Paul C. Ho

In vivo photodynamic therapy using upconversion nanoparticles as remote-controlled nanotransducers

Conventional photodynamic therapy (PDT) is limited by the penetration depth of visible light needed for its activation. Here we used mesoporous-silica–coated upconversion fluorescent nanoparticles (UCNs) as a nanotransducer to convert deeply penetrating near-infrared light to visible wavelengths and a carrier of photosensitizers. We also used the multicolor-emission capability of the UCNs at a single excitation wavelength for simultaneous activation of two photosensitizers for enhanced PDT. We showed a greater PDT efficacy with the dual-photosensitizer approach compared to approaches using a single photosensitizer, as determined by enhanced generation of singlet oxygen and reduced cell viability. In vivo studies also showed tumor growth inhibition in PDT-treated mice by direct injection of UCNs into melanoma tumors or intravenous injection of UCNs conjugated with a tumor-targeting agent into tumor-bearing mice. As the first demonstration, to the best of our knowledge, of the photosensitizer-loaded UCN as an in vivo–targeted PDT agent, this finding may serve as a platform for future noninvasive deep-cancer therapy.

Herb-drug interactions: a literature review.

AbstractHerbs are often administered in combination with therapeutic drugs, raising the potential of herb-drug interactions. An extensive review of the literature identified reported herb-drug interactions with clinical significance, many of which are from case reports and limited clinical observations.Cases have been published reporting enhanced anticoagulation and bleeding when patients on long-term warfarin therapy also took Salvia miltiorrhiza (danshen). Allium sativum (garlic) decreased the area under the plasma concentration-time curve (AUC) and maximum plasma concentration of saquinavir, but not ritonavir and paracetamol (acetaminophen), in volunteers. A. sativum increased the clotting time and international normalised ratio of warfarin and caused hypoglycaemia when taken with chlorpropamide. Ginkgo biloba (ginkgo) caused bleeding when combined with warfarin or aspirin (acetylsalicylic acid), raised blood pressure when combined with a thiazide diuretic and even caused coma when combined with trazodone in patients. Panax ginseng (ginseng) reduced the blood concentrations of alcohol (ethanol) and warfarin, and induced mania when used concomitantly with phenelzine, but ginseng increased the efficacy of influenza vaccination. Scutellaria baicalensis (huangqin) ameliorated irinotecan-induced gastrointestinal toxicity in cancer patients. Piper methysticum (kava) increased the ‘off’ periods in patients with parkinsonism taking levodopa and induced a semicomatose state when given concomitantly with alprazolam. Kava enhanced the hypnotic effect of alcohol in mice, but this was not observed in humans. Silybum marianum (milk thistle) decreased the trough concentrations of indinavir in humans. Piperine from black (Piper nigrum Linn) and long (P. longum Linn) peppers increased the AUC of phenytoin, propranolol and theophylline in healthy volunteers and plasma concentrations of rifamipicin (rifampin) in patients with pulmonary tuberculosis. Eleutheroccus senticosus (Siberian ginseng) increased the serum concentration of digoxin, but did not alter the pharmacokinetics of dextromethorphan and alprazolam in humans. Hypericum perforatum (hypericum; St John’s wort) decreased the blood concentrations of ciclosporin (cyclosporin), midazolam, tacrolimus, amitriptyline, digoxin, indinavir, warfarin, phenprocoumon and theophylline, but did not alter the pharmacokinetics of carbamazepine, pravastatin, mycophenolate mofetil and dextromethorphan. Cases have been reported where decreased ciclosporin concentrations led to organ rejection. Hypericum also caused breakthrough bleeding and unplanned pregnancies when used concomitantly with oral contraceptives. It also caused serotonin syndrome when used in combination with selective serotonin reuptake inhibitors (e.g. sertraline and paroxetine).In conclusion, interactions between herbal medicines and prescribed drugs can occur and may lead to serious clinical consequences. There are other theoretical interactions indicated by preclinical data. Both pharmacokinetic and/or pharmacodynamic mechanisms have been considered to play a role in these interactions, although the underlying mechanisms for the altered drug effects and/or concentrations by concomitant herbal medicines are yet to be determined. The clinical importance of herb-drug interactions depends on many factors associated with the particular herb, drug and patient. Herbs should be appropriately labeled to alert consumers to potential interactions when concomitantly used with drugs, and to recommend a consultation with their general practitioners and other medical carers.

Mesoporous-silica-coated up-conversion fluorescent nanoparticles for photodynamic therapy.

Near-infrared (NIR)-to-visible up-conversion fluorescent nanoparticles have potential to be used for photodynamic therapy (PDT) in deep tissue because NIR light can penetrate thick tissue due to weak absorption in the optical window. Here a uniform layer of mesoporous silica is coated onto NaYF(4) up-converting nanocrystals, with a large surface area of approximately 770 m(2) g(-1) and an average pore size of 2 nm. A photosensitizer, zinc phthalocyanine, is incorporated into the mesoporous silica. Upon excitation by a NIR laser, the nanocrystals convert NIR light to visible light, which further activates the photosensitizer to release reactive singlet oxygen to kill cancer cells. The photosensitizer encapsulated in mesoporous silica is protected from degradation in the harsh biological environment. It is demonstrated that the photosensitizers loaded into the porous silica shell of the nanoparticles are not released out of the silica while they continuously produce singlet oxygen upon excitation by a NIR laser. The nanoparticles are reusable as the photosensitizers encapsulated in the silica are removed by soaking in ethanol.

Gas chromatography/mass spectrometry in metabolic profiling of biological fluids

One of the objectives of metabonomics is to identify subtle changes in metabolite profiles between biological systems of different physiological or pathological states. Gas chromatography mass spectrometry (GC/MS) is a widely used analytical tool for metabolic profiling in various biofluids, such as urine and blood due to its high sensitivity, peak resolution and reproducibility. The availability of the GC/MS electron impact (EI) spectral library further facilitates the identification of diagnostic biomarkers and aids the subsequent mechanistic elucidation of the biological or pathological variations. With the advent of new comprehensive two dimensional GC (GC x GC) coupled to time-of-flight mass spectrometry (TOFMS), it is possible to detect more than 1200 compounds in a single analytical run. In this review, we discuss the applications of GC/MS in the metabolic profiling of urine and blood, and discuss its advances in methodologies and technologies.

Tracking transplanted cells in live animal using upconversion fluorescent nanoparticles

With the emergence of cell transplant as an attractive treatment modality for various diseases, there is a parallel need to track the fate of these cells to assess their therapeutic effectiveness. Here, we report the use of upconversion fluorescent nanoparticles, silica/NaYF(4):Yb,Er, to dynamically track live myoblast cells in vitro and in a living mouse model of cryoinjured hind limb. Nanoparticles loaded into cells were confirmed for its intracellular uptake by confocal imaging, spectrophotometry and inductively coupled plasma analysis. Loaded nanoparticles demonstrated absolute resistance to photobleaching and were applied for dynamic imaging to real time track in vitro cell migratory activity for a continuous 5 h duration using a time-lapse confocal microscope. Direct observation on the direction, speed and cell-cell interaction of migrating cells was clearly visualized. In vivo confocal imaging of nanoparticle-loaded cells intravenously injected into a mouse tail vein showed them flowing in the ear blood vessels. Nanoparticle-loaded cells were also unambiguously identified with superior contrast against a negligible background at least 1300 microm deep in a fully vascularized living tissue upon intramuscular injection. Spatiotemporal migratory activity of the transplanted cells within the three-dimensional living tissue was captured for at least 7 days post-delivery. Direct in vivo visualization of cell dynamics in the native tissue was unobtrusively followed over a 4 h time course and revealed subtle migratory activity of the transplanted cells. With these unique optical properties, we present silica/NaYF(4):Yb,Er nanoparticles as a new fluorescent live cell tracker probe for superior in vitro and in vivo dynamic imaging.

Terpenes in ethanol: haloperidol permeation and partition through human skin and stratum corneum changes

Carvacrol, linalool and alpha-terpineol (5% w/v) in 50% ethanol were used to enhance the permeation of haloperidol (HP) through human skin in vitro and their enhancement mechanism was investigated with HP-stratum corneum (SC) binding studies, fourier transform infrared spectroscopy (FT-IR) and differential scanning calorimetry (DSC). Carvacrol followed by terpineol and linalool enhanced flux and permeability coefficient but only carvacrol provided the required plasma concentration and the permeated daily doses. All terpenes increased the activity coefficient of HP in the skin. Carvacrol increased the lag time, which could be due to slow redistribution within SC. The thermogram of hydrated SC showed two lipid endotherms T1 and T2 at 65 and 78 degrees C and protein endotherm T3 at 97 degrees C. All endotherms were absent after SC treated for 48 h with 12 ml of terpene solutions and a decrease in melting points (m.p.) of lipids with a shift of protein endotherm were observed after 12 h treatment with 7 ml of terpene solutions. Linalool and terpineol decreased the m.p. of T1 to 33 degrees C. Carvacrol increased the T1 peak area, which was attributed to lateral lipid bilayer swelling. The IR spectra showed decreases in peak areas and heights of CH2 stretchings but did not show shift of these peaks, increase in their peak widths and shift in amide bands. All the three terpenes disrupted the lipid bilayer and extracted the lipids. Moreover, carvacrol increased the partition of HP whilst linalool and terpineol fluidized the lipids at skin temperature. There could be other possible protein-terpene interactions.

A nanocapsular combinatorial sequential drug delivery system for antiangiogenesis and anticancer activities.

We reported a precise engineered nanocapsule encapsulating a neovasculature disruption agent, combretastatin A4 (CA4) in a matrix that was made up of paclitaxel (PTX) conjugated amphiphilic polyester. The nanocapsule was able to release CA4 and PTX sequentially for temporal antiangiogenesis and anticancer activities. The nanocapsule has a small particle size at 68 nm with narrow size distribution (approximately 0.15). Cellular uptake of the nanocapsule was efficient, and detectable at as early as 20 min, and drugs sequestered in the nanocapsule could exert effective therapeutic effects on tumor neovasculature and cancer cells, respectively. Biodistribution experiments demonstrated the long circulation of nanocapsule in body fluid and the preferential accumulation of nanocapsule in tumor. Both in vivo artificial pro-angiogenesis and tumor xenograft assays demonstrated the promising therapeutic effect of the nanocapsule on tumor vasculature disruption, tumor cell proliferation inhibition and tumor cell apoptosis induction. The intrasplenic liver metastasis experiment also confirmed the liver metastatic prevention capacity of this nanocapsule. In summary, the findings indicated that this dual drug loaded nanocapsule with sequential drug delivery capacity is a promising candidate in combinatorial therapy in fighting against cancer, and may open an avenue for cancer therapy and diagnosis.

Histone deacetylase inhibitors MS-275 and SAHA induced growth arrest and suppressed lipopolysaccharide-stimulated NF-κB p65 nuclear accumulation in human rheumatoid arthritis synovial fibroblastic E11 cells

OBJECTIVES MS-275 and suberoylanilide hydroxamic acid (SAHA) are histone deacetylase (HDAC) inhibitors currently tested in oncology trials. They have also been found to display potent anti-rheumatic activities in rodent models for RA. However, the anti-rheumatic mechanisms of action remain unknown. The study was carried out with the intent of determining the anti-inflammatory and anti-rheumatic mechanisms of the HDAC inhibitors. METHODS In this study, the anti-rheumatic mechanisms of MS-275 and SAHA were investigated in several cell culture models. RESULTS MS-275 and SAHA inhibited human RA synovial fibroblastic E11 cell proliferation in a non-cytotoxic manner. The anti-proliferative activities were associated with G(0)/G(1) phase arrest and induction of cyclin-dependent kinase inhibitor p21. In addition, MS-275 and SAHA suppressed lipopolysaccharide (LPS)-induced NF-kappaB p65 nuclear accumulation, IL-6, IL-18 and nitric oxide (NO) secretion as well as down-regulated pro-angiogenic VEGF and MMP-2 and MMP-9 production in E11 cells at sub-micromolar levels. At similar concentrations, MS-275 and SAHA suppressed LPS-induced NF-kappaB p65 nuclear accumulation and IL-1beta, IL-6, IL-18 and TNF-alpha secretion in THP-1 monocytic cells. Moreover, NO secretion in RAW264.7 macrophage cells was also inhibited. CONCLUSIONS In summary, MS-275 and SAHA exhibited their anti-rheumatic activities by growth arrest in RA synovial fibroblasts, inhibition of pro-inflammatory cytokines and NO, as well as down-regulation in angiogenesis and MMPs. Their anti-rheumatic activities may be mediated through induction of p21 and suppression of NF-kappaB nuclear accumulation.

High-performance liquid chromatography/atmospheric pressure chemical ionization mass spectrometric method for the analysis of catecholamines and metanephrines in human urine

An assay of norepinephrine (NE), epinephrine (E), dopamine (DA), normetanephrine (NE) and metanephrine (MN) based on high-performance liquid chromatography (HPLC) in combination with atmospheric pressure chemical ionization mass spectrometry (APcI-MS) is described. The catecholamines and metanephrines were extracted from urine and aqueous samples using Bio-Rex 70 cation-exchange resin and subjected to analysis by HPLC/APcI-MS. The separation was performed on a C18 column in 50 mM ammonium formate buffer, pH 3.0, using a flow rate of 0.8 mL/min. Acetonitrile was added post-column at a flow rate of 0.2 mL/min via a post-column addition tee. The total analysis time was 6.5 min. The quantitative analysis was performed using 3,4-dihydroxybenzylamine (DHBA) as the internal standard (I.S.). Selected ion monitoring detection was applied: m/z 170 (for NE), 184 (for E and NM), 154 (for DA), 198 (for MN) and 140 (for DHBA, I.S.). The limits of quantitation were 5 ng/mL for NE, E and DA and 2.5 ng/mL for NM and MN. The recovery ranged from 75 to 83% for each analyte. The method was found to be simple and highly selective for the determination of catecholamines and metanephrines in the urine of patients suspected of pheochromocytoma.

The medicinal use of realgar (As4S4) and its recent development as an anticancer agent

ETHNOPHARMACOLOGICAL RELEVANCE Arsenicals have been known as poisons and paradoxically as therapeutic agents. In the early 1970s, Chinese physicians from Harbin revived the medicinal use of arsenicals as anticancer agents. Notable success was observed in the treatment of acute promyelocytic leukemia (APL) with arsenic trioxide (ATO). The FDA approved ATO injection in the year 2000 for the treatment of APL. In contrast, the clinical use of the other arsenical, realgar (As₄S₄), is currently much less established, though it has also long been used in medical history. According to ancient medical records and recent findings in clinical trials, realgar was found as effective as ATO, but with relatively good oral safety profiles even on chronic administration. These give realgar an advantage over ATO in maintenance treatment. Though there is increasing understanding on the mechanisms of action and metabolic profiles of ATO, similar aspects of realgar are unclear to date. MATERIALS AND METHODS We outline the use of realgar in traditional medicines, especially in traditional Chinese medicines (TCM) from ancient times to present. The clinical and experimental observations on realgar as a therapeutic agent are described with an emphasis on those findings that may imply the rationale and future directions of realgar as a potential anticancer drug candidate. RESULTS There is an increasing understanding in the mechanisms of action of realgar as an antileukemic agent. However, there is still sparse information on its metabolism and toxicity profiles. CONCLUSIONS Realgar is poorly soluble in water. Recently, several types of realgar nanoparticles (NPs) have been developed. Some of these realgar NPs also possess the unique optical properties of quantum dots. The activities and bioavailability of realgar NPs are much influenced by their sizes, making realgar an interesting biomedical and pharmaceutical research candidate.