Antibacterial and conductive injectable hydrogels based on quaternized chitosan-graft-polyaniline/oxidized dextran for tissue engineering

Biomaterials with injectability, conductivity and antibacterial effect simultaneously have been rarely reported. Herein, we developed a new series of in situ forming antibacterial conductive degradable hydrogels using quaternized chitosan (QCS) grafted polyaniline with oxidized dextran as crosslinker. The chemical structures, morphologies, electrochemical property, conductivity, swelling ratio, rheological property, in vitro biodegradation and gelation time of hydrogels were characterized. Injectability was verified by in vivo subcutaneous injection on a Sprague Dawley rat. The antibacterial activity of the hydrogels was firstly evaluated employing antibacterial assay using Escherichia coli and Staphylococcus aureus in vitro. The hydrogels containing polyaniline showed enhanced antibacterial activity compared to QCS hydrogel, especially for hydrogels with 3 wt% polyaniline showing 95 kill% and 90kill% for E. coli and S. aureus, respectively. Compared with QCS hydrogel, the hydrogels with 3 wt% polyaniline still showed enhanced antibacterial activity for E. coli in vivo. The adipose-derived mesenchymal stem cells (ADMSCs) were used to evaluate the cytotoxicity of the hydrogels and hydrogels with polyaniline showed better cytocompatibility than QCS hydrogel. The electroactive hydrogels could significantly enhance the proliferation of C2C12 myoblasts compared to QCS hydrogel. This work opens the way to fabricate in situ forming antibacterial and electroactive degradable hydrogels as a new class of bioactive scaffolds for tissue regeneration applications.

Prehospital hypertonic saline/dextran infusion for post-traumatic hypotension. The U.S.A. Multicenter Trial

The safety and efficacy of 7.5% sodium chloride in 6% dextran 70 (HSD) in posttraumatic hypotension was evaluated in Houston, Denver, and Milwaukee. Multicentered, blinded, prospective randomized studies were developed comparing 250 mL of HSD versus 250 mL of normal crystalloid solution administered before routine prehospital and emergency center resuscitation. During a 13-month period, 422 patients were enrolled, 211 of whom subsequently underwent operative procedures. Three hundred fifty-nine patients met criteria for efficacy analysis, 51% of whom were in the HSD group. Seventy-two per cent of all patients were victims of penetrating trauma. The mean injury severity score (19), Trauma Score plus Injury Severity Score (TRISS) probability of survival, revised trauma scores (5.9), age, ambulance times, preinfusion blood pressure, and etiology distribution were identical between groups. The total amount of fluid administered, white blood cell count, arterial blood gases, potassium, or bicarbonate also were identical between groups. The HSD group had an improved blood pressure (p = 0.024). Hematocrit, sodium chloride, and osmolality levels were significantly elevated in the Emergency Center. Although no difference in overall survival was demonstrated, the HSD group requiring surgery did have a better survival (p = 0.02), with some variance among centers. The HSD group had fewer complications that the standard treatment group (7 versus 24). A greater incidence of adult respiratory distress syndrome, renal failure, and coagulopathy occurred in the standard treatment group. No anaphylactoid nor Dextran-related coagulopathies occurred in the HSD group. Although this trial demonstrated trends supportive of HSD in hypotensive hemorrhagic shock patients requiring surgery, a larger sample size will be required to establish which subgroups of trauma patients might maximally benefit from the prehospital use of a small volume of hyperosmolar solution. This study demonstrates the safety of administering 250 mL 7.5% HDS to this group of patients.

Single-cell electroporation for gene transfer in vivo

We report an electroporation technique for targeting gene transfer to individual cells in intact tissue. Electrical stimulation through a micropipette filled with DNA or other macromolecules electroporates a single cell at the tip of the micropipette. Electroporation of a plasmid encoding enhanced green fluorescent protein (GFP) into the brain of intact Xenopus tadpoles or rat hippocampal slices resulted in GFP expression in single neurons and glia. In vivo imaging showed morphologies, dendritic arbor dynamics, and growth rates characteristic of healthy cells. Coelectroporation of two plasmids resulted in expression of both proteins, while electroporation of fluorescent dextrans allowed direct visualization of transfer of molecules into cells. This technique will allow unprecedented spatial and temporal control over gene delivery and protein expression.

Multi-pulse drug delivery from a resorbable polymeric microchip device

Controlled-release drug delivery systems have many applications, including treatments for hormone deficiencies and chronic pain. A biodegradable device that could provide multi-dose drug delivery would be advantageous for long-term treatment of conditions requiring pulsatile drug release. In this work, biodegradable polymeric microchips were fabricated that released four pulses of radiolabelled dextran, human growth hormone or heparin in vitro. Heparin that was released over 142 days retained on average 96 +/- 12% of its bioactivity. The microchips were 1.2 cm in diameter, 480-560 microm thick and had 36 reservoirs that could each be filled with a different chemical. The devices were fabricated from poly(L-lactic acid) and had poly(D,L-lactic-co-glycolic acid) membranes of different molecular masses covering the reservoirs. A drug delivery system can be designed with the potential to release pulses of different drugs at intervals after implantation in a patient by using different molecular masses or materials for the membrane.

Randomized, controlled trial on the effect of a 20% mannitol solution and a 7.5% saline/6% dextran solution on increased intracranial pressure after brain injury*

OBJECTIVE

The aim of this pilot study was to compare the effects of equimolar doses of hypertonic saline and dextran solution (HSD, Rescueflow) with 20% mannitol solution for reduction of increased intracranial pressure.

DESIGN

Prospective, randomized, controlled, crossover trial in the intensive care unit of a large teaching hospital.

SETTING

Academic hospital and tertiary referral center for neuroscience.

PATIENTS

Nine patients with an intracranial pressure of >20 mm Hg were recruited and received two treatments of each, HSD and 20% mannitol, in a randomized order.

INTERVENTION

Equimolar, rapid intravenous infusions of either 200 mL of 20% mannitol or 100 mL of 7.5% saline and 6% dextran-70 solution (HSD) over 5 mins.

MEASUREMENTS

Intracranial pressure, blood pressure, serum and urine sodium and osmolality, and urine output.

MAIN RESULTS

Treatments reduced intracranial pressure with both mannitol (median decrease, 7.5 mm Hg, 95% confidence interval, 5.8-11.8) and HSD (median decrease, 13 mm Hg; 95% confidence interval, 11.5-17.3). HSD caused a significantly greater decrease in intracranial pressure than mannitol (p = .044). HSD had a longer duration of effect than mannitol (p = .044).

CONCLUSION

When given in an equimolar, rapid, intravenous infusion, HSD reduces intracranial pressure more effectively than mannitol.

The permeability of glomerular capillaries to graded dextrans. Identification of the basement membrane as the primary filtration barrier

Graded dextrans have been used as tracers to identify the primary permeability barrier(s) to macromolecules among the structural elements (endothelium, mesangium, basement membrane, epithelium) of the glomerular capillary wall. Three narrow-range fractions of specified molecular weights and Einstein-Stokes radii (ESR) were prepared by gel filtration: (a) 32,000 mol wt, ESR = 38 A; (b) 62,000 mol wt, ESR = 55 A; and (c) 125,000 mol wt, ESR = 78 A. These fractions are known to be extensively filtered, filtered in only small amounts, and largely retained, respectively, by the glomerular capillaries. Tracer solutions were infused i.v. into Wistar-Furth rats, and the left kidney was fixed after 5 min to 4 h. The preparations behaved as predicted: initially, all three fractions appeared in the urinary spaces, with 32,000 > 62,000 >> 125,000. The smallest fraction was totally cleared from the blood and urinary spaces by 2.5 h, whereas the intermediate and largest fractions were retained in the circulation at high concentrations up to 4 h. With all fractions, when particles occurred in high concentration in the capillary lumina, they were present in similarly high concentrations in the endothelial fenestrae and inner (subendothelial) portions of the basement membrane, but there was a sharp drop in their concentration at this level-i.e., between the inner, looser portions of the basement membrane and its outer, more compact portions. With the two largest fractions, accumulation of particles occurred against the basement membrane in the mesangial regions with time. No accumulation was seen with any of the fractions in the epithelial slits or against the slit membranes. Dextran was also seen in phagosomes in mesangial cells, and in absorption droplets in the glomerular and proximal tubule epithelium. It is concluded that the basement membrane is the main glomerular permeability barrier to dextrans, and (since their behavior is known to be similar) to proteins of comparable dimensions (40,000-200,000 mol wt). The findings are discussed in relation to previous work using electron-opaque tracers to localize the glomerular permeability barrier and in relation to models proposed for the functions of the various glomerular structural elements.

Out-of-hospital hypertonic resuscitation after traumatic hypovolemic shock: a randomized, placebo controlled trial

OBJECTIVE

To determine whether out-of-hospital administration of hypertonic fluids would improve survival after severe injury with hemorrhagic shock.

BACKGROUND

Hypertonic fluids have potential benefit in the resuscitation of severely injured patients because of rapid restoration of tissue perfusion, with a smaller volume, and modulation of the inflammatory response, to reduce subsequent organ injury.

METHODS

Multicenter, randomized, blinded clinical trial, May 2006 to August 2008, 114 emergency medical services agencies in North America within the Resuscitation Outcomes Consortium.

INCLUSION CRITERIA

injured patients, age ≥ 15 years with hypovolemic shock (systolic blood pressure ≤ 70 mm Hg or systolic blood pressure 71-90 mm Hg with heart rate ≥ 108 beats per minute). Initial resuscitation fluid, 250 mL of either 7.5% saline per 6% dextran 70 (hypertonic saline/dextran, HSD), 7.5% saline (hypertonic saline, HS), or 0.9% saline (normal saline, NS) administered by out-of-hospital providers. Primary outcome was 28-day survival. On the recommendation of the data and safety monitoring board, the study was stopped early (23% of proposed sample size) for futility and potential safety concern.

RESULTS

 : A total of 853 treated patients were enrolled, among whom 62% were with blunt trauma, 38% with penetrating. There was no difference in 28-day survival-HSD: 74.5% (0.1; 95% confidence interval [CI], -7.5 to 7.8); HS: 73.0% (-1.4; 95% CI, -8.7-6.0); and NS: 74.4%, P = 0.91. There was a higher mortality for the postrandomization subgroup of patients who did not receive blood transfusions in the first 24 hours, who received hypertonic fluids compared to NS [28-day mortality-HSD: 10% (5.2; 95% CI, 0.4-10.1); HS: 12.2% (7.4; 95% CI, 2.5-12.2); and NS: 4.8%, P < 0.01].

CONCLUSION

Among injured patients with hypovolemic shock, initial resuscitation fluid treatment with either HS or HSD compared with NS, did not result in superior 28-day survival. However, interpretation of these findings is limited by the early stopping of the trial.

CLINICAL TRIAL REGISTRATION

Clinical Trials.gov, NCT00316017.

Minimally invasive treatment of vesicoureteral reflux with endoscopic injection of dextranomer/hyaluronic acid copolymer: the Children's Hospitals of Atlanta experience

PURPOSE

Emerging data demonstrate that injection of dextranomer/hyaluronic acid (Dx/HA) copolymer (Deflux, Q-Med Scandinavia, Uppsala, Sweden) is a safe and effective treatment for most patients with vesicoureteral reflux (VUR). We sought to determine the efficacy and factors predictive of outcome in patients treated with Dx/HA.

MATERIALS AND METHODS

A total of 180 children 7 months to 15 years old (mean age 4.6 years) underwent subureteral injection of Dx/HA for VUR between October 2001 and February 2003. Dx/HA was injected submucosally within or beneath the intramural ureter. The average volume of injected material was measured for each ureter. At 2 weeks and 3 months postoperatively bladder ultrasounds were performed to measure the volume of Dx/HA (mm3) in the trigone using the volume of an ellipsoid (V = 4/3pir(1)r(2)r(3)). Renal sonography was performed to determine whether hydronephrosis was present. At 3 months fluoroscopic voiding cystourethrograms were used to evaluate for the presence of VUR.

RESULTS

A total of 292 ureters in 180 children were treated (112 bilateral cases). There were 141 girls and 39 boys. Mean maximum grade per patient was 2.6 (out of 5). Average injected volume per ureter was 0.83 +/- 0.03 ml (830 +/- 30 mm3). At 2 weeks the average measured volume was 663 +/- 70 mm3 (18% decrease from original volume), which decreased an additional 1% by 3 months to 656 +/- 103 mm3. There were no cases of hydronephrosis at up to 12 months postoperatively.There were 134 patients with at least 3 months of followup. After 1 treatment 72% (96) were cured (grade 0), while 55% of the failures (21 of 38) were improved. New contralateral VUR was seen in 6 patients (4.5%) who had neither a history of VUR nor an abnormal appearing ureteral orifice at cystoscopy. A lower success rate (60%) was seen in the first 20 patients compared with the last 20 patients (80%). The cure rate per grade was 90% for grade I, 82% for grade II, 73% for grade III and 65% for grade IV reflux. Local migration of material caudal to the ureteral orifice was seen in 61% of patients (11 of 18) at the time of reinjection of Dx/HA after initial treatment failure. There was no statistically significant difference in age, grade, volume injected, bilaterality or gender when successes were compared with failures.

CONCLUSIONS

The majority of patients (72%) undergoing minimally invasive treatment of VUR with Dx/HA are cured after 1 treatment. Contralateral treatment of nonrefluxing ureters should be considered in view of the increased incidence of new reflux (4.5%) and absence of morbidity with Dx/HA injection. There is a definite learning curve with injection therapy. The location of injected material and experience with the technique appear to correlate with the outcome of the procedure.

3% NaCl and 7.5% NaCl/dextran 70 in the resuscitation of severely injured patients

Cardiovascular resuscitation of the severely injured patient in the field remains unsatisfactory because large volumes of intravenous fluid are needed to keep up with ongoing blood losses and because only small volumes of fluid can be given. In the first study reported here, small volumes (less than or equal to 12 mL/kg) of 3% NaCl were given to patients who were having surgery for severe injuries. The 3% NaCl restored blood pressure, pH, and urine output with approximately one half of the cumulative fluid requirement of patients who received isotonic fluids (p less than 0.05). In a second study, 7.5% NaCl/dextran 70, 250 mL, was given in a prospective, randomized, and double-blinded trial to injured patients in the field. Blood pressure in the hypertonic/hyperoncotic group increased 49 mmHg during transport (p less than 0.005); blood pressure in patients given lactated Ringer's solution increased 19 mmHg (NS). Survival favored the hypertonic/hyperoncotic group. The 7.5% NaCl/dextran 70 solution appears particularly promising for treatment of injured patients in the field.

A Systematic Review of the Comparative Safety of Colloids

HYPOTHESIS

Safety differences exist among colloids widely used for fluid management in acutely ill patients, as judged according to the comparative incidence of adverse events.

DATA SOURCES

Colloid safety data for human subjects were sought, without language or time period restrictions, by means of computer searches of bibliographic and clinical trial databases, hand searches of medical journals and Index Medicus, inquiries with investigators and colloid suppliers, and examination of reference lists. Search terms included "colloids", "morbidity", and "mortality".

STUDY SELECTION

Controlled trials, cohort studies, pharmacovigilance studies, and prior meta-analyses were independently selected by 2 unblinded investigators. Of 189 candidate studies, 113 were included, with safety data encompassing 1.54 x 10(6) patients and 1.09 x 10(8) colloid infusions.

DATA EXTRACTION

Two unblinded investigators independently extracted data. Study limitations and confounding factors were tabulated.

DATA SYNTHESIS

With albumin as the reference colloid, the incidence rate ratio for anaphylactoid reactions was 4.51 (95% confidence interval, 2.06-9.89) after hydroxyethyl starch administration, 2.32 (95% confidence interval, 1.21-4.45) after dextran, and 12.4 (95% confidence interval, 6.40-24.0) after gelatin. Pruritus occurrence was significantly increased by hydroxyethyl starch exposure (odds ratio, 1.78; 95% confidence interval, 1.23-2.58). Artificial colloid administration was consistently associated with coagulopathy and clinical bleeding, most frequently in cardiac surgery patients receiving hydroxyethyl starch. On the basis of large-scale pharmacovigilance study results, albumin infusion resulted in a low rate of both total adverse events (3.1 to 8.6 per 10(5) infusions) and serious adverse events (1.29 per 10(6) infusions).

CONCLUSIONS

Significant safety differences exist among colloids. Therefore, conclusions regarding the clinical usefulness of colloids as a fluid class should be formed with caution.

Normothermic perfusion of donor lungs for preservation and assessment with the Organ Care System Lung before bilateral transplantation: a pilot study of 12 patients

BACKGROUND

Cold flush and static cold storage is the standard preservation technique for donor lungs before transplantations. Several research groups have assessed normothermic perfusion of donor lungs but all devices investigated were non-portable. We report first-in-man experience of the portable Organ Care System (OCS) Lung device for concomitant preservation, assessment, and transport of donor lungs.

METHODS

Between Feb 18, and July 1, 2011, 12 patients were transplanted at two academic lung transplantation centres in Hanover, Germany and Madrid, Spain. Lungs were perfused with low-potassium dextran solution, explanted, immediately connected to the OCS Lung, perfused with Steen's solution supplemented with two red-cell concentrates. We assessed donor and recipient characteristics and monitored extended criteria donor lung scores; primary graft dysfunction scores at 0, 24, 48, and 72 h; time on mechanical ventilation after surgery; length of stays in hospital and the intensive-care unit after surgery; blood gases; and survival of grafts and patients.

FINDINGS

Eight donors were female and four were male (mean age 44·5 years, range 14-72). Seven recipients were female and five were male (mean age 50·0 years, range 31-59). The preharvest donor ratio of partial pressure of oxyen (PaO(2)) to fractional concentration of oxygen in inspired air (F(I)O(2)) was 463·9 (SD 91·4). The final ratio of PaO(2) to F(I)O(2) measured with the OCS Lung was 471·58 (127·9). The difference between these ratios was not significant (p=0·72). All grafts and patients survived to 30 days; all recipients recovered and were discharged from hospital.

INTERPRETATION

Lungs can be safely preserved with the OCS Lung, resulting in complete organ use and successful transplantation in our series of high-risk recipients. In November, 2011, we began recruitment for a prospective, randomised, multicentre trial (INSPIRE) to compare preservation with OCS Lung with standard cold storage.

FUNDING

TransMedics and German Federal Ministry of Education and Research.

Plasma volume changes after infusion of various plasma expanders

In the immediate post-operative period after moderate surgical procedures, 1 litre of a colloid solution or saline was given intravenously. The plasma volume expansion after infusion of dextran 70 (Macrodex), hydroxyethylstarch (Volex), polygelatin (Haemaccel), albumin and saline was found to be between 790 and 180 ml. The most efficent plasma expander was dextran, followed by hydroxyethylstarch. Polygelatin and saline did not give full restitution, although twice the calculated loss was infused. Total plasma protein concentration was lowered in all groups in proportion to the dilution, except for the patients given albumin, in whom the concentration of total protein increased. Calculation of the total circulating protein mass showed no decrease during the period immediately after the infusion. This investigation has demonstrated that the most efficient plasma volume expander is dextran but that hydroxyethylstarch offers an almost equal alternative in terms of volume expansion. Dextran, however, exerts an advantageous effect on the microcirculation. As the metabolic pathways of hydroxyethylstarch have not yet been further explored, dextran is preferred when using artificial colloids. Judged by its secondary effects alone, including the influence on plasma protein patterns, albumin seems to be the compound of choice. Polygelatin and saline are not efficient expanders when hypovolaemia is to be corrected rapidly.

Dynamic aspects of acute mitral regurgitation: effects of ventricular volume, pressure and contractility on the effective regurgitant orifice area

The dynamics of acute mitral regurgitation were studied in six open-chest dogs in whom a portion of the anterior leaflet was excised. Phasic mitral and aortic flows were measured electromagnetically and left ventricular filling volume, regurgitant volume (RV) and forward stroke volume (SV) were calculated. The systolic pressure gradient (SPG) between the left ventricle (LV) and left atrium (LA) was obtained from high-fidelity pressure transducers. The effective mitral regurgitant orifice area (MRA) was calculated from the hydraulic equation of Gorlin. Volume infusion resulted in significant increases in both left atrial and left ventricular pressures; thus, the SPG was unchanged and the increase in RV was due primarily to the increase in MRA. Angiotensin infused to raise arterial pressure resulted in greater increments in left ventricular than left atrial pressure, so that SPG rose significantly. The increase in RV was due to increases in both MRA and SPG. Norepinephrine infusion increased systolic left ventricular pressure and SPG, while left ventricular end-diastolic pressure and left atrial pressure diminished. Despite a significant increase in SPG, RV did not increase, due to a substantial decrease in MRA. Thus, angiotensin and volume infusion induced a substantial increase in regurgitation due to the increase in MRA, while augmentation of contractility after norepinephrine infusion resulted in a decrease in regurgitation through reduction of MRA. These findings support the clinical view that maintaining a small LV with sustained myocardial contractility will reduce mitral regurgitation. Alternatively, left ventricular dilatation can enhance mitral regurgitation by increasing the effective regurgitant orifice independent of SPG.

Molecules of various pharmacologically-relevant sizes can cross the ultrasound-induced blood-brain barrier opening in vivo

Focused ultrasound (FUS) is hereby shown to noninvasively and selectively deliver compounds at pharmacologically relevant molecular weights through the opened blood-brain barrier (BBB). A complete examination on the size of the FUS-induced BBB opening, the spatial distribution of the delivered agents and its dependence on the agent's molecular weight were imaged and quantified using fluorescence microscopy. BBB opening in mice (n=13) was achieved in vivo after systemic administration of microbubbles and subsequent application of pulsed FUS (frequency: 1.525MHz, peak-rarefactional pressure in situ: 570 kPa) to the left murine hippocampus through the intact skin and skull. BBB-impermeant, fluorescent-tagged dextrans at three distinct molecular weights spanning over several orders of magnitude were systemically administered and acted as model therapeutic compounds. First, dextrans of 3 and 70 kDa were delivered trans-BBB while 2000 kDa dextran was not. Second, compared with 70 kDa dextran, a higher concentration of 3 kDa dextran was delivered through the opened BBB. Third, the 3 and 70 kDa dextrans were both diffusely distributed throughout the targeted brain region. However, high concentrations of 70 kDa dextran appeared more punctated throughout the targeted region. In conclusion, FUS combined with microbubbles opened the BBB sufficiently to allow passage of compounds of at least 70 kDa, but not greater than 2000 kDa into the brain parenchyma. This noninvasive and localized BBB opening technique could, thus, provide a unique means for the delivery of compounds of several magnitudes of kDa that include agents with shown therapeutic promise in vitro but whose in vivo translation has been hampered by their associated BBB impermeability. (E-mail: ek2191@columbia.edu).

Prophylaxis of venous thromboembolism: analysis of cost effectiveness

The rapidly expanding literature regarding prevention of venous thromboembolism is confusing and contradictory, but, when analysed in the aggregate, the collective experience permits a judgment about the relative efficacy of different prophylactic regimens in specific patient populations, who vary in the risk factors predisposing them to thromboembolism. The dollar cost of the several approaches to prevention and their consequences should also be a matter of concern. Efficacy and dollar cost together determine cost effectiveness, which provides a practical guide to selection of the prophylactic approach appropriate to an individual patient.

Hemostatic factors and replacement of major blood loss with plasma-poor red cell concentrates

The purpose of this study was to assess the change of platelet and fibrinogen concentrations and the change of activities of prothrombin and factors V and VII when major surgical blood loss was replaced with plasma-poor red cell concentrates (RCCs) and colloid plasma substitutes. Sixty patients were studied. The average blood loss was 65% +/- 41% of the calculated blood volume (CBV). Blood loss was monitored carefully and replaced without delay to ensure stable blood volume. Blood samples were obtained at the induction of anesthesia and at the end of the recovery room period, or before the patient was given fresh frozen plasma. In addition, a platelet count was determined after each 20% blood loss. The results were converted to relative values, and simple linear regression with logarithmic transformation was applied. The initial platelet concentration was 257 +/- 89 x 10(3)/mm3 and the extrapolation of the regression line intercepted the critical level of 50 x 10(3)/mm3 at 230% (confidence interval 169%-294%) blood loss. The initial fibrinogen concentration was 3.7 +/- 1.1 g/L and the hemostatically significant level of 1.0 g/L was already reached at 142% (117%-169%) blood loss (r2 = 0.90). Activities of prothrombin and coagulation factors V and VII reached their critical levels at 201% (160%-244%), 229% (167%-300%), and 236% (198%-277%) blood loss, respectively. We conclude that deficiency of fibrinogen develops earlier than any other hemostatic abnormality when plasma-poor RCCs are used for the replacement of major blood loss.

A randomized controlled trial of hemodilution therapy in acute ischemic stroke

Rapid hemodilution in the early phase of ischemic stroke by the combination of venesection (250-650 ml during the first 2 days) and administration of low-molecular weight dextran was evaluated in a prospective controlled trial. Fifty-two patients were randomized to hemodilution therapy and 50 to a control group; the two groups were comparable in important prognostic variables. Mean hemoglobin was reduced from 147 to 127 g/l, hematocrit from 43 to 37% and, in a subsample of patients, whole-blood viscosity at a shear rate of 23 sec-1 from 7.0 to 4.3 cps over the first 2 days. Hemodilution was then maintained by repeated dextran infusions. Of the hemodiluted patients, 85% improved in neurological scoring over the first 10 days as compared to 64% of the control patients (p less than 0.025). The case fatality rate during the first 3 months was little affected by hemodilution. Among the survivors, 8% of the hemodiluted and 31% of the non-hemodiluted patients were unable to walk at 3 months. The proportion of surviving patients still hospitalized at the 3-month follow-up was 13% in the hemodilution group and 39% in the control group (p less than 0.01). The combination of venesection and dextran 40 administration is thus an unsophisticated but effective way to achieve rapid hemodilution in patients with acute cerebral infarction, and it improves the overall clinical outcome over the first 3 months.

Treatment of Vesicoureteral Reflux by Endoscopic Injection of Dextranomer/Hyaluronic Acid Copolymer: Preliminary Results

PURPOSE

Endoscopic subureteral injection of tissue augmenting substances has become an established alternative to long-term antibiotic prophylaxis and open surgery for the management of vesicoureteral reflux (VUR) in children. Recently, dextranomer/hyaluronic acid copolymer (Deflux, Q-Med AB, Uppsala, Sweden) a biodegradable injectable material has been reported to be a promising alternative to other tissue augmenting substances. However, the experience with dextranomer/hyaluronic acid copolymer is limited. We prospectively evaluate the effectiveness of dextranomer/hyaluronic acid copolymer in the endoscopic treatment of VUR.

MATERIALS AND METHODS

A total of 32 males and 81 females with a median age of 1 year (range 3 months to 10 years) underwent endoscopic correction of primary VUR with dextranomer/hyaluronic acid copolymer. Reflux was unilateral in 58 cases and bilateral in 54, affecting 166 ureters. Reflux was grades II to V in 7 (4.2%) cases, 91 (54.8%), 63 (38%) and 5 (3%), respectively. All patients underwent endoscopic correction as a day procedure and have been followed for 3 months to 1 year.

RESULTS

The reflux was corrected in 143 (86%) of the 166 ureters after a single injection, and resolved after a second and third injection in 22 (13%) and 1 (1%) ureter, respectively. No untoward effects were seen in any of these patients with the use of dextranomer/hyaluronic acid copolymer as an injectable material.

CONCLUSIONS

Dextranomer/hyaluronic acid copolymer is an effective tissue augmenting substance in the endoscopic treatment of all grades of VUR.

Intravenous iron dextran in clinical medicine

Four hundred seventy-one adult patients and ten adult prisoner volunteers received 2,099 intravenous (IV) injections of iron dextran (Imferon), usually 250 to 500 mg at less than 100 mg/min. Intravenous iron supplies enough iron to permit RBC formation greater than 50 mL/day and repletion of tissue iron. Tissue iron did not always supply iron at an optimal rate. Hemoglobin production was higher after IV than oral or intramuscular iron if the hemoglobin level was less than 9 g/dL. Three life-threatening immediate anaphylactoid and eight severe delayed reactions were observed. There were no deaths. Delayed reactions were more frequent in women and collagen-vascular diseases and less frequent in pregnancy. Because anaphylactoid reactions are serious and unpredictable, IV iron dextran should be used only when iron deficiency anemia cannot be treated adequately with oral iron.

Rapidly dissolving polymeric microneedles for minimally invasive intraocular drug delivery

In this study, dissolving microneedles (MNs) were used to enhance ocular drug delivery of macromolecules. MNs were fabricated using polyvinylpyrrolidone (PVP) polymer of various molecular weights (MWs) containing three model molecules of increasing MW, namely fluorescein sodium and fluorescein isothiocyanate-dextrans (with MW of 70 k and 150 k Da). Arrays (3 × 3) of PVP MNs with conical shape measuring about 800 μm in height with a 300 μm base diameter, containing the model drugs, were fabricated and characterized for their fracture forces, insertion forces (in the sclera and cornea), depth of penetration (using OCT and confocal imaging), dissolution time and in vitro permeation. The average drug content of the MNs (only in MN shafts) ranged from 0.96 to 9.91 μg, and the average moisture content was below 11 %. High MW PVP produced MNs that can withstand higher forces with minimal reduction in needle height. PVP MNs showed rapid dissolution that ranged from 10 to 180 s, which was dependent upon PVP's MW. In vitro studies showed significant enhancement of macromolecule permeation when MNs were used, across both the corneal and scleral tissues, in comparison to topically applied aqueous solutions. Confocal images showed that the macromolecules formed depots within the tissues, which led to sustained permeation. However, use of MNs did not significantly benefit the permeation of small molecules; nevertheless, MN application has the potential for drug retention within the selected ocular tissues unlike topical application for small molecules. The material used in the fabrication of the MNs was found to be biocompatible with retinal cells (i.e. ARPE-19). Overall, this study reported the design and fabrication of minimally invasive rapidly dissolving polymeric MN arrays which were able to deliver high MW molecules to the eye via the intrastromal or intrascleral route. Thus, dissolving MNs have potential applications in enhancing ocular delivery of both small and macromolecules.

Colon Targeted Delivery Systems: Review of Polysaccharides for Encapsulation and Delivery

Colon-targeted delivery of bioactives has recently gained importance in addressing specific needs in the therapy of colon-based diseases. Many approaches have been attempted for the development of colon-specific delivery systems, with not much success in the past. Recent research into the utilization of the metabolic activity and the colonic microenvironment in the lower gastrointestinal tract has attained great value in the design of novel colon-targeted delivery systems based on natural biodegradable polymers. In the current article, special emphasis has been placed on polysaccharide systems, with minimal chemical modification, that have been exploitedfor colon targeting. These polysaccharide based encapsulation and targeted delivery systems are envisaged to have an immense potential for the development of food/nutraceutical formulations for colon-based diseases, including colorectal cancer.

Long-circulating nanoparticles bearing heparin or dextran covalently bound to poly(methyl methacrylate)

PURPOSE

In a biomimetic approach to the development of drug carriers escaping early capture by phagocytes, nanoparticles made of amphiphilic copolymers of either heparin or dextran and methyl methacrylate were evaluated relative to their in vivo blood circulation time. They were compared to bare PMMA nanoparticles.

METHODS

Owing to the fluorescent properties of the covalently attached N-vinyl carbazole, the particles could be detected directly in mouse plasma. Samples were drawn at different time intervals and fluorescence was recorded.

RESULTS

After an initial phase of elimination from the blood with a half-life of 5 h, the remaining heparin nanoparticles circulated for more than 48 h and were still detectable in the plasma at 72 h. Dextran nanoparticles were also eliminated very slowly over 48 h. Bare poly (methyl methacrylate) nanoparticles were found to have a half-life of only 3 min.

CONCLUSIONS

Both types of nanoparticles proved to be long-circulating. The potent capacity for opsonisation of the poly(methyl methacrylate) core were hidden by the protective effect of either polysaccharide, probably due to a dense brush-like structure. In the case of heparin nanoparticles, the "stealth" effect was probably increased by its inhibiting properties against complement activation.

A robust microparticle platform for a STING-targeted adjuvant that enhances both humoral and cellular immunity during vaccination

Most FDA-approved adjuvants for infectious agents boost humoral but not cellular immunity, and have poorly-understood mechanisms. Stimulator of interferon genes (STING, also known as MITA, MPYS, or ERIS) is an exciting adjuvant target due to its role in cyclic dinucleotide (CDN)-driven anti-viral immunity; however, a major hindrance is STING's cytosolic localization which requires intracellular delivery of its agonists. As a result, STING agonists administered in a soluble form have elicited suboptimal immune responses. Delivery of STING agonists via particle platforms has proven a more successful strategy, but the opportunity for improved formulations and bioactivity remains. In this study we evaluated the adjuvant activity of the potent STING agonist, CDN 3'3'-cGAMP (cGAMP), encapsulated in acid-sensitive acetalated dextran (Ace-DEX) polymeric microparticles (MPs) which passively target antigen-presenting cells for intracellular release. This formulation was superior to all particle delivery systems evaluated and maintained its bioactivity following a sterilizing dose of gamma irradiation. Compared to soluble cGAMP, the Ace-DEX cGAMP MPs enhanced type-I interferon responses nearly 1000-fold in vitro and 50-fold in vivo, caused up to a 104-fold boost in antibody titers, increased Th1-associated responses, and expanded germinal center B cells and memory T cells. Furthermore, the encapsulated cGAMP elicited no observable toxicity in animals and achieved protective immunity against a lethal influenza challenge seven months post-immunization when using CDN adjuvant doses up to 100-fold lower than previous reports. For these reasons, Ace-DEX MP-encapsulated cGAMP represents a potent vaccine adjuvant of humoral and cellular immunity.

Hemodynamic effects of fluid loading in acute massive pulmonary embolism

OBJECTIVE

To assess the hemodynamic effects of fluid loading in patients with acute circulatory failure caused by acute massive pulmonary embolism (AMPE).

DESIGN

Prospective study.

SETTING

Respiratory critical care unit of a university hospital.

PATIENTS

Thirteen patients free of previous cardiopulmonary disease with angiographically proven AMPE (Miller index = 24 +/- 1), with acute circulatory failure defined by a cardiac index (CI) lower than 2.5 L/min/m2.

INTERVENTION

Infusion of 500 mL of dextran 40 over 20 mins.

MEASUREMENTS AND MAIN RESULTS

Fluid loading induced a substantial increase in right atrial pressure from 9 +/- 1 mm Hg to 17 +/- 1 mm Hg and in right ventricular end-diastolic volume index from 123 +/- 14 mL/m2 to 150 +/- 11 mL/m2 (p < .05 for both comparisons). The increase in right ventricular preload was associated with an increase in Cl from 1.6 +/- 0.1 to 2.0 +/- 0.1 L/min/m2 (p < .05), whereas right ventricular ejection fraction (15 +/- 3% at baseline vs. 16 +/- 3% after fluid loading) and total pulmonary vascular resistance index (1689 +/- 187 dyne x sec/cm5 x m2 at baseline vs. 1492 +/- 166 dyne x sec/ cm5 x m2 after fluid loading) remained unchanged. The increase in Cl induced by fluid loading was inversely correlated to baseline right ventricular end-diastolic volume index (r = -.89 ; p< .05).

CONCLUSIONS

These results suggest that fluid loading can improve hemodynamic status in patients with acute circulatory failure caused by AMPE.