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Previous characterization of the genome and transcriptome of glioblastoma (GBM) has revealed molecular alterations that potentially drive GBM pathogenesis and heterogeneity 1-6 . These open-resources are evolving, such as The Cancer Genome Atlas (TCGA) and The Cancer Imaging Atlas (TCIA) at the National Institute of Health comprising a large cohort of molecular and MRI data. Yet, no report deciphers the link between molecular signatures and MRI-classified GBM. The necessity to re-form molecular and imaging data motivated our computational approach to integrate TCIA and TCGA datasets derived from GBM. We uncovered common and distinct molecular signatures across GBM patients and specific to tumor locations, respectively. Despite heterogeneity in GBM, the top 12 genes from our analysis highlights that the dysregulation of a subset of neurotransmitter receptor or transporter and synaptic activity is common across GBM patients. The coherent layer of imaging and molecular information would help us stratify precision neuro-oncology and treatment options in ways that are not possible through MRI or genomic data alone. Our findings provide molecular targets in the disrupted neurocircuit of GBM, suggesting imbalanced excitation and inhibition. Given the fact that GBM patients exhibit similar symptoms resembling patients with neurodegenerative diseases and seizures, our results supported the hypothesis-GBM in the context of neurological disorders beyond a solely cancerous disease.

Introduction: Enhancer of zeste homolog 2 (Ezh2) is responsible for trimethylation of histone 3 at lysine 27 (H3K27me3), resulting in repression of gene expression. Here, we explore the role of Ezh2 in forebrain GABAergic interneuron development., Methods: We removed Ezh2 in the MGE by generating Nkx2-1Cre;Ezh2 conditional knockout mice. We then characterized changes in MGE-derived interneuron fate and electrophysiological properties in juvenile mice, as well as alterations in gene expression, chromatin accessibility and histone modifications in the MGE., Results: Loss of Ezh2 increases somatostatin-expressing (SST+) and decreases parvalbumin-expressing (PV+) interneurons in the forebrain. We observe fewer MGE-derived interneurons in the first postnatal week, indicating reduced interneuron production. Intrinsic electrophysiological properties in SST+ and PV+ interneurons are normal, but PV+ interneurons display increased axonal complexity in Ezh2 mutant mice. Single nuclei multiome analysis revealed differential gene expression patterns in the embryonic MGE that are predictive of these cell fate changes. Lastly, CUT&Tag analysis revealed that some genomic loci are particularly resistant or susceptible to shifts in H3K27me3 levels in the absence of Ezh2 , indicating differential selectivity to epigenetic perturbation., Discussion: Thus, loss of Ezh2 in the MGE alters interneuron fate, morphology, and gene expression and regulation. These findings have important implications for both normal development and potentially in disease etiologies., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest. The author(s) declared that they were an editorial board member of Frontiers, at the time of submission. This had no impact on the peer review process and the final decision., (Copyright © 2024 Rhodes, Asokumar, Sohn, Naskar, Elisha, Stevenson, Lee, Zhang, Rocha, Dale, Lee and Petros.)

Efficient protocols to generate single-cell and single-nuclei suspensions are critical for the burgeoning field of single-cell/single-nuclei sequencing. Here we describe procedures to generate single-cell and single-nuclei suspensions from embryonic and adult mouse brains. This protocol can be modified for any brain region and/or neural cell type. For complete details on the use and execution of this protocol, please refer to Lee et al. (2022), 1 Rhodes et al. (2022), 2 Mahadevan et al. (2021), 3 Ekins et al. (2020), 4 and Wester et al. (2019). 5 ., Competing Interests: Declaration of interests The authors declare no competing interests., (Published by Elsevier Inc.)

Mechanisms regulating neurogenesis involve broad and complex processes that represent intriguing therapeutic targets in the field of regenerative medicine. One influential factor guiding neural stem cell proliferation and cellular differentiation during neurogenesis are epigenetic mechanisms. We present an overview of epigenetic mechanisms including chromatin structure and histone modifications; and discuss novel roles of two histone modifiers, Ezh2 and Suv4-20h1/Suv4-20h2 (collectively referred to as Suv4-20h), in neurodevelopment and neurogenesis. This review will focus on broadly reviewing epigenetic regulatory components, the roles of epigenetic components during neurogenesis, and potential applications in regenerative medicine., Competing Interests: None

A comprehensive characterization of epigenomic organization in the embryonic mouse forebrain will enhance our understanding of neurodevelopment and provide insight into mechanisms of neurological disease. Here we collected single-cell chromatin accessibility profiles from four distinct neurogenic regions of the embryonic mouse forebrain using single nuclei ATAC-Seq (snATAC-Seq). We identified thousands of differentially accessible peaks, many restricted to distinct progenitor cell types or brain regions. We integrated snATAC-Seq and single cell transcriptome data to characterize changes of chromatin accessibility at enhancers and promoters with associated transcript abundance. Multi-modal integration of histone modifications (CUT&Tag and CUT&RUN), promoter-enhancer interactions (Capture-C) and high-order chromatin structure (Hi-C) extended these initial observations. This dataset reveals a diverse chromatin landscape with region-specific regulatory mechanisms and genomic interactions in distinct neurogenic regions of the embryonic mouse brain and represents an extensive public resource of a 'ground truth' epigenomic landscape at this critical stage of neurogenesis., (© 2022. This is a U.S. Government work and not under copyright protection in the US; foreign copyright protection may apply.)

The cell fate transition from radial glial-like (RGL) cells to neurons and astrocytes is crucial for development and pathological conditions. Two chromatin repressors-the enhancer of zeste homolog 2 and suppressor of variegation 4-20 homolog-are expressed in RGL cells in the hippocampus, implicating these epigenetic regulators in hippocampal cell fate commitment. Using a double knockout mouse model, we demonstrated that loss of both chromatin repressors in the RGL population leads to deficits in hippocampal development. Single-nuclei RNA-Seq revealed differential gene expression and provided mechanistic insight into how the two chromatin repressors are critical for the maintenance of cycling cells in the dentate gyrus as well as the balance of cell trajectories between neuronal and astroglial lineages., (© 2021 Federation of European Biochemical Societies.)

Objectives: To assess the impact of the COVID-19 pandemic on clinical research and the use of electronic approaches to mitigate this impact., Methods: We compared the utilization of electronic consenting, remote visits, and remote monitoring by study monitors in all research studies conducted at Mayo Clinic sites (Arizona, Florida, and Minnesota) before and during the COVID-19 pandemic (ie, between May 1, 2019 and December 31, 2020). Participants are consented through a participant-tracking system linked to the electronic health record., Results: Between May 2019, and December 2020, there were 130,800 new consents across every modality (electronic and paper) to participate in a non-trial (107,176 [82%]) or a clinical trial (23,624 [18%]). New consents declined from 5741 in February 2020 to 913 in April 2020 but increased to 11,864 in November 2020. The mean (standard deviation [SD]) proportion of electronic consent increased from 22 (2%) before to 45 (20%) during the pandemic (P=.001). Mean (SD) remote electronic consenting increased from 0.3 (0.5%) to 29 (21%) (P<.001). The mean (SD) number of patients with virtual visits increased from 3.5 (2.4%) to 172 (135%) (P=.003) per month between pre-COVID (July 2019 to February 2020) and post-COVID (March to December 2020) periods. Virtual visits used telemedicine (68%) or video (32%). Requests for remote monitor access to complete visits increased from 44 (17%) per month between May 2019 and February 2020 to 111 (74%) per month between March and December 2020 (P=.10)., Conclusion: After a sharp early decline, the enrollment of new participants and ongoing study visits recovered during the COVID-19 pandemic. This recovery was accompanied by the increased use of electronic tools., (Copyright © 2021 Mayo Foundation for Medical Education and Research. Published by Elsevier Inc. All rights reserved.)

Neocortical circuits consist of stereotypical motifs that must self-assemble during development. Recent evidence suggests that the subtype identity of both excitatory projection neurons (PNs) and inhibitory interneurons (INs) is important for this process. We knocked out the transcription factor Satb2 in PNs to induce those of the intratelencephalic (IT) type to adopt a pyramidal tract (PT)-type identity. Loss of IT-type PNs selectively disrupted the lamination and circuit integration of INs derived from the caudal ganglionic eminence (CGE). Strikingly, reprogrammed PNs demonstrated reduced synaptic targeting of CGE-derived INs relative to controls. In control mice, IT-type PNs targeted neighboring CGE INs, while PT-type PNs did not in deep layers, confirming this lineage-dependent motif. Finally, single-cell RNA sequencing revealed that major CGE IN subtypes were conserved after loss of IT PNs, but with differential transcription of synaptic proteins and signaling molecules. Thus, IT-type PNs influence CGE-derived INs in a non-cell-autonomous manner during cortical development., (Published by Elsevier Inc.)

Histone methyltransferases (HMTs) are present in heterogeneous cell populations within the adult brain including neurogenic niches. Yet the question remains whether loss of HMTs and the resulting changes in histone methylation alter cell fate in a region-specific manner. We utilized stereotaxic injection of Cre recombinant protein into the adult neurogenic niches, the subventricular zone (SVZ) adjacent to the lateral ventricle and the subgranular zone (SGZ) of the dentate gyrus. We confirmed that Cre protein was enzymatically active in vivo and recombination events were restricted to the vicinity of injection areas. In this study, we focus on using Cre mediated recombination in mice harboring floxed HMT: enhancer of zeste homolog 2 (EZH2) or suppressor of variegation homolog (Suv4-20h). Injectable Cre protein successfully knocked out either EZH2 or Suv4-20h, allowing assessment of long-term effects in a region-specific fashion. We performed meso-scale imaging and flow cytometry for phenotype analysis and unbiased quantification. We demonstrated that regional loss of EZH2 affects the differentiation paradigm of neural stem progenitor cells as well as the maintenance of stem cell population. We further demonstrated that regional loss of Suv4-20h influences the cell cycle but does not affect stem cell differentiation patterns. Therefore, Cre protein mediated knock-out a given HMT unravel their distinguishable and important roles in adult neurogenic niches. This Cre protein-based approach offers tightly-controlled knockouts in multiple cell types simultaneously for studying diverse regulatory mechanisms and is optimal for region-specific manipulation within complex, heterogeneous brain architectures.

Glioblastoma (GBM) is a highly aggressive brain cancer with limited therapeutic options. While efforts to identify genes responsible for GBM have revealed mutations and aberrant gene expression associated with distinct types of GBM, patients with GBM are often diagnosed and classified based on MRI features. Therefore, we seek to identify molecular representatives in parallel with MRI classification for group I and group II primary GBM associated with the subventricular zone (SVZ). As group I and II GBM contain stem-like signature, we compared gene expression profiles between these 2 groups of primary GBM and endogenous neural stem progenitor cells to reveal dysregulation of cell cycle, chromatin status, cellular morphogenesis, and signaling pathways in these 2 types of MRI-classified GBM. In the absence of IDH mutation, several genes associated with metabolism are differentially expressed in these subtypes of primary GBM, implicating metabolic reprogramming occurs in tumor microenvironment. Furthermore, histone lysine methyltransferase EZH2 was upregulated while histone lysine demethylases KDM2 and KDM4 were downregulated in both group I and II primary GBM. Lastly, we identified 9 common genes across large data sets of gene expression profiles among MRI-classified group I/II GBM, a large cohort of GBM subtypes from TCGA, and glioma stem cells by unsupervised clustering comparison. These commonly upregulated genes have known functions in cell cycle, centromere assembly, chromosome segregation, and mitotic progression. Our findings highlight altered expression of genes important in chromosome integrity across all GBM, suggesting a common mechanism of disrupted fidelity of chromosome structure in GBM.

Neural stem progenitor cells (NSPCs) in the human subventricular zone (SVZ) potentially contribute to life-long neurogenesis, yet subtypes of glioblastoma multiforme (GBM) contain NSPC signatures that highlight the importance of cell fate regulation. Among numerous regulatory mechanisms, the post-translational methylations onto histone tails are crucial regulator of cell fate. The work presented here focuses on the role of two repressive chromatin marks tri-methylations on histone H3 lysine 27 (H3K27me3) and histone H4 lysine 20 (H4K20me3) in the adult NSPC within the SVZ. To best model healthy human NSPCs as they exist in vivo for epigenetic profiling of H3K27me3 and H4K20me3, we utilized NSPCs isolated from the adult SVZ of baboon brain ( Papio anubis ) with brain structure and genomic level similar to human. The putative role of H3K27me3 in normal NSPCs predominantly falls into the regulation of gene expression, cell cycle, and differentiation, whereas H4K20me3 is involved in DNA replication/repair, metabolism, and cell cycle. Using conditional knock-out mouse models to diminish Ezh2 and Suv4-20h responsible for H3K27me3 and H4K20me3, respectively, we found that both repressive marks have irrefutable function for cell cycle regulation in the NSPC population. While both EZH2/H3K27me3 and Suv4-20h/H4K20me3 have implication in cancers, our comparative genomics approach between healthy NSPCs and human GBM specimens revealed that substantial sets of genes enriched with H3K27me3 and H4K20me3 in the NSPCs are altered in the human GBM. In sum, our integrated analyses across species highlight important roles of H3K27me3 and H4K20me3 in normal and disease conditions in the context of NSPC.

Histone 3 Lysine 9 (H3K9) methylation is known to be associated with pericentric heterochromatin and important in genomic stability. In this study, we show that trimethylation at H3K9 (H3K9me3) is enriched in an adult neural stem cell niche- the subventricular zone (SVZ) on the walls of the lateral ventricle in both rodent and non-human primate baboon brain. Previous studies have shown that there is significant correlation between baboon and human regarding genomic similarity and brain structure, suggesting that findings in baboon are relevant to human. To understand the function of H3K9me3 in this adult neurogenic niche, we performed genome-wide analyses using ChIP-Seq (chromatin immunoprecipitation and deep-sequencing) and RNA-Seq for in vivo SVZ cells purified from baboon brain. Through integrated analyses of ChIP-Seq and RNA-Seq, we found that H3K9me3-enriched genes associated with cellular maintenance, post-transcriptional and translational modifications, signaling pathways, and DNA replication are expressed, while genes involved in axon/neuron, hepatic stellate cell, or immune-response activation are not expressed. As neurogenesis progresses in the adult SVZ, cell fate restriction is essential to direct proper lineage commitment. Our findings highlight that H3K9me3 repression in undifferentiated SVZ cells is engaged in the maintenance of cell type integrity, implicating a role for H3K9me3 as an epigenetic mechanism to control cell fate transition within this adult germinal niche.

Histone 3 lysine 4 trimethylation (H3K4me3) is known to be associated with transcriptionally active or poised genes and required for postnatal neurogenesis within the subventricular zone (SVZ) in the rodent model. Previous comparisons have shown significant correlation between baboon (Papio anubis) and human brain. In this study, we demonstrate that chromatin activation mark H3K4me3 is present in undifferentiated progenitor cells within the SVZ of adult baboon brain. To identify the targets and regulatory role of H3K4me3 within the baboon SVZ, we developed a technique to purify undifferentiated SVZ cells while preserving the endogenous nature without introducing culture artifact to maintain the in vivo chromatin state for genome-wide studies (ChIP-Seq and RNA-Seq). Overall, H3K4me3 is significantly enriched for genes involved in cell cycle, metabolism, protein synthesis, signaling pathways, and cancer mechanisms. Additionally, we found elevated levels of H3K4me3 in the MRI-classified SVZ-associated Glioblastoma Multiforme (GBM), which has a transcriptional profile that reflects the H3K4me3 modifications in the undifferentiated progenitor cells of the baboon SVZ. Our findings highlight the importance of H3K4me3 in coordinating distinct networks and pathways for life-long neurogenesis, and suggest that subtypes of GBM could occur, at least in part, due to aberrant H3K4me3 epigenetic regulation.

The interaction of water with excipients that can form moisture-protective coatings was examined earlier by the application of theoretical models. In this study, thermodynamic analysis of water-excipient film systems has been performed to elucidate the mechanistic details of the water-excipient interaction. Partial molal free energies, enthalpies, and entropies were computed for films of lipidic (glyceryl behenate, GB) and polymeric (polyvinyl alcohol, PVA) coating excipients using the temperature dependence of the adsorption process. The analysis of free energy changes showed that excipient films were not inert participants in the water sorption process. The isoteric heats of adsorption confirmed that water formed hydrogen bonds with the excipient films and allowed estimation of number of hydrogen bonds per water molecule. This result also provided the reason for hysteresis during drying. A comparative evaluation of the application of theoretical models and thermodynamic analysis revealed that results obtained from both approaches were not always complementary. An exponential relationship was found to exist between sorption microrate constants and water activity for the PVA films at all temperatures.

Hot-melt coating allows encapsulation of water-labile, drug-laden substrates to form a barrier that resists moisture ingress. To understand the interaction of water with excipients that can form moisture-protective coatings, sorption behavior of films of lipidic (glyceryl behenate) and polymeric (polyvinyl alcohol) coating excipients was investigated. A simple and rapid method using a new, fully automated instrumental technique to investigate the sorption/desorption behavior of excipient films is reported. Further, the influence of temperature and film thickness on the sorption behavior of films is examined. Both excipient films displayed sorption isotherms that were classified as type III and demonstrated hysteresis during desorption. The sorption data for both films did not follow the Langmuir model, and the BET model could only be used restrictively. The GAB model fitted the sorption data at all conditions and over the entire range of water activity studied. The ability of the Young and Nelson model to explain the hysteresis behavior, from analytical and mechanistic perspectives, is evaluated. Temperature and film thickness were found to profoundly influence the nature of moisture interaction and distribution of moisture in the excipient films. An Arrhenius-type relationship was observed between equilibrium moisture content of excipient films and temperature at constant water activity.

A novel in situ method for the preparation of injectable biodegradable poly(lactide-co-glycolide) (PLGA) microspheres for the controlled delivery of drugs is described here. A stable dispersion of PLGA microglobules ('premicrospheres' or 'embryonic microspheres') in a vehicle mixture on injection, comes in contact with water from aqueous buffer or physiological fluid, thereby hardening the microglobules into solid matrix type microparticles entrapping the drug (in situ formed microspheres). The drug is then released from these microspheres in a controlled fashion. The effect of the following formulation variables on the characteristics of the novel drug delivery system (NDDS) was investigated: (i) the concentrations of polyethylene glycol 400 (PEG 400), the encapsulated drug, and the hydrophilic excipient (mannitol); and (ii) the types of encapsulated drug (micromolecules and macromolecules such as protein) and vehicles (replacing triacetin and Miglyol 812 by triethyl citrate and soybean oil respectively). Also, the effect of formulation, process, and storage (15 days/4 degrees C) conditions on the physical stability of the encapsulated protein was evaluated. The in vitro drug release was enhanced with decrease in the PEG 400 concentration and increase in the drug and mannitol concentration. The drug release was retarded with increase in the molecular weight of the encapsulated drug. Substitution of triacetin by triethyl citrate and miglyol 812 by soybean oil resulted in variation in the release of the drug from the in situ formed microspheres. A preliminary investigation of the physical stability of the myoglobin revealed that the alpha-helical structure was unaffected by the formulation, process, and the storage conditions.

A novel method for in situ preparation of injectable biodegradable microspheres from the copolymer, poly(lactide-co-glycolide) (PLGA), without incorporating unacceptable organic solvents is described. The delivery system is a dispersion of PLGA microglobules ('premicrospheres' or 'embryonic microspheres') in an acceptable vehicle mixture (continuous phase) and whose integrity is maintained by the use of appropriate stabilizers. A solution of PLGA, triacetin, a model protein (cytochrome c), PEG 400, and Tween 80 (oil phase 1) is added dropwise with continuous homogenization to Miglyol 812-Span 80 solution (oil phase 2), thereby inducing phase separation (coacervation) of PLGA and forming PLGA microglobules (containing cytochrome c) dispersed in the continuous phase. This novel drug delivery system (NDDS) is a dispersion and has a viscous consistency, but is sufficiently syringeable. When injected, it comes in contact with water from an aqueous buffer or physiological fluid and, as a result, the microglobules harden to form solid matrix type microparticles entrapping cytochrome c (in situ formed microspheres). Cytochrome c is then released from these microspheres in a controlled fashion. The composition, rationale, and optimization of the NDDS are described here. Various formulation variables such as the PLGA concentration and type and the substitution of the continuous phase by a fresh oil phase 2 influenced the characteristics of this system. A preliminary investigation of the reproducibility and stability of the NDDS, as well as the physical stability of the encapsulated cytochrome c, revealed that these characteristics were not adversely affected.

Solid dispersion and crystallization of a very slightly water-soluble drug, allopurinol, were prepared using urea, sodium salicylate and beta-cyclodextrin (beta-CD) as carriers. The spectroscopic infra-red (IR), differential scanning calorimetry (DSC) and powder X-ray diffractometry (PXRD) data indicate a role of these carriers in decreasing the crystallinity of allopurinol and complexing abilities. Solid dispersion and crystallization of the drug with these carriers were used in suppository formulations to investigate their role in enhancement of drug release through the membrane barrier. The bases used included Suppocire AM and the mixture of polyethylene glycols (PEGs). The release rates of allopurinol from lipophilic and hydrophilic suppository bases were examined and compared with those obtained for their inclusion compounds incorporated in the same bases. The prepared suppositories were evaluated for in-vitro drug release, when fresh and on storage. The release of pure allopurinol from the lipophilic base was remarkably higher than that from the hydrophilic one. The release of allopurinol from lipophilic as well as hydrophilic bases was significantly enhanced by crystallization of the drug from 5% w/v of sodium salicylate. Allopurinol crystallized from sodium salicylate, showed enhanced release reaching about 100% in 1 h from the Suppocire AM base. The obtained data from these experiments proved the superiority of the PEG formulations containing coevaporates of the drug to sodium salicylate, ratio 1:1, or of the drug to beta-CD, ratio 1:2; T(90%),12 and 36 min, respectively. A significant decrease of uric acid excretion in rabbits was observed after rectal administration of suppositories containing allopurinol crystallized from sodium salicylate.

The chemical stability of three compounded batches of cefazolin ophthalmic solution was monitored by a stability-indicating high-performance liquid chromatography assay. The degradation was governed by first-order kinetics, and the effect of temperature on reaction rate was in accordance with the Arrhenius equation at and above 17 deg C. Although the stability of all three batches was essentially the same, buffering the formulations may be useful. Even using a most cautious and conservative approach to the assignment of a beyond-use date for this type of product, it appears that, if the product is stored at controlled room temperature, a beyond-use date of six days would be fully justifiable. If the product is stored in a refrigerator, then a beyond-use date of 14 days could be assigned.

The purpose of this research was to prepare various injectable, protein (cytochrome c)-loaded biodegradable poly(lactide-co-glycolide) (PLGA) devices by a novel microencapsulation method and to compare their characteristics. Syringeable mixtures of polymer and protein solidified upon injection when coming in contact with water, and formed a solid matrix-type implant or microspheres (in-situ-formed implant or in-situ-formed microspheres, respectively) with cytochrome c entrapped. These devices exhibited different characteristics in terms of in vitro cytochrome c release profile, percentage cytochrome c encapsulation efficiency, and particle size. The burst effect from these devices exhibited the following trend: in-situ-formed implant > in-situ-formed microspheres > isolated microspheres. The in-situ-formed microspheres were larger in size than the isolated microspheres. Also, the isolated microspheres exhibited the slowest release of cytochrome c, whereas the in-situ-formed implant exhibited the fastest release. The microencapsulation process can produce various drug-loaded injectable biodegradable PLGA devices having different characteristics.

The international acceptance of the definition of controlled room temperature (CRT) has given additional impetus to the use of mean kinetic temperature (MKT) as a method of quantifying temperatures during transport and storage and consequent possible effects on drug product stability. The present paper explores some of the implications of the MKT concept and considers the effect of temperature excursions on MKT values and hence on stability of drug products.

The stability of a luteinizing hormone-releasing hormone (LHRH) analog in rat serum was studied under reproduced experimental analysis conditions. Serum samples of deslorelin [D-Trp6, Des-Gly, NH2(10)] LHRH ethylamide were exposed to multiple freeze-thaw cycles to determine the maximum number of cycles the serum sample can be exposed to without producing any quantitative changes in radioimmunoassay (RIA) measurements of deslorelin. A significant cycle effect was observed after completion of the sixth cycle. Serum samples were also stored at standardized -50 degrees C conditions for variable periods of time to determine the effects of acute and chronic storage time on deslorelin stability. Matched-pair t-test analysis showed no significant changes in deslorelin values as measured by RIA for a 3-week, 4-month, or 2-year storage period. The conditions in which the rat serum samples were stored prior to analytical analysis were sufficient to prevent detectable degradation of the deslorelin peptide.

This paper reviews contemporary trends in the stability testing of pharmaceutical products. In particular, it considers the progress toward globalization and harmonization and indicates stability problems, which probably will be the focus of attention for pharmaceutical scientists and regulators in the near future. Attention is specifically directed to monitoring stability in the channels of distribution.

Present trends in the evolution of the design and interpretations of bioequivalency studies are reviewed. It is suggested that, although such tests are now being increasingly regarded as clinical mirrors rather than simply quality control tests for final product testing, there is still the possibility of simplifying such procedures. However, care must be exercised to ensure that changes in bioequivalency tests are introduced only after careful public discussions, which should involve both regulators and pharmaceutical scientists from academia and industry. Further, it is important that bioequivalency standards shall be internally consistent and applied in a politically neutral manner.

The chemical stability of a hydrophobic Leukotriene receptor antagonist drug was investigated in the presence of lactose (both hydrous and anhydrous) under various humidity and temperature conditions. The effect of wet-granulation and direct-mixing on the stability of the drug was also studied. Mixtures of drug:lactose in the ratio 1:25, 1:50 and 1:100 were prepared and analyzed over a 6 week period after storage at 40, 83 and 97% RH (all at 25 degreesC) and 75% RH at 40 degreesC. The mixtures were subjected to LOD, Karl--Fischer titrimetry, HPLC and DSC analysis to evaluate the amount of moisture pickup, percent potency and presence of drug-moisture-lactose interaction. Mixtures containing lactose anhydrous picked up more moisture and exhibited greater drug degradation than those containing lactose hydrous. Also, mixtures stored under high temperature and humidity condition showed greater moisture uptake than those stored at high humidity alone. Lactose anhydrous becomes hydrated on exposure to high humidity/temperature and storage conditions. The transition state of lactose and not its stable state may be responsible for its greater interaction and subsequent degradation of the drug. Therefore, the normal belief that lactose anhydrous, which has less than 0.5% moisture, should provide greater stability as compared to lactose hydrous, needs to be properly evaluated., (Copyright 1998 Elsevier Science B.V. All rights reserved.)

There has been extensive research on drug delivery by biodegradable polymeric devices since bioresorbable surgical sutures entered the market two decades ago. Among the different classes of biodegradable polymers, the thermoplastic aliphatic poly(esters) such as poly(lactide) (PLA), poly(glycolide) (PGA), and especially the copolymer of lactide and glycolide referred to as poly(lactide-co-glycolide) (PLGA) have generated tremendous interest because of their excellent biocompatibility, biodegradability, and mechanical strength. They are easy to formulate into various devices for carrying a variety of drug classes such as vaccines, peptides, proteins, and micromolecules. Most importantly, they have been approved by the United States Food and Drug Administration (FDA) for drug delivery. This review presents different preparation techniques of various drug-loaded PLGA devices, with special emphasis on preparing microparticles. Certain issues about other related biodegradable polyesters are discussed.

Purpose: We report on the development of a novel controlled-release gastric retention system, which consists of a matrix tablet, coated with a permeable membrane. When immersed in simulated gastric fluid, the tablet expands. The tablet remains expanded for eighteen to twenty hours, during which time the drug is released. The tablet then either disintegrates into fragments or loses its integrity., Methods: Tablets containing a soluble drug (chlorpheniramine maleate, i.e., CPM) and a poorly soluble drug (riboflavin 5' phosphate, i.e., R5'P) were compressed. They were coated with a permeable and elastic polymer (Eudragit). Dissolution profiles of these tablets were studied. The changes in the pH, viscosity, and deformation characteristics as a function of time were measured., Results: Carbopol provided a firm structure to the swollen tablet. Polyvinyl pyrrolidone XL (PVP XL) contributed to the swelling of the tablet. Carbonates provided the initial alkaline micro-environment for Carbopol to gel and conferred buoyancy to the tablet. Coating provided the support needed for the core to remain intact during drug release and, at the same time, it allowed drug release due to its permeable nature. During release, the gelling properties of Carbopol lessened, resulting in a decrease in the firmness of the core. This was evident from the decrease in the viscosity of the core. The energy required at 50% strain also decreased as the drug release progressed., Conclusions: When this tablet is ingested, the chances of its elimination through the pylorus should be greatly reduced due to tablet's expansion, and due to its disintegration or loss in integrity it should then be expelled out of the stomach at the end of the drug release.

Purpose: Near-infrared reflectance spectroscopy (NIRS) was used to evaluate and quantify the effect of compression force on the NIR spectra of tablets., Methods: Flat, white tablets with no orientation (scoring, etc.) were manufactured on a Stokes Rotary Tablet Press. NIRS was used to predict tablet hardness on the following four formulations and one placebo matrix: hydrochlorothiazide (HCTZ) 15% and 20% in a placebo matrix (microcrystalline cellulose and magnesium stearate), and chlorpheniramine maleate (CTM) 2% and 6% in a placebo matrix. Five or six levels of tablet hardness from 2 to 12 kg were used for each formulation. Laboratory hardness data was compared to NIR reflectance data using a NIRSystems Rapid Content Analyzer. Multiple linear regression and partial least squares regression techniques were used to determine the relationship between tablet hardness and NIRS spectra., Results: An increase in tablet hardness produced an upward shift (increase in absorbance) in the NIRS spectra. A series of equations was developed by calibrating tablet hardness data against NIR reflectance response for each formulation. The results of NIRS hardness prediction were at least as precise as the laboratory hardness test (SE = 0.32)., Conclusions: A NIRS method is presented which has the potential as an alternative to conventional hardness testing of tablets.

Liposome drug delivery systems are being developed for a variety of drugs. Scale-up process to larger size batches is often a monumental task for the process development scientists. This article reviews various aspects of process development work pertinent to aseptic process techniques for liposomes. This article also has discussed the bilayer properties of liposomes and showed the nomenclature used to classify the liposomes. Discussed is the pH gradient method to load liposomes. Issues and challenges involved in prolonging the shelf-life of liposomes is presented. This review covered the importance of complete removal of organic solvent that is used in the process. Finally the authors presented an HPLC method for quick identification and assay of various phospholipids in a mixture of phospholipids.

We have previously developed a spray dried formulation of a model protein (beta-galactosidase) of a size suitable for evaluation in dry powder inhaler devices. In this study, we wished to evaluate the roles of various methods available for the laboratory testing of dry powders for inhalation (cascade impactor, twin impinger, aerodynamic time of flight and image analysis). Secondly we wished to compare different inhaler devices using formulations with and without a carrier. Both the cascade impactor and twin impinger were appropriate methods for the testing of dry powder inhalers, and gave comparable estimates of respirable fraction. Image analysis and aerodynamic time of flight were suitable methods for determining the particle size of the dry powders, although the former was considerably more time consuming than the latter. The four inhalers evaluated differed greatly in terms of in vitro deposition properties. The presence of a carrier significantly improved respirable fraction with the poorer inhalers, but was less critical to the performance of the more efficient devices.

A pH gradient across liposome bilayers was established in order to load a model drug (orciprenaline sulphate) into liposome vesicles. This method of liposome loading resulted in yields as high as 80-85% encapsulation. An eight-step process was designed to scale-up the process and was evaluated. In this process a diafiltration technique was successfully used to remove the excess orciprenaline sulphate present in the external medium. Finally, drug-loaded liposomes were lyophilized using lactose as an internal and external liposomal cryoprotectant. Five-month stability data for the liposomes is reported. An HPLC technique was used to determine the drug concentration and a laser light-scattering technique was employed to determine the liposome vesicle size and polydispersity factor. Liposomes prepared by the pH-gradient method showed high encapsulation efficiency. Upon storage at 2-8 degrees C the vesicle size increased and encapsulation efficiency decreased with time. These phenomena are attributed to gradual fusion of liposomes and loss of drug to the extra-liposomal media.

The objective of this study was to evaluate the joint effects of various processing and formulation variables on the properties of spray-dried beta-galactosidase using statistically designed experiments. The key response variables evaluated were product yield, residual enzymatic activity, moisture content and particle size and appearance. The residual enzymatic activity and product yield were significantly affected by the processing variables. The highest product yields were obtained when the drier outlet temperature was relatively high, resulting in extensive protein denaturation. Subsequent experiments, therefore, compared the relative effectiveness of four stabilizers (mannitol, sucrose, arginine hydrochloride and trehalose) in terms of their ability to preserve enzymatic activity during the spray-drying process and during long-term storage. Trehalose was the most suitable stabilizer. The effect of a number of other formulation variables (total solids level, ratio of stabilizer to protein, presence of surfactant and presence of buffer) was also investigated. A final formulation consisting of 6% beta-galactosidase and 10% trehalose in deionized water was selected. Spray-drying at inlet and outlet temperatures of 140 and 95 degrees C, respectively, results in greater than 70% yields of a fully active product with a moisture content of 2-5% and a mean particle size of 2-4 microns.

Thermal analysis, thermodynamics of solution and molecular modelling of (+)-ibuprofen and (+/-)-ibuprofen gave information on how heterochiral or homochiral interactions would affect the processing of ibuprofen. The study confirmed that (+/-)-ibuprofen exists as a true racemate with a 10% eutectic pure enantiomer composition. Both the racemate and the (+)-isomer crystal unit cells include four molecules and crystallize in the P2(1/c) and P2(1) space groups, respectively. Thus the intermolecular forces were different in each crystal. As a consequence the (+)-enantiomer lattice was more fragile but only slightly more soluble than the racemate in aqueous media. The solid-state structure contributions to solubility were different for the two crystals (delta H (+) = 51.1 and delta H(+/-) = 32.2 kJ mol-1) but the standard free energies of the solutions were comparable for both compounds.

In an on going effort to optimize ibuprofen antiinflammatory therapy, development studies on the active stereoisomer of ibuprofen have been conducted. The effects of pharmaceutical processing on the racemate (RAC-ibuprofen) and the enantiomer (S(+)-ibuprofen) were investigated. The formulation of the new stereospecific system, was impossible using wet granulation. The pharmaceutical development of S(+)-ibuprofen using direct compression appeared as a practical solution to this problem. The biopharmaceutical properties of the resulting tablets were well within pharmacopeia requirements. Nevertheless, mixing S(+)-ibuprofen with the excipients induced a drop in the enthalpy of fusion and after compaction, a low temperature eutectic appeared on the differential scanning calorimetry endotherms. Aging studies indicated that the raw material and pharmaceutical mixtures of S(+)-ibuprofen should be stored under strictly controlled conditions or processed immediately.

Data from a reverse phase gradient elution HPLC assay for human epidermal growth factor (EGF) was compared and correlated with data obtained from a competitive heterogeneous radioimmunoassay (RIA). The RIA was established to measure very low concentrations of EGF in formulation drug release and compatibility studies. The HPLC assay, capable of resolving parent and possible modified or fragmented forms of EGF isolated from human urine, was studied as a potential development tool for stability and final product evaluation. As independent analytical methods, the HPLC and the RIA procedures produced correlated results when quantifying freshly prepared and certain degraded samples of EGF. The capacity of the HPLC method to serve as a stability indicating assay was examined. Degradation of EGF was induced by storage in 0.05 M phosphate buffer pH 7.4 at 25, 37 or 50 degrees C. The same three degradation products were detected at each temperature by the HPLC method, one of which was identified as L-isoaspartyl EGF.

It is known that depending on the manufacturing and synthetic processes, drugs may exist as different forms. As a result, physicochemical properties, compression characteristics, intrinsic dissolution and bioavailability may vary substantially. The purpose of this study was to investigate the effect of different sources of ibuprofen on the processing of tablets and on their properties. Another emphasis of this work was to rationalize one or several key characteristics of the raw material as directly related to wet granulation parameters and to the behavior of final tablets. Commercially available ibuprofen was obtained from different manufacturers and a preformulation program, including X-ray crystallography, differential scanning calorimetry, scanning electron microscopy, determination of particle size distribution and flowability, was performed to characterize the raw material. Granules were prepared with a planetary mixer and liquid requirements for the end point were obtained by monitoring power consumption. Tablets were manufactured on Stokes rotary and single punch instrumented presses. Data acquisition interfaces produced compression data for each formulation. Granules and final tablets were analyzed for hardness, dissolution profiles and content uniformity. Statistical evaluations using analysis of variance and multiple comparison procedures were performed on the results to determine the significance of the variability between independent parameters. The ibuprofen tested was found to be a unique polymorphic form with some differences in the external crystallinity. The particle size characteristics of the material also allowed a differentiation between sources and although there was no differences in dissolution patterns or content uniformity, particle size was found to account for 50% of the variability in tablet hardness. Two sources of ibuprofen with lower mean particle size showed significant variations in end point liquid requirements resulting in variable tablet crushing strength.

Three simple formulations, with various physicochemical characteristics, were designed as potential pharmaceutical bases for delivery of epidermal growth factor (EGF) to open wounds. The compatibility of EGF with formulation excipients and the release of EGF from each formulation were evaluated in vitro using a release cell apparatus. Samples were analyzed by competitive heterogeneous radioimmunoassay. The apparatus and procedures used in the study were validated to ensure EGF stability during the study, and to verify the absence of excipient interference with analytical procedure. Batches of Pluronic F-127 25% gel formulation and Carbopol gel formulation showed similar average EGF release rates of 17.12 and 16.55 micrograms/cm2/hr, respectively. A vanishing cream formulation similar to the commercial product Silvadene showed much slower release of 0.5 microgram/cm2/hr.

Using a pharmacokinetic model recently proposed to explain ibuprofen disposition in man, plasma concentrations of pure ibuprofen enantiomers were simulated following oral administration of (-)-(R)-ibuprofen, (+)-(S)-ibuprofen, or rac-ibuprofen. Simulated and literature values for AUC's were used to compare S/R ratios for different cases of the model and for different methods of calculating the fraction of R bioinverted to S. Numerical simulation using STELLA confirmed previous results for different cases of bioinversion. Simulated S/R AUC ratios, for administration of the racemate, ranged from 4.0 (presystemic bioinversion) to 1.66 (systemic bioinversion). Literature values for S/R AUC ratios averaged 1.53 +/- 0.2 for administration of the racemate; therefore, systemic bioinversion was concluded to be representative of ibuprofen disposition. Additional simulations of S/R AUC ratios, for administration of (-)-(R)-ibuprofen only, ranged from 1.5 (presystemic bioinversion) to 0.66 (systemic bioinversion). Literature values for S/R AUC ratios averaged 0.50 +/- 0.9 for administration of (-)-(R)-ibuprofen only, which again supported conclusions of systemic bioinversion. Using different equations for estimation of fraction of R inverted to S (FR----S), results based on simulated data were identical; however, FR----S values based on literature data were different. Therefore, assumptions made for different FR----S equations do not appear to be rigorous. Calculations of FR----S, based on literature data, averaged 0.52 overall, indicating bioavailability of (+)-(S)-ibuprofen may be similar for a 150 mg dose of (+)-(S)-ibuprofen compared to a 200 mg dose of racemate.

Dissolution tests have been in use in the pharmaceutical industry for over 20 years, and they are official in The United States Pharmacopeia since the early 1960s. The dissolution test, reviewed primarily as a quality control tool, replaced the use of disintegration tests which had been official in The United States Pharmacopeia since 1950. Refinements in the dissolution test equipment and methodology have occurred over the years in order to enhance its relevance. The Subcommittees of the USP Committee of Revision dealing with these issues have developed and refined compendial dissolution standards and policies for conventional solid-oral dosage forms and modified-release dosage forms.

The ability of a high-affinity colchicine-binding monoclonal antibody to reverse the effects of colchicine on Chinese hamster ovary cells was investigated. Using flow cytometry, a complete mitotic blockade was demonstrated after 16 hours with 2.5 x 10(-7) mol/l (molar) colchicine. Colchicine-induced changes were reversible when equimolar antibody was added simultaneously with or up to 6 hours after colchicine. With further delay in addition of antibody, a progressive irreversible increase in mitotic blockade and increase in mean cell size was observed. Prolonged colchicine exposure, without antibody reversal, led to polyploidy and structural chromosome breakage. Early antibody reversal restored cells to the diploid state, whereas delayed reversal resulted in a time-dependent increase in polyploidy. Colchicine-induced polyploidy and chromosomal aberrations may be the basis for both colchicine toxicity and the time-dependent increase in irreversibility of colchicine effects.

The pharmacological activity of salicylates is related to the non-protein-bound fraction of drug in the plasma. Free fatty acids have been shown to displace bound drug and to increase the serum levels of salicylates. Continuous ultrafiltration was used to measure unbound salicylic acid at 37 degrees. A nonlinear analysis of the ultrafiltration data using whole number values for the number of binding sites indicates that sodium oleate displaces the salicylic acid competitively at both binding sites. Increased concentrations of fatty acids due to disease or the infusion of fatty acid emulsions perhaps may produce toxic levels of salicylic acid.

The aging of direct compression tablets made using dibasic calcium phosphate dihydrate as the tablet matrix was investigated over 16 weeks. The formula included 6% amaranth as a dye tracer. Two sets of stress storage conditions were used: 25 degrees and 50% relative humidity and 45 degrees and 75% relative humidity. Tablets were evaluated periodically by visual inspection; determination of the weight of 10 separate tablets, the size of 10 tablets measured by a micrometer screw gauge, and the hardness of 10 tablets as indicated by a Strong-Cobb hardness tester; the USP disintegration time test; and the USP dissolution test. Tablets stored at 25 degrees and 50% relative humidity showed an approximately linear increase in disintegration and dissolution time over 16 weeks with no other significant changes. Storage at 45 degrees and 75% relative himidity resulted in significant changes in most measured parameters; tablets showed blotching, substantial weight loss, and complex changes in disintegration and dissolution. The changes at elevated temperatures are related to loss of water of hydration; changes at 25 degrees must be due to other causes.

The effect of varying concentrations of sodium oleate on the binding of furosemide to human serum albumin was investigated using continuous ultrafiltration. The furosemide fraction free was 1.37% in the absence of sodium oleate increasing to 3.52% in the presence of 2 mEq/l of sodium oleate. Furosemide bound to two types of binding sites on the albumin molecule. It was found that the numbers of binding sites of each type were constant with the addition of free fatty acid (FFA); however, the decrease in the affinity constants for each site was directly proportional to the increase in FFA over the range of 0-2 mEq/l added sodium oleate. Sodium palmitate and linoleic acid were tested individually to determine the effect of interaction, the fraction free increasing to 2.59 and 1.96% in the presence of 2 mEq/l of sodium palmitate and linoleic acid, respectively.

Parameters affecting the spectrophotometric kinetic assay for nitroglycerin are described. It is shown that the assay is highly specific; results are not significantly affected by many of the tablet diluents found in commercially-available nitroglycerin tablets. Further, the assay is insensitive to glycerol, nitrate, nitrite and glyceryl dinitrates. This simple, precise and specific nitroglycerin assay is well suited for routine analysis of the drug in commercial tablets and parenteral solutions in hospital pharmacies.