Synergy Assessment of Four Antimicrobial Bioactive Compounds for the Combinational Treatment of Bacterial Pathogens

Antimicrobial resistance (AMR) has become a topic of great concern in recent years, with much effort being committed to developing alternative treatments for resistant bacterial pathogens. Drug combinational therapies have been a major area of research for several years, with modern iterations using combining well-established antibiotics and other antimicrobials with the aim of discovering complementary mechanisms. Previously, we characterised four GRAS antimicrobials that can withstand thermal polymer extrusion processes for novel medical device-based and therapeutic applications. In the present study, four antimicrobial bioactive-silver nitrate, nisin, chitosan and zinc oxide-were assessed for their potential combined use as an alternative synergistic treatment for AMR bacteria via a broth microdilution assay based on a checkerboard format. The bioactives were tested in arrangements of two-, three- and four-drug combinations, and their interactions were determined and expressed in terms of a synergy score. Results have revealed interesting interactions based on treatments against recognised test bacterial strains that cause human and animal infections, namely E. coli, S. aureus and S. epidermidis. Silver nitrate was seen to greatly enhance the efficacy of its paired treatment. Combinations with nisin, which is a lantibiotic, exhibited the most interesting results, as nisin has no effect against Gram-negative bacteria when used alone; however, it demonstrated antimicrobial effects when combined with silver nitrate or chitosan. This study constitutes the first study to both report on practical three- and four-drug combinational assays and utilise these methods for the assessment of established and emerging antimicrobials. The novel methods and results presented in this study show the potential to explore previously unknown drug combination compatibility measures in an ease-of-use- and high-throughput-based format, which can greatly help future research that aims to identify appropriate alternative treatments for AMR, including the screening of potential new bioactives biorefined from various sources.

Development of a low-temperature extrusion process for production of GRAS bioactive-polymer loaded compounds for targeting antimicrobial-resistant (AMR) bacteria

Antimicrobial resistance (AMR) is recognised globally as one of the greatest threats to human and animal health; thus, discovery of alternative antibacterial agents to address AMR is a priority challenge. This study constitutes the first report of a low-melting temperature, polymer- extrusion process for the smart delivery of thermally-sensitive antimicrobial bioactives, including generally-regarded-as-safe (GRAS) bioactives derived from various sources. Bioactives were assessed before and after extrusion by determining their respective minimum inhibitory concentrations (MIC). WHO-priority AMR-bacterial isolates causing zoonotic infections were evaluated along with use of standard ATCC strains. Findings revealed that this copolymer method was capable of delivering thermally-sensitive bioactives with varying degrees of growth inhibition against the AMR-bacterial strains. The extrusion process was found to increase the effect of nisin against MRSA (4-fold increase) and L. monocytogenes (6.4-fold increase), silver nitrate (AgNO₃) against E. coli (3.6-fold increase) and S. epidermidis (1.25-fold increase), and chitosan against S. aureus (1.25-fold). Findings show the potential applicability of this polymer extrusion process for developing future bioactive-loaded polymer compounds; thus, highlighting the potential of converging bio-based industry with novel materials for enabling 'One-Health' solutions.

A Bilayer Vaginal Tablet for the Localized Delivery of Disulfiram and 5-Fluorouracil to the Cervix

This study was performed to develop an adjuvant therapy in the form of a self-administered vaginal tablet regimen for the localized delivery of chemotherapeutic drugs. This therapy will help to reduce relapse by eradicating cancerous cells in the margin of cervical tumors. The vaginal tablet is a very common formulation that is easy to manufacture, easy to place in the vagina, and has a low cost of manufacture, making them ideal for use in developing countries. A combination of disulfiram and 5-fluorouracil, which are both off-patent drugs and provide different modes of action, were evaluated. The tablets developed were evaluated for weight variation, thickness, hardness, friability, swelling index, differential scanning calorimetry (DSC), particle morphology, in vitro drug release, and cytotoxicity on Ca-Ski cells. Both layers were designed to release both drugs concurrently for a synergistic effect. The polymer–polymer interaction between the layers was able to reduce the loss of formulation due to chitosan. While the bilayer tablet had satisfactory performance in the physicochemical tests, in vitro cell culture with Ca-Ski also showed a synergistic effect using a combination of drugs at a low dose. However, the formulation only had 24-h dose release before degradation. Further drug combinations should be evaluated in subsequent studies.

Year-Round Monitoring of Contaminants in Neal and Rogers Creeks, Hood River Basin, Oregon, 2011-12, and Assessment of Risks to Salmonids

Pesticide presence in streams is a potential threat to Endangered Species Act listed salmonids in the Hood River basin, Oregon, a primarily forested and agricultural basin. Two types of passive samplers, polar organic chemical integrative samplers (POCIS) and semipermeable membrane devices (SPMDs), were simultaneously deployed at four sites in the basin during Mar. 2011-Mar. 2012 to measure the presence of pesticides, polybrominated diphenyl ethers (PBDEs), and polychlorinated biphenyls (PCBs). The year-round use of passive samplers is a novel approach and offers several new insights. Currently used pesticides and legacy contaminants, including many chlorinated pesticides and PBDEs, were present throughout the year in the basin's streams. PCBs were not detected. Time-weighted average water concentrations for the 2-month deployment periods were estimated from concentrations of chemicals measured in the passive samplers. Currently used pesticide concentrations peaked during spring and were detected beyond their seasons of expected use. Summed concentrations of legacy contaminants in Neal Creek were highest during July-Sept., the period with the lowest streamflows. Endosulfan was the only pesticide detected in passive samplers at concentrations exceeding Oregon or U.S. Environmental Protection Agency water-quality thresholds. A Sensitive Pesticide Toxicity Index (SPTI) was used to estimate the relative acute potential toxicity among sample mixtures. The acute potential toxicity of the detected mixtures was likely greater for invertebrates than for fish and for all samples in Neal Creek compared to Rogers Creek, but the indices appear to be low overall (<0.1). Endosulfans and pyrethroid insecticides were the largest contributors to the SPTIs for both sites. SPTIs of some discrete (grab) samples from the basin that were used for comparison exceeded 0.1 when some insecticides (azinphos methyl, chlorpyrifos, malathion) were detected at concentrations near or exceeding acute water-quality thresholds. Early life stages and adults of several sensitive fish species, including salmonids, are present in surface waters of the basin throughout the year, including during periods of peak estimated potential toxicity. Based on these data, direct toxicity to salmonids from in-stream pesticide exposure is unlikely, but indirect impacts (reduced fitness due to cumulative exposures or negative impacts to invertebrate prey populations) are unknown.

Imprinting and expression of Dio3os mirrors Dio3 in rat

Genomic imprinting, the preferential expression of maternal or paternal alleles of imprinted genes, is often maintained through expression of imprinted long non-coding (lnc) “antisense” RNAs. These may overlap imprinted transcripts, and are expressed from the opposite allele. Previously we have described brain region-specific imprinted expression of the Dio3 gene in rat, which is preferentially modified by fetal ethanol exposure. The Dio3os (opposite strand) transcript is transcribed in opposite orientation to Dio3 in mouse and human, partially overlaps the Dio3 promoter, and mirrors total Dio3 developmental expression levels. Here, we present that the rat Dio3os transcript(s) exhibits brain region-specific imprinted expression patterns similar to those of Dio3. Rat Dio3os transcript expression is also similarly modified by fetal ethanol exposure. Uniquely, both Dio3 and Dio3os expression occur on the same, rather than opposite, alleles, as determined by strand-specific RT-PCR. Future studies will require direct manipulation of the Dio3os transcript to determine whether the novel paralleling of total and allele-specific expression patterns of this sense/antisense imprinted gene pair reflects an as-yet undefined regulatory mechanism for lncRNA mediated tissue-specific imprinted expression, or rather is a consequence of a more straightforward, but previously undescribed transcriptional coregulation process.

In vivo myocardial infarct area at risk assessment in the rat using manganese enhanced magnetic resonance imaging (MEMRI) at 1.5T

The aim of this study was to measure the myocardial area at risk in rat, using MRI and manganese injection during a coronary occlusion/reperfusion model at 1.5T. A sequential protocol with occlusion and MnCl2 injection immediately followed by MRI was used with the assumption that MnCl2-induced contrast persistence is enough to accurately image the area at risk 90 min after occlusion. A total of 15 adult rats underwent a single 30-min episode of coronary occlusion followed by reperfusion. MnCl2 was injected (25 micromol/kg) at the beginning of the occlusion for 11 rats (group 1) and 6 h after reperfusion for four animals (group 2). A deficit of signal enhancement was observed in all rats. Hypoenhancement area in group 1 was correlated to the area at risk delineated by methylene blue (r=0.96, P<0.0001) whereas in group 2 it was correlated to the infarct area given by triphenyltetrazolium chloride (TTC) solution (r=0.98, P=0.003). The area at risk size was significantly correlated with left ventricle ejection fraction (LVEF), end-systolic volume and anterolateral wall thickening. This work demonstrates that hypoenhanced zone obtained after manganese injection during occlusion represents the area at risk and not only the infarct zone.

Pre-hospital discharge car safety seat testing in infants following congenital heart surgery

The purpose of this study was to expand the American Academy of Pediatrics' (AAP) car safety seat testing recommendation to include high-risk infants following cardiac surgery. Car safety seat testing (< or =4 days prior to discharge) was retrospectively reviewed for 66 postoperative infants. Car safety seat testing was performed according to AAP guidelines. Failure of the test was defined as the occurrence of apnea, bradycardia, or oxygen desaturation. Average birth weight was 3.1 +/- 0.5 kg. Two patients were born <37 weeks of gestation. Surgical procedures included modified Blalock-Taussig shunt (15), arterial switch operation (12), Norwood-Sano modification (11), coarctation repair (8), repair of tetralogy of Fallot (6), repair of truncus arteriosus (4), repair of total anomalous pulmonary venous return (3), pacemaker (2), repair of interrupted aortic arch and ventricular septal defect (VSD) (1), repair of coarctation/VSD (1), orthotopic heart transplant (1), repair of VSD (1), and patent ductus arteriosus ligation (1). Average age at discharge was 28 +/- 21 days. Four patients (6%) failed car safety seat testing secondary to a decrease in oxygen saturation. One of four passed on retesting after parental education; three of 4 (75%) were discharged home in a supine car safety seat. There was no relationship between the type of surgery and car safety seat test failure. It may be beneficial to extend the AAP recommendations for car safety seat testing to include this high-risk patient population.

Prehospital discharge car safety seat testing of infants after congenital heart surgery

BACKGROUND

This study aimed to expand the American Academy of Pediatrics (AAP) car safety seat testing recommendation to include high-risk infants after cardiac surgery.

METHODS

Car safety seat testing (< or =4 days before discharge), performed according to AAP guidelines, was retrospectively reviewed for 66 postoperative infants. Failure was defined as apnea, bradycardia, or oxygen desaturation.

RESULTS

The average birth weight of the study infants was 3.1 +/- 0.5 kg. Two patients were born at less than 37 weeks gestation. Surgical procedures included modified Blalock-Taussig shunt technique (n = 15), arterial switch operation (n = 12), Norwood Sano modification (n = 11), coarctation repair (n = 8), repair of tetralogy of Fallot (n = 6), repair of truncus arteriosus (n = 4), repair of total anomalous pulmonary venous return (n = 3), pacemaker placement (n = 2), repair of interrupted aortic arch and ventriculoseptal defect (VSD) (n = 1), repair of coarctation and VSD (n = 1), orthotopic heart transplant (n = 1), repair of VSD (n = 1), and patent ductus arteriosus ligation (n = 1). The average age at discharge was 28 +/- 21 days. Four patients (6%) failed car safety seat testing because of a fall in oxygen saturation. One of the four patients passed on retesting after parental education, whereas three of the four (75%) were discharged home in a supine car safety seat. There was no relationship between the type of surgery and car safety seat test failure.

CONCLUSION

It may be beneficial to extend the AAP recommendations for car safety seat testing to include high-risk infants after cardiac surgery.

Effect of brushing with sonic and counterrotational toothbrushes on the bond strength of orthodontic brackets

The purpose of this study was to evaluate the effect of brushing with both a sonic and mechanical counter rotary power toothbrush on the bond strength of orthodontic brackets. Forty-five extracted teeth were divided into three random groups and had orthodontic brackets bonded to them. One group was brushed with a counterrotational toothbrush, the Interplak, one group with a sonic toothbrush, the Sonicare, and a third group was not brushed and was held as a control. After the equivalent of 2 years brushing, the teeth were placed in an Instron machine and the shear force to remove the brackets was recorded. Group 1, the counter rotary power brush, had a mean of 107.5 kg/cm2, the second group, the sonic brush, had a mean of 79.7 kg/cm2, and the control group had a mean of 125. 4 kg/cm2. Single factor analysis of variance followed by the Fisher-Hayter Multiple Comparison Procedure showed a statistically significant difference between the sonic power brush and the control (P <.01), but no significant difference between the counter rotary and the control (P >.05). There was no significant difference between the two power brushes (P >.05).

Suicide by jumping from high-rise hotels. Fulton County, Georgia, 1967-1986

During a 20-year period from 1967 through 1986, 19 suicidal jumps from high-rise hotels (HRHs) accounted for 24% of all fatal jumping episodes and 1% of all suicides in Fulton County, Georgia, U.S.A. The rate of suicidal jumps from HRHs did not increase during the study period. The number of fatal jumps per hotel-year correlated with the height of the interior hotel atrium. The mean age for all victims was 34 years, and 63% of victims were white males. The majority of victims were local residents who were alone when they jumped and were not registered hotel guests. Registered guests tended to jump from the floor on which their room was located whereas nonregistered individuals tended to jump from the upper-most floors in the hotel. Of 19 HRH jumps, 13 occurred from the inside. Suicide notes were found in 37% of cases. HRH jumps were least common between 6 p.m. and midnight, all decedents were dressed in street clothing, only one was heard to have screamed, and all but one were dead on the scene. Alcohol and drug involvement was minimal. We hope that this information will be useful to those who investigate such deaths and to those who study the behavioral manifestations of suicide.

An intrathoracic left ventricular assist system: utilization of results from a development program

An intrathoracic, electrohydraulically actuated, left ventricular assist system (LVAS) was subjected to formal device readiness testing. Endurance testing was initiated on eight systems before testing was halted due to failure of four of the systems. Three failed due to environmental leakage. Solutions were straightforward, involving gasket changes and o-ring resizing. The fourth failure involved a magnetic coupling piston swelling and seizing. The failure was attributed, after long investigation, to hydrogen adsorption by the samarium-cobalt magnets. An unknown number of coupling magnets were affected in this fashion, necessitating complete replacement of magnets to resolve the problem. However, this was beyond the scope of the program, and no further endurance testing was accomplished. The test experience of the Nimbus/CCF LVAS has demonstrated all functional aspects of the complete LVAS, both in vitro and in vivo, and the endurance and reliability potential is indicated as well. Although the LVAS program is currently inactive, its legacy of technical innovations continue to drive the development of other medical devices.

In vitro and in vivo performance evaluation of a totally implantable electrohydraulic left ventricular assist system

The biolized electrohydraulic left ventricle assist devices were tested in 14 calves with an average survival time of 162 days and as long as 250 days without the use of anticoagulants. In vitro, the system pumped 4.1 L/min at a low 4.8 mmHg fill pressure with a mean afterload of 100 mmHg and rate of 46 bpm. A flow rate of 13.5 L/min was observed at 155 bpm and 110 mmHg afterload. Motor frequency and current increased with increasing flow rate (162 Hz, 0.67 amp at 2.5 L/min; 484 Hz, 2.43 amp at 13.5 L/min). Flow rate did not change significantly with afterload pressure. The complete system was implanted in a 100 kg calf. Synchronization of the blood pump with the natural heart was demonstrated at heart rates of 85 to 167 bpm. The synchronized flow rate varied from 6 to 10.5 L/min despite the considerable heart rate changes and stroke variations. The system hemodynamic performances were acceptable and met NIH requirements.