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BackgroundMask leak and airway obstruction are common with mask ventilation in newborn infants, leading to suboptimal ventilation. We aimed to perform a pilot study measuring respiratory mechanics during one-person and two-person mask ventilation in preterm infants at birth.MethodsInfants less than 30 weeks’ gestation were eligible for the study. In the two-person method, one person holds the mask in place and the other provides positive pressure ventilation compared with the standard one-person mask hold. A respiratory function monitor was used in line with a T-piece resuscitator to measure mask leak and airway obstruction. Deferred consent was obtained.ResultsTwenty-five infants were recruited. The mean (SD) birth weight was 920.4 g (188.3), and mean (SD) gestational age was 27.3 weeks (3.0). Percentage mask leak was higher in the one-person mask method (26.4±18.5) compared with the two-person mask method (17.6±9.3) (p=0.018). The mean (SD) expired tidal volume (VTe, mL) in breaths with leak was 3.9 (1.57) in the one-person method compared with 3.05 (1.0) the two-person method (p=0.31). A significantly lower mean (SD) end-tidal carbon dioxide (EtCO2,mm Hg) was measured at 25.3 (9.9) in breaths with mask leak, compared with 30.8 (12.1) in breaths without leak. The breaths with airway obstruction had lower mean EtCO2(25.9 vs 30.8, p=0.003) and lower mean VTe(1.71 vs 6.95, pConclusionMask leak and airway obstruction are common in resuscitation of preterm infants at birth. The use of the two-person mask technique is effective and it could be a useful option if mask ventilation with the one-person method is not effective.Trial registration numberACTRN12614000245695.

Bergmann's rule states that, within species of mammals, individuals tend to be larger in cooler environments. However, the validity of the rule has been debated. We examined the relationship between size and latitude as well as size and temperature within various species of mammals. We also tested the idea that smaller mammals follow Bergmann's rule more strongly than larger mammals, as expected if heat conservation is the cause of the rule. When all studies were included, the percentage of species showing a positive correlation between size and latitude was significantly50% (78 of 110 species). Similarly, the percentage of species showing a negative correlation between size and temperature was significantly50% (48 of 64). Analyses using only significant studies or only studies that sampled extensively also support Bergmann's rule. The size-latitude and size-temperature trends were consistent within all orders and most families for which data are available. We did not find support for the hypothesis that smaller mammals conform more strongly to Bergmann's rule than larger mammals. Thus, we found broad support for Bergmann's rule as a general trend for mammals; however, our analyses do not support heat conservation as the explanation.

Lipid nanoparticles (LNPs) have proven to be highly efficient carriers of short-interfering RNAs (siRNAs) to hepatocytes in vivo; however, the precise mechanism by which this efficient delivery occurs has yet to be elucidated. We found that apolipoprotein E (apoE), which plays a major role in the clearance and hepatocellular uptake of physiological lipoproteins, also acts as an endogenous targeting ligand for ionizable LNPs (iLNPs), but not cationic LNPs (cLNPs). The role of apoE was investigated using both in vitro studies employing recombinant apoE and in vivo studies in wild-type and apoE(-/-) mice. Receptor dependence was explored in vitro and in vivo using low-density lipoprotein receptor (LDLR(-/-))-deficient mice. As an alternative to endogenous apoE-based targeting, we developed a targeting approach using an exogenous ligand containing a multivalent N-acetylgalactosamine (GalNAc)-cluster, which binds with high affinity to the asialoglycoprotein receptor (ASGPR) expressed on hepatocytes. Both apoE-based endogenous and GalNAc-based exogenous targeting appear to be highly effective strategies for the delivery of iLNPs to liver.

We adopted a rational approach to design cationic lipids for use in formulations to deliver small interfering RNA (siRNA). Starting with the ionizable cationic lipid 1,2-dilinoleyloxy-3-dimethylaminopropane (DLinDMA), a key lipid component of stable nucleic acid lipid particles (SNALP) as a benchmark, we used the proposed in vivo mechanism of action of ionizable cationic lipids to guide the design of DLinDMA-based lipids with superior delivery capacity. The best-performing lipid recovered after screening (DLin-KC2-DMA) was formulated and characterized in SNALP and demonstrated to have in vivo activity at siRNA doses as low as 0.01 mg/kg in rodents and 0.1 mg/kg in nonhuman primates. To our knowledge, this represents a substantial improvement over previous reports of in vivo endogenous hepatic gene silencing.

Background: Studies of related individuals have consistently demonstrated notable familial aggregation of cancer. We aim to estimate the heritability and genetic correlation attributable to the additive effects of common single-nucleotide polymorphisms (SNPs) for cancer at 13 anatomical sites. Methods: Between 2007 and 2014, the US National Cancer Institute has generated data from genome-wide association studies (GWAS) for 49 492 cancer case patients and 34 131 control patients. We apply novel mixed model methodology (GCTA) to this GWAS data to estimate the heritability of individual cancers, as well as the proportion of heritability attributable to cigarette smoking in smoking-related cancers, and the genetic correlation between pairs of cancers. Results: GWAS heritability was statistically significant at nearly all sites, with the estimates of array-based heritability, h(l)(2), on the liability threshold (LT) scale ranging from 0.05 to 0.38. Estimating the combined heritability of multiple smoking characteristics, we calculate that at least 24% (95% confidence interval [CI] = 14% to 37%) and 7% (95% CI = 4% to 11%) of the heritability for lung and bladder cancer, respectively, can be attributed to genetic determinants of smoking. Most pairs of cancers studied did not show evidence of strong genetic correlation. We found only four pairs of cancers with marginally statistically significant correlations, specifically kidney and testes (rho = 0.73, SE = 0.28), diffuse large B-cell lymphoma (DLBCL) and pediatric osteosarcoma (rho = 0.53, SE = 0.21), DLBCL and chronic lymphocytic leukemia (CLL) (rho = 0.51, SE = 0.18), and bladder and lung (rho = 0.35, SE = 0.14). Correlation analysis also indicates that the genetic architecture of lung cancer differs between a smoking population of European ancestry and a nonsmoking Asian population, allowing for the possibility that the genetic etiology for the same disease can vary by population and environmental exposures. Conclusion: Our results provide important insights into the genetic architecture of cancers and suggest new avenues for investigation.

This study demonstrates the use of biodegradable poly(lactide- co -glycolide) (PLG) microspheres as a moldable scaffold for cartilage tissue engineering. Chondrocytes were delivered to a cylindrical mold with or without PLG microspheres and cultured in vitro for up to 8 weeks. Cartilagenous tissue formed using chondrocytes and microspheres maintained thickness, shape, and chondrocyte collagen type II phenotype, as indicated by type II collagen staining. The presence of microspheres further enhanced total tissue mass and the amount of glycosaminoglycan that accumulated. Evaluation of microsphere composition demonstrated effects of polymer molecular weight, end group chemistry, and buffer inclusion on tissue-engineered cartilage growth. Higher molecular weight PLG resulted in a larger mass of cartilage-like tissue formed and a higher content of proteoglycans. Cartilage-like tissue formed using microspheres made from low molecular weight and free carboxylic acid end groups did not display increases in tissue mass, yet a modest increased proteoglycan accumulation was detected. Microspheres comprised of PLG with methyl ester end groups yielded a steady increase in tissue mass, with no real increase in matrix accumulation. The microencapsulation of Mg(OH) 2 had negative effects on tissue mass and matrix accumulation. The data herein reflect the potential utility of a moldable PLG-chondrocyte system for tissue-engineering applications.

This study documents the use of biodegradable poly(lactide-co-glycolide) (PLG) microspheres as a novel, injectable scaffold for cartilage tissue engineering. Chondrocytes were delivered via injection to the subcutaneous space of athymic mice in the presence and absence of PLG microspheres. Tissue formation was evaluated up to 8 weeks post-injection. Progressive cartilage formation was observed in samples containing microspheres. The presence of microspheres increased the quantity of tissue formed, the amount of glycosaminoglycan that accumulated, and the uniformity of type II collagen deposition. Microsphere composition influenced the growth of the tissue engineered cartilage. Higher molecular weight PLG resulted in a larger mass of cartilage formed and a higher content of proteoglycans. Microspheres comprised PLG with methyl ester end groups yielded increased tissue mass and matrix accumulation, but did not display homogenous matrix deposition. The microencapsulation of Mg(OH)2 had negative effects on tissue mass and matrix accumulation. Matrix accumulation, cell number, and tissue mass were unchanged by microsphere size, but larger microspheres increased the frequency of central necrosis in implants. The data herein reflect the promising utility of an injectable PLG-chondrocyte system for tissue engineering applications.

Purpose. To investigate the effect of atomization conditions on particle size and stability of spray-freeze dried protein.

Protein adsorption has been implicated in the variability of drug release from biodegradable microspheres. We used optical reflectometry to measure the extent and kinetics of bovine serum albumin (BSA) adsorption to smooth spin-cast films prepared from two poly(lactide-co-glycolide) (PLG) samples that have different end-groups, one being a hydrophilic carboxylic end group and the other a hydrophobic ester end group. One of us has previously shown that these end-groups influence microsphere degradation (Tracy et al. , 1998, Factors affecting the degradation rate of poly(lactide-co-glycolide) microspheres in vivo and in vitro. Biomaterials: submitted for publication.). Both films were moderately hydrophobic, and their wettability was independent of the type of end-group. BSA adsorbed readily to both native PLG films, attaining as much as 50% surface coverage by area and was insensitive to the type of end-group. Aging the films in water for 24 h prior to BSA exposure decreased the hydrophobicity of the films and this in turn correlated with a significant decrease in the initial BSA adsorption rate. This was consistent with the often-observed trend that surface hydrophobicity favors protein adsorption. In spite of the lower adsorption affinity revealed by this decreased initial adsorption rate, the final adsorbed amounts on the aged films exceeded those attained on native films, presumably due to the increase in total surface area produced by partial PLG erosion.

Special (lipid) delivery: The role of the ionizable lipid pK(a) in the in vivo delivery of siRNA by lipid nanoparticles has been studied with a large number of head group modifications to the lipids. A tight correlation between the lipid pK(a) value and silencing of the mouse FVII gene (FVII ED(50) ) was found, with an optimal pK(a) range of 6.2-6.5. The most potent cationic lipid from this study has ED(50) levels around 0.005 mg kg(-1) in mice and less than 0.03 mg kg(-1) in non-human primates.

Five composite liquids consisting of the rigid rod polymer poly(γ-benzyl α,L-glutamate) and narrowly dispersed, spherical silica particles were studied in DMF by dynamic (DLS) and total intensity (TILS) light scattering. The diffusion constant of the spheres was measured by DLS. The effects of sphere size, rod length, and rod concentration on the diffusion of the spheres were investigated to probe the rod solution microstructure. Microviscosities as low as one-half of the solution viscosity were determined from the sphere diffusion constants near the rod concentration c * , which marks the onset of semidilute dynamics

The aim of the study is to compare mask leak and delivered ventilation during Neopuff (NP) mask ventilation in two modes: (i) with NP pressure dial hidden and resuscitator watching chest wall (CW) rise with, (ii) CW movement hidden and resuscitator watching NP pressure dial.Thirty-six participants gave mask ventilation to a modified manikin designed to measure mask leak and delivered ventilation for two minutes in each mode randomly assigned. Paired t-tests were used to analyse differences in mean values. Linear regression was used to determine the association of mask leak with delivered ventilation.Of 7277 inflations analysed, 3621 were observing chest wall mode (CWM) and 3656 observing NP mode (NPM). Mask leak was similar between the groups; 31.6% for CWM and 31.5% (p = 0.56) for NPM. There were no significant differences in airways pressures and expired tidal volumes (TVe) between modes. Mask leak was strongly associated with TVe (R = -0.86 p0.0001) and with peak inspiratory pressure (PIP) (R = -0.51 p0.0001). TVe was associated with PIP (R = 0.51 p0.0001).This study provides reassurance that NP mask leak is not greater when resuscitators watch the NP pressure dial. Mask leak is related to TVe. Mask ventilation training with manikins should include tidal volume measurements.

A new rod/sphere composite liquid was synthesized, characterized, and studied by dynamic light scattering (DLS). The liquid consists of coated silica spheres and poly(7-benzyl-a,L-glutamate) rods (PBLG) in dimethylformamide (DMF). Diffusion constants for spheres of radius 60.4 nm and PBLG rods of length 70 nm were measured by DLS in binary sphere/DMF and rod/DMF solutions as functions of concentration. The diffusion in the binary solutions is compared to that in ternary sphere/rod/DMF solutions at similar sphere and rod concentrations. These studies show that the diffusion of each species in the composite liquid can be measured simultaneously. No evidence was found for aggregation in either the binary or the ternary solutions. Changing the solvent to a mixture of DMF and pyridine allowed the spheres to be refractive index matched to the solvent, greatly decreasing their light scattering intensity. The diffusion of the rods in the composite liquid consisting of dilute spheres and rods of varying concentration was essentially the same as that in the binary rod/DMF solution. The transition between dilute and semidilute rod behavior was found to fall at 8.4 mg/mL or nL3 = 17, in the middle of the concentration range studied (2 < nL3 < 60.4). This value is similar to that found by Zero and Pecora for PBLG in dichloroethane. As the rod concentration increases, the product of the sphere diffusion constant and the solution viscosity remains constant, indicating that the sphere diffusion is consistent with the Stokes-Einstein equation. The dependences of the sphere diffusion constant and the solution viscosity on the rod concentration are well fit by a stretched exponential: DIDO = r)o/r) = exp (-0.16~~.~~). The dependence is comparable to that found from experiments using flexible coils as the background polymer. Theoretical predictions for rods, however, give a cO.5 dependence. The similar concentration dependence for silica spheres found in rod and coil solutions suggests that polymer flexibility alone does not account for the deviation from the theoretical predictions. Instead, rod-rod hydrodynamic interactions may play an important role in this deviation.

The selenium (Se) concentration of paired blood and serum samples from cattle was determined by 2 methods: 1) atomic absorption spectroscopy using hydride generation (HG-AAS), and 2) inductively coupled argon plasma emission spectroscopy using hydride generation (ICP). Samples from 327 cattle were analyzed by HG-AAS, and samples from 344 cattle were analyzed by ICP. The data were examined by linear regression analysis, and the technique of inverse prediction was utilized to determine prediction intervals for estimating blood Se concentration from known serum Se concentration. The correlation coefficients, by simple linear regression of serum Se on blood Se, were 0.79 ( r2 = 0.62) and 0.88 ( r2 = 0.77) for the HG-AAS data and the ICP data, respectively. For the HG-AAS data, the inverse prediction formula for estimating blood Se when serum Se is known, at the 95% prediction interval, was For the ICP data, the inverse prediction formula for estimating blood Se when serum Se is known, at the 95% prediction interval, was The prediction intervals were quite wide, and the accuracy of estimating blood Se from a known serum Se was not useful for diagnostic purposes. The use of serum Se concentration to assess nutritional status of cattle with respect to Se does not appear to be appropriate.

Total arsenic Is determined by Inductively coupled plasma atomic emission using hydride vapor generation. A 1 g sample is wet ashed in a 16 X 150 mm 10 mL volumetric test tube on a programmed heating block with nitric, sulfuric, and perchloric acids at up to 310 °C. After treatment with hydrochloric acid and potassium iodide, arsenic Is reduced by sodium borohydride to arsine In a simplified continuous flow manifold. A standard pneumatic nebulizer effects the gasliquid separation of AsH3, which is quantified by ICP atomic emission at 193.756 nm. The instrument detection limit for the method has been determined to be 0.4 μg/L. For a 10:1 dilution of a nominal 1 g sample, the detection limit is 4 μg/kg and the linear range Is up to 4 mg/kg. Recoveries from 3 matrixes were 99-104%, with a typical RSD of 2%. The method has demonstrated statistical control for samples of biological interest and is especially well suited to analysis of small samples.

The synthesis, characterization, and some studies of the dynamics of a new rod/sphere composite liquid are discussed here. The composite liquid consists of silica spheres (39.4 and 60.4 nm radius) and poly(γ-benzyl-α,L-glutamate) rods (102 000 and 249 700 g/mol molecular weight) dispersed without aggregation in dimethylformamide (DMF) or a mixture of DMF and pyridine. The solvent mixture was used to refractive-index-match dilute solutions of spheres. Dynamic light scattering (DLS) was used to measure the diffusion constants of both the rods and the spheres simultaneously in the solution. Two dynamical regimes were observed for the diffusion of the rods with or without the spheres. The transition point between these two regimes was attributed to the change from dilute to semidilute dynamics. Sphere diffusion constants up to a value two times larger than expected from the Stokes-Einstein equation were measured for the composite liquid containing the large rod (249 700 g/mol) and the small sphere (39.4 nm) in accordance with the argument of Langevin and Rondelez [17]. The sphere diffusion constants measured for the liquid containing the large sphere (60.4 nm) and the small rod (102 000 g/mol) followed a stretched exponential decay with increasing polymer concentration: D/D 0=exp (−0.16 c 0.81). The c 0.81 dependence compares well to experimental results using coil polymers but not to the theories for rod solutions which predict a c 0.5 dependence. The similar concentration dependence found for rod and coil solutions suggests that polymer flexibility alone does not account for the deviation from the theoretical c 0.5 predictions. Instead, rod-rod hydrodynamic interactions may play an important role in this deviation.

To study the association between volume of hospital births per annum and birth outcome for low risk women.Population-based study using the National Perinatal Data Collection (NPDC).Australia.Of 750,491 women who gave birth during 1999-2001, there were 331,147 (47.14%) medically 'low risk' including 132,696 (40.07%) primiparae and 198,451 (59.93%) multiparae.The frequency of each birth and infant outcome was described according to the size of the hospital where birth took place. We investigated whether unit size (defined by volume) was an independent risk factor for each outcome factor using public hospitals with greater than 2000 births per annum as a reference point.Rates of intervention at birth and neonatal mortality for low risk women in relation to hospitals with100, 100-500, 501-1000, 1001-2000 and2001 births per annum.Neonatal death was less likely in hospitals with less than 2000 births per annum regardless of parity. For multiparous low risk women in hospitals of 100 and 500 births per annum compared with hospitals of2000 births per annum the adjusted odds of neonatal mortality [adjusted odds ratio (AOR) 0.36; 99% confidence interval (CI) 0.14-0.93]. For low risk primiparous women in hospitals with less than 100 births per annum, there were lower rates of induction of labour (AOR 0.62; 99% CI 0.54-0.73); intrathecal analgesia/anaesthesia (AOR 0.34; 99% CI 0.28-0.42); instrumental birth (AOR 0.80; 99% CI 0.69-0.93); caesarean section after labour (AOR 0.59; 99% CI 0.49-0.72) and admission to a neonatal unit (AOR 0.15; 99% CI 0.10-0.22) and for low risk multiparous women in hospitals with less than 100 births per annum: induction (AOR 0.69; 99% CI 0.62-0.76); intrathecal analgesia/anaesthesia (AOR 0.32; 99% CI 0.29-0.36); instrumental birth (AOR 0.52; 99% CI 0.41-0.67); caesarean section after labour (AOR 0.41; 99% CI 0.33-0.52); and admission to a neonatal unit (AOR 0.09; 99% CI 0.07-0.12).In Australia, lower hospital volume is not associated with adverse outcomes for low risk women.

To estimate the cost of "the cascade" of obstetric interventions introduced during labour for low risk women.A cost formula derived from population data.New South Wales, Australia.All 171,157 women having a live baby during 1996 and 1997.Four groups of interventions that occur during labour were identified. A cost model was constructed using the known age-adjusted rates for low risk women having one of three birth outcomes following these pre-specified interventions. Costs were based on statewide averages for the cost of labour and birth in hospital.The outcome measure is an "average cost unit per woman" for low risk women, predicted by the level of intervention during labour. Obstetric care is classified as either private obstetric care in a private or public hospital, or routine public hospital care.The relative cost of birth increased by up to 50% for low risk primiparous women and up to 36% for low risk multiparous women as labour interventions accumulated. An epidural was associated with a sharp increase in cost of up to 32% for some primiparous low risk women, and up to 36% for some multiparous low risk women. Private obstetric care increased the overall relative cost by 9% for primiparous low risk women and 4% for multiparous low risk women.The initiation of a cascade of obstetric interventions during labour for low risk women is costly to the health system. Private obstetric care adds further to the cost of care for low risk women.

The objective of this study was to examine the effects of formulation and process variables on particle size and other characteristics of a spray-dried model protein, bovine serum albumin (BSA), using a partial factorial design for experiments. Formulation variables tested include concentration and zinc:protein complexation ratio. Process variables explored were inlet temperature, liquid feed rate, drying air flow rate, and atomizing nitrogen pressure on a lab-scale spray dryer. Statistical data analysis was used to determine F ratios for each of the inputs, which provided a means of ranking the importance of variables relative to one another for each powder characteristic of interest. It was found that protein concentration and atomizing nitrogen pressure had the greatest effects on the particle size of the protein powder. For determining product yield, results showed that protein concentration was the critical variable. Finally, the outlet temperature was mostly influenced by inlet temperature and liquid feed rate. Mathematical models based on these input-output relationships were constructed; these models provide insight into some of the controllable variables of the spray-drying process.

Spray freeze drying produces protein particles suitable for microencapsulation into polymeric microspheres intended for sustained release. Accessibility of encapsulated protein particles to the microsphere surface increases as the protein particle size is increased. Thus, it is desirable that the encapsulated protein particle size be minimized to limit initial release. We have investigated the effect of formulation on spray freeze-dried bovine serum albumin (BSA) as a model protein. Atomization conditions were fixed such that in the absence of excipient, the particle size of the sonicated powder was submicron, and there was substantial protein degradation (loss of monomer). Addition of low concentrations of surfactants (up to the CMC) or mannitol (up to the point where it tended to crystallize upon dehydration) resulted in partial stabilization without impacting particle size. Trehalose was successful in stabilizing the protein; however, there was a marked increase in particle size at the highest levels tested. Ammonium sulfate provided partial stabilization, but also tended to form crystals and increase particle size. FTIR measurements showed a loss of native secondary structure upon spray freeze drying that was ameliorated by addition of trehalose. Other excipients did not prevent structural perturbations. In general, stabilization of spray freeze-dried BSA was related to lowering of the specific surface area in the powder. A balance must be achieved when spray freeze drying proteins intended for encapsulation in sustained-release systems.

Objectives: To examine the rates of obstetric intervention and associated perinatal mortality and morbidity in the first 28 days among low-risk women giving birth in private and public hospitals in NSW (2000–2008). Design: Linked data population-based retrospective cohort study involving five data sets. Setting: New South Wales, Australia. Participants: 691 738 women giving birth to a singleton baby during the period 2000–2008. Main outcome measures: Rates of neonatal resuscitation, perinatal mortality, neonatal admission following birth and readmission to hospital in the first 28 days of life in public and private obstetric units. Results: Rates of obstetric intervention among low-risk women were higher in private hospitals, with primiparous women 20% less likely to have a normal vaginal birth compared to the public sector. Neonates born in private hospitals were more likely to be less than 40 weeks; more likely to have some form of resuscitation; less likely to have an Apgar

It is an exciting time in the RNA interference (RNAi) field. We are in the midst of a rich period of clinical translationmade possible by advances in delivery science and technology. Over the past few years alone, human of proof of concept for RNAi has been demonstrated using systemically administered small interfering RNA (siRNA) therapeutics. Also, siRNA and microRNA (miRNA)-based therapeutics have advanced to the clinic for a variety of important diseases including rare diseases like transthyretin (TTR) amyloidosis, infectious diseases such as hepatitis B, and cancer resulting in a growing pipeline of RNAi-based medicines. In addition, it is increasingly apparent that circulating RNAs in vivo may serve as biomarkers for use in clinical development and disease treatment. Techniques developed to capture and quantitate these RNA markers from serum and other body fluids will facilitate the development of RNAi-based and other medicines. The RNAi field has come a long way in the decade or so since the fundamental discoveries by Fire and Mello, Tuschl, and others during the period from 1998 to 2001 launched hope and high expectations for a new class of therapeutics based on RNAi. The ability to harness the potential of this biological discovery and achieve clinical translation is being made possible by progress in delivery science and technology. Transporting a highly negatively charged RNA macromolecule susceptible to enzymatic degradation and rapid clearance systemically to a specific cell type in the body and then intracellularly into the cell’s cytoplasm to engage the natural RNAi machinery is a tremendous challenge in drug delivery. This must be done with a delivery system that is both potent and safe in humans at a therapeutically relevant dose. The RNAi delivery field has now accomplished this feat, however, for specific cell types mostly in the liver. This issue of Drug Delivery and Translational Research (DDTR) provides an excellent overview of the state of the progress RNAi field with respect to delivery and clinical translation as well as a window on future directions in RNAi delivery from leading scientists in the field. While we have a considerable way to go to match the early expectations for RNAi, namely developing therapeutics to silence any gene in the genome, an increasing number of important new RNAi-based medicines enabled by the latest advances in delivery technology are now in the clinic to address significant unmet medical needs. As we consider where we stand today in the overall development of RNAi technology for new medicines, a historical perspective is helpful. Recombinant DNA technology for producing protein therapeutics was discovered in the 1970s. The first products emerged in the 1980s, and the technology was considered a platform in the pharmaceutical and emerging biotechnology industries with multiple commercialized products by the 1990s. This was a 20-year cycle. Similarly for monoclonal antibodies: discovery in the 1980s, first products in the 1990s, and platform in the 2000s. If RNAi technology follows this pattern, we are on track to see the first RNAi-based medicines commercialized in the next few years with the potential for RNAi technology to grow into a platform technology for new medicines over the next decade. Progress in delivery science and technology will continue to play a central role in determining this trajectory. This issue of DDTR provides an invaluable resource and reference for research and clinical translation in this exciting emerging field.

The purpose of this work was to study the degradation of poly(lactide-co-glycolide) (PLG) microspheres in vivo and in vitro. Degradation rate constants were determined by measuring the polymer molecular weight as a function of time by gel-permeation chromatography. The effects of PLG chemistry and the effects of encapsulating the sparingly soluble salt zinc carbonate and the protein recombinant human growth hormone (rhGH) on the degradation rate were assessed. It was found that in vivo degradation was faster than in vitro degradation. In addition, different types of PLGs were found to degrade at different rates depending on the chemistry of the polymer end group and, to a lesser extent, the molecular weight. Finally, zinc carbonate was found to retard the degradation of some PLGs. These degradation studies have proved valuable in the design of sustained release microsphere products.

R ecent developments in biotechnology have resulted in a number of powerful new protein therapies for many heretofore untreatable conditions, including hepatitis C, multiple sclerosis, hormonal disorders, and different cancers. In spite of this, the use of most protein drugs is limited by the

This paper reviews the development path for the ProLease injectable microsphere delivery system for proteins using human growth hormone as an example. The process consists of four stages, the selection of a lead formulation for clinical testing, the preclinical evaluation of the lead formulation including toxicology and stability studies, the manufacture of phase I clinical supplies, and the scale-up for phase II and phase III clinical trials. The approaches used to overcome obstacles during each stage are summarized including ways of stabilizing the protein, obtaining desirable release kinetics, and manufacturing sterile batches for clinical testing. Stability, release, toxicology, and scale-up results for ProLease recombinant human growth hormone (rhGH) are given. The phase I clinical data show that bioactive rhGH was released for about 1 month in humans. This work shows that processes and procedures have been developed that enable the production of microsphere sustained release formulations for proteins suitable for clinical trails and commercialization.

Five composite liquid solutions (CL1-5) were prepared consisting of silica spheres and the rigid rod polymer poly(γ-benzyl α,L-glutamate) (PBLG) in the polar organic solvent dimethylformamide. The sizes of the macromolecular components in each solution were chosen such that the sphere radius/rod length ratio decreased from CL1 to CL5. The sphere diffusion constants in the composite liquids were measured as a function of the rod concentration by dynamic light scattering. Microviscosities (η μ ) as low as 1/2 of the solution viscosity (η) were found. The sphere diffusion constant data was fit to a stretched exponential of the form D/D o equals exp(-αc v ) which is predicted by several models for the diffusion of spheres in polymer solutions. From these fits, we conclude (1) the stretched exponential fit is worst if η μ μ < η, and (3) the experimentally determined values for v compare well to other experimental data but not to theoretical predictions.

Composite liquids – liquids composed of polymers, particles, and small molecule solvents – constitute an important class of synthetic and naturally occurring materials. Examples include molecular composites, ceramic precursors, lubricants, adhesives, and the cytoplasm in biological cells. Due to the complexity of these liquids, experimental studies of precisely defined systems are essential in developing an understanding of the interactions between all components in the liquid. Unfortunately, such fundamental studies have been relatively rare due to both the difficulty of synthesizing precisely defined composite liquids and the lack of adequate experimental methods to monitor the motions of the various constituents.We have recently reported the synthesis, characterization and some studies of the dynamics of a rod/sphere composite liquid system [1]. In our case the “polymer” constituent is a rigid rod polymer, poly(γ-benzyl-α,L-glutamate) (PBLG). Rigid rod polymers are frequently used in composite liquids as viscosity enhancers. PBLG is commercially available in a wide range of molecular weights and its static and dynamic behavior in dilute and nondilute solutions has been studied. It, in addition, forms mesophases in the concentrated regime. The ceramic “particles” in our composite liquid are coated silica spheres. These spheres are synthesized by the method of Stober et. al. [2] and coated with an organic coating (3-(trimethoxysilyl)propyl methacrylate (TPM)) following a procedure based on that of Philipse et. al. [3] to render them dispersible in organic solvents. The spheres with sizes in the range from 10 nm up to almost 1μm can be synthesized with a relatively narrow size distribution. The solvent in our studies is dimethylformamide (DMF). Both polymer and particle are dispersible as singlets (nonaggregating) in these solvents and the PBLG retains its rigid (or nearly rigid) rod conformation. The diffusion of both the polymer and the sphere in the composite liquid is measured by dynamic light scattering (DLS) [4]. In this paper, we focus on the spheres and examine the effects of rod concentration and rod length on the diffusion of different size spheres. This study suggests that the solution microstructure has an important influence on sphere diffusion.

Dans l'acetonitrile anhydre, l'espece instable Ag(NO 3 ) 4 2− , peut etre produite soit par electrolyse du nitrate d'argent, soit par la reaction d'equilibre N 2 O 5 +Ag + +3NO 3 − ⇄Ag(NO 3 ) 4 2− +NO 2 . Etudes des composes formes par spectrometries RPE et Raman