1
|
Joerger M, Metaxas Y, Zaman K, Michielin O, Mach N, Bettini A, Schmitt AM, Cantoni N, Caspar CB, Stettler S, Malval R, Pless M, Britschgi C, Renner C, Koeberle D, Schulz JD, Kopp C, Hayoz S, Stathis A, von Moos R. Outcome and Prognostic Factors of COVID-19 Infection in Swiss Cancer Patients: Final Results of SAKK 80/20 (CaSA). Cancers (Basel) 2022; 14:2191. [PMID: 35565320 PMCID: PMC9104745 DOI: 10.3390/cancers14092191] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2022] [Revised: 04/24/2022] [Accepted: 04/25/2022] [Indexed: 02/04/2023] Open
Abstract
Purpose: These are the final results of a national registry on cancer patients with COVID-19 in Switzerland. Methods: We collected data on symptomatic COVID-19-infected cancer patients from 23 Swiss sites over a one-year period starting on 1 March 2020. The main objective was to assess the outcome (i.e., mortality, rate of hospitalization, ICU admission) of COVID-19 infection in cancer patients; the main secondary objective was to define prognostic factors. Results: From 455 patients included, 205 patients (45%) had non-curative disease, 241 patients (53%) were hospitalized for COVID-19, 213 (47%) required oxygen, 43 (9%) invasive ventilation and 62 (14%) were admitted to the ICU. Death from COVID-19 infection occurred in 98 patients, resulting in a mortality rate of 21.5%. Age ≥65 years versus <65 years (OR 3.14, p = 0.003), non-curative versus curative disease (OR 2.42, p = 0.012), ICU admission (OR 4.45, p < 0.001) and oxygen requirement (OR 20.28, p < 0.001) were independently associated with increased mortality. Conclusions: We confirmed high COVID-19 severity and mortality in real-world cancer patients during the first and second wave of the pandemic in a country with a decentralized, high-quality, universal-access health care system. COVID-19-associated mortality was particularly high for those of older age in a non-curative disease setting, requiring oxygen or ICU care.
Collapse
Affiliation(s)
- Markus Joerger
- Department of Oncology, Cantonal Hospital, 9007 St. Gallen, Switzerland
| | - Yannis Metaxas
- Department of Medical Oncology, Cantonal Hospital, 8596 Muensterlingen, Switzerland;
| | - Khalil Zaman
- Breast Center, Department of Medical Oncology, University Hospital, 1011 Lausanne, Switzerland;
| | - Olivier Michielin
- Department of Medical Oncology, University Hospital, 1011 Lausanne, Switzerland;
| | - Nicolas Mach
- Department of Medical Oncology, University Hospital, 1205 Geneva, Switzerland;
| | - Adrienne Bettini
- Department of Medical Oncology, HFR Fribourg-Hôpital Cantonal, 1752 Fribourg, Switzerland;
| | - Andreas M. Schmitt
- Department of Medical Oncology, University Hospital, 4031 Basel, Switzerland;
| | - Nathan Cantoni
- Oncology, Hematology and Transfusion Medicine, Cantonal Hospital, 5001 Aarau, Switzerland;
| | - Clemens B. Caspar
- Division of Hematology and Oncology, Cantonal Hospital, 5404 Baden, Switzerland;
| | - Sonja Stettler
- Division of Medical Oncology, Lucerne Cantonal Hospital, 6000 Lucerne, Switzerland;
| | | | - Miklos Pless
- Division of Medical Oncology and Hematology, Cantonal Hospital, 8400 Winterthur, Switzerland;
| | - Christian Britschgi
- Department of Medical Oncology and Hematology, University Hospital, 8091 Zurich, Switzerland;
| | - Christoph Renner
- Department of Medical Oncology, Oncological Center Zurich, 8038 Zurich, Switzerland;
| | - Dieter Koeberle
- Department of Oncology, Claraspital, 4058 Basel, Switzerland;
| | - Jessica D. Schulz
- SAKK Coordinating Center, 3008 Bern, Switzerland; (J.D.S.); (C.K.); (S.H.)
| | - Christoph Kopp
- SAKK Coordinating Center, 3008 Bern, Switzerland; (J.D.S.); (C.K.); (S.H.)
| | - Stefanie Hayoz
- SAKK Coordinating Center, 3008 Bern, Switzerland; (J.D.S.); (C.K.); (S.H.)
| | - Anastasios Stathis
- Oncology Institute of Southern Switzerland, 6500 Bellinzona, Switzerland;
| | - Roger von Moos
- Department of Medical Oncology/Hematology, Cantonal Hospital Graubuenden, 7000 Chur, Switzerland;
| |
Collapse
|
2
|
Schulz JD, Coulibaly JT, Schindler C, Wimmersberger D, Keiser J. Pharmacokinetics of ascending doses of ivermectin in Trichuris trichiura-infected children aged 2-12 years. J Antimicrob Chemother 2020; 74:1642-1647. [PMID: 30859185 PMCID: PMC6524481 DOI: 10.1093/jac/dkz083] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2018] [Revised: 10/29/2018] [Accepted: 02/05/2019] [Indexed: 12/20/2022] Open
Abstract
BACKGROUND Yearly, millions of children are treated globally with ivermectin mainly for neglected tropical diseases. Anatomical, physiological and biochemical differences between children and adults may result in changes in pharmacokinetics. However, paediatric pharmacokinetic data of ivermectin are lacking. METHODS In the framework of a randomized controlled dose-finding trial in rural Côte d'Ivoire, Trichuris trichiura-infected pre-school-aged children (PSAC, 2-5 years) and school-aged children (SAC, 6-12 years) were assigned to 100 or 200 μg/kg and 200, 400 or 600 μg/kg ivermectin, respectively (ISRCTN registry no. ISRCTN15871729). Capillary blood was collected on dried blood spot cards until 72 h post-treatment. Ivermectin was quantified by LC-MS/MS, and pharmacokinetic parameters were evaluated by non-compartmental analysis. RESULTS C max and AUC increased in PSAC and SAC with ascending doses and were similar in both age groups when the current standard dose (200 μg/kg) was administered (∼23 ng/mL and ∼350 ng×h/mL, respectively). PSAC with lower BMI were associated with significantly higher AUCs. AUC and Cmax were ∼2-fold lower in children compared with parameters previously studied in adults, whereas body weight-adjusted CL/F (∼0.35 L/h/kg) was significantly higher in children. Tmax (∼6 h), t1/2 (∼18 h), mean residence time (MRTINF) (∼28 h) and V/F (∼8 L/kg) were similar in all paediatric treatment arms. CONCLUSIONS A positive association of AUC or Cmax with dose was observed in both age groups. Undernutrition might influence the AUC of ivermectin in PSAC. Ivermectin shows a lower exposure profile in children compared with adults, highlighting the need to establish dosing recommendations for different age groups.
Collapse
Affiliation(s)
- Jessica D Schulz
- Department of Medical Parasitology and Infection Biology, Swiss Tropical and Public Health Institute, Basel, Switzerland.,University of Basel, Basel, Switzerland
| | - Jean T Coulibaly
- Department of Medical Parasitology and Infection Biology, Swiss Tropical and Public Health Institute, Basel, Switzerland.,University of Basel, Basel, Switzerland.,Unité de Formation et de Recherche Biosciences, Université Félix Houphouët-Boigny, Abidjan, Côte d'Ivoire.,Centre Suisse de Recherches Scientifiques en Côte d'Ivoire, Abidjan, Côte d'Ivoire
| | - Christian Schindler
- Department of Medical Parasitology and Infection Biology, Swiss Tropical and Public Health Institute, Basel, Switzerland.,University of Basel, Basel, Switzerland
| | - David Wimmersberger
- Department of Medical Parasitology and Infection Biology, Swiss Tropical and Public Health Institute, Basel, Switzerland.,University of Basel, Basel, Switzerland
| | - Jennifer Keiser
- Department of Medical Parasitology and Infection Biology, Swiss Tropical and Public Health Institute, Basel, Switzerland.,University of Basel, Basel, Switzerland
| |
Collapse
|
3
|
Patel C, Coulibaly JT, Schulz JD, N'Gbesso Y, Hattendorf J, Keiser J. Efficacy and safety of ascending dosages of albendazole against Trichuris trichiura in preschool-aged children, school-aged children and adults: A multi-cohort randomized controlled trial. EClinicalMedicine 2020; 22:100335. [PMID: 32405623 PMCID: PMC7210508 DOI: 10.1016/j.eclinm.2020.100335] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
BACKGROUND The efficacy of the widely used albendazole against the soil-transmitted helminth Trichuris trichiura is limited; yet optimal doses, which may provide increased efficacy, have not been thoroughly investigated to date. METHODS A randomized-controlled trial was conducted in Côte d'Ivoire with preschool-aged children (PSAC), school-aged children (SAC), and adults infected with T. trichiura. Participants were randomly assigned (1:1:1:1) using computer-generated randomization. PSAC were randomized to 200 mg, 400 mg, 600 mg of albendazole or placebo. SAC and adults were randomized to 400 mg, 600 mg, 800 mg of albendazole or placebo. The primary outcome was cure rates (CRs) against trichuriasis. Secondary outcomes were T. trichiura egg reduction rates (ERRs), safety, CRs and ERRs against other soil-transmitted helminths. Outcome assessors and the trial statistician were blinded. Trial registration at ClinicalTrial.gov: NCT03527745. FINDINGS 111 PSAC, 180 SAC, and 42 adults were randomized and 86, 172, and 35 provided follow-up stool samples, respectively. The highest observed CR among PSAC was 27·8% (95% CI: 9·7%-53·5%) in the 600 mg albendazole treatment arm. The most efficacious arm for SAC was 600 mg of albendazole showing a CR of 25·6% (95% CI: 13·5%-41·2%), and for adults it was 400 mg of albendazole with a CR of 55·6% (95% CI: 21·2%-86·3%). CRs and ERRs did not differ significantly among treatment arms and flat dose-responses were observed. 17·9% and 0·4% of participants reported any adverse event at 3 and 24 h follow-up, respectively. INTERPRETATION Albendazole shows low efficacy against T. trichiura in all populations and doses studied, though findings for PSAC and adults should be carefully interpreted as recruitment targets were not met. New drugs, treatment regimens, and combinations are needed in the management of T. trichiura infections. FUNDING Bill and Melinda Gates Foundation.
Collapse
Affiliation(s)
- Chandni Patel
- Swiss Tropical and Public Health Institute, Basel, Switzerland
- University of Basel, Basel, Switzerland
| | - Jean T. Coulibaly
- Swiss Tropical and Public Health Institute, Basel, Switzerland
- Unité de Formation et de Recherche Biosciences, Université Félix Houphouët-Boigny, Abidjan, Côte d'Ivoire and Centre Suisse de Recherches Scientifiques en Côte d'Ivoire, Abidjan, Côte d'Ivoire
| | - Jessica D. Schulz
- Swiss Tropical and Public Health Institute, Basel, Switzerland
- University of Basel, Basel, Switzerland
| | - Yves N'Gbesso
- Department de Agboville, Centre de Santé Urbain d'Azaguié, Côte d'Ivoire
| | - Jan Hattendorf
- Swiss Tropical and Public Health Institute, Basel, Switzerland
- University of Basel, Basel, Switzerland
| | - Jennifer Keiser
- Swiss Tropical and Public Health Institute, Basel, Switzerland
- University of Basel, Basel, Switzerland
- Corresponding author.
| |
Collapse
|
4
|
Wimmersberger D, Schulz JD, Keiser J. Reply to Nalin. Clin Infect Dis 2019; 69:376-377. [DOI: 10.1093/cid/ciy1015] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- David Wimmersberger
- Department of Medical Parasitology and Infection Biology, Swiss Tropical and Public Health Institute, Basel, Switzerland
| | - Jessica D Schulz
- Department of Medical Parasitology and Infection Biology, Swiss Tropical and Public Health Institute, Basel, Switzerland
| | - Jennifer Keiser
- Department of Medical Parasitology and Infection Biology, Swiss Tropical and Public Health Institute, Basel, Switzerland
| |
Collapse
|
5
|
Brussee JM, Schulz JD, Coulibaly JT, Keiser J, Pfister M. Ivermectin Dosing Strategy to Achieve Equivalent Exposure Coverage in Children and Adults. Clin Pharmacol Ther 2019; 106:661-667. [PMID: 30993667 DOI: 10.1002/cpt.1456] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2019] [Accepted: 03/22/2019] [Indexed: 12/12/2022]
Abstract
Ivermectin is a commonly used broad-spectrum antiparasitic drug, yet doses that produce consistent exposure coverage across age have not been characterized, and no data are available in children weighing < 15 kg. First, a population pharmacokinetic model is developed based on data from 200 children and 11 adults, treated with 100-600 μg/kg ivermectin. Second, model-based simulations are performed to identify a dosing strategy that achieves equivalent exposure coverage in children and adults. Median (90% confidence interval) clearance of 0.346 (0.12-0.73) L/hour/kg in pre-school-aged (2-5 years) children is similar to 0.352 (0.17-0.69) L/hour/kg in school-aged (6-12 years) children but higher than in adults (0.199 (0.10-0.31) L/hour/kg), resulting in significantly lower exposure in children following a 200 μg/kg dose. Simulations indicate that a dose increase to 300 and 250 μg/kg in children aged 2-5 and 6-12 years, respectively, will achieve equivalent ivermectin exposure coverage in children and adults.
Collapse
Affiliation(s)
- Janneke M Brussee
- Department of Medical Parasitology and Infection Biology, Swiss Tropical and Public Health Institute, Basel, Switzerland.,University of Basel, Basel, Switzerland.,Pediatric Pharmacology and Pharmacometrics, University Children's Hospital Basel (UKBB), University of Basel, Basel, Switzerland
| | - Jessica D Schulz
- Department of Medical Parasitology and Infection Biology, Swiss Tropical and Public Health Institute, Basel, Switzerland.,University of Basel, Basel, Switzerland
| | - Jean T Coulibaly
- Department of Medical Parasitology and Infection Biology, Swiss Tropical and Public Health Institute, Basel, Switzerland.,University of Basel, Basel, Switzerland.,Unité de Formation et de Recherche Biosciences, Université Félix Houphouët-Boigny, Abidjan, Côte d'Ivoire.,Centre Suisse de Recherches Scientifiques en Côte d'Ivoire, Abidjan, Côte d'Ivoire
| | - Jennifer Keiser
- Department of Medical Parasitology and Infection Biology, Swiss Tropical and Public Health Institute, Basel, Switzerland.,University of Basel, Basel, Switzerland
| | - Marc Pfister
- University of Basel, Basel, Switzerland.,Pediatric Pharmacology and Pharmacometrics, University Children's Hospital Basel (UKBB), University of Basel, Basel, Switzerland.,Certara LP, Princeton, New Jersey, USA
| |
Collapse
|
6
|
Schulz JD, Moser W, Hürlimann E, Keiser J. Preventive Chemotherapy in the Fight against Soil-Transmitted Helminthiasis: Achievements and Limitations. Trends Parasitol 2018; 34:590-602. [DOI: 10.1016/j.pt.2018.04.008] [Citation(s) in RCA: 36] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2018] [Revised: 04/26/2018] [Accepted: 04/27/2018] [Indexed: 02/06/2023]
|
7
|
Wimmersberger D, Coulibaly JT, Schulz JD, Puchkow M, Huwyler J, N’Gbesso Y, Hattendorf J, Keiser J. Efficacy and Safety of Ivermectin Against Trichuris trichiura in Preschool-aged and School-aged Children: A Randomized Controlled Dose-finding Trial. Clin Infect Dis 2018; 67:1247-1255. [DOI: 10.1093/cid/ciy246] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2018] [Accepted: 03/22/2018] [Indexed: 12/30/2022] Open
Affiliation(s)
- David Wimmersberger
- Department of Medical Parasitology and Infection Biology, Swiss Tropical and Public Health Institute
- University of Basel Switzerland
| | - Jean T Coulibaly
- Department of Medical Parasitology and Infection Biology, Swiss Tropical and Public Health Institute
- University of Basel Switzerland
- Unité de Formation et de Recherche Biosciences, Université Félix Houphouët-Boigny, Abidjan, Côte d’Ivoire
| | - Jessica D Schulz
- Department of Medical Parasitology and Infection Biology, Swiss Tropical and Public Health Institute
- University of Basel Switzerland
| | - Maxim Puchkow
- Department of Pharmaceutical Sciences, Division of Pharmaceutical Technology, University of Basel, Switzerland
| | - Jörg Huwyler
- Department of Pharmaceutical Sciences, Division of Pharmaceutical Technology, University of Basel, Switzerland
| | - Yves N’Gbesso
- Centre de Santé Urbain d’Azaguié, Departement d’Agboville, Côte d’Ivoire
| | - Jan Hattendorf
- University of Basel Switzerland
- Department of Epidemiology and Public Health, Swiss Tropical and Public Health Institute, Basel, Switzerland
| | - Jennifer Keiser
- Department of Medical Parasitology and Infection Biology, Swiss Tropical and Public Health Institute
- University of Basel Switzerland
| |
Collapse
|
8
|
Schulz JD, Patt M, Basler S, Kries H, Hilvert D, Gauthier MA, Leroux JC. Site-Specific Polymer Conjugation Stabilizes Therapeutic Enzymes in the Gastrointestinal Tract. Adv Mater 2016; 28:1455-1460. [PMID: 26640034 DOI: 10.1002/adma.201504797] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/29/2015] [Revised: 10/30/2015] [Indexed: 06/05/2023]
Abstract
The site-specific conjugation of polymers to multiple engineered cysteine residues of a prolyl endopeptidase leads to its stabilization in the gastrointestinal tract of rats, without compromising the activity relative to the native enzyme. The importance of polymer attachment sites is investigated, as well as the significance of polymer structure.
Collapse
Affiliation(s)
- Jessica D Schulz
- Department of Chemistry and Applied Biosciences, Institute of Pharmaceutical Sciences, Swiss Federal Institute of Technology Zurich (ETH Zurich), 8093, Zurich, Switzerland
| | - Melanie Patt
- Department of Chemistry and Applied Biosciences, Institute of Pharmaceutical Sciences, Swiss Federal Institute of Technology Zurich (ETH Zurich), 8093, Zurich, Switzerland
| | - Sophie Basler
- Department of Chemistry and Applied Biosciences, Institute of Pharmaceutical Sciences, Swiss Federal Institute of Technology Zurich (ETH Zurich), 8093, Zurich, Switzerland
| | - Hajo Kries
- Department of Chemistry and Applied Biosciences, Laboratory of Organic Chemistry, Swiss Federal Institute of Technology Zurich (ETH Zurich), 8093, Zurich, Switzerland
| | - Donald Hilvert
- Department of Chemistry and Applied Biosciences, Laboratory of Organic Chemistry, Swiss Federal Institute of Technology Zurich (ETH Zurich), 8093, Zurich, Switzerland
| | - Marc A Gauthier
- EMT Research Center, Institut National de la Recherche Scientifique (INRS), J3X 1S2 Varennes, Quebec, Canada
| | - Jean-Christophe Leroux
- Department of Chemistry and Applied Biosciences, Institute of Pharmaceutical Sciences, Swiss Federal Institute of Technology Zurich (ETH Zurich), 8093, Zurich, Switzerland
| |
Collapse
|
9
|
Schulz JD, Gauthier MA, Leroux JC. Improving oral drug bioavailability with polycations? Eur J Pharm Biopharm 2015; 97:427-37. [DOI: 10.1016/j.ejpb.2015.04.025] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2015] [Revised: 03/30/2015] [Accepted: 04/22/2015] [Indexed: 11/24/2022]
|
10
|
Preiswerk N, Beck T, Schulz JD, Milovník P, Mayer C, Siegel JB, Baker D, Hilvert D. Impact of scaffold rigidity on the design and evolution of an artificial Diels-Alderase. Proc Natl Acad Sci U S A 2014; 111:8013-8. [PMID: 24847076 PMCID: PMC4050586 DOI: 10.1073/pnas.1401073111] [Citation(s) in RCA: 102] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
By combining targeted mutagenesis, computational refinement, and directed evolution, a modestly active, computationally designed Diels-Alderase was converted into the most proficient biocatalyst for [4+2] cycloadditions known. The high stereoselectivity and minimal product inhibition of the evolved enzyme enabled preparative scale synthesis of a single product diastereomer. X-ray crystallography of the enzyme-product complex shows that the molecular changes introduced over the course of optimization, including addition of a lid structure, gradually reshaped the pocket for more effective substrate preorganization and transition state stabilization. The good overall agreement between the experimental structure and the original design model with respect to the orientations of both the bound product and the catalytic side chains contrasts with other computationally designed enzymes. Because design accuracy appears to correlate with scaffold rigidity, improved control over backbone conformation will likely be the key to future efforts to design more efficient enzymes for diverse chemical reactions.
Collapse
Affiliation(s)
- Nathalie Preiswerk
- Laboratory of Organic Chemistry, Eidgenössische Technische Hochschule Zürich, 8093 Zurich, Switzerland
| | - Tobias Beck
- Laboratory of Organic Chemistry, Eidgenössische Technische Hochschule Zürich, 8093 Zurich, Switzerland
| | - Jessica D Schulz
- Laboratory of Organic Chemistry, Eidgenössische Technische Hochschule Zürich, 8093 Zurich, Switzerland
| | - Peter Milovník
- Laboratory of Organic Chemistry, Eidgenössische Technische Hochschule Zürich, 8093 Zurich, Switzerland
| | - Clemens Mayer
- Laboratory of Organic Chemistry, Eidgenössische Technische Hochschule Zürich, 8093 Zurich, Switzerland
| | - Justin B Siegel
- Department of Biochemistry, University of Washington, Seattle, WA 98195; andDepartments of Biochemistry and Molecular Medicine andChemistry, andGenome Center, University of California, Davis, CA 95616
| | - David Baker
- Department of Biochemistry, University of Washington, Seattle, WA 98195; and
| | - Donald Hilvert
- Laboratory of Organic Chemistry, Eidgenössische Technische Hochschule Zürich, 8093 Zurich, Switzerland;
| |
Collapse
|
11
|
Abstract
Many potent drugs are difficult to administer intravenously due to poor aqueous solubility. One validated approach for addressing this issue is to process them into colloidal dispersions known as "nanocrystals" (NCs). However, NCs possess high-energy surfaces that must be stabilized with surfactants to prevent aggregation. In addition, the stabilizer provides a means of anchoring targeting moieties to the NCs for achieving deposition or uptake at specified locations. Nevertheless, a critical challenge is that the surfactant (and consequently the targeting agents) can be shed upon high dilution. This work demonstrates successful cross-linking by click chemistry of stabilizers around paclitaxel NCs to form polymeric "nanocages". Cross-linking does not cause aggregation, as evidenced by transmission electron microscopy, and the nanocages retained the particulate drug through a combination of physical entrapment and physisorption. Size measurements by dynamic light scattering showed that nanocages act as sterically stabilizing barriers to particle-particle interactions and aggregation. The nanocages were shown to be less shed from the NCs than comparable non-cross-linked stabilizers. This contribution provides crucial general tools for preparing poorly sheddable stabilizing coatings to NCs and potentially other classes of nanoparticles for which covalent attachment of the stabilizer to the particle is undesirable (e.g., a drug) or impossible (chemically inert). The presented approach also offers the possibility of more stably attaching targeting moieties to the latter by use of heterotelechelic PEG derivatives, which may favor active targeting and internalization by cells.
Collapse
Affiliation(s)
- Kathrin Fuhrmann
- Institute of Pharmaceutical Sciences, Department of Chemistry and Applied Biosciences, Swiss Federal Institute of Technology Zurich (ETH), Wolfgang-Pauli-Str. 10, 8093 Zurich, Switzerland
| | | | | | | |
Collapse
|
12
|
Schulz JD, Hawkes EL, Shaw CA. Cycad toxins, Helicobacter pylori and parkinsonism: cholesterol glucosides as the common denomenator. Med Hypotheses 2006; 66:1222-6. [PMID: 16488551 DOI: 10.1016/j.mehy.2004.12.033] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2004] [Accepted: 12/16/2004] [Indexed: 12/27/2022]
Abstract
Understanding sporadic cases of age-dependent neurodegenerative diseases such as parkinsonism requires the evaluation of potential environmental factors. Amyotrophic lateral sclerosis-parkinsonism dementia complex (ALS-PDC), a neurological disorder in which features of parkinsonism are present and for which no consistent genetic explanation has been found, has been linked to the consumption of cycad (Cycas micronesica). Similarly, epidemiological evidence suggests an association between parkinsonism and gastric ulcer caused by Helicobacter pylori infection. While common immunological and inflammatory changes have been proposed to account for the link between parkinsonism and H. pylori infection, we propose an alternate explanation based on our work on the "cycad theory" of ALS-PDC. Recent experiments in our laboratory have identified several sterol glucosides in cycad that have neurotoxic properties in vitro and that appear to be linked to the development of neurodegenerative disease in vivo. Specifically, mice fed cycad display behavioural symptoms of parkinsonism such as reduced gait length, as well as neuropathological signs such as a loss of striatal dopaminergic (DAergic) terminals and an upregulation of the dopamine D2 receptor. These cycad-derived sterol glucosides are structurally similar to cholesterol glucosides that account for a significant part pf the lipid profile of H. pylori. We hypothesize that cholesterol glucosides arising from H. pylori infection may act as neurotoxins, promoting the degeneration of the DAergic neurons affected in parkinsonism, in a similar reaction to that which is thought to link cycad consumption and ALS-PDC. This hypothesis will be tested in future studies that will include exposing mice to purified sterol or cholestorol glucosides derived from cycad and comparing these mice behaviourally and neuropathologically to ones chronically infected with H. pylori.
Collapse
Affiliation(s)
- J D Schulz
- Department of Ophthalmology, University of British Columbia, Vancouver, Canada
| | | | | |
Collapse
|
13
|
|