Ligand-targeted liposomes

Liposomes have gained increased attention as systemic drug delivery vehicles following recent regulatory approvals of several vesicle-formulated drugs. These products have demonstrated improved therapeutic indices over their corresponding conventional drugs by avoiding sensitive tissues and/or increasing delivery to specific targets in vivo. They have achieved these improvements primarily through physical means: (1) by retaining drug within vesicles while in the circulation, thus avoiding or minimizing uptake by sensitive normal tissues; and (2) by selectively extravasating into target tissues, releasing active drug. In order to improve upon these therapies in the future, clinically active liposome delivery systems most likely will need to include site-directed surface ligands to further enhance their selective delivery. This may be crucial for the in vivo transport and delivery of macromolecules, including antisense, oligonucleotide aptamers, and genes, which-unlike most conventional drugs-do not circulate well and often require cellular uptake by fusion, endocytosis, or other processes to reach their active sites. This manuscript reviews technologies applicable to directing liposomes and their contents to selected in vivo targets using surface-bound, site-specific ligands. Presented are the biological barriers to be overcome, criteria for selecting the determinants to be targeted, various targeting ligands and overall delivery system design considerations. Several novel targets as well as novel ligand constructs for site-directed therapy are reviewed and discussed. Systemic liposome therapy, which currently must be administered by the intravenous route, is the principal focus of this analysis.

Inorganic species in geologic fluids: correlations among standard molal thermodynamic properties of aqueous ions and hydroxide complexes

Correlations among experimentally determined standard partial molal thermodynamic properties of inorganic aqueous species at 25 degrees C and 1 bar allow estimates of these properties for numerous monatomic cations and anions, polyatomic anions, oxyanions, acid oxyanions, neutral oxy-acid species, dissolved gases, and hydroxide complexes of metal cations. Combined with correlations among parameters in the revised Helgeson-Kirkham-Flowers (HKF) equation of state (Shock et al., 1992), these estimates permit predictions of standard partial molal volumes, heat capacities, and entropies, as well as apparent standard partial molal enthalpies and Gibbs free energies of formation to 1000 degrees C and 5 kb for hundreds of inorganic aqueous species of interest in geochemistry. Data and parameters for more than 300 inorganic aqueous species are presented. Close agreement between calculated and experimentally determined equilibrium constants for acid dissociation reactions and cation hydrolysis reactions supports the generality and validity of these predictive methods. These data facilitate the calculation of the speciation of major, minor, and trace elements in hydrothermal and metamorphic fluids throughout most of the crust of the Earth.

Unexpected Stability of Al4H6: A Borane Analog?

Whereas boron has many hydrides, aluminum has been thought to exhibit relatively few. A combined anion photoelectron and density functional theory computational study of the Al4H-6 anion and its corresponding neutral, Al4H6, showed that Al4H6 can be understood in terms of the Wade-Mingos rules for electron counting, suggesting that it may be a borane analog. The data support an Al4H6 structure with a distorted tetrahedral aluminum atom framework, four terminal Al-H bonds, and two sets of counter-positioned Al-H-Al bridging bonds. The large gap between the highest occupied and the lowest unoccupied molecular orbitals found for Al4H6, together with its exceptionally high heat of combustion, further suggests that Al4H6 may be an important energetic material if it can be prepared in bulk.

Alemtuzumab for multiple sclerosis: Long term follow-up in a multi-centre cohort

Background:

Alemtuzumab has recently been approved for treatment of relapsing MS, but concerns remain about its use since long-term studies of adverse events remain limited. Furthermore, a clear understanding of its application and durability of effect in clinical practice has yet to evolve.

Objectives:

To investigate long-term efficacy and safety outcomes in a multicentre cohort of patients treated with alemtuzumab.

Methods:

Patients treated from 2000 and followed-up at three regional centres were identified. Baseline and prospective data were obtained and validated by clinical record review.

Results:

One hundred patients were identified with a mean follow-up of 6.1 years (range 1–13). Forty patients were retreated with at least one further treatment cycle. Annualized relapse rates fell from 2.1 to 0.2 ( p<0.0001) post-treatment and were sustained for up to eight years of follow-up. Mean change in EDSS score was +0.14. Forty-seven patients developed secondary autoimmunity.

Conclusion:

Observed reduction in relapse rates reflected those reported in clinical trials, but we were unable to corroborate previous observations of disability reversal. 40% of patients required additional treatment cycles. Autoimmune adverse events were common, occurring at a higher rate than previously reported, but were largely predictable, and could be managed effectively within a rigorous monitoring regime.

Cost-effectiveness of treating deep diabetic foot ulcers with Promogran in four European countries

OBJECTIVE

This study aimed to estimate the cost-effectiveness of treating non-superficial diabetic foot ulcers with Promogran plus good wound care (GWC) compared with GWC alone in four European countries (France, Germany, Switzerland and UK).

METHODS

An existing Markov-based health economic model of non-superficial diabetic foot ulcers was adapted to incorporate the relative efficacy of Promogran compared with GWC alone as demonstrated in a randomised controlled trial. Treatment with Promogran was modelled for a maximum of three months. Country-specific treatment costs were used to estimate the incremental cost per ulcer-free day gained over 12 months. Some parameter assumptions were changed to assess the sensitivity of the results.

RESULTS

Within the first three months of treatment, 26% of ulcers in the Promogran cohort healed compared with 20.7% in the GWC cohort. Over the 12 months, the average number of months spent in the healed state was 3.41 (GWC) and 3.75 (Promogran). Promogran treatment was found to be cost-saving in all four countries, using year 2000 Euro values.

CONCLUSION

Promogran with GWC may be cost-effective, perhaps even cost-saving, under a wide variety of assumptions for the treatment of neuropathic foot ulcers.

DECLARATION OF INTEREST

This study was funded by Ethicon Gmbh (Johnson and Johnson), Germany.

A single-device universal logic gate based on a magnetically enhanced memristor

Memristors are one of the most promising candidates for future information and communications technology (ICT) architectures. Two experimental proofs of concept are presented based on the intermixing of spintronic and memristive effects into a single device, a magnetically enhanced memristor (MEM). By exploiting the interaction between the memristance and the giant magnetoresistance (GMR), a universal implication (IMP) logic gate based on a single MEM device is realized.

Expanded clinical and molecular spectrum of guanidinoacetate methyltransferase (GAMT) deficiency

Guanidinoacetate methyltransferase (GAMT) deficiency is a disorder of creatine biosynthesis, characterized by excessive amounts of guanidinoacetate in body fluids, deficiency of creatine in the brain, and presence of mutations in the GAMT gene. We present here 8 new patients with GAMT deficiency along with their clinical, biochemical and molecular data. The age at diagnosis of our patients ranges from 0 to 14 years. The age of onset of seizures usually ranges from infancy to 3 years. However, one of our patients developed seizures at age 5; progressing to myoclonic epilepsy at age 8 years and another patient has not developed seizures at age 17 years. Five novel mutations were identified: c.37ins26 (p.G13PfsX38), c.403G>T (p.D135Y), c.507_521dup15 (p.C169_S173dup), c.402C>G (p.Y134X) and c.610_611delAGinsGAA (p.R204EfsX63). Six patients had the c.327G>A (last nucleotide of exon 2) splice-site mutation which suggests that this is one of the most common mutations in the GAMT gene, second only to the known Portuguese founder mutation, c.59G>C (p.W20S). Our data suggests that the clinical presentation can be variable and the diagnosis may be overlooked due to unawareness of this disorder. Therefore, GAMT deficiency should be considered in the differential diagnosis of progressive myoclonic epilepsy as well as in unexplained developmental delay or regression with dystonia, even if the patient has no history of seizures. As more patients are reported, the prevalence of GAMT deficiency will become known and guidelines for prenatal diagnosis, newborn screening, presymptomatic testing and treatment, will need to be formulated.

Isotopic decay of urinary or plasma 3-methylhistidine as a potential biomarker of pathologic skeletal muscle loss

BACKGROUND

Skeletal muscle loss accompanying aging or cancer is associated with reduced physical function and predicts morbidity and mortality. 3-Methylhistidine (3MH) has been proposed as a biomarker of myofibrillar proteolysis, which may contribute to skeletal muscle loss.

METHODS

We hypothesized that the terminal portion of the isotope decay curve following an oral dose of isotopically labeled 3MH can be measured non-invasively from timed spot urine samples. We investigated the feasibility of this approach by determining isotope enrichment in spot urine samples and corresponding plasma samples and whether meat intake up to the time of dosing influences the isotope decay.

RESULTS

Isotope decay constants (k) were similar in plasma and urine, regardless of diet. Post hoc comparison of hourly sampling over 10 h with three samples distributed over 10 or fewer hours suggests that three distributed samples over 5-6 h of plasma or urine sampling yield decay constants similar to those obtained over 10 h of hourly sampling.

CONCLUSION

The findings from this study suggest that an index of 3MH production can be obtained from an easily administered test involving oral administration of a stable isotope tracer of 3MH followed by three plasma or urine samples collected over 5-6 h the next day.

Cost effectiveness of Becaplermin in the treatment of diabetic foot ulcers in four European countries

OBJECTIVE

The primary objective of this study was to estimate the cost effectiveness of treating diabetic foot ulcers with becaplermin (Regranex) plus good wound care (GWC) compared with GWC alone in a variety of European healthcare settings. A secondary objective was to analyse the effect of different treatment practices on the economics of caring for diabetic foot ulcers.

DESIGN AND SETTING

Markov-based simulation study from the perspective of a national health system.

METHODS

A 12-month Markov computer simulation model was used to assess the cost effectiveness in 4 European countries of treating diabetic foot ulcers with becaplermin plus GWC versus GWC alone. Transition probabilities were taken from a prospective study of 183 patients and becaplermin efficacy was based on 20-week healing rates in a recent meta-analysis of clinical trials involving 449 patients. Country-specific treatment cost data were collected in collaboration with local economic consultations and combined with the disease model to estimate the incremental cost per ulcer-free month gained. The model was then run using hypothetical low- and high-intensity resource usage profiles to investigate the economics of caring for diabetic foot ulcers.

RESULTS

Over the course of 1 year, individuals who received becaplermin plus GWC were, on average, predicted to spend an additional 0.81 months (24% longer) free of ulcers and to experience a 9% lower risk of undergoing a lower extremity amputation than individuals who received GWC alone. Consequently, becaplermin plus GWC was estimated to be net cost saving in Sweden, Switzerland and the UK. In France, the addition of becaplermin was estimated to add $US19 (1999 values) for each additional ulcer-free month gained. There were substantial intercountry differences in treatment practices and the costs of treating diabetic foot ulcers.

CONCLUSIONS

Becaplermin may be a cost-effective treatment for neuropathic diabetic foot ulcers in a wide range of European settings. In Sweden, Switzerland and the UK, becaplermin may even be cost saving. Substantial intercountry differences in resource patterns appear, at least partly, to be the logical outcome of differences in unit costs.

Effects of fructose-1,6-diphosphate, glucose, and saline on cardiac resuscitation

Severe hypoxemia causes respiratory and cardiac arrest, in part, because severe hypoxemia decreases glycolysis and adenosine triphosphate (ATP) production by a lactic acid-induced decrease in the activity of phosphofructokinase and glyceraldehyde-3-P dehydrogenase. Fructose-1,6-diphosphate (FDP) administration increases the ATP concentration of blood. The authors hypothesized that FDP might increase the number of rabbits that could be resuscitated from hypoxemic cardiac arrest. To test this hypothesis, heart rate, arterial pressure, left ventricular end-diastolic pressure, and blood gases and pH were measured during normoxemia (FIO2 = 0.21) and again during hypoxemia (FIO2 = 0.04) in 28 adult, white, New Zealand rabbits anesthetized with pentobarbital. With the onset of hypoxemia, we gave either 40 mg/kg of 5% FDP (n = 10), 5% glucose (n = 11), or an equal volume (2.5 ml) of normal saline (n = 7) intravenously and began a continuous infusion of 2.0 mg X kg-1 X min-1 of the same sugar or 0.12 ml/min of saline. FDP-treated rabbits breathed for 20.9 +/- 4.9 (mean +/- SEM) min after initiation of hypoxemia; glucose-treated rabbits breathed for 1.4 +/- 0.2 min, and saline-treated rabbits breathed 10.3 +/- 4 min. Cardiac arrest occurred 2.5 +/- 0.5 min after the onset of respiratory arrest in FDP-treated rabbits, 4.1 +/- 0.2 min in glucose-treated rabbits, and 2.9 +/- 0.4 min in saline-treated rabbits. We could resuscitate all ten FDP-treated rabbits; two of 11 glucose-treated (FDP vs. glucose, P less than 0.001); and one of seven saline-treated rabbits (FDP vs. saline, P less than 0.001) from cardiac arrest.(ABSTRACT TRUNCATED AT 250 WORDS)

CT of the liver and spleen with EOE-13: review of 225 examinations

EOE-13 is an experimental liver-spleen-specific computed tomographic (CT) contrast agent developed at the National Institutes of Health. Experience with this agent in 225 clinical examinations is described. On average, use of EOE-13 increases the attenuation of normal liver by 32.5 H and that of normal spleen by 52.3 H. Tumors in these organs increase only 2.6 H, making them more easily detectable. Most of the iodine in EOE-13 appears to clear from the liver and spleen by 24 hr after injection. No deaths or permanent morbidity have been observed. The complication rate is 3.6%. EOE-13 is valuable for the detection of hepatic and splenic tumors.

The cost-effectiveness of treating diabetic lower extremity ulcers with becaplermin (Regranex): a core model with an application using Swedish cost data

OBJECTIVES

The objective of this study was to develop a model capable of assessing the cost-effectiveness in Sweden of treating diabetic neuropathic lower extremity ulcers with becaplermin gel (Regranex) plus good wound care (GWC) relative to treating them with GWC alone.

METHODS

A Markov simulation model was developed that includes six health states: Uninfected Ulcer, Infected Ulcer, Gangrene, Healed Ulcer, Healed Ulcer-History of Amputation, and Deceased. To predict clinical outcomes, information was taken from a specially designed prospective 9-month follow-up study of 183 neuropathic patients in the US treated with GWC. Cost of treatment data were taken primarily from a study of a cohort of 314 patients in Sweden. The efficacy of becaplermin was assumed equal to that achieved in a pooled analysis of four randomized clinical trials. A model application provides expected clinical outcomes for a cohort of patients. Annual treatment costs per patient were estimated using treatment practice and unit prices from Sweden.

RESULTS

Due to a higher rate of healing and a shorter average healing time, treatment with becaplermin gel was predicted to increase the average number of months spent in the healed state over the first year following development of an ulcer by 24% relative to GWC alone. In addition, the corresponding number of amputations was 9% lower for the becaplermin-treated cohort. The average expected cost of $12,078 US for an individual treated with GWC alone declines to $11,708 US for one treated with becaplermin, in spite of $1262 becaplermin costs. Expenses related to topical treatment and inpatient care account for 83% of the resources conserved.

CONCLUSIONS

Our results suggest that in Sweden treatment with becaplermin in conjunction with GWC consumes fewer resources and generates better outcomes than treatment with GWC alone for diabetic neuropathic ulcers. In light of the high and increasing incidence of such ulcers, the potential savings in costs and suffering may be important. Results are difficult to extrapolate internationally because they are strongly related to country-specific treatment practices and price levels.

Computed tomography of the liver and spleen with intravenous lipoid contrast material: review of 60 examinations

In 60 computed tomographic examinations of the liver and spleen in 55 patients, a new intravenous lipoid contrast material, Ethiodized Oil Emulsion 13, was used. This organ-specific contrast material, retained by the reticuloendothelial cells of the liver and spleen, caused marked increase in the attenuation of the liver and spleen, but did not appreciably change the attenuation of the tumor involving these organs, thereby significantly increasing the density differential between normal and abnormal tissue. Toxicity was considered to be well within tolerable limits with the most frequently noted untoward side effects of chills, fever, headaches, and foul metallic taste. Ethiodized Oil Emulsion 13 holds the promise to become a valuable clinical tool by which hepatic and splenic imaging may be significantly improved and lesions less than 1 cm in diameter demonstrated in the liver and spleen.

Engineering spin propagation across a hybrid organic/inorganic interface using a polar layer

Spintronics has shown a remarkable and rapid development, for example from the initial discovery of giant magnetoresistance in spin valves to their ubiquity in hard-disk read heads in a relatively short time. However, the ability to fully harness electron spin as another degree of freedom in semiconductor devices has been slower to take off. One future avenue that may expand the spintronic technology base is to take advantage of the flexibility intrinsic to organic semiconductors (OSCs), where it is possible to engineer and control their electronic properties and tailor them to obtain new device concepts. Here we show that we can control the spin polarization of extracted charge carriers from an OSC by the inclusion of a thin interfacial layer of polar material. The electric dipole moment brought about by this layer shifts the OSC highest occupied molecular orbital with respect to the Fermi energy of the ferromagnetic contact. This approach allows us full control of the spin band appropriate for charge-carrier extraction, opening up new spintronic device concepts for future exploitation.

Importance of spin-orbit interaction for the electron spin relaxation in organic semiconductors

Despite the great interest organic spintronics has recently attracted, there is only a partial understanding of the fundamental physics behind electron spin relaxation in organic semiconductors. Mechanisms based on hyperfine interaction have been demonstrated, but the role of the spin-orbit interaction remains elusive. Here, we report muon spin spectroscopy and time-resolved photoluminescence measurements on two series of molecular semiconductors in which the strength of the spin-orbit interaction has been systematically modified with a targeted chemical substitution of different atoms at a particular molecular site. We find that the spin-orbit interaction is a significant source of electron spin relaxation in these materials.

Nifedipine therapy for diffuse esophageal spasm

Although nifedipine therapy resulted in substantial relief of dysphagia in six patients with diffuse esophageal spasm, significant side effects, particularly in young working subjects, precluded prolonged use.

Detection of hepatic metastases: comparison of EOE-13 computed tomography and scintigraphy

Accurate detection of hepatic metastases is necessary to properly stage and follow many malignancies. Nineteen patients underwent computed tomographic (CT) examination with ethiodized oil emulsion 13 (EOE-CT) and liver scintigraphy within 1 month of an exploratory laparotomy. The sensitivity, specificity, and accuracy of these two imaging procedures were evaluated statistically. No differences were seen when the patients were scored as positive or negative for metastases. However, in a lesion-by-lesion analysis of 58 hepatic lesions, the sensitivity of EOE-CT was 69.0% and the sensitivity of scintigraphy was 32.8% (p less than 0.001). All lesions detected scintigraphy were also detected by EOE-CT. EOE-CT had a size threshold of 1.0-1.5 cm, while liver scintigraphy had a threshold of 2.5-3.0 cm. EOE-CT is a more sensitive examination for detection of small hepatic metastases than liver scintigraphy.

The effect of time of cord clamping and maternal blood pressure on placental transfusion with cesarean section

We measured the residual placental blood volume (RPBV) of 20 infants delivered at term by cesarean section of women not in labor. In all cases, the umbilical cord was clamped within 40 seconds of birth. RPBV decreased significantly with increasing age at cord clamping. In addition, RPBV for infants with cords clamped within 20 seconds of birth correlated inversely with maternal systolic blood pressure (mean RPBV = 54.8 ml. per kilogram at 105 torr and 28.4 ml. per kilogram at 148 torr). However, RPBV did not correlate with maternal blood pressure for the whole group of 20 infants or for those with cords clamped later than 20 seconds after birth. These data indicated that in infants delivered by cesarean section placental transfusion is time related during the first 40 seconds of life and that maternal blood pressure also influences the magnitude of placental transfusion during the first 20 seconds after birth. Analysis of data from this study combined with data from a previous study shows that after 40 seconds the net flow between placenta and infant reverses and that cord clamping delayed beyond this point is accompanied by a rise in RPBV back to the level found when the cord was clamped before 20 seconds.

The effect of paralysis on oxygen consumption in normoxic children after cardiac surgery

To determine whether paralysis reduces oxygen consumption (V02) after cardiac surgery in infants, the authors measured V02 before and after paralysis in 17 sedated infants who were ventilated mechanically after cardiac surgery. Oxygen consumption was determined as being the difference between oxygen content of inspired and expired gases. The absence or presence of "movement" (breathing or repeated movement of the extremities) before paralysis was noted. For eight infants who did not "move" before paralysis, VO2 was similar before (9.1 +/- 1.2 ml . kg-1 . min-1, mean +/- SD) and after (9.0 +/- 1.5 ml . kg-1 . min-1) paralysis (P = 0.81). However, for nine infants who did "move" before paralysis, VO2 decreased from 9.2 +/- 1.4 ml . kg-1 . min-1 before paralysis to 8.0 +/- 1.4 ml . kg-1 . min-1 after paralysis (P less than 0.05). One infant in each group had an increase in VO2 greater than 10% of the baseline value (i.e., 12% and 14%). In conclusion, if breathing or repeated movement is present before paralysis, paralysis decreases VO2 by 13% in sedated infants after cardiac surgery. If repeated or regular movement is not present before paralysis, paralysis does not decrease VO2. These data suggest that in normoxic patients, muscle paralysis does not significantly alter V02 and therefore should not be used for this purpose.

Perfusion preservation of hearts for 6 to 9 days at room temperature

The combination of a defined medium with single-pass perfusion has made possible long-term maintenance of beating rat hearts at 22 degrees C in vitro. The 6- to 9-day survival period appears to be the longest so far reported for hearts. This method provides a stable system which should be useful for investigating the role of single factors in myocardial preservation and evaluating the effects of exposure to pharmacological and toxicological agents.

Unconventional natural gas development and hospitalizations: evidence from Pennsylvania, United States, 2003-2014

OBJECTIVES

To examine relationships between short-term and long-term exposures to unconventional natural gas development, commonly known as fracking, and county hospitalization rates for a variety of broad disease categories.

STUDY DESIGN

This is an ecological study based on county-level data for Pennsylvania, United States, 2003-2014.

METHODS

We estimated multivariate regressions with county and year fixed effects, using two 12-year panels: all 67 Pennsylvania counties and 54 counties that are not large metropolitan.

RESULTS

After correcting for multiple comparisons, we found a positive association of cumulative well density (per km2) with genitourinary hospitalization rates. When large metropolitan counties were excluded, this relationship persisted, and positive associations of skin-related hospitalization rates with cumulative well count and well density were observed. The association with genitourinary hospitalization rates is driven by females in 20-64 years group, particularly for kidney infections, calculus of ureter, and urinary tract infection. Contemporaneous wells drilled were not significantly associated with hospitalizations after adjustment for multiple comparisons.

CONCLUSIONS

Our study shows that long-term exposure to unconventional gas development may have an impact on prevalence of hospitalizations for certain diseases in the affected populations and identifies areas of future research on unconventional gas development and health.