Modification of the P-Glycoprotein Dependent Pharmacokinetics of Digoxin in Rats by Human Recombinant Interferon-α

Purpose This study was conducted to investigate in vivo the impact of interferon-alpha (IFN)-α on P-glycoprotein (P-gp) activity in rats by studying how its administration modifies the bioavailability of digoxin, a fairly pure P-gp substrate. Methods Human recombinant IFN-α was given to rats (n = 5–7 per group) daily for 8 days at different doses (IntronA^? 10⁶, 2.10⁶, or 4.10⁶ IU kg⁻¹, s.c.), whereas pegylated-IFN-α (ViraferonPeg^?, 29 μg kg⁻¹) was given s.c. three times a week. Rats were then given digoxin (32 μg kg⁻¹) i.v. or orally. The pharmacokinetics of digoxin was studied. Intestinal P-gp expression was also examined. Results The pharmacokinetics of i.v. administered digoxin was not modified by IFN-α, but a dose-dependent increase in areas under the curve (AUCs) was observed in the orally administered digoxin parameters in rats (AUCs: 392 ± 83 min μg L⁻¹, p < 0.01 and 550 ± 97 min μg L⁻¹, p < 0.001, respectively, vs. 286 ± 111 min μg L⁻¹ for control). A decrease in P-gp expression in the ileum (relative intensities: 0.70 ± 0.19 for 4 Million International Unit (MIU) kg⁻¹ IFN-α-treated animals vs. 1.00 ± 0.13 for controls, p < 0.05) and mainly in the jejunum (relative intensities: 0.46 ± 0.13 for 4 MIU kg⁻¹ IFN-α-treated animals vs. 1.00 ± 0.08 for controls, p < 0.001) was observed. Conclusion IFN-α induces in vivo a significant dose-dependent inhibitory effect on intestinal P-gp activity related to a local decrease in its expression, thereby predicting important clinical consequences when IFN-α and other P-gp substrates are associated.     

Stable Formulations of Recombinant Human Growth Hormone and Interferon-γ for Microencapsulation in Biodegradable Mircospheres

Purpose. The successful development of controlled release formulations for proteins requires that the protein not be denatured during the manufacturing process. The major objective was to develop formulations that stabilize two recombinant human proteins, human growth hormone (rhGH) and interferon- (rhIFN-), at high protein concentrations (>100 mg/mL) in organic solvents commonly used for microencapsulation, methylene chloride and ethyl acetate. Methods. Several excipients were screened to obtain the maximum solubility of each protein. These formulations (aqueous, lyophilized, milled, spray dried, or isoelectric precipitate) were then rapidly screened by emulsification in the organic solvent followed by recovery into excess buffer. Additional screening was performed with solid protein that was suspended in the organic solvent and then recovered with excess buffer. The recovery of native protein was determined by native size exclusion chromatography (SEC-HPLC) and circular dichroism (CD). The selected formulations were encapsulated in poly-lactic-coglycolic acid (PLGA) microspheres by either water-in-oil-in-water (W/O/W) or solid-in-oil-in-water (S/O/W) methods. The initial protein released from the microspheres incubated at physiological conditions was analyzed by SEC-HPLC, CD, and biological assays. Results. The stability of a given formulation in the rapid screening method correlated well with stability during encapsulation in PLGA microspheres. Formulations of rhGH containing Tween 20 or 80 resulted in lower recovery of native protein, while trehalose and mannitol formulations (phosphate buffer, pH 8.0) yielded complete recovery of native rhGH. Other additives such as carboxymethyl cellulose, gelatin, and dextran 70 were not effective stabilizers, and polyethylene glycol provided some stabilization of rhGH. Trehalose/rhGH (1:4 mass ratio) and mannitol/rhGH (1:2 mass ratio) formulations (potassium phosphate buffer, pH 8.0) were lyophilized, reconstituted to 200 and 400 mg/mL rhGH, respectively, and then encapsulated in PLGA micro-spheres. The protein was released from these microspheres in its native state. Lyophilized formulations of rhGH yielded analogous results indicating the ability of trehalose and mannitol to stabilize the protein. Small solid particles of rhGH generated by spray drying (both air and freeze-drying) formulations containing Tween 20 or PEG were stable in ethyl acetate, but not methylene chloride. Similar results were also obtained with rhIFN- (137 mg/mL in succinate buffer, pH 5.0), where both mannitol and trehalose were observed to stabilize the protein during exposure to the organic solvents resulting in the release of native rhIFN- from PLGA microspheres. Conclusions. The rapid screening method allowed the development of stable concentrated protein solutions or solid protein formulations that could be successfully encapsulated in PLGA microspheres. The excipients observed to stabilize these proteins function by preferential hydration of the protein, and in the dry state (e.g., trehalose) may stabilize the protein via water substitution yielding a protective coating around the protein surface. Studies of other proteins should provide further insight into this mechanism of protein stabilization during encapsulation.     

Pharmacokinetics of Recombinant Human Interferon-βser in Healthy Volunteers and Its Effect on Serum Neopterin

The pharmacokinetics of and biologic response modification by recombinant human interferon-_ser (rIFN-_ser) were evaluated in 12 healthy male volunteers. Subjects received a single intravenous (iv) injection of 90 × 10⁶ IU of rIFN-_ser followed by a single or eight consecutive daily 90 × 10⁶ IU subcutaneous (sc) doses. Blood samples collected after the iv, first sc, and last sc doses and prior to each sc dose were assayed for interferon antiviral activity and the inter-feron-inducible marker neopterin. Following iv administration, serum interferon concentrations generally declined biexponentially, with a mean serum clearance of 0.76 ± 0.28 L/hr-kg, a mean steady-state volume of distribution of 2.88 ± 1.81 L/kg, and a mean terminal half-life of 4.29 ± 2.29 hr as determined by noncompartmental analysis. Following sc administration, absorption of rIFN-_ser was prolonged, with serum concentrations generally below 100 IU/mL. No accumulation of rIFN-_ser in serum was noted after eight daily sc injections. In contrast, serum neopterin levels did not increase above baseline levels until 12 hr after iv dosing and 24 hr after sc dosing. The mean increase in serum neopterin at 24 hr post iv injection was significantly greater than that at 24 hr post sc dosing.     

Is Stability Prediction Possible for Protein Drugs? Denaturation Kinetics of β- Galactosidase in Solution

Denaturation and aggregation kinetics of Aspergillus oryzae -galactosidase in solution were studied in order to determine whether the stability of protein drugs can be predicted. Denaturation of -galactosidase, monitored by measuring enzyme activity, conformed to first-order kinetics, whereas aggregation of the denatured form, monitored by high performance size exclusion chromatography, showed a reaction order higher than 1. Denaturation of -galactosidase was irreversible and exhibited a biphasic kinetic pattern which could be explained by assuming that two isoenzymes denatured irreversibly at different rates. Linear Arrhenius plots were obtained for the estimated rate constants, and H and S were estimated according to the Eyring equation. The estimated H was much larger than H observed in usual chemical reactions. The present study suggests that the denaturation of protein drugs can be analyzed by the Eyring equation in the same manner as chemical degradation, contradicting the general consensus that accelerated testing can not be used to predict the stability of protein formulations.     

Determination of β-Endorphin and Fragments Thereof in Human Plasma Using High-Performance Liquid Chromatography and a Multiple Radioimmunoassay System

A method for the determination of -endorphin and -endorphin fragments in human plasma was developed. -Endorphin-related peptides were extracted from plasma using octadecasilyl-silica cartridges. Extracts were subjected to re versed-phase high-performance liquid chromatography (HPLC). Extracts as well as HPLC column eluates were assayed using a multiple radioimmunoassay system; several antibodies directed against various distinct regions of the -endorphin molecule were employed. Using this method, evidence for the presence of multiple -endorphin fragments in the plasma of healthy young volunteers (under normal conditions) was obtained.     

Changes in the NMR Metabolic Profile of Live Human Neuron-Like SH-SY5Y Cells Exposed to Interferon-α2

Interferon (IFN)-α2 is an extensively therapeutically used pro-inflammatory cytokine. Though its efficacy in controlling viral replication and tumor cells proliferation, administration of IFN-α2 is often associated with the development of central side effects. Magnetic resonance spectroscopy studies have demonstrated that IFN-α2 administration affects brain metabolism, however the exact nature of this effect is not completely known. We hypothesized that IFN-α2 can affect metabolic activity of human neuron-like SH-SY5Y cells which possess many characteristics of neurons and represent one of the most used models for studying mechanisms involved in neurotoxicity or neuroprotection. To test our hypothesis we have characterized the metabolic signature of live SH-SY5Y, and their conditioned media, after 24 and 72 h of exposure to vehicle or IFN-α2 (100 ng/ml) by using High Resolution-Magic Angle Spinning (HR-MAS) Nuclear Magnetic Resonance (NMR) spectroscopy. Our results revealed that 1) the use of HR-MAS NMR is ideally suitable for the characterization of the metabolic profile of live cells and their conditioned media without extraction procedures; and 2) a 72 h exposure to IFN-α2 increases the level of metabolites involved in maintaining energetic (including creatine and lactate) and osmotic (such as myo-inositol, scyllo-inositol, taurine and glycerophosphorylcholine) balances in neuron-like cells and of metabolic waste products (namely lactate, ethanol and acetate), glycine and glutamine in their growth media. These results may contribute to gain more knowledge about the IFN-α2 induced effect on the brain and support the interpretation of magnetic resonance spectroscopy studies performed in humans.     

Interferon-β-1b: a review of its use in multiple sclerosis

Interferon-β-1b has been used as a disease-modifying therapy in multiple sclerosis (MS) for many years. Although its mechanism of action in MS has not been fully elucidated, it appears to involve immunomodulatory effects mediated by interactions with specific receptors. Large, randomized, multicentre, clinical trials of 2-3.5 years' duration have demonstrated the efficacy of interferon-β-1b 250 μg subcutaneously every other day in patients with a first clinical event suggestive of MS (i.e. those with clinically isolated syndrome [CIS]) and in those with relapsing-remitting MS (RRMS). In terms of its efficacy on primary (or co-primary) endpoints, interferon-β-1b significantly reduced the risk of developing clinically definite MS compared with placebo in patients with CIS in the BENEFIT study. In patients with RRMS, interferon-β-1b was associated with a significantly lower annualized relapse rate and a significantly higher proportion of relapse-free patients compared with placebo in a registration trial conducted by the Interferon-β MS Study Group. The INCOMIN trial in patients with RRMS showed a significant advantage of interferon-β-1b over intramuscular interferon-β-1a in terms of the percentage of relapse- and progression-free patients and the proportion of patients without new MRI-documented lesions. Other active-comparator trials in RRMS used a variety of primary (or co-primary) endpoints and showed no significant differences between interferon-β-1b and either subcutaneous glatiramer acetate (BECOME and BEYOND trials) or subcutaneous interferon-β-1a (Danish MS Group trial) for these outcomes. In patients with secondary progressive MS (SPMS), the European Study Group showed that interferon-β-1b significantly increased the time to confirmed disease progression compared with placebo, although there was no significant between-group difference for this primary endpoint in a similar trial conducted by the North American Study Group. The studies allowed inclusion of patients with superimposed relapse, and both trials showed a significant reduction in annualized relapse rate with interferon-β-1b. The most frequently reported adverse events with interferon-β-1b are flu-like symptoms and injection-site reactions, which can usually be managed. The incidence of these adverse events generally declines markedly after the first year of treatment. Lymphopenia is the most frequently reported laboratory abnormality and occurs in the majority of patients. Depression, suicidal ideation and injection-site necrosis were the most serious adverse events reported with interferon-β-1b in clinical trials. Long-term safety data over a 16-year follow-up period showed no unexpected adverse events among patients treated with interferon-β-1b. Thus, interferon-β-1b is a well established, first-line, disease-modifying therapy that has demonstrated efficacy in newly emerging MS, RRMS and SPMS with superimposed relapse in well designed clinical trials, and has a generally manageable tolerability profile, with no unexpected adverse events after many years of follow-up.     

Leydig Cell Hyperplasia and Adenomas in Mice Treated with Finasteride,a 5α-Reductase Inhibitor: A Possible Mechanism

Leydig Cell Hyperplasia and Adenomas in Mice Treated with Finasteride, a 5α-Reductase Inhibitor: A Possible Mechanism. Prahalada, S., Majka, J. A., Soper, K. A., Nett, T. M., Bagdon, W. J., Peter, C. P, Burek, J. D., MacDonald, J. S., and van Zwieten, M. J. (1994). Fundam. Appl. Toxicol. 22, 211-219.Finasteride is a selective inhibitor of the enzyme 5α-reductase which is responsible for the conversion of testosterone (T) to dihydrotestosterone (DHT). Finasteride is indicated for the treatment of benign prostatic hyperplasia in man (∼ 0.1 mg/kg/day). The effect of long-term treatment was studied in mice given high doses (2.5, 25, and 250 mg/kg/day) of finasteride for 83 weeks. In finasteride-treated mice, increased incidences of testicular Leydig cell hyperplasia (52% compared to 24% in control group) at doses equal to or greater than 25 mg/kg/day and Leydig cell adenomas (32% compared to 0.5% in control group) at 250 mg/kg/day were observed. There were no drug-related effects on the seminiferous tubules. Since luteinizing hormone (LH) is a trophic hormone for Leydig cells, short-term studies (5 to 14 weeks) were clone to investigate the relationship between Leydig cell hyperplasia and serum LH levels in finasteride-treated mice. In these studies, there was a positive correlation between the drug-related increased incidence of Leydig cell hyperplasia and a statistically significant (p ⩽ 0.05) increase in serum LH levels in finasteride-treated (250 mg/kg/day) mice. Furthermore, studies in castrated male mice showed that the suppression of serum LH levels by T is reversible by inhibition of conversion of T to DHT with finasteride (250 mg/kg/day), supporting the hypothesis that DHT is involved in the regulation of LH release in mice. The data presented support the conclusion that the effects of finasteride on Leydig cells appear to be secondary to increased serum LH levels and that they occur only at very high doses when compared to the therapeutic dose (approximately 0.1 mg/kg/day) in man.     

Pegylated IFN-α-2a and ribavirin in the treatment of hepatitis C infection in children

The epidemiology, natural history and efficacy of treatment for chronic hepatitis C in children are presented. An increase in the number of vertical infections of this etiology is suggested. In children, especially in those vertically infected, spontaneous elimination of hepatitis C virus (HCV) is observed more often than it is in adults. The most common HCV genotype detected in children is genotype 1, but Italian researchers have described an increase of infection with genotypes 3 and 4 HCV in children in recent years. In the context of recent opinions suggesting a more rapid progression of HCV 3 genotype infection, treatment of these children should begin immediately. The high efficacy (sustained viral response > 50%), safety (few adverse events with less intensity as compared to adults) and good tolerance of therapy with pegylated IFN α-2a and ribavirin have been revealed in children. The differences in the efficacy and tolerability of HCV treatment between children and adults are described. A recommendation for inclusion and monitoring parameters of children’s physical and mental development during HCV treatment is presented. Regarding new anti-HCV therapies with very high efficacy, including IFN-free treatment, the introduction of these therapies to children is recommended.     

Solid-State Stability of Human Insulin I. Mechanism and the Effect of Water on the Kinetics of Degradation in Lyophiles from pH 2–5 Solutions

Purpose. Previous studies have established that in aqueous solution at low pH human insulin decomposition proceeds through a cyclic anhydride intermediate leading to the formation of both deamidated and covalent dimer products. This study examines the mechanism and kinetics of insulin degradation in the amorphous solid state (lyophilized powders) as a function of water content over a similar pH range. Methods. Solutions of 1.0 mg/mL insulin were adjusted to pH 2–5 using HC1, freeze-dried, then exposed to various relative humidities at 35°C. The water content within the powders was determined by Karl Fischer titration, and the concentrations of insulin and its degradation products were determined by HPLC. Degradation kinetics were determined by both the initial rates of product formation and insulin disappearance. Results. Semi-logarithmic plots of insulin remaining in lyophilized powders versus time were non-linear, asymptotically approaching non-zero apparent plateau values, mathematically describable by a reversible, first-order kinetic model. The rate of degradation of insulin in the solid state was observed to increase with decreasing apparent pH (pH) yielding, at any given water content, solid-state pH-rate profiles parallel to the solution pH-rate profile. This pH dependence could be accounted for in terms of the fraction of the insulin A21 carboxyl in its neutral form, with an apparent pKa of 4, independent of water content. Aniline trapping studies established that the mechanism of degradation of human insulin in lyophilized powders between pH 3–5 and at 35°C involves rate-limiting intramolecular nucleophilic attack of the Asn_A21 C-terminal carboxylic acid onto the side-chain amide carbonyl to form a reactive cyclic anhydride intermediate, which further reacts with either water or an N-terminal primary amino group (e.g., Phe_B1, and Gly_Al) of another insulin molecule to generate either deamidated insulin (Asp_A21) or an amide-linked covalent dimer (e.g., [Asp_A21-Phe_B1] or [Asp_A21-Gly_A1]), respectively. The rate of insulin degradation in lyophilized powders at 35°C increases with water content at levels of hydration well below the suspected glass transition and approaches the rate in solution at or near the water content (20–50%) required to induce a glass transition. Conclusions. The decomposition of human insulin in lyophilized powders between pH 3–5 is a water induced solid-state reaction accelerated by the plasticization effect of sorbed water. The formation of the cyclic anhydride intermediate at A21 occurs readily even in the glassy state, presumably due to the conformational flexibility of the A21 segment even under conditions in which the insulin molecules as a whole are largely immobile.     

Patterns and correlates of polytobacco use in the United States over a decade: NSDUH 2002–2011

BackgroundFew studies have examined the patterns and correlates of polytobacco use among a large, nationally representative population over an extended period of time.MethodsThis study examined 10 years of data from the National Survey on Drug Use and Health (NSDUH) to establish time trends and correlates for exclusive and mixed use of cigarettes, smokeless tobacco (SLT), cigars, and pipes.ResultsResults show that rates of polytobacco use were essentially unchanged from 2002 to 2011 (8.7% to 7.4%), though some product combinations, including cigarettes and SLT, cigars and SLT, and use of more than two products have increased. In tobacco users under age 26, the proportion of polytobacco use increased, even as overall tobacco use declined. The factors associated with polytobacco use among tobacco users included sex, income, education, risk taking/seeking behaviors, and outward indicators of ‘risk-liability’.ConclusionsFindings provide a snapshot of trends of single and polytobacco product use as well as trends in combinations of product use. Longitudinal studies are needed to examine the sequence of individual patterns of tobacco product use and to identify whether polytobacco use results in greater nicotine dependence, increased exposure to harmful and potentially harmful constituents and/or greater risk of tobacco related disease.     

The Changes of P-glycoprotein Activity by Interferon-γ and Tumor Necrosis Factor-α in Primary and Immortalized Human Brain Microvascular Endothelial Cells

The purpose of this study was to investigate the modification of expression and functionality of the drug transporter P-glycoprotein (P-gp) by tumor necrosis factor-alpha (TNF-α) and interferon-gamma (IFN-γ) at the blood-brain barrier (BBB). We used immortalized human brain microvessel endothelial cells (iHBMEC) and primary human brain microvessel endothelial cells (pHBMEC) as in vitro BBB model. To investigate the change of p-gp expression, we carried out real time PCR analysis and Western blotting. To test the change of p-gp activity, we performed rhodamin123 (Rh123) accumulation study in the cells. In results of real time PCR analysis, the P-gp mRNA expression was increased by TNF-α or IFN-γ treatment for 24 hr in both cell types. However, 48 hr treatment of TNF-α or IFN-γ did not affect P-gp mRNA expression. In addition, co-treatment of TNF-α and IFN-γ markedly increased the P-gp mRNA expression in both cells. TNF-α or IFN-γ did not influence P-gp protein expression whatever the concentration of cytokines or duration of treatment in both cells. However, P-gp expression was increased after treatments of both cytokines together in iHBMEC cells only compared with untreated control. Furthermore, in both cell lines, TNF-α or IFN-γ induced significant decrease of P-gp activity for 24 hr treatment. And, both cytokines combination treatment also decreased significantly P-gp activity. These results suggest that P-gp expression and function at the BBB is modulated by TNF-α or/and IFN-γ. Therefore, the distribution of P-gp depending drugs in the central nervous system can be modulated by neurological inflammatory diseases.     

Use of 2-Hydroxypropyl-β-cyclodextrin as a Solubilizing and Stabilizing Excipient for Protein Drugs

A chemically modified, amorphous -cyclodextrin, namely, 2-hydroxypropyl--cyclodextrin (HPCD), was examined as a solubilizing and stabilizing agent for protein drugs. The aqueous solubility of ovine growth hormone at pH 7.4 was increased through the use of HPCD. This effect was manifested by higher UV transparency at 600 nm. Interleukin-2 (IL-2) is rendered insoluble upon lyophilization in the absence of stabilizers. Use of aqueous HPCD provides a clear solution, as indicated by fluorometric light scattering, and inhibits aggregate formation, as shown by ultracentrifugation and Western blot analyses. In addition, there were no major conformational changes of IL-2 in HPCD formulation as indicated by fourth-derivative ultraviolet spectroscopy. Finally, IL-2 retained 100% of its biopotency when prepared in HPCD solutions. Aggregation of insulin was also suppressed by HPCD. These data, as well as the i.v. safety of HPCD and its well-characterized chemical composition, suggest that this starch derivative may be a potentially useful excipient for protein drugs intended for parenteral use.     

Protein binding of 2-chloro 2′-deoxyadenosine (cladribine) in healthy subjects and in patients with leukaemia

The plasma protein binding of 2-chloro-2-deoxyadenosine (CdA) at 37°;C was studied by ultrafiltration in 5 healthy volunteers, in 11 patients with haematological malignancies and in purified protein preparations. In the patients, the binding of CdA to plasma proteins was 25.0% and in healthy subjects it was 21.1%. In a solution of human serum albumin (40 g·1^–1), 24.3% CdA was bound, but less than 5% was bound in a solution of ₁-acid-glycoprotein (0.7 g·1^–1). No dependence of binding on the concentration of CdA was found within a range 25–1000 nmol·1^–1.In conclusion, due to its limited binding to plasma proteins, any change in the binding of CdA is unlikely to have a major influence on its pharmacological effect.     

Interferon-γ reduces tumor-induced Ia− macrophage-mediated suppression: role of prostaglandin E2, Ia,and tumor necrosis factor-α

Tumor growth enhances macrophage (Mφ) suppressor activity by causing Mφ to increase synthesis of inhibitory molecules such as prostaglandin E₂ (PGE₂) or decreasing their expression of up-regulatory molecules such as the class II MHC protein Ia. Although these tumor-induced changes are correlated, it is unknownwhether tumor-bearing host (TBH) Ia⁻ Mφ become more suppressive by increasing their PGE₂ synthesis. To assess the role of PGE₂ in tumor-induced Ia⁻ Mφ-mediated suppression of CD4⁺ T-cell alloreactivity, unseparated (Ia⁺ -enriched) or Ia⁺ -depleted (Ia⁻) populations of murine normal host (NH) or TBH splenic Mφ were added to mixed lymphocyte reaction (MLR) cultures. NH or TBH Ia⁻ Mφ were significantly more suppressive than their respective unseparated populations, and TBH Ia⁻ Mφ were more suppressive than their NH counterparts. When PGE₂ production was blocked with indomethacin, TBH Ia⁻ Mφ-mediated suppression was reduced more than suppression mediated by all other Mφ populations. A PGE₂-specific ELISA showed more PGE₂ in Ia⁻ Mφ-containing cultures than in those with whole Mφ and more cultures containing TBH Ia⁻ Mφ than in their NH counterparts. Because interferon-γ (IFN-γ) is a potent Mφ activation molecule that regulates both Ia expression and PGE₂ production, the effects of IFN-γ on tumor-induced Ia⁻ Mφ-mediated suppression were investigated. Exogenous IFN-γ reduced suppression mediated by all Mφ populations except NH unseparated Mφ. IFN-γ suppressed alloreactivity without Mφ or with NH unseparated Mφ. Suppression mediated by NH or TBH Ia⁻, and TBH unseparated Mφ was also reduced when Mφ were pre-incubated with IFN-γ before their addition to MLR cultures. IFN-γ addition did not block Ia⁻ Mφ-mediated suppression by decreasing Mφ PGE₂ production. In fact, IFN-γ addition increased PGE₂ production two-fold in MLR cultures. However, IFN-γ partly reduced suppression mediated by exogenous PGE₂ added to Mφ-depleted cultures. Cytofluorometric analysis showed that IFN-γ increased the percentage of Ia⁺ Mφ in NH and TBH Ia⁻ Mφ populations. Blocking TNF-α activity with anti-TNF-α antibodies caused IFN-γ to suppress alloreactivity in all Mφ-added cultures. Collectively, these data show that tumor-induced suppression mediated by Ia⁻ Mφ is caused by increased PGE₂ synthesis. IFN-γ strongly reduces Ia⁻ Mφ-mediated suppression by blocking PGE₂-mediated suppression, enhancing Ia⁻ Mφ production of the up-regulatory molecule TNF-α, and possibly by increasing the number of Ia⁺ Mφ. These effects of IFN-γ on Ia⁻ Mφ suggest that this cytokine increases immunity and Mφ-mediated cytotoxicity during cancer.     

IFN-α-2a (Interferon) and ribavirin induced suicidal attempt in a patient of chronic HCV: A rare case report

Interferons (IFNs) are proteins produced by cells, fibroblasts and macrophages, in response to viral invasion, and mediates immune response. IFN-α and ribavirin are the approved treatment for HCV infection, but also carries a risk of neuropsychiatric adverse effects, viz. insomnia, irritability, mood changes, and depression.We present a case report of depression induced by IFN-α and ribavirin, leading to attempted suicide. Following the episode, antidepressant paroxetine (20 mg o.d.) and zolpidem (10 mg h.s) were added with psychotherapy. No significant improvement was observed. Patient was given a drug dechallenge (IFN-α and ribavirin). Dramatic improvement was seen over 1 month. Following rechallenge with combination, patient again experienced depressive symptoms with suicidal ideation. IFN-α and ribavirin were promptly stopped. Naranjo causality assessment scale revealed probable association with IFN-α and ribavirin. The report intends to improve awareness among clinicians to facilitate early diagnosis and intervention of similar cases.     

Protein binding modulates the cellular uptake of silver nanoparticles into human cells: Implications for in vitro to in vivo extrapolations?

Nanoparticles (NP) absorbed in the body will come in contact with blood proteins and form NP/protein complexes termed protein coronas, which may modulate NP cellular uptake. This study quantitated human epidermal keratinocyte (HEK) uptake of silver (Ag) NP complexed to different human serum proteins. Prior to HEK dosing, AgNP (20 nm and 110 nm citrate BioPure™; 40 nm and 120 nm silica-coated) were preincubated for 2 h at 37 °C without (control) or with physiological levels of albumin (44 mg/ml), IgG (14.5 mg/ml) or transferrin (3 mg/ml) to form protein-complexed NP. HEK were exposed to the protein incubated AgNP for 3 h, rinsed and incubated for 24 h, rinsed in buffer and lysed. Ag was assayed by inductively-coupled plasma optical emission spectrometry. Uptake of Ag in HEK was <4.1% of applied dose with proteins suppressing citrate, but not silica coated Ag uptake. IgG exposure dramatically reduced 110 nm citrate AgNP uptake. In contrast, greatest uptake of 20 nm silica AgNP was seen with IgG, while 110 nm silica AgNP showed minimal protein effects. Electron microscopy confirmed cellular uptake of all NP but showed differences in the appearance and agglomeration state of the NP within HEK vacuoles. This work suggests that NP association with different serum proteins, purportedly forming different protein coronas, significantly modulates Ag uptake into HEK compared to native NP uptake, suggesting caution in extrapolating in vitro uptake data to predict behavior in vivo where the nature of the protein corona may determine patterns of cellular uptake, and thus biodistribution, biological activity and toxicity.