effectiveness of an anticancer prodrug activation strategy based on the combination of a cytochrome P450 gene with the gene encoding RED.

Effects of tubeimoside-1 on HIV core protein p24 and cytopathogenesis in vitro

Tubeimoside-1 (Tub) is a triterpenoid saponin first isolated in China from Bolbostemma paniculatum (Maxim) Franquet, Cucurbitaceae. To find out whether Tub has any anti-infective activity on human immunodeficiency virus (HIV), we tested its effects on HIV core protein p24 (with an ELISA) and HIV-mediated cytopathogenesis (using a colorimetric assay). The results showed that Tub inhibited both p24 production and cytopathogenesis mediated by HTLV-IIIB, and the median effective concentrations (EC50) were 24.1 and 22.9 micrograms.ml-1, respectively. Tub also effectively neutralized the infection of 2 other isolates, HTLV-IIIRF and HTLV-IIIMN. It is concluded that Tub had an inhibitory action on the infection of HIV-1 isolates and would be a promising candidate for treatment of AIDS.

Aluminum content of source plasma and sodium citrate anticoagulant

The concentration of aluminum was determined in samples of source plasma collected by the normal plasmapheresis procedure, which involves collection in anticoagulant and immediate freezing. Samples of sodium citrate anticoagulant used in the collection of source plasma were also tested for aluminum, as were empty source plasma containers and 0.9% sodium chloride infusion (USP). Samples of source plasma were collected from a geographic cross-section of the donor population in the USA by three different manufacturers. Aliquots of these samples were mixed with Triton X-100 and sulfuric acid and analyzed for aluminum by atomic absorption spectrometry using electrothermal atomization (graphite furnace) and Zeeman background correction. The arithmetic mean and standard deviation for the aluminum content of 28 samples of source plasma were found to be 25.5 +/- 8.4 ng Al/ml. The aluminum content of the individual samples of source plasma ranged from 12 to 48 ng Al/ml. The aluminum content of 6 samples from two manufacturers of the sodium citrate anticoagulant that is used in source plasma ranged from 410 to 2,080 ng/ml. Aluminum levels found in saline for infusion and nitric acid leachates from empty source plasma containers were less than 6.9 ng/ml. The level of aluminum expected in uncontaminated human blood has been estimated to be 10 ng Al/ml or less. Comparison of this figure with the present data indicates that the sodium citrate anticoagulant contributes significantly to the aluminum load of source plasma and, therefore, to the aluminum content of products such as albumin derived from source plasma.

Potent anti-tumorigenic effect of tubeimoside 1 isolated from the bulb of Bolbostemma paniculatum (Maxim) Franquet

Tubeimoside 1, one of the new triterpenoid saponins from the bulb of Bolbostemma paniculatum (Maxim) Franquet, had an anti-inflammatory effect on mouse ear edema induced by arachidonic acid and 12-O-tetradecanoylphorbol-13-acetate (TPA). Furthermore, a potent anti-tumorigenic effect of tubeimoside 1 was observed in 2-stage carcinogenesis of mouse skin after oral administration as well as topical application. Thus, tubeimoside 1 appears to be a promising agent for cancer chemoprevention.

Biochemical and genetic characterization of the multidrug resistance phenotype in murine macrophage-like J774.2 cells

The development of multidrug resistance (MDR) in malignant tumors is a major obstacle to the treatment of many cancers. MDR sublines have been derived from the J774.2 mouse macrophage-like cell line and utilized to characterize the phenotype at the biochemical and genetic level. Two isoforms of the drug resistance-associated P-glycoprotein are present and distinguishable both electrophoretically and pharmacologically. Genetic analysis has revealed the presence of a three-member gene family; expression of two of these genes, mdr1a and mdr1b, is associated with MDR whereas the expression of the third, mdr2, is not. Studies of these three genes have revealed similarities and differences in the manner in which they are regulated at the transcriptional level, and have suggested that post-transcriptional effects may also be important.

Effect of exogenous fat emulsion on phagocytic activity of polymorphonuclear cells in septic rats

The effect of exogenous fat emulsion on phagocytic activity of polymorphonuclear (PMN) cells in sepsis was studied in rats. The rats were divided into four groups. Group I, non-septic rats received saline infusion; group II, non-septic rats received exogenous fat emulsion; group III, septic rats received saline infusion; and group IV, septic rats received exogenous fat emulsion. Twenty hours after operation to induce sepsis, normal saline or exogenous fat emulsion was injected. Two hours later, the animal was sacrificed and the blood harvested. PMN cells were isolated from the blood, and phagocytic activity of the cells was studied by culture with Candida albicans. The results revealed that although sepsis led to a suppression of phagocytic function of PMN cells, infusion of exogenous fat emulsion had no deterious effect on the cell phagocytic activity in either septic or non-septic rats.

Effects of exogenous fat emulsion on lymphocyte function in septic rats

Effects of exogenous fat emulsion (Intralipid) on lymphocyte function were studied, in vivo, with rats. Abdominal sepsis was induced in Sprague Dawley rats by cecal ligation and puncture. Following a bolus infusion of the fat emulsion or normal saline, lymphocyte proliferations after stimulation with bacto-concanavalin A (Con A), phytohemagglutinin (PHA), and pokeweed mitogen (PWM) were evaluated in animals divided into the following groups: group I, non-septic rats receiving saline infusion (NS-S); group II, non-septic rats receiving the fat emulsion (NS-F); group III, septic rats receiving saline (S-S); group IV, septic rats receiving the fat emulsion (S-F). Results of the study demonstrated that lymphocyte function was not suppressed by the presence of sepsis, and infusion of the exogenous fat emulsion also did not lead to a suppression of the lymphocyte function in either the septic or the non-septic rats. The results obtained from a previous, as well as this present, study suggest that although infusion of exogenous fat emulsion may suppress the function of monocyte and polymorphonuclear cells, lymphocyte function is not affected.

Effects of exogenous fat emulsion (Intralipid) on chemotactic function of monocytes and polymorphonuclear cells in sepsis

Effects of exogenous fat emulsion (Intralipid) on the chemotactic function of monocytes and polymorphonuclear (PMN) cells were studied in vivo with rats. Abdominal sepsis was induced in Sprague Dawley rats by cecal ligation and puncture. Following a bolus infusion of the fat emulsion or saline, chemotactic function of monocytes and PMN cells was evaluated in animals divided into the following four groups: Group I, non-septic rats receiving saline infusion (NS-S); Group II, non-septic rats receiving the fat emulsion (NS-F); Group III, septic rats receiving saline (S-S); Group IV, septic rats receiving the fat emulsion (S-F). Results of the study revealed that monocyte function was suppressed by the sepsis, whether saline or the fat emulsion was infused, and administration of the fat emulsion resulted in suppression of monocyte chemotaxis both in the non-septic and the septic rats. Although in this study chemotactic function of PMN cells was not significantly suppressed by the sepsis, administration of the fat emulsion again led to a suppression of PMN cell function, in both the non-septic and the septic rats. Results of the study confirmed that administration of an exogenous fat emulsion may suppress the chemotactic function of the monocytes and PMN cells and, in the presence of severe sepsis, infusion of the fat emulsion may lead to a further deterioration of immunologic function of the host. Special care, therefore, should be taken against the use of exogenous fat emulsion in septic individuals or in those at risk of infection.