Role of endothelin ETA receptors in the hypertension induced by the VEGFR-2 kinase inhibitors axitinib and lenvatinib in conscious freely-moving rats

Receptor tyrosine kinase inhibitors (RTKIs) suppress tumour growth by targeting vascular endothelial growth factor receptor 2 (VEGFR-2) which is an important mediator of angiogenesis. Here, we demonstrate that two potent RTKIs, axitinib and lenvatinib, are associated with hypertensive side effects. Doppler flowmetry was used to evaluate regional haemodynamic profiles of axitinib and lenvatinib. Male Sprague Dawley rats (350-500 g) were instrumented with Doppler flow probes (renal and mesenteric arteries and descending abdominal aorta) and catheters (jugular vein and distal abdominal aorta, via the caudal artery). Rats were dosed daily with axitinib (3 or 6 mg.kg-1) or lenvatinib (1 or 3 mg.kg-1) and regional haemodynamics were recorded over a maximum of 4 days. Both RTKIs caused significant (p < 0.05) increases in mean arterial pressure (MAP), which was accompanied by significant (p < 0.05) vasoconstriction in both the mesenteric and hindquarters vascular beds. To gain insight into the involvement of endothelin-1 (ET-1) in RTKI-mediated hypertension, we also monitored heart rate (HR) and MAP in response to axitinib or lenvatinib in animals treated with the ETA receptor selective antagonist sitaxentan (5 mg.kg-1) or the mixed ETA/ETB receptor antagonist bosentan (15 mg.kg-1) over two days. Co-treatment with bosentan or sitaxentan markedly reduced the MAP effects mediated by both RTKIs (p < 0.05). Bosentan, but not sitaxentan, also attenuated ET-1 mediated increases in HR. These data suggest that selective antagonists of ETA receptors may be appropriate to alleviate the hypertensive effects of axitinib and lenvatinib.

Reducing Patient Care Delays in Radiation Oncology via Optimization of Insurance Pre-Authorization

PURPOSE/OBJECTIVE(S)

Difficulties and delays in insurance pre-authorization (pre-auth) can negatively impact patient care, resulting in postponing, modifying, or even cancelling radiation therapy for patients. Unfortunately, pre-auth delays are not uncommon. The purpose of our project was to perform a root cause analysis of reasons for pre-auth delays, and implement solutions to optimize our workflow to better serve our patients. Our primary objectives were to decrease the mean time for clinical treatment plan (CTP) completion, and for number of cases delayed/denied, by 50% each.

MATERIALS/METHODS

We performed a root cause analysis of reasons for pre-auth delays and used the PDSA & A3 quality improvement methods. We sampled ∼2 cases per disease site (total 19 cases from July - Aug 2022) to determine the "current state," pre-interventions. Countermeasures included: 1) customizing our CTP templates for each disease site to contain the specific clinical information required by each insurer, 2) formalizing earlier completion of CTPs through task automation at time of scheduling CT simulation in our Care Path, and 3) continuously refining our countermeasures based on monthly status updates and department meetings. We tracked various physician, authorization, and outcome-metrics between October 2022 and January 2023, including mean time for CTP completion, % usage of our Care Path, % usage of revised CTP templates, mean time until pre-auth initiated & completed, % of cases requiring peer-to-peer phone calls, and % of cases denied/delayed.

RESULTS

There were 417 patients from a variety of disease sites who had a CT simulation at our institution between October 1, 2022, and January 31, 2023. Mean time for CTP completion (from the time of CT simulation request) improved from 16 days at baseline to 7 days by the end of the project. In the beginning, only 5% of CTPs were completed within 2 days of scheduling the CT simulation, and this improved to 42-56% during the project period. Percent usage of the Care Path improved dramatically from 16% to 91%, as did % usage of our revised CTP templates, from 0% to 96%. Despite initial lag in pre-authorization team workflow changes, the % of pre-authorizations initiated by day 3 from CT request improved from 32% at baseline to 48% by month 4. Mean time to complete insurance pre-authorizations improved from 16 days at baseline to 10 days. The percent of cases requiring peer to peer or were denied was reduced significantly from 32% at baseline to 4-11%.

CONCLUSION

Improvingtimeliness and details of CTP documentation by using our Care Path and revising CTP templates improved efficiency of insurance pre-auth completion, and reduced the number of cases delayed/denied.

Effects of axitinib and lenvatinib on cardiovascular function and haemodynamic

Funding Acknowledgements

Type of funding sources: Public grant(s) – EU funding. Main funding source(s): EU Horizon 2020 Research and Innovation programme, under the Marie Skłodowska-Curie European Training Network

Background

The introduction of novel anticancer treatments, targeting vascular endothelial growth factor receptors (VEGFRs), has changed the therapeutic approach in oncology. However, with their introduction in clinical practice, unanticipated cardiovascular complications emerged, including hypertension, left ventricular dysfunction and thromboembolism [1]. Even though these therapeutics strongly affect haemodynamic balance in patients, the pathophysiological mechanisms by which they impair cardiovascular function are still largely unknown, leading to a reduction of therapeutic dosage or to a temporary or permanent treatment interruption [2].

Purpose

The severity of cardiovascular complications following the treatment with VEGFR inhibitors, along with the lack of antihypertensive strategies able to adequately manage these events, require an unequivocal and urgent assessment of their cardiovascular safety. This study aims to determine the extent to which VEGFR inhibitors impact on cardiovascular function, profiling their effect on regional haemodynamic responses. Their cardiovascular assessment represents a valuable opportunity to investigate the mechanisms underlying cardiovascular toxicities induced by these novel antiangiogenic treatments.

Methods

This study evaluated the haemodynamic effects of selected receptor tyrosine kinase inhibitors (RTKIs), namely axitinib and lenvatinib, in conscious and freely moving rats using the Doppler Flowmetry technique. Male Sprague Dawley Rats (350-450 g) were chronically implanted with pulsed Doppler flow probes (around the renal and mesenteric arteries, and the descending abdominal aorta) and catheters (jugular vein and distal abdominal aorta) [3]. Haemodynamic parameters were measured over 4 days, before and after daily administration of axitinib (3 and 6 mg/kg, 3 and 6 mg/kg/h for 1 h, i.v.), or lenvatinib (3 and 6 mg/kg, 3 and 6 mg/kg/h for 1 h, i.v.).

Results

Both axitinib and lenvatinib evoked a significant hypertensive response, which progressively increased over the 4 days. This pressor effect was associated with a notable decrease of vascular conductance in the hindquarters. Lenvatinib caused a more marked vasoconstriction in mesenteric and renal vessels when compared to axitinib, which only elicited a renal vasoconstrictive effect at the highest dose used.

Conclusions

This study showed that the axitinib- and lenvatinib-induced hypertensive response is associated with regionally selective vasoconstrictions, which consistently occur in the hindquarters vascular bed. However, their vasoconstrictive profile differs in the renal and mesenteric vasculature. In addition, the Doppler Flowmetry model showed to be a translational approach to predict the detrimental cardiovascular effects of these anticancer drugs, since the increase in blood pressure observed with this method reflects the hypertensive response reported in clinical practice.

Involvement of β-adrenoceptors in the cardiovascular responses induced by selective adenosine A2A and A2B receptor agonists

A_2A and A_2B adenosine receptors produce regionally selective regulation of vascular tone and elicit differing effects on mean arterial pressure (MAP), whilst inducing tachycardia. The tachycardia induced by the stimulation of A_2A or A_2B receptors has been suggested to be mediated by a reflex increase in sympathetic activity. Here, we have investigated the role of β₁ - and β₂ -adrenoceptors in mediating the different cardiovascular responses to selective A_2A and A_2B receptor stimulation. Hemodynamic variables were measured in conscious male Sprague-Dawley rats (350-450 g) via pulsed Doppler flowmetry. The effect of intravenous infusion (3 min per dose) of the A_2A -selective agonist CGS 21680 (0.1, 0.3, 1.0 µg.kg^-1 .min^-1 ) or the A_2B -selective agonist BAY 60-6583 (4.0, 13.3, 40.0 µg.kg^-1 .min^-1 ) in the absence or following pre-treatment with the non-selective β-antagonist propranolol (1.0 mg.kg^-1 ), the selective β₁ -antagonist CGP 20712A (200 µg.kg^-1 ), or the selective β₂ -antagonist ICI 118,551 (2.0 mg.kg^-1 ) was investigated (maintenance doses also administered). CGP 20712A and propranolol significantly reduced the tachycardic response to CGS 21680, with no change in the effect on MAP. ICI 118,551 increased BAY 60-6583-mediated renal and mesenteric flows, but did not affect the heart rate response. CGP 20712A attenuated the BAY 60-6583-induced tachycardia. These data imply a direct stimulation of the sympathetic activity via cardiac β₁ -adrenoceptors as a mechanism for the A_2A - and A_2B -induced tachycardia. However, the regionally selective effects of A_2B agonists on vascular conductance were independent of sympathetic activity and may be exploitable for the treatment of acute kidney injury and mesenteric ischemia.

Regionally selective cardiovascular responses to adenosine A2A and A2B receptor activation

Adenosine is a local mediator that regulates changes in the cardiovascular system via activation of four G protein-coupled receptors (A₁ , A_2A , A_2B , A₃ ). Here, we have investigated the effect of A_2A and A_2B -selective agonists on vasodilatation in three distinct vascular beds of the rat cardiovascular system. NanoBRET ligand binding studies were used to confirm receptor selectivity. The regional hemodynamic effects of adenosine A_2A and A_2B selective agonists were investigated in conscious rats. Male Sprague-Dawley rats (350-450 g) were chronically implanted with pulsed Doppler flow probes on the renal artery, mesenteric artery, and the descending abdominal aorta. Cardiovascular responses were measured following intravenous infusion (3 min for each dose) of the A_2A -selective agonist CGS 21680 (0.1, 0.3, 1 µg kg^-1 min^-1 ) or the A_2B -selective agonist BAY 60-6583 (4,13.3, 40 µg kg^-1 min^-1 ) following predosing with the A_2A -selective antagonist SCH 58261 (0.1 or 1 mg kg^-1 min^-1 ), the A_2B /A_2A antagonist PSB 1115 (10 mg kg^-1 min^-1 ) or vehicle. The A_2A -selective agonist CGS 21680 produced a striking increase in heart rate (HR) and hindquarters vascular conductance (VC) that was accompanied by a significant decrease in mean arterial pressure (MAP) in conscious rats. In marked contrast, the A_2B -selective agonist BAY 60-6583 significantly increased HR and VC in the renal and mesenteric vascular beds, but not in the hindquarters. Taken together, these data indicate that A_2A and A_2B receptors are regionally selective in their regulation of vascular tone. These results suggest that the development of A_2B receptor agonists to induce vasodilatation in the kidney may provide a good therapeutic approach for the treatment of acute kidney injury.

Incidence and prediction of HBsAg seroclearance in a prospective multi-ethnic HBeAg-negative chronic hepatitis B cohort

BACKGROUND AND AIMS

Achieving HBsAg loss is an important landmark in the natural history of chronic hepatitis B (CHB). A more personalized approach to prediction of HBsAg loss is relevant in counseling patients. This study sought to develop and validate a prediction model for HBsAg loss based on quantitative HBsAg levels (qHBsAg) and other baseline characteristics.

METHODS

The Hepatitis B Research Network (HBRN) is a prospective cohort including 1240 untreated HBeAg-negative patients (1150 adults, 90 children) with median follow-up of 5.5 years. Incidence rates of HBsAg loss and hepatitis B surface antibody (anti-HBs) acquisition were determined, and a predictor score of HBsAg loss using readily available variables was developed and externally validated.

RESULTS

Crude incidence rates of HBsAg loss and anti-HBs acquisition were 1.6 and 1.1 per 100 person-years (PY); 67 achieved sustained HBsAg loss for an incidence rate of 1.2 per 100 PY. Increased HBsAg loss was significantly associated with older age, non-Asian race, HBV phenotype (inactive CHB vs. others), HBV genotype A, lower HBV-DNA levels, and lower and greater change in qHBsAg. The HBRN-SQuARe (sex,∆quantHBsAg, age, race) score predicted HBsAg loss over time with area under the receiver operating characteristic curve (AUROC) (95% CIs) at 1 and 3 years of 0.99 (95% CI: 0.987-1.00) and 0.95 (95% CI 0.91-1.00), respectively. In validation in another cohort of 1253 HBeAg-negative patients with median follow-up of 3.1 years, HBRN SQuARe predicted HBsAg loss at 1 and 3 years with AUROC values of 0.99 (0.98-1.00) and 0.88 (0.77-0.99), respectively.

CONCLUSION

HBsAg loss in predominantly untreated patients with HBeAg-negative CHB can be accurately predicted over a 3-year horizon using a simple validated score (HBRN SQuARe). This prognostication tool can be used to support patient care and counseling.

Monitoring haemodynamic changes in rodent models to better inform safety pharmacology: Novel insights from

Animal models are essential for assessing cardiovascular responses to novel therapeutics. Cardiovascular safety liabilities represent a leading cause of drug attrition and better preclinical measurements are essential to predict drug-related toxicities. Presently, radiotelemetric approaches recording blood pressure are routinely used in preclinical in vivo haemodynamic assessments, providing valuable information on therapy-associated cardiovascular effects. Nonetheless, this technique is chiefly limited to the monitoring of blood pressure and heart rate alone. Alongside these measurements, Doppler flowmetry can provide additional information on the vasculature by simultaneously measuring changes in blood flow in multiple different regional vascular beds. However, due to the time-consuming and expensive nature of this approach, it is not widely used in the industry. Currently, analysis of waveform data obtained from telemetry and Doppler flowmetry typically examines averages or peak values of waveforms. Subtle changes in the morphology and variability of physiological waveforms have previously been shown to be early markers of toxicity and pathology. Therefore, a detailed analysis of pressure and flowmetry waveforms could enhance the understanding of toxicological mechanisms and the ability to translate these preclinical observations to clinical outcomes. In this review, we give an overview of the different approaches to monitor the effects of drugs on cardiovascular parameters (particularly regional blood flow, heart rate and blood pressure) and suggest that further development of waveform analysis could enhance our understanding of safety pharmacology, providing valuable information without increasing the number of in vivo studies needed.

Role of the Renin-Angiotensin-Aldosterone and Kinin-Kallikrein Systems in the Cardiovascular Complications of COVID-19 and Long COVID

Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) is the virus responsible for the COVID-19 pandemic. Patients may present as asymptomatic or demonstrate mild to severe and life-threatening symptoms. Although COVID-19 has a respiratory focus, there are major cardiovascular complications (CVCs) associated with infection. The reported CVCs include myocarditis, heart failure, arrhythmias, thromboembolism and blood pressure abnormalities. These occur, in part, because of dysregulation of the Renin-Angiotensin-Aldosterone System (RAAS) and Kinin-Kallikrein System (KKS). A major route by which SARS-CoV-2 gains cellular entry is via the docking of the viral spike (S) protein to the membrane-bound angiotensin converting enzyme 2 (ACE2). The roles of ACE2 within the cardiovascular and immune systems are vital to ensure homeostasis. The key routes for the development of CVCs and the recently described long COVID have been hypothesised as the direct consequences of the viral S protein/ACE2 axis, downregulation of ACE2 and the resulting damage inflicted by the immune response. Here, we review the impact of COVID-19 on the cardiovascular system, the mechanisms by which dysregulation of the RAAS and KKS can occur following virus infection and the future implications for pharmacological therapies.

The effect of two selective A1 -receptor agonists and the bitopic ligand VCP746 on heart rate and regional vascular conductance in conscious rats

Background and Purpose

Adenosine is a local mediator that regulates physiological and pathological processes via activation of four GPCRs (A₁, A_2A, A_2B, and A₃). We have investigated the effect of two A₁‐receptor‐selective agonists and the novel A₁‐receptor bitopic ligand VCP746 on the rat cardiovascular system.

Experimental Approach

The regional haemodynamic responses of these agonist was investigated in conscious rats. Male Sprague–Dawley rats (350–450 g) were chronically implanted with pulsed Doppler flow probes on the renal, mesenteric arteries and the descending abdominal aorta and the jugular vein and caudal artery catheterized. Cardiovascular responses were measured following intravenous infusion (3 min each dose) of CCPA (120, 400, and 1,200 ng·kg⁻¹·min⁻¹), capadenoson or adenosine (30, 100, and 300 μg·kg⁻¹·min⁻¹), or VCP746 (6, 20, and 60 μg·kg⁻¹·min⁻¹) following pre‐dosing with DPCPX (0.1 mg·kg⁻¹, i.v.) or vehicle.

Key Results

CCPA produced a significant A₁‐receptor‐mediated decrease in heart rate that was accompanied by vasoconstrictions in the renal and mesenteric vascular beds but an increase in hindquarters vascular conductance. The partial agonist capadenoson also produced an A₁‐receptor‐mediated bradycardia. In contrast, VCP746 produced increases in heart rate and renal and mesenteric vascular conductance that were not mediated by A₁‐receptors. In vitro studies confirmed that VCP746 had potent agonist activity at both A_2A‐ and A_2B‐receptors.

Conclusions and Implications

These results suggest VCP746 mediates its cardiovascular effects via activation of A₂ rather than A₁ adenosine receptors. This has implications for the design of future bitopic ligands that incorporate A₁ allosteric ligand moieties.

Long-term cardiovascular effects of vandetanib and pazopanib in normotensive rats

Vandetanib and pazopanib are clinically available, multi-targeted inhibitors of vascular endothelial growth factor (VEGF) and platelet-derived growth factor (PDGF) receptor tyrosine kinases. Short-term VEGF receptor inhibition is associated with hypertension in 15%-60% of patients, which may limit the use of these anticancer therapies over the longer term. To evaluate the longer-term cardiovascular implications of treatment, we investigated the "on"-treatment (21 days) and "off"-treatment (10 days) effects following daily administration of vandetanib, pazopanib, or vehicle, in conscious rats. Cardiovascular variables were monitored in unrestrained Sprague-Dawley rats instrumented with radiotelemetric devices. In Study 1, rats were randomly assigned to receive either daily intraperitoneal injections of vehicle (volume 0.5 mL; n = 5) or vandetanib 25 mg/kg/day (volume 0.5 mL; n = 6). In Study 2, rats received either vehicle (volume 0.5 mL; n = 4) or pazopanib 30 mg/kg/day (volume 0.5 mL; n = 7), dosed once every 24 hours for 21 days. All solutions were in 2% Tween, 5% propylene glycol in 0.9% saline solution. Vandetanib caused sustained increases in mean arterial pressure (MAP), systolic blood pressure (SBP), and diastolic blood pressure (DBP) compared to baseline and vehicle. Vandetanib also significantly altered the circadian cycling of MAP, SBP, and DBP. Elevations in SBP were detectable 162 hours after the last dose of vandetanib. Pazopanib also caused increases in MAP, SBP, and DBP. However, compared to vandetanib, these increases were of slower onset and a smaller magnitude. These data suggest that the cardiovascular consequences of vandetanib and pazopanib treatment are sustained, even after prolonged cessation of drug treatment.

Emergent Vibronic Excitations in the Magnetodielectric Regime of Ce_{2}O_{3}

The strong coupling between spin, lattice, and electronic degrees of freedom in magnetic materials can produce interesting phenomena, including multiferroic and magnetodielectric (MD) behavior, and exotic coupled excitations, such as electromagnons. We present a temperature- and magnetic field-dependent inelastic light (Raman) scattering study that reveals the emergence of vibronic modes, i.e., coupled vibrational and crystal-electric-field (CEF) electronic excitations, in the unconventional rare-earth MD material Ce_{2}O_{3}. The energies and intensities of these emergent vibronic modes are indicative of enhanced vibronic coupling and increased modulation of the dielectric susceptibility in the Néel state (T_{N}≈6.2  K). The field dependences of the energies and intensities of these vibronic modes are consistent with a decrease of both the vibronic coupling and the dielectric fluctuations associated with these modes below T_{N}. These results suggest a distinctive mechanism for MD behavior in Ce_{2}O_{3} that is associated with a field-tunable coupling between CEF and phonon states.

Probe dependence of allosteric enhancers on the binding affinity of adenosine A1 -receptor agonists at rat and human A1 -receptors measured using NanoBRET

BACKGROUND AND PURPOSE

Adenosine is a local mediator that regulates a number of physiological and pathological processes via activation of adenosine A₁ -receptors. The activity of adenosine can be regulated at the level of its target receptor via drugs that bind to an allosteric site on the A₁ -receptor. Here, we have investigated the species and probe dependence of two allosteric modulators on the binding characteristics of fluorescent and nonfluorescent A₁ -receptor agonists.

EXPERIMENTAL APPROACH

A Nano-luciferase (Nluc) BRET (NanoBRET) methodology was used. This used N-terminal Nluc-tagged A₁ -receptors expressed in HEK293T cells in conjunction with both fluorescent A₁ -receptor agonists (adenosine and NECA analogues) and a fluorescent antagonist CA200645.

KEY RESULTS

PD 81,723 and VCP171 elicited positive allosteric effects on the binding affinity of orthosteric agonists at both the rat and human A₁ -receptors that showed clear probe dependence. Thus, the allosteric effect on the highly selective partial agonist capadenoson was much less marked than for the full agonists NECA, adenosine, and CCPA in both species. VCP171 and, to a lesser extent, PD 81,723, also increased the specific binding of three fluorescent A₁ -receptor agonists in a species-dependent manner that involved increases in B_max and pK_D .

CONCLUSIONS AND IMPLICATIONS

These results demonstrate the power of the NanoBRET ligand-binding approach to study the effect of allosteric ligands on the binding of fluorescent agonists to the adenosine A₁ -receptor in intact living cells. Furthermore, our studies suggest that VCP171 and PD 81,723 may switch a proportion of A₁ -receptors to an active agonist conformation (R*).

Nafamostat Mesilate, a Broad Spectrum Protease Inhibitor, Modulates Platelet, Neutrophil and Contact Activation in Simulated Extracorporeal Circulation

Activation of humoral and cellular participants in inflammation enhances the risk of postoperative bleeding and multiple organ damage in cardiopulmonary bypass (CPB). We now compare the effects of heparin alone in combination with nafamostat mesilate (NM), a protease inhibitor with specificity of trypsin-like enzymes, in an extracorporeal circuit which simulates CPB. NM significantly inhibits the release of platelet (β-thromboglobulin (βTG) at 60 and 120 min. Platelet counts do not differ. ADP-induced aggregation decreases in circuits with NM, which is due to a direct effect of NM on platelet function. NM prevents any significant release of neutrophil elastase; at 120 min, plasma elastase-α1antitrypsin complex is 0.16 μg/ml in the NM group and 1.24 μg/ml in the control group. NM completely inhibits formation of complexes of C1 inhibitor with kallikrein and FXIIa. NM does not alter markers of complement activation (C1-C1-inhibitor complex and C5b-9), or indicators of thrombin formation (F1.2). However, at 120 min, thrombin activity as measured by release of fibrinopeptide A is significantly decreased. The data indicate that complement activation during CPB correlates poorly with neutrophil activation and that either kallikrein or FXIIa or both may be more important agonists. The ability of NM to inhibit two important contact system proteins and platelet and neutrophil release raises the possibility of suppressing the inflammatory response during clinical CPB.

The Ex Vivo Effect of Preadsorbed Vitronectin on Platelet Activation

The activation of ex vivo canine platelets by preadsorbed vitronectin (VN) was sensitive not only to the polymer substrate utilized but also to the adsorption conditions employed. Lower levels of maximal platelet deposition were obtained for VN-coated silicone rubber (SR) than for other VN-coated substrates with comparable levels of adsorbed VN, but this effect was diminished with increased residence time of VN on the SR surface. Submonolayer and monolayer surface concentrations of VN elicited similar maximal levels of platelet deposition at both short (<3 h) and long (>12 h) residence times, but thrombi were larger and more dense for the submonolayer surface concentrations. VN was also more effective in forming thrombi when adsorbed sequentially before albumin instead of after albumin. To further examine these differences in the nature of adsorbed VN between substrates and adsorption conditions, sodium dodecyl sulfate (SDS) elutability measurements and Fourier transform infrared spectroscopy with attenuated total reflectance optics (FTIR-ATR) evaluations of the adsorbed protein were performed. An SDS solution was able to remove a greater percentage of the VN which was adsorbed to a submonolayer than a monolayer surface concentration when SDS displacement was initiated immediately after adsorption was terminated. However, if the adsorbed protein was allowed to reside on the surface for a length of time before the introduction of the SDS displacing media, a greater percentage of the monolayer surface concentration was removed. The submonolayer surface concentration may be better able to increase its strength of contact with the surface during the added residence time than the monolayer surface concentration. FTIR-ATR spectra of VN showed less structural alterations when it was adsorbing to SR than to a segmented polyurethane, a more thrombogenic material when coated with VN. Thus, the ability of VN to stimulate thrombus formation appeared to correlate with the percentage of VN which was nonelutable by SDS and the amount of structural alterations observed by FTIR-ATR, both of which are indications of its extent of contact with the surface.

Assessment of the construct validity of the Australian Health Star Rating: a nutrient profiling diagnostic accuracy study

BACKGROUND/OBJECTIVES

Nutrient profiling models classify the healthiness of foods based on their nutritional composition and provide the science that underlies nutrition signposting schemes. The two objectives were to examine the construct validity of the Health Star Rating (HSR) system by determining its diagnostic accuracy and to detect the optimal HSR cutoff points to define healthiness in packaged dairy foods. We hypothesised that ultra-processed dairy, defined by NOVA, would have less stars (less healthy) and non-ultra-processed dairy would have more stars (more healthy).

SUBJECTS/METHODS

The diagnostic accuracy of the HSR system used for 621 dairy foods for sale in an Australian regional supermarket was investigated. The healthiness of packaged dairy was measured using the NOVA food classification system.

RESULTS

The dairy beverages model was found to discriminate between healthy and less healthy dairy beverages as classified by NOVA (AUC: 0.653; 95% CI: 0.556-0.750; P=0.005). A receiver operating characteristic curve analysis for dairy beverages demonstrated that the optimal cutoff point corresponded to a rating of four stars. There was no discrimination power when using the HSR for predicting the health value of yoghurt and other dairy, or cheeses.

CONCLUSIONS

At the optimal cutoff point of four stars the HSR has a high sensitivity but a low specificity to correctly classify healthy packaged dairy beverages, as defined by NOVA. We provide evidence to support the construct validity of the HSR model for dairy beverages, but not for the models used for yoghurts and other dairy products, or cheeses.

Inelastic light scattering measurements of a pressure-induced quantum liquid in KCuF3

Pressure-dependent, low-temperature inelastic light (Raman) scattering measurements of KCuF(3) show that applied pressure above P* ~ 7 kbar suppresses a previously observed structural phase transition temperature to zero temperature in KCuF(3), resulting in the development of a fluctuational (quasielastic) response near T ~ 0 K. This pressure-induced fluctuational response--which we associate with slow fluctuations of the CuF(6) octahedral orientation--is temperature independent and exhibits a characteristic fluctuation rate that is much larger than the temperature, consistent with quantum fluctuations of the CuF(6) octahedra. A model of pseudospin-phonon coupling provides a qualitative description of both the temperature- and pressure-dependent evolution of the Raman spectra of KCuF(3).

Hepatitis B in the Greater San Francisco Bay Area: an integrated programme to respond to a diverse local epidemic

Although chronic hepatitis B (CHB) affects approximately 2 million United States residents, there is no systematic screening of at-risk individuals, and most remain unaware of their hepatitis B virus (HBV) infection. Unmonitored and untreated, CHB results in a 25-30% risk of death from liver cancer and/or cirrhosis, inflicting an increasing healthcare burden in high-prevalence regions. Despite high prevalence in immigrant Asians and Pacific Islanders, among whom CHB is a leading cause of death, community and healthcare provider awareness remains low. Because safe and effective vaccines and effective antiviral treatments exist, there is an urgent need for integrated programmes that identify, follow and treat people with existing CHB, while vaccinating the susceptible. We describe an extant San Francisco programme that integrates culturally targeted, population-based, HBV screening, vaccination or reassurance, management and research. After screening over 3000 at-risk individuals, we here review our operational and practical experience and describe a simple, rationally designed model that could be successfully used to greatly improve the current approach to hepatitis B while ultimately reducing the related healthcare costs, especially in the high-risk populations, which are currently underserved.

Mapping the magnetostructural quantum phases of Mn3O4

We present temperature-dependent x-ray diffraction and temperature- and field-dependent Raman scattering studies of single-crystal Mn3O4, which reveal the magnetostructural phases that evolve in the spinels due to the interplay between strong spin-orbital coupling, geometric frustration, and applied magnetic field. We present evidence that the magnetoelastic and magnetodielectric behavior in this material is governed by magnetic-field-controlled tetragonal-to-monoclinic phase changes. Most interestingly, for an applied field transverse to the ferrimagnetic ordering direction, H parallel [110], we find evidence for a field-tuned quantum phase transition to a tetragonal spin-disordered phase, indicating that a structurally symmetric, spin frustrated phase can be recovered at T approximately 0 for intermediate transverse fields in Mn3O4.

Interactions between endothelial cells and electrospun methacrylic terpolymer fibers for engineered vascular replacements

A compliant terpolymer made of hexylmethacrylate (HMA), methylmethacrylate (MMA), and methacrylic acid (MAA) intended for use in small diameter vascular graft applications has been developed. The mechanical properties and in vitro biostability of this terpolymer have been previously characterized. The goal of this investigation was to examine the interactions between endothelial cells and the new terpolymer and to evaluate endothelial cell function. Electrospinning was used to produce both oriented and random terpolymer fiber scaffolds. Smooth solution cast films and tissue culture polystyrene were used as negative and positive controls, respectively. Human blood outgrowth endothelial cells and human umbilical vein endothelial cells were incubated with the test and control samples and characterized with respect to initial cell attachment, proliferation, viability, and maintenance of the endothelial cell phenotype. It was found that the terpolymer is cytocompatible allowing endothelial cell growth, with random fibers being more effective in promoting enhanced cellular activities than oriented fibers. In addition, endothelial cells cultured on these substrates appeared to maintain their phenotype. The results from this study demonstrate that electrospun HMA:MMA:MAA terpolymer has the potential to be used successfully in fabricating small diameter blood vessel replacements.

Quantum and classical mode softening near the charge-density-wave-superconductor transition of CuxTiSe2

Temperature- and x-dependent Raman scattering studies of the charge-density-wave (CDW) amplitude modes in Cu(x)TiSe(2) show that the amplitude mode frequency omega(0) exhibits identical power-law scaling with the reduced temperature T/T(CDW) and the reduced Cu content x/x(c), i.e., omega(0) approximately (1-p)(0.15) for p=T/T(CDW) or x/x(c), suggesting that mode softening is independent of the control parameter used to approach the CDW transition. We provide evidence that x-dependent mode softening in Cu(x)TiSe(2) is associated with the reduction of the electron-phonon coupling constant, and that x-dependent "quantum" (T approximately 0) mode softening suggests the presence of a quantum critical point within the superconductor phase of Cu(x)TiSe(2).

Antibodies to a novel antigen in acute hepatitis C virus infections

BACKGROUND

Conformational viral proteins potentially play an important role in the immunobiology of acute hepatitis C virus (HCV) infection and may enable earlier antibody detection.

MATERIALS AND METHODS

HCV RNA was detected using nucleic acid testing. Early antibody production was evaluated using three enzyme immunoassays (EIAs) containing antigenic proteins not present in licensed EIAs. Respectively, these contained: (1) multiple-epitope fusion antigen (MEFA) 7.1-NS3/4a, (2) F and Core, and (3) E1/E2 proteins. NS3/4a is a conformational antigen retaining protease and helicase enzymatic activities. MEFA 7.1 contains the linear epitopes used in licenced EIAs, including the latest EIA-3.0, in combination with genotype 1-3 specific epitopes. Forty-two RNA positive, EIA-3.0 negative samples, including two persistently serosilent cases, were used to evaluate these research EIAs. As controls, 54 EIA-3.0 negative/RNA negative and three HCV RNA+/antibody positive specimens were included.

RESULTS

Only the MEFA 7.1-NS3/4a EIA was positive in seven (17%) of the 42 HCV RNA + specimens, in all three EIA-3.0 positive controls but in none of 54 EIA-3.0 negative/HCV RNA negative controls. Notably, six of the seven (86%) specimens had evidence of active hepatitis (ALT > 210 IU/l). The two serosilent cases were research EIA negative.

CONCLUSION

A novel EIA with conformational and linear epitopes detected HCV antibodies in 17% of viraemic specimens missed by the standard reference EIA-3.0. Our research EIA appears to detect HCV antibodies closer to the initiation of acute hepatitis. Given that the average RNA-positive, antibody-negative window period is 56.4 days, this 17% yield would translate into a 10-day earlier detection of antibodies.

Field- and pressure-induced phases in Sr4Ru3O10: a spectroscopic investigation

We have investigated the magnetic-field- and pressure-induced structural and magnetic phases of the triple-layer ruthenate Sr4Ru3O10. Magnetic-field-induced changes in the phonon spectra reveal dramatic spin-reorientation transitions and strong magnetoelastic coupling in this material. Further, we are able to deduce key magnetoelastic coupling parameters, and evidence that the magnetic moments are localized on the Ru sites. Additionally, pressure-dependent Raman measurements at different temperatures reveal an anomalous negative Gruneisen parameter associated with the B(1g) mode (approximately 380 cm(-1)) at low temperatures (T < 75 K), which can be explained consistently with the field-dependent Raman data.

Optical sum rules that relate to the potential energy of strongly correlated systems

A class of sum rules for inelastic light scattering is developed. We show that the first moment of the nonresonant response provides information about the potential energy in strongly correlated systems. The polarization dependence of the sum rules provides information about the electronic excitations in different regions of the Brillouin zone. We determine the sum rule for the Falicov-Kimball model, which possesses a metal-insulator transition, and compare our results to the light scattering experiments in SmB(6).

Field-induced orbital and magnetic phases in Ca3Ru2O7

Magnetic-field- and temperature-dependent Raman scattering studies of Ca3Ru2O7 reveal dramatic field-dependent properties arising from transitions between various complex orbital and magnetic phases, including a field-induced orbital-ordered to orbital-disordered transition (H(o) // hard axis), and a reentrant orbital-ordered to orbital-disordered to orbital-ordered transition (H(o) // easy axis). We find that the dramatic magnetic-field properties are most prevalent in a "mixed"-magnetic and -orbital phase regime, providing evidence for a strong connection between orbital phase inhomogeneity and "colossal" field effects in the ruthenates.

Manipulation of the n-3 polyunsaturated fatty acid content of muscle and adipose tissue in lambs1

Fifty Suffolk-crossbred wether lambs, with an initial live weight of 29 +/- 2.1 kg, were allocated to one of five concentrate-based diets formulated to have a similar fatty acid content (60 g/kg DM), but containing either linseed oil (high in 18:3n-3); fish oil (high in 20:5n-3 and 22:6n-3); protected linseed and soybean (PLS; high in 18:2n-6 and 18:3n-3); fish oil and marine algae (fish/algae; high in 20:5n-3 and 22:6n-3); or PLS and algae (PLS/algae; high in 18:3n-3 and 22:6n-3). Lambs were slaughtered when they reached 40 kg. Growth performance and intake were similar (P > 0.35) among treatments. By contrast, gain:feed was higher (P < 0.05) in lambs fed the fish oil compared with the linseed oil or PLS/algae diets. Total fatty acid concentration (mg/100 g) in the neutral lipid of the longissimus muscle was not affected by treatment (P > 0.87) but was least (P < 0.05) in the phospholipid fraction in lambs fed the linseed oil diet. Lambs fed either diet containing marine algae contained the highest (P < 0.05) percentage of 22:6n-3 in the phospholipid (mean of 5.2%), 2.8-fold higher than in sheep fed the fish oil diet. In lambs fed the fish/algae diet, the percentage of 20:5n-3 was highest (P < 0.05), contributing some 8.7, 0.8, and 0.5% of the total fatty acids in the muscle phospholipid, neutral lipids, and adipose tissue, respectively. The percentage of 18:3n-3 in the phospholipid fraction of the LM was highest (P < 0.05) in lambs fed the linseed oil diet (6.9%), a value double that of sheep fed the PLS diet. By contrast, lambs fed the PLS diet had twice the percentage of 18:3n-3 in the muscle neutral lipids (3.8%) than those offered the linseed oil diet, and 5.5-fold greater than lambs fed the fish/algae treatment (P < 0.05), an effect that was similar in the adipose tissue. The percentage of 18:2n-6 was highest (P < 0.05) in lambs fed the PLS diet, where it contributed 33.7, 10.1, and 11.2% in the muscle phospholipid, neutral lipids, and adipose tissue, respectively. The highest (P < 0.05) muscle PUFA-to-saturated fatty acid (P:S) ratio was obtained in lambs fed the PLS diet (0.57), followed by the PLS/algae diet (0.46), and those fed the fish oil or linseed oil diets had the lowest ratios (0.19 and 0.26, respectively). The favorable P:S ratio of lambs fed the PLS/algae diet, in conjunction with the increased levels of 20:5n-3 and 22:6n-3, enhanced the nutritional qualities of lamb to more closely resemble what is recommended for the human diet.

Quantum melting of the charge-density-wave state in 1T-TiSe2

We report a Raman scattering study of low-temperature, pressure-induced melting of the charge-density-wave (CDW) phase of 1T-TiSe2. Our measurements reveal that the collapse of the CDW state occurs in three stages: (i) For P<5 kbar, the pressure dependence of the CDW amplitude mode energies and intensities are indicative of a "crystalline" CDW regime; (ii) for 5<P<25 kbar, there is a decrease in the CDW amplitude mode energies and intensities with increasing pressure that suggests a regime in which the CDW softens, and exhibits enhanced fluctuations; and (iii) for P>25 kbar, the absence of amplitude modes reveals a metallic regime in which the CDW has melted.

Pressure-tuned collapse of the Mott-like state in Ca(n+1)Ru(n)O(3n+1) (n=1,2): Raman spectroscopic studies

We report a Raman scattering study of the pressure-induced collapse of the Mott-like phases of Ca3Ru2O7 (T(N)=56 K) and Ca2RuO4 (T(N)=110 K). The pressure dependence of the phonon and two-magnon excitations in these materials indicate (i) a T approximately 0 pressure-induced collapse of the antiferromagnetic (AF) insulating phase above P(*) approximately 55 kbar in Ca3Ru2O7 and P(*) approximately 5-10 kbar in Ca2RuO4, (ii) a remarkable insensitivity of the exchange interaction to pressure in both systems, and (iii) evidence for persistent AF correlations above the critical pressure of Ca2RuO4, suggestive of phase separation involving AF insulator and ferromagnetic metal phases.

Evolution of magnetic polarons and spin-carrier interactions through the metal-insulator transition in Eu(1-x)Gd(x)O

Raman scattering studies as functions of temperature, magnetic field, and Gd substitution are used to investigate the evolution of magnetic polarons and spin-carrier interactions through the metal-insulator transition in Eu(1-x)Gd(x)O. These studies reveal a spin-fluctuation-dominated paramagnetic (PM) regime for T>T*>T(C), and a coexistence regime for T<T* in which spin polarons develop and coexist with remnants of the PM phase. They further show a strong connection between spin cluster formation and the dramatic field effects observed in these materials.

Quaternary ammonium functionalized poly(propylene imine) dendrimers as effective antimicrobials: structure-activity studies

Quaternary ammonium functionalized poly(propyleneimine) dendrimers were synthesized and their antibacterial properties were evaluated using a bioluminescence method. These quaternary ammonium dendrimers are very potent biocides. The antibacterial properties depend on the size of the dendrimer, the length of hydrophobic chains in the quaternary ammonium groups, and the counteranion. Since these dendrimers are well characterized and monodisperse, they also serve as an effective system to study the structure-activity relationship. The antimicrobial properties of these dendrimer biocides have a parabolic dependence on molecular weight, which is different from the bell-shaped molecular weight dependence of conventional polymer biocides. The dependence on the hydrophobic chain of the quaternary ammonium structure is similar to conventional polymer biocides, and shows a parabolic relationship with dendrimer biocides carrying C10 hydrophobes the most potent. The antimicrobial properties of these novel biocides with bromide anions are more potent than those with chloride anions. Biocides derived from hyperbranched polymers were also synthesized and found to possess somewhat lower effectiveness.

The influence of thrombus components in mediating bacterial adhesion to biomaterials

Thrombosis and infection represent the two largest limiting factors determining the long term success of implanted biomaterials. Infections associated with biomaterials are difficult to treat, and appear to evade the host defense systems. Mechanisms relating infection to thrombosis are described. Investigations into the role of receptors in mediating adhesion to thrombi are also discussed, in addition to strategies to reduce bacterial adhesion to biomaterial surfaces.

Synthesis and characterization of non-leaching biocidal polyurethanes

The biocidal activities of a series of quaternized polyurethanes were examined against Staphylococcus aureus and Escherichia coli. The percentage of dead cells on a surface was found to depend on the alkyl halide used for quaternization, the concentration of quaternized moieties in the polyurethane, the gram-type of the microorganism, and the contact time of the organism with the surface. N,N-bis(2-hydroxyethyl)isonicotinamide (BIN) was incorporated as the chain extender in a series of poly(tetramethylene oxide)-based polyurethane block copolymers. Three families of materials were synthesized that contained increasing hard segment fractions and therefore increasing concentrations of BIN. The pyridine ring in BIN was quaternized with a variety of alkyl halides to form cationic polyurethanes that possessed biocidal activity. The effect of quaternization on material properties was examined with tensile testing, water absorption analysis, and contact angle measurements. The antibacterial action of the polymers was investigated with zone of inhibition experiments and fluorescence microscopy, which was established as a reliable technique to determine the viability of organisms attached to a polymer surface.

Assessment of hypercholesterolemia control in a managed care organization

To determine the extent of achievement of goal low-density lipoprotein cholesterol (LDL) as defined by National Cholesterol Education Program-Adult Treatment Panel II (NCEP-ATP 11) and American Diabetes Association (ADA) 2000 guidelines, we conducted a retrospective study by integrating data from medical, laboratory, and pharmacy claims databases. Subjects were selected from a 232,000-member staff-model managed care organization consisting of 19 clinics in the Minneapolis-St. Paul, Minnesota, metropolitan area. A total of 124,971 members aged 18 years and older, who had been continuously enrolled from July 1, 1996-June 6, 1998, were included. Outcome measures were the extent of achievement of goal LDL as defined by NCEP-ATP II and the use of antihyperlipidemic drugs for patients with and without diabetes at various levels of risk for coronary heart disease (CHD). Of 124,971 subjects, 6538 had a history of CHD, 1523 of whom met their LDL goal. Of the population with CHD who did not achieve goal, 1141 (43%) missed by over 30 mg/dl; 621 (54%) of these patients were not receiving drug therapy A total of 17,267 had no history of CHD but had two or more risk factors; 3,298 of these achieved their LDL goal. Of those who did not achieve goal, 1,136 (35%) missed by over 30 mg/dl; 897 (79%) of these were not receiving drug therapy A total of 6,586 had a history of diabetes; 1,004 and 2,340 reached an LDL of 100 mg/dl or lower and less than 130 mg/dl, respectively Of those with diabetes who had an LDL greater than 100 mg/dl, 1,276 (49%) missed their goal by over 30 mg/dl; 898 (70%) of these were not receiving drug therapy. Inadequate use of pharmacologic agents plays a significant role in failure to achieve goal LDL for patients with CHD, without CHD, and with diabetes. Analysis of the data based on the new ADA guidelines for LDL demonstrates the need for continued vigilance. Finally, the successful merging of medical, laboratory, and pharmacy claims databases provides a benchmark for other institutions.

Design, synthesis, and proposed active site binding analysis of monocyclic 2-azetidinone inhibitors of prostate specific antigen

A homology derived molecular model of prostate specific antigen (PSA) was created and refined. The active site region was investigated for specific interacting functionality and a binding model postulated for the novel 2-azetidinone acyl enzyme inhibitor 1 (IC(50) = 8.98 +/- 0.90 microM) which was used as a lead compound in this study. A single low energy conformation structure II (Figure 2) was adopted as most likely to represent binding after minimization and dynamics calculations. Systematic analysis of the binding importance of all three side chains appended to the 2-azetidinone was conducted by the synthesis of several analogues. A proposed salt bridge to Lys-145 with 4 (IC(50) = 5.84 +/- 0.92 microM) gave improved inhibition, but generally the binding of the N-1 side chain in a specific secondary aromatic binding site did not tolerate much structural alteration. A hydrophobic interaction of the C-4 side chain afforded inhibitor 6 (IC(50) = 1.43 +/- 0.19 microM), and polar functionality could also be added in a proposed interaction with Gln-166 in 5 (IC(50) = 1.34 +/- 0.05 microM). Reversal of the C-4 ester connectivity furnished inhibitors 7 (IC(50) = 1.59 +/- 0.15 microM), 11 (IC(50) = 3.08 +/- 0.41 microM), and 13 (IC(50) = 2.19 +/- 0.36 microM) which were perceived to bind to PSA by a rotation of 180 degrees relative to the C-4 ester of normal connectivity. Incorporation of hydroxyl functionality into the C-3 side chain provided 16 (IC(50) = 348 +/- 50 nM) with the greatest increase in PSA inhibition by a single modification. Multiple copy simultaneous search (MCSS) analysis of the PSA active site further supported our model and suggested that 18 would bind strongly. Asymmetric synthesis yielded 18 (IC(50) = 226 +/- 10 nM) as the most potent inhibitor of PSA reported to date. It is concluded that our design approach has been successful in developing PSA inhibitors and could also be applied to the inhibition of other enzymes, especially in the absence of crystallographic information.

Raman scattering study of anomalous spin, charge, and lattice dynamics in the charge-ordered phase of Bi1-xCaxMnO3 (x > 0.5)

We report an inelastic light scattering study of the effects of charge ordering on the spin, charge, and lattice dynamics of Bi1-xCaxMnO3 (x>0.5). We find that charge ordering results in anomalous phonon behavior, such as the appearance of "activated" modes. More significantly, however, the transition to the charge-ordered phase results in the appearance of a quasielastic scattering response with the symmetry of the spin-chirality operator ( T(1g)); this scattering response is thus indicative of magnetic or chiral spin fluctuations in the antiferromagnetic charge-ordered phase.

Leukocyte adhesion on model surfaces under flow: effects of surface chemistry, protein adsorption, and shear rate

The effect of specific chemical functionalities on the adhesion of polymorphonuclear leukocytes (PMNs) under flow was investigated using a set of well-characterized, chemically functionalized surfaces prepared by self-assembly of alkanethiolate monolayers on gold surfaces. Terminal functionalities included CH(3), CH(2)OH, COOH, and (OCH(2)CH(2))(3)OH groups. A new surface modification was used to incorporate a phosphorylcholine moiety on the hydroxyl-terminated monolayer. Surface modification was verified using contact-angle measurements, ellipsometry, and X-ray photoelectron spectroscopy. Adhesion on the surfaces was studied in the presence and absence of pre-adsorbed fibrinogen. Fibrinogen adsorption on self-assembled monolayers (SAMs) was quantified using radioisotope detection. PMN adhesion was found to be dependent on the monolayer's terminal functionality. Adhesion was higher on the hydrophobic CH(3) surface and the polar COOH monolayer. Leukocyte adhesion was least on the phosphorylcholine-rich surface, followed by the ethylene-oxide-containing monolayer. Cell adhesion also was low on the hydrophilic OH monolayer. Attachment was decreased with increasing shear rate, exhibiting a three-fold decrease between 20 and 100 s(-1). Fibrinogen adsorption was higher on the CH(3) monolayer but comparable for the other four SAMs. Preincubation of the surfaces with fibrinogen decreased adhesion on all SAMs examined.

Rapid evolution of NK cell receptor systems demonstrated by comparison of chimpanzees and humans

That NK cell receptors engage fast-evolving MHC class I ligands suggests that they, too, evolve rapidly. To test this hypothesis, the structure and class I specificity of chimpanzee KIR and CD94:NKG2 receptors were determined and compared to their human counterparts. The KIR families are divergent, with only three KIR conserved between chimpanzees and humans. By contrast, CD94:NKG2 receptors are conserved. Whereas receptors for polymorphic class I are divergent, those for nonpolymorphic class I are conserved. Although chimpanzee and human NK cells exhibit identical receptor specificities for MHC-C, they are mediated by nonorthologous KIR. These results demonstrate the rapid evolution of NK cell receptor systems and imply that "catching up" with class I is not the only force driving this evolution.

High-molecular-weight kininogen preadsorbed to glass surface markedly reduces neutrophil adhesion

Adsorbed proteins on biomaterial surfaces determine whether cells adhere, but rheological variables are also critical. Neutrophil adhesion under well-defined radial flow conditions was studied on glass preadsorbed with plasma proteins or plasma protein domain fragments. Fibrinogen, low-molecular-weight kininogen (LK), high-molecular-weight kininogen (HK), cleaved HK (HKa), and recombinant HK domains 3 and 5 (D3 and D5H) were used. The number of adherent cells on the HK and HKa surfaces was less than 10% that found on the fibrinogen absorbed surface. The degree of spreading was minimal and detachment of adherent neutrophils was observed. HK and HKa contain binding sites for both anionic surfaces and neutrophils in the same domain (D5H). When adsorbed to surfaces, HK and HKa did not have the neutrophil binding sites available and therefore exhibited an anti-adhesive effect. Although D5H contains anionic surface binding sites, its small molecular size required a higher number of adsorbed molecules to cover the surface before a significant decrease in cell adhesion was observed. Since LK and D3 do not possess specific anionic surface binding sites, the adsorption of these proteins on glass was very low compared to HK and HKa. Thus, extensive cell adhesion and spreading were observed on the surfaces partially covered with preadsorbed LK and D3.

Bacterial colonization of functionalized polyurethanes

A protocol was developed for studying the growth of bacteria upon polyurethanes subsequent to the establishment of an adherent bacterial population. An inocula of approximately 10(5) cfu S. aureus were spread on functionalized polyurethanes which included Pellethane, sulfonated Pellethane, phosphonated Pellethane, quaternized amine polyurethanes, and a zwitterionic phosphonated polyurethane. After 24 h incubation, Pellethane, sulfonated Pellethane, and phosphonated Pellethane showed bacterial growth by at least a factor of 10. In contrast, the zwitterionic phosphonated polyurethane showed a factor of 10 decrease in bacteria after 24 h and the quaternized amine polyurethanes reduced the bacteria to only a few hundred after only 1 h. When treated with bovine serum albumin, Pellethane, sulfonated Pellethane, and phosphonated Pellethane again showed bacterial growth by as much as a factor of 10 over 24 h. The quaternized amine polyurethanes and the zwitterionic phosphonated polyurethane still exhibited bactericidal abilities even when coated with bovine serum albumin, with the zwitterionic material reducing bacteria by more than a factor of 10 over 24 h and the quaternized amine polyurethane reducing the bacteria to only a few hundred after only 1 h. A zone of inhibition study suggested that the bactericidal activity of the zwitterionic phosphonated polyurethane was due to the leaching of cadmium ions. A quaternized amine polyurethane which contained chloride instead of iodide as the counterion to the amine moiety was less bactericidal than the iodide-containing polymer when treated with albumin. Thus, bacteria were able to colonize Pellethane, phosphonated sulfonated Pellethane, and phosphonated Pellethane, but the iodide-containing quaternized amine polyurethane and the zwitterionic polyurethane prevented colonization.

Neutrophil adhesion on polyurethanes preadsorbed with high molecular weight kininogen

Interaction of biomaterials with blood components including neutrophils is responsible for some of the clinical complications that have occurred in cardiopulmonary bypass, hemodialysis, and ventricular assist procedures. The possibility of inhibiting the initial adhesion of neutrophils to biomaterials has been studied extensively, but the problem remains unsolved. In this study, we investigated the effect of HK adsorption on polyurethane, a widely used component of extracorporeal and intracorporeal devices. HK and HKa were allowed to adsorb on 4 different charged polyurethanes: noncharged (PU), cationic (NR(4)), anionic (SO(3)), and zwitterionic (GPC) polyurethanes. The effect of kininogen adsorption on neutrophil adhesion, the surface density of the adsorbed kininogen, and the exposure of HK domains 3 and 5 (D(3) and D(5H)), which are responsible for the binding of HK to the neutrophil integrin alpha(m)beta(2) or Mac-1, were examined. On PU, NR(4), and SO(3), kininogen adsorption reached 80% of monolayer coverage when 100 pmol/mL or higher concentration of protein solutions were used. The NR(4) surface adsorbed the most kininogen along with a high exposure of D(3) and D(5H). The availability of D(3) and D(5H) allowed neutrophils to bind to the surface via the Mac-1 receptor; thus, on the NR(4) surface, adsorbed kininogens lost their antiadhesive property, which resulted in a high degree of neutrophil adhesion. Increasing Mac-1 expression by exposure to fMLP increased the neutrophil adhesion on this surface. In contrast, exposure of D(3) and D(5H) on SO(3) was significantly less, because HK binds to anionic surfaces with similar protein sequences used for cell binding. This low binding site exposure preserved the antiadhesive property of HK. GPC was resistant to neutrophil adhesion even in the absence of adsorbed kininogens because of its phosphorylcholine moiety. Thus, both SO(3) coupled with kininogen (or kininogen peptides) and GPC have the potential to markedly reduce neutrophil adhesion to biomaterial devices.

The effect of high molecular weight kininogen on neutrophil adhesion to polymer surfaces

The adhesion of neutrophils on a biomaterial surface depends on the surface chemistry of the material and the cell, as well as the composition and conformation of adsorbed protein and the adherence of other cells when the biomaterial is exposed to circulating blood. In this study, HK and HKa were allowed to adsorb on three different polyurethanes: underivatized (PU-base), quaternized (PU-NR4), sulfonated (PU-SO3). The effect of kininogen adsorption on the degree of neutrophil adhesion was examined. The surface density of the adsorbed protein was also investigated. The PU-NR4 surface adsorbed the most HK and HKa and had the high degree of neutrophil adhesion. Although the surface density of adsorbed HK and HKa on the PU-SO3 surface, the degree of neutrophil on adhesion was significantly lower when compared to the PU-NR4 and PU-base surfaces. HK and HKa contain binding sites for both anionic surfaces and neutrophils in the same domain (D5H). When adsorbed to the anionic PU-SO3 surfaces, HK and HKa did not have the neutrophil binding sites available and therefore, exhibited an anti-adhesive effect. In contrast, the neutrophil binding domains D3 and DsH of adsorbed kininogens were available on the PU-NR4 and PU-base surfaces. Thus, adsorbed kininogens on these two surfaces lost their anti-adhesive property and this led to a high degree of neutrophil adhesion.

Surface properties and hemocompatibility of alkyl-siloxane monolayers supported on silicone rubber: effect of alkyl chain length and ionic functionality

Self-assembled monolayers of alkylsiloxanes supported on poly(dimethylsiloxane) (PDMS) rubber were used as model systems to study the relation between blood compatibility and surface composition. The inner lumen of PDMS tubes were first treated with an oxygen plasma. The resultant oxidized surfaces were post-derivatized by reaction with alkyltrichlorosilanes to form the monolayer films. The alkyl chain lengths used were slightly longer than in a previous study, and this may alter the phase-state of the monolayer from liquid-like to crystalline. The chemical properties of the monolayer were controlled by varying the chemical composition of the alkyltrichlorosilanes used. Terminal functionalities included -CH3, -CF3, -COOH, -SO3H and -(CH2CH2O)4OH. Surface derivatization was verified with static contact angle measurements and X-ray photoelectron spectroscopy. Blood compatibility was evaluated using a canine ex vivo arterio-venous series shunt model. Surfaces grafted with hydrophobic head groups such as -CH3 and -CF3 were significantly less thrombogenic than the surfaces composed of ionic head groups such as -COOH and -SO3H. Surfaces enriched in -(CH2CH2O)4OH had an intermediate thrombogenicity. Silastic pump grade tubing and polyethylene tubing, used as controls, were found to be the least thrombogenic of all the surfaces tested.

Aprotinin inhibits thrombin formation and monocyte tissue factor in simulated cardiopulmonary bypass

BACKGROUND

Aprotinin reduces perioperative bleeding after open heart surgery, primarily by inhibiting fibrinolysis. In addition, the drug has both procoagulant and anticoagulant effects that involve complex reactions of coagulation proteins and cells that are incompletely understood. This study tests the hypothesis that aprotinin has an anticoagulant effect on the extrinsic coagulation pathway.

METHODS

Human heparinized blood was recirculated through a membrane oxygenator with and without high concentrations of aprotinin (18.4 microM). Serial plasma samples were obtained at intervals up to 240 minutes.

RESULTS

Aprotinin significantly reduced the progressive increase in prothrombin fragments (F1.2) and thrombin-antithrombin complex beginning immediately. Aprotinin also significantly reduced monocyte expression of tissue factor and Mac-1. Aprotinin did not significantly reduce factor VII or factor VIIa.

CONCLUSIONS

During simulated cardiopulmonary bypass, aprotinin immediately inhibits kallikrein and thrombin formation via the intrinsic coagulation pathway. Later, aprotinin inhibits monocyte expression of tissue factor and the extrinsic coagulation pathway. The ability of aprotinin to inhibit monocyte tissue factor provides a means to reduce thrombin formation in blood aspirated from the wound during open heart surgery.

Bacterial adhesion to functionalized polyurethanes

The effect of fibrinogen and high molecular weight kininogen on bacterial adhesion to functionalized polyurethanes was studied. Glass slides were coated with different polyurethanes, including Pellethane, sulfonated Pellethane, phosphonated Pellethane, a zwitterionic phosphonated polyurethane, and quaternized amine polyurethanes. The polymer-coated glass squares were exposed to radiolabelled S. aureus. When comparing adhesion to bare polyurethanes, it was found that adhesion was lowest on the phosphonated Pellethane and the zwitterionic phosphonated polyurethane while highest on the methyl quaternized polyurethanes. Fibrinogen-mediated adhesion was studied by first exposing the polymers to increasing concentrations of canine fibrinogen before incubating them with S. aureus. All the polymers except the quaternized amine polyurethanes exhibited at least ten-fold increases in bacterial adhesion as the fibrinogen treatment concentration was increased from 0.0 to 10.0 microg ml(-1). The quaternized amine polyurethanes maintained their relatively high amount of bacterial adhesion regardless of the fibrinogen concentration. The effect of two-chain high molecular weight kininogen (TCHMWK) on fibrinogen-mediated bacterial adhesion was assessed by exposing the polymers to 1.0 microg ml(-1) fibrinogen followed by two different concentrations of TCHMWK. Decreases in bacterial adhesion were observed on all the polymers except the quaternized amine polyurethanes, which again retained their relatively high amount of bacterial adhesion.

Thrombus deposition on polyurethanes designed for biomedical applications

Thrombogenicity was assessed by measuring the amount of 111In-platelets and 125I-fibrinogen deposited on the inner luminal surface of six polyurethanes for up to 60 min of blood contact in a canine ex-vivo shunt model. Commercial and laboratory synthesized polymers were examined. Two of the commercially synthesized polyurethanes (Biostable PURs) do not contain ether linkages in the polymer backbone and have previously shown resistance to oxidative and hydrolytic degradation. Static contact angle measurements, dynamic contact angle measurements, and ESCA were used to characterize the surfaces of these polyurethanes. The effectiveness of an acetone extraction used to remove extrusion waxes from Pellethane 2363-80A was similarly studied. Both Pellethane 2363-80A and the ether-free materials had relatively nonthrombogenic surfaces, as indicated by low platelet and fibrinogen deposition, making them potentially good candidates for biomedical applications.

Hydrophobic Aggregation in Polyurethane Ionomer Solutions

Model polyurethane ionomers were synthesized with regularly spaced ionic groups along the polymeric backbone. Viscometry and static and dynamic light scattering applied to these ionomer solutions in a polar solvent, N-methylformamide, revealed hydrophobic interactions and aggregated ionomer chains in solution. A new regime in the solution behavior of ionomers characterized by low reduced viscosity at all dilute concentrations has been identified. Spherical particles of radius 30 nm with a polymer core and an outer ionic shell are formed. The solutions have very low viscosity because of the formation of compact structures. The electrostatic interactions in these solutions are effectively screened, resulting in the absence of polyelectrolyte behavior. Polymer-solvent interactions are found to be very important in determining the ionomer solution behavior in polar solvents. Copyright 1998 Academic Press.

Three noncontiguous peptides comprise binding sites on high-molecular-weight kininogen to neutrophils

The binding of high-molecular-weight kininogen (HK) to neutrophils (polymorphonuclear leukocytes, PMN) is required for the stimulation of aggregation and degranulation by human plasma kallikrein as well as the displacement of fibrinogen from this cell surface. The putative receptor for HK is the leukocyte integrin alphaMbeta2, and domains 3 (D3) and 5 (D5) of HK form its binding site. To further map the binding sites on HK for PMN, we used D3 recombinant exon products and designed peptides from D3 and D5. In D3, a heptapeptide, Leu271-Ala277, from exon 7 product, and a peptide, Cys333-Cys352, from exon 9 product can inhibit binding of kininogen to PMN. Two contiguous peptides from D5 in the histidine-glycine-rich region, Gly442-Lys458 and Phe459-Lys478, each inhibit the binding of HK to PMN. This study has thus delineated three noncontiguous surface-oriented sequences on HK, which together comprise all or most of the binding site for human PMN.

Influence of thrombus components in mediating Staphylococcus aureus adhesion to polyurethane surfaces

The role of protein and cellular components of thrombi in mediating bacterial adhesion on artificial surfaces was investigated in this study. The attachment of Staphylococcus aureus on polyurethane surfaces was observed directly using an automated video microscopy system. Surfaces were preconditioned with components of platelet-fibrin thrombi, including fibrinogen, thrombin, plasma, and isolated platelets. Experiments were performed in a radial flow chamber, and attachment rate constants were compared on the preconditioned surfaces in an effort to understand the complex relationship that exists between bacterial infection and thrombosis on synthetic biomaterials. Preadsorption of fibrinogen to surfaces significantly increased S. aureus adhesion compared to those preadsorbed with albumin alone while the presence of fibrin dramatically increased bacterial attachment compared to plasma preadsorbed surfaces. While the presence of adherent platelets also increased bacterial attachment, fibrin appeared to play a larger role in mediating bacterial adhesion on polyurethane surfaces. Striking results were obtained on the zwitterionic phosphonated polyurethane for a number of pretreatment conditions with regard to decreased bacterial adhesion and fibrinogen deposition.

Neutrophil adhesion on phosphorylcholine-containing polyurethanes

Polyurethanes have been synthesized using glycerophosphorylcholine (GPC) as a chain extender. By altering the ratio of GPC to butanediol (BD), a series of polymers was obtained composed of different contents of phosphorylcholine. Bulk and surface characterization of the polymers was carried out. Differential scanning calorimetry and dynamic mechanical analysis showed that the polymer with the highest phosphorylcholine content (PU-GPC-20) had the lowest soft segment Tg and the highest tensile strength and Young's modulus among the polymers studied. This is due to the high degree of microphase separation in PU-GPC-20 as a result of by ionic aggregation and hydrogen bonding from the zwitterionic phosphorylcholine moiety. PU-GPC-20 contained approximately 20 wt%, of glycerophosphorylcholine. Dynamic contact angle analysis showed that these polymers, especially the ones with high phosphorylcholine content, rearranged themselves to minimize their interfacial tension upon contacting an aqueous environment. Under shear rates of from 20 to 120 s(-1), neutrophils did not adhere to PU-GPC-20. Under similar conditions neutrophil adhesion was observed only at 20 s(-1) on PU-GPC-10, PU-GPC-5 and on the control polyurethane (PU-base). Cell spreading was observed on the control polyurethane but not on any of the other surfaces. The incorporation of phosphorylcholine into the polyurethane backbone effectively reduced neutrophil adhesion and thus potentially could result in lower inflammatory and foreign body responses.

Drug use management in board and care facilities

The purpose of this study was to describe medication management in board and care facilities throughout Minnesota. A triangulation of data collection methods was used, including mail questionnaires (N = 98 facilities), telephone interviews (N = 64 facilities), and site visits (N = 15 facilities). Major issues examined included characteristics of board and care facilities, staffing, residents, and drug management systems. Results showed that staff in 86% of the board and care facilities surveyed provided medication storage, 83% gave medication reminders, and 69% administered medications to one or more residents. Site visits revealed a wide diversity in the characteristics of managers and their attitudes toward medication administration.