Health care resource utilization and costs in patients with painful diabetic neuropathy treated with 10 kHz spinal cord stimulation therapy

BACKGROUND: Diabetic peripheral neuropathy, a common comorbidity of diabetes, is a neurodegenerative disorder that targets sensory, autonomic, and motor nerves frequently associated with painful diabetic neuropathy (PDN). PDN carries an economic burden as the result of reduced work and productivity. A recent multicenter randomized controlled trial, SENZA-PDN (NCT03228420), assessed the impact of high-frequency (10 kHz) spinal cord stimulation (SCS) on pain relief. The effects of high-frequency SCS on health care resource utilization and medical costs are not known. OBJECTIVE: To evaluate the effect of high-frequency (10 kHz) SCS on health care resource utilization (HRU) and medical costs in patients with PDN using data from the SENZA-PDN trial. METHODS: Participants with PDN were randomly assigned 1:1 to receive either 10 kHz SCS plus conventional medical management (CMM) (SCS treatment group) or CMM alone (CMM treatment group). Patient outcomes and HRU up to the 6-month follow-up are reported here. Costs (2020 USD) for each service was estimated based on publicly available Medicare fee schedules, Medicare claims data, and literature. HRU metrics of inpatient and outpatient contacts and costs are reported as means and SDs. Univariate and bivariate analyses were used to compare SCS and CMM treatment groups at 6 months. RESULTS: At 6-month follow up, the SCS arm experienced approximately half the mean rate of hospitalizations per patient compared with the CMM treatment group (0.08 vs 0.15; P = 0.066). The CMM treatment group's total health care costs per patient were approximately 51% higher compared with the SCS treatment group (equivalent to mean annual cost per patient of $9,532 vs $6,300). CONCLUSIONS: Our analysis of the SENZA-PDN trial indicates that the addition of 10 kHz SCS therapy results in lower rates of hospitalization and consequently lower health care costs among patients with PDN compared with those receiving conventional management alone.

Long-term efficacy of high-frequency (10 kHz) spinal cord stimulation for the treatment of painful diabetic neuropathy: 24-Month results of a randomized controlled trial

AIMS

To evaluate the long-term efficacy of high-frequency (10 kHz) spinal cord stimulation (SCS) for treating refractory painful diabetic neuropathy (PDN).

METHODS

The SENZA-PDN study was a prospective, multicenter, randomized controlled trial that compared conventional medical management (CMM) alone with 10 kHz SCS plus CMM (10 kHz SCS+CMM) in 216 patients with refractory PDN. After 6 months, participants with insufficient pain relief could cross over to the other treatment. In total, 142 patients with a 10 kHz SCS system were followed for 24 months, including 84 initial 10 kHz SCS+CMM recipients and 58 crossovers from CMM alone. Assessments included pain intensity, health-related quality of life (HRQoL), sleep, and neurological function. Investigators assessed neurological function via sensory, reflex, and motor tests. They identified a clinically meaningful improvement relative to the baseline assessment if there was a significant persistent improvement in neurological function that impacted the participant's well-being and was attributable to a neurological finding.

RESULTS

At 24 months, 10 kHz SCS reduced pain by a mean of 79.9% compared to baseline, with 90.1% of participants experiencing ≥50% pain relief. Participants had significantly improved HRQoL and sleep, and 65.7% demonstrated clinically meaningful neurological improvement. Five (3.2%) SCS systems were explanted due to infection.

CONCLUSIONS

Over 24 months, 10 kHz SCS provided durable pain relief and significant improvements in HRQoL and sleep. Furthermore, the majority of participants demonstrated neurological improvement. These long-term data support 10 kHz SCS as a safe and highly effective therapy for PDN.

TRIAL REGISTRATION

ClincalTrials.gov Identifier, NCT03228420.

High-Frequency 10-kHz Spinal Cord Stimulation Improves Health-Related Quality of Life in Patients With Refractory Painful Diabetic Neuropathy: 12-Month Results From a Randomized Controlled Trial

Objective

To evaluate high-frequency (10-kHz) spinal cord stimulation (SCS) treatment in refractory painful diabetic neuropathy.

Patients and Methods

A prospective, multicenter randomized controlled trial was conducted between Aug 28, 2017 and March 16, 2021, comparing conventional medical management (CMM) with 10-kHz SCS+CMM. The participants had hemoglobin A1c level of less than or equal to 10% and pain greater than or equal to 5 of 10 cm on visual analog scale, with painful diabetic neuropathy symptoms 12 months or more refractory to gabapentinoids and at least 1 other analgesic class. Assessments included measures of pain, neurologic function, and health-related quality of life (HRQoL) over 12 months with optional crossover at 6 months.

Results

The participants were randomized 1:1 to CMM (n=103) or 10-kHz SCS+CMM (n=113). At 6 months, 77 of 95 (81%) CMM group participants opted for crossover, whereas none of the 10-kHz SCS group participants did so. At 12 months, the mean pain relief from baseline among participants implanted with 10-kHz SCS was 74.3% (95% CI, 70.1-78.5), and 121 of 142 (85%) participants were treatment responders (≥50% pain relief). Treatment with 10-kHz SCS improved HRQoL, including a mean improvement in the EuroQol 5-dimensional questionnaire index score of 0.136 (95% CI, 0.104-0.169). The participants also reported significantly less pain interference with sleep, mood, and daily activities. At 12 months, 131 of 142 (92%) participants were "satisfied" or "very satisfied" with the 10-kHz SCS treatment.

Conclusion

The 10-kHz SCS treatment resulted in substantial pain relief and improvement in overall HRQoL 2.5- to 4.5-fold higher than the minimal clinically important difference. The outcomes were durable over 12 months and support 10-kHz SCS treatment in patients with refractory painful diabetic neuropathy.

Trial registration

clincaltrials.gov Identifier: NCT03228420.

Effect of High-frequency (10-kHz) Spinal Cord Stimulation in Patients With Painful Diabetic Neuropathy: A Randomized Clinical Trial

Question

Will 10-kHz spinal cord stimulation improve pain relief for patients with painful diabetic neuropathy refractory to medical management?

Findings

In this randomized clinical trial including 216 patients, there was a significant benefit of 10-kHz spinal cord stimulation, with 79% of treatment responders whose underlying neurological deficits did not worsen compared with 5% of controls treated with conventional medical management.

Meaning

Patients with painful diabetic neuropathy with inadequate pain relief despite best available medical treatments should be considered for 10-kHz spinal cord stimulation.

Importance

Many patients with diabetic peripheral neuropathy experience chronic pain and inadequate relief despite best available medical treatments.

Objective

To determine whether 10-kHz spinal cord stimulation (SCS) improves outcomes for patients with refractory painful diabetic neuropathy (PDN).

Design, Setting, and Participants

The prospective, multicenter, open-label SENZA-PDN randomized clinical trial compared conventional medical management (CMM) with 10-kHz SCS plus CMM. Participants with PDN for 1 year or more refractory to gabapentinoids and at least 1 other analgesic class, lower limb pain intensity of 5 cm or more on a 10-cm visual analogue scale (VAS), body mass index (calculated as weight in kilograms divided by height in meters squared) of 45 or less, hemoglobin A_1c (HbA_1c) of 10% or less, daily morphine equivalents of 120 mg or less, and medically appropriate for the procedure were recruited from clinic patient populations and digital advertising. Participants were enrolled from multiple sites across the US, including academic centers and community pain clinics, between August 2017 and August 2019 with 6-month follow-up and optional crossover at 6 months. Screening 430 patients resulted in 214 who were excluded or declined participation and 216 who were randomized. At 6-month follow-up, 187 patients were evaluated.

Interventions

Implanted medical device delivering 10-kHz SCS.

Main Outcomes and Measures

The prespecified primary end point was percentage of participants with 50% pain relief or more on VAS without worsening of baseline neurological deficits at 3 months. Secondary end points were tested hierarchically, as prespecified in the analysis plan. Measures included pain VAS, neurological examination, health-related quality of life (EuroQol Five-Dimension questionnaire), and HbA_1c over 6 months.

Results

Of 216 randomized patients, 136 (63.0%) were male, and the mean (SD) age was 60.8 (10.7) years. Additionally, the median (interquartile range) duration of diabetes and peripheral neuropathy were 10.9 (6.3-16.4) years and 5.6 (3.0-10.1) years, respectively. The primary end point assessed in the intention-to-treat population was met by 5 of 94 patients in the CMM group (5%) and 75 of 95 patients in the 10-kHz SCS plus CMM group (79%; difference, 73.6%; 95% CI, 64.2-83.0; P < .001). Infections requiring device explant occurred in 2 patients in the 10-kHz SCS plus CMM group (2%). For the CMM group, the mean pain VAS score was 7.0 cm (95% CI, 6.7-7.3) at baseline and 6.9 cm (95% CI, 6.5-7.3) at 6 months. For the 10-kHz SCS plus CMM group, the mean pain VAS score was 7.6 cm (95% CI, 7.3-7.9) at baseline and 1.7 cm (95% CI, 1.3-2.1) at 6 months. Investigators observed neurological examination improvements for 3 of 92 patients in the CMM group (3%) and 52 of 84 in the 10-kHz SCS plus CMM group (62%) at 6 months (difference, 58.6%; 95% CI, 47.6-69.6; P < .001).

Conclusions and Relevance

Substantial pain relief and improved health-related quality of life sustained over 6 months demonstrates 10-kHz SCS can safely and effectively treat patients with refractory PDN.

Trial Registration

ClincalTrials.gov Identifier: NCT03228420

Assessing diagnostic coding practices among a sample of healthcare facilities in Lyme disease endemic areas: Maryland and New York - A Brief Report

The value of using diagnostic codes in Lyme disease (LD) surveillance in highly endemic states has not been well studied. Surveys of healthcare facilities in Maryland (MD) and New York (NY) regarding coding practices were conducted to evaluate the feasibility of using diagnostic codes as a potential method for LD surveillance. Most respondents indicated that their practice utilized electronic medical records (53%) and processed medical/billing claims electronically (74%). Most facilities were able to search office visits associated with specific ICD-9-CM and CPT codes (74% and 73%, respectively); no discernible differences existed between the healthcare facilities in both states. These codes were most commonly assigned by the practitioner (82%), and approximately 70% of respondents indicated that these codes were later validated by administrative staff. These results provide evidence for the possibility of using diagnostic codes in LD surveillance. However, the utility of these codes as an alternative to traditional LD surveillance requires further evaluation.

The role of the family in HIV status disclosure among women in Vietnam: Familial dependence and independence

Insights into disclosure by people living with HIV and AIDS (PLWHA) can inform strategies for treatment and support, yet Vietnamese women's self-disclosure patterns are poorly understood. We conducted interviews with 12 HIV-positive women, identifying three principal factors influencing disclosure to family members: patrilocal residence, desire to protect own family, and the need for financial support. Women's decision-making about disclosure was significantly affected by dependence on or independence of parents-in-law and their own parents. We believe that our findings reveal the complex interplay of stigma and disclosure within Vietnamese families, highlighting the need for specific social measures that promote self-disclosure combined with family support for female PLWHA.

From Reliving to Relieving

Embodied Imagination (EI) is a psychotherapeutic technique in which a dream or memory environment is reexperienced in a hypnagogic state as a composite of its many perspectives simultaneously. While this method has been employed by mental health professionals to treat trauma survivors, there is scant documentation of its use with combat veterans. This case study focuses on the role of EI in helping a high-ranking Marine work through the stressful memories of war and the indecisiveness that marked his civilian life. Only in the last 6 months of his 2-year treatment could he reveal the recurring intrusive memory and nightmare of a high-risk mission he had authorized as a commanding officer in Afghanistan. The memory of certain decisions he had made on this mission left him with lingering guilt, shame, and doubt. Key to this process was the embodiment of a safe place that contained the patient, allowing him to integrate the more difficult parts of the memory without retraumatization. While EI is similar to other methods for working with nightmares, its emphasis on the non-self-perspective through the exploration of ego-alien images—while hewing closely to the original images—may be unique. EI appears to be a method that encourages posttraumatic growth.

A randomized controlled trial of the efficacy and safety of twice-daily saxagliptin plus metformin combination therapy in patients with type 2 diabetes and inadequate glycemic control on metformin monotherapy

BACKGROUND

To compare the safety and efficacy of saxagliptin 2.5 mg twice daily (BID) versus placebo add-on therapy to metformin immediate release (IR) in patients with type 2 diabetes and inadequate glycemic control with metformin alone.

METHODS

This multicenter, 12-week, double-blind, parallel-group trial enrolled adult outpatients with type 2 diabetes (glycated hemoglobin [HbA1c] 7.0%-10.0%) on stable metformin IR monotherapy (≥1500 mg, BID for ≥8 weeks). Patients were randomized to double-blind saxagliptin 2.5 mg BID or placebo added on to metformin IR following a 2-week, single-blind, placebo add-on therapy lead-in period. The primary end point was the change from baseline to week 12 in HbA1c. Key secondary end points included change from baseline to week 12 in fasting plasma glucose (FPG) and the proportion of patients achieving HbA1c <7.0% or HbA1c ≤ 6.5% at week 12. Efficacy was analyzed in all patients who received randomized study drug with ≥1 postbaseline assessment. Safety was assessed in all treated patients.

RESULTS

In total, 74 patients were randomized to double-blind saxagliptin add-on therapy and 86 to placebo add-on therapy. At week 12, least-squares mean changes (95% CI) from baseline HbA1c (adjusted for baseline HbA1c) were significantly greater (P = 0.006) in the saxagliptin + metformin group -0.56% (-0.74% to -0.38%) versus the placebo + metformin group -0.22% (-0.39% to -0.06%). Adjusted mean changes from baseline in FPG were numerically greater with saxagliptin versus placebo; the difference (95% CI) -9.5 mg/dL (-21.7 to 2.7) was not statistically significant (P = 0.12). A numerically greater proportion of patients in the saxagliptin group than the placebo group achieved HbA1c < 7.0% (37.5% vs 24.2%) or HbA1c ≤6.5% (24.6% vs 10.7%). There were no unexpected safety findings. Hypoglycemia occurred in 4 patients (5.4%) in the saxagliptin group and 1 patient (1.2%) in the placebo group; confirmed hypoglycemia (symptoms plus fingerstick glucose ≤50 mg/dL) occurred in 1 patient in the placebo group.

CONCLUSIONS

Addition of saxagliptin 2.5 mg BID to metformin therapy in patients with type 2 diabetes and inadequate glycemic control on metformin monotherapy reduced HbA1c compared with placebo added to metformin, with an adverse events profile similar to placebo and no unexpected safety findings.

TRIAL REGISTRATION

ClinicalTrials.gov NCT00885378.

Auger electron angular distribution of double core-hole states in the molecular reference frame

The Linac Coherent Light Source free electron laser is a source of high brightness x rays, 2×10(11) photons in a ∼5 fs pulse, that can be focused to produce double core vacancies through rapid sequential ionization. This enables double core vacancy Auger electron spectroscopy, an entirely new way to study femtosecond chemical dynamics with Auger electrons that probe the local valence structure of molecules near a specific atomic core. Using 1.1 keV photons for sequential x-ray ionization of impulsively aligned molecular nitrogen, we observed a rich single-site double core vacancy Auger electron spectrum near 413 eV, in good agreement with ab initio calculations, and we measured the corresponding Auger electron angle dependence in the molecular frame.

Time-resolved pump-probe experiments at the LCLS

The first time-resolved x-ray/optical pump-probe experiments at the SLAC Linac Coherent Light Source (LCLS) used a combination of feedback methods and post-analysis binning techniques to synchronize an ultrafast optical laser to the linac-based x-ray laser. Transient molecular nitrogen alignment revival features were resolved in time-dependent x-ray-induced fragmentation spectra. These alignment features were used to find the temporal overlap of the pump and probe pulses. The strong-field dissociation of x-ray generated quasi-bound molecular dications was used to establish the residual timing jitter. This analysis shows that the relative arrival time of the Ti:Sapphire laser and the x-ray pulses had a distribution with a standard deviation of approximately 120 fs. The largest contribution to the jitter noise spectrum was the locking of the laser oscillator to the reference RF of the accelerator, which suggests that simple technical improvements could reduce the jitter to better than 50 fs.

Effect of cordycepin triphosphate on in vitro RNA synthesis by plant viral replicases

In vitro RNA synthesis by tobacco mosaic virus and cowpea chlorotic mottle virus replicase were inhibited by cordycepin triphosphate. Inhibition could be overcome with higher concentrations of ATP in assay mixtures but not with UTP. Products synthesized in vitro by tobacco mosaic virus RNA replicase in the presence of inhibitor revealed replicative form but not replicative intermediate RNAs. These results suggest that cordycepin triphosphate competes specifically with ATP and results in premature termination of viral RNA synthesis in vitro.

The effect of breast support on kinetics during overground running performance

Changes in ground reaction forces that result from different breast support conditions may have implications for sports performance and transmission of forces through the skeleton. The aim of this investigation was to compare kinetic variables and breast motion in a no-bra, everyday-bra and two sports-bra conditions. Following ethical approval, eight female participants with D-cup breasts had retro-reflective markers placed on the left and right nipples, anterior superior iliac spines and clavicles. Five calibrated ProReflex infra-red cameras (100 Hz; Qualisys) measured 3-D displacement of markers and synchronised kinetic data were collected using a force platform (500 Hz, Kistler 9281CA). A repeated measures one-way ANOVA revealed a significantly higher medial impact force in the no-bra condition (0.15 times body weight) compared with the compression sports-bra condition (0.12 times body weight) (F = 3.64 (3,21), p = 0.03). Findings suggest that inadequate breast support affects a female's running kinetics, which may have negative physiological consequences on sports performance.

Characterization of aluminium-containing adjuvants

The approved aluminium-containing vaccine adjuvants have been shown to be poorly crystalline aluminium oxyhydroxide (AIO(OH)) and amorphous aluminium hydroxyphosphate of varying phosphate content. Adsorption of the antigen by the adjuvant is implied in many proposed mechanisms of antibody production enhancement caused by the adjuvants. The World Health Organization recommends adsorption of 80% or more of tetanus and diphtheria toxoid by the aluminium-containing adjuvants. Thus, one objective in the preparation of vaccines containing these adjuvants is to optimize adsorption of the antigen on the adjuvant. Production of a consistent adjuvant effect in vaccines would be facilitated by the thorough characterization of aluminium-containing adjuvants with reference to properties that affect adsorption and other colloidal behaviour. Such properties include surface area, surface charge, chemical composition, structure, and morphology. Techniques and measurements such as X-ray diffraction, infrared spectroscopy, transmission electron microscopy, energy-dispersive spectrometry, Doppler electrophoretic light scattering analysis, dissolution rates, and adsorption isotherms provide a basis for understanding and predicting interactions and behaviour in monovalent as well as multivalent vaccines. Such characterization would be crucial in vaccine standardization and quality control.

Effect of pyrolysis temperature on the mutagenicity of tobacco smoke condensate

Tobacco smoke aerosols with fewer mutagens in the particulate fraction may present reduced risk to the smoker. The objective of this study was to test the hypothesis that the temperature at which tobacco is pyrolyzed or combusted can affect the mutagenicity of the particulate fraction of the smoke aerosol. Tobacco smoke aerosol was generated under precisely controlled temperature conditions from 250 to 550 degrees C by heating compressed tobacco tablets in air. The tobacco aerosols generated had a cigarette smoke-like appearance and aroma. The tobacco smoke aerosol was passed through a Cambridge filter pad to collect the particulate fraction, termed the smoke condensate. Although condensates of tobacco smoke and whole cigarette mainstream smoke share many of the same chemical components, there are physical and chemical differences between the two complex mixtures. The condensates from smoke aerosols prepared at different temperatures were assayed in the Ames Salmonella microsome test with metabolic activation by rat liver S9 using tester strains TA98 and TA100. Tobacco smoke condensates were not detectably mutagenic in strain TA98 when the tobacco smoke aerosol was generated at temperatures below 400 degrees C. Above 400 degrees C, condensates were mutagenic in strain TA98. Similarly, condensates prepared from tobacco smoke aerosols generated at temperatures below 475 degrees C were not detectably mutagenic in strain TA100. In contrast, tobacco tablets heated to temperatures of 475 degrees C or greater generated smoke aerosol that was detectably mutagenic as measured in TA100. Therefore, heating and pyrolyzing tobacco at temperatures below those found in tobacco burning cigarettes reduces the mutagenicity of the smoke condensate. Highly mutagenic heterocyclic amines derived from the pyrolysis of tobacco leaf protein may be important contributors to the high temperature production of tobacco smoke Ames Salmonella mutagens. The relevance of these findings regarding cancer risk in humans is difficult to assess because of the lack of a direct correlation between mutagenicity in the Ames Salmonella test and carcinogenicity.

Degree of antigen adsorption in the vaccine or interstitial fluid and its effect on the antibody response in rabbits

The effect of the degree of adsorption of lysozyme by aluminium hydroxide adjuvant on the immune response in rabbits was studied. The surface charge of the adjuvant was modified by pretreatment with phosphate anion to produce five vaccines having degrees of adsorption ranging from 3 to 90%. The degree of adsorption of vaccines exhibiting 3, 35 or 85% adsorption changed to 40% within 1 h after each vaccine was mixed with sheep interstitial fluid to simulate subcutaneous administration. The mean anti-lysozyme antibody titers produced by the vaccines were the same and were four times greater than that produced by a lysozyme solution. Thus, the degree of adsorption of lysozyme in sheep interstitial fluid rather than the degree of adsorption in the vaccine correlated with the immune response.

Measurement of CP-violating asymmetries in B0 decays to CP eigenstates

We present measurements of time-dependent CP-violating asymmetries in neutral B decays to several CP eigenstates. The measurement uses a data sample of 23x10(6) Upsilon(4S)-->BbarB decays collected by the BABAR detector at the PEP-II asymmetric B Factory at SLAC. In this sample, we find events in which one neutral B meson is fully reconstructed in a CP eigenstate containing charmonium and the flavor of the other neutral B meson is determined from its decay products. The amplitude of the CP-violating asymmetry, which in the standard model is proportional to sin2beta, is derived from the decay time distributions in such events. The result is sin2beta = 0.34+/-0.20 (stat)+/-0.05 (syst).

Effects of intrathecal morphine on the ventilatory response to hypoxia

BACKGROUND

Intrathecal administration of morphine produces intense analgesia, but it depresses respiration, an effect that can be life-threatening. Whether intrathecal morphine affects the ventilatory response to hypoxia, however, is not known.

METHODS

We randomly assigned 30 men to receive one of three study treatments in a double-blind fashion: intravenous morphine (0.14 mg per kilogram of body weight) with intrathecal placebo; intrathecal morphine (0.3 mg) with intravenous placebo; or intravenous and intrathecal placebo. The selected doses of intravenous and intrathecal morphine produce similar degrees of analgesia. The ventilatory response to hypercapnia, the subsequent response to acute hypoxia during hypercapnic breathing (targeted end-tidal partial pressures of expired oxygen and carbon dioxide, 45 mm Hg), and the plasma levels of morphine and morphine metabolites were measured at base line (before drug administration) and 1, 2, 4, 6, 8, 10, and 12 hours after drug administration.

RESULTS

At base line, the mean (+/-SD) values for the ventilatory response to hypoxia (calculated as the difference between the minute ventilation during the second full minute of hypoxia and the fifth minute of hypercapnic ventilation) were similar in the three groups: 38.3+/-23.2 liters per minute in the placebo group, 33.5+/-16.4 liters per minute in the intravenous-morphine group, and 30.2+/-11.6 liters per minute in the intrathecal-morphine group (P=0.61). The overall ventilatory response to hypoxia (the area under the curve) was significantly lower after either intravenous morphine (20.2+/-10.8 liters per minute) or intrathecal morphine (14.5+/-6.4 liters per minute) than after placebo (36.8+/-19.2 liters per minute) (P=O.003). Twelve hours after treatment, the ventilatory response to hypoxia in the intrathecal-morphine group (19.9+/-8.9 liters per minute), but not in the intravenous-morphine group (30+/-15.8 liters per minute), remained significantly depressed as compared with the response in the placebo group (40.9+/-19.0 liters per minute) (P= 0.02 for intrathecal morphine vs. placebo). Plasma concentrations of morphine and morphine metabolites either were not detectable after intrathecal morphine or were much lower after intrathecal morphine than after intravenous morphine.

CONCLUSIONS

Depression of the ventilatory response to hypoxia after the administration of intrathecal morphine is similar in magnitude to, but longer-lasting than, that after the administration of an equianalgesic dose of intravenous morphine.

Aluminium phosphate adjuvants prepared by precipitation at constant pH. Part I: composition and structure

Aluminium phosphate adjuvant was precipitated under constant pH conditions in an effort to characterize materials formed at defined precipitation conditions. A reaction vessel was designed to provide a continuous steady-state process. An aqueous solution containing aluminium chloride and sodium dihydrogen phosphate was pumped into the reaction vessel at a constant rate. A second pump infused a sodium hydroxide solution at the rate required to maintain the desired pH. Precipitations were performed between pH 3.0 and 7.5, at intervals of pH 0.5. The adjuvants were characterized using 27Al NMR, FTIR, Raman and X-ray diffraction methods along with elemental analysis. The results of this study indicate that a continuum of amorphous aluminium hydroxyphosphates were formed having properties that changed as a continuous function of the precipitation pH. The phosphate content decreased as the pH of precipitation increased. 27Al NMR spectra revealed that the majority of the aluminium was octahedrally coordinated, with a small percentage of tetrahedrally coordinated aluminium. The density of the adjuvants was directly related to the pH of precipitation. The most prominent feature of the IR and Raman spectra is the P-O stretching vibration of the structural PO(4) groups. The positions of these bands decreased linearly as the precipitation pH increased. The results of selective deuteration FTIR experiments are consistent with high surface area materials as most of the OH groups were exposed near the surface of the adjuvant.

Aluminium phosphate adjuvants prepared by precipitation at constant pH. Part II: physicochemical properties

The impact of the pH of precipitation on the physicochemical properties of aluminium phosphate adjuvants was investigated by precipitating aluminium phosphate adjuvants under constant pH conditions at pH values from 3.0 to 7.5 at intervals of 0.5. The pH of precipitation did not affect the morphology, but the point of zero charge (PZC) and rate of acid neutralization varied directly with pH of precipitation. Aggregation and protein adsorption capacity exhibited a parabolic relationship to the pH of precipitation. Minimum protein adsorption and maximum aggregation were observed at pH 5.5. In contrast to adjuvants precipitated from the same reactants but under uncontrolled pH conditions, the pH of all of the adjuvants precipitated under constant pH conditions remained constant for a 3-month aging period at room temperature.

Stability of aluminium-containing adjuvants during aging at room temperature

Aluminium phosphate adjuvant and aluminium hydroxide adjuvant became more ordered during aging at room temperature. The increased degree of order was accompanied by a decrease in protein adsorption capacity.

Effect of inhibitors on the ubiquinone binding capacity of the primary energy conversion site in the Rhodobacter capsulatus cytochrome bc(1) complex

A key issue concerning the primary conversion (Q(O)) site function in the cytochrome bc(1) complex is the stoichiometry of ubiquinone/ubihydroquinone occupancy. Previous evidence suggests that the Q(O) site is able to accommodate two ubiquinone molecules, the double occupancy model [Ding, H., Robertson, D. E., Daldal, F., and Dutton, P. L. (1992) Biochemistry 31, 3144-3158]. In the recently reported crystal structures of the cytochrome bc(1) complex, no electron density was identified in the Q(O) site that could be ascribed to ubiquinone. To provide further insight into this issue, we have manipulated the cytochrome bc(1) complex Q(O) site occupancy in photosynthetic membranes from Rhodobacter capsulatus by using inhibitor titrations and ubiquinone extraction to modulate the amount of ubiquinone bound in the site. The nature of the Q(O) site occupants was probed via the sensitivity of the reduced [2Fe-2S] cluster electron paramagnetic resonance (EPR) spectra to modulation of Q(O) site occupancy. Diphenylamine (DPA) and methoxyacrylate (MOA)-stilbene are known Q(O) site inhibitors of the cytochrome bc(1) complex. Addition of stoichiometric concentrations of MOA-stilbene or excess DPA to cytochrome bc(1) complexes with natural levels of ubiquinone elicits the same change in the [2Fe-2S] cluster EPR spectra; the g(x)() resonance broadens and shifts from 1. 800 to 1.783. This is exactly the same signal as that obtained when there is only one ubiquinone present in the Q(O) site. Furthermore, addition of MOA-stilbene or DPA to the cytochrome bc(1) complex depleted of ubiquinone does not alter the [2Fe-2S] cluster EPR spectral line shapes, which remain indicative of one ubiquinone or zero ubiquinones in the Q(O) site, with broad g(x)() resonances at 1. 783 or 1.765, respectively. The results are quite consistent with the Q(O) site double occupancy model, in which MOA-stilbene and DPA inhibit by displacing one, but not both, of the Q(O) site ubiquinones.

The in vitro displacement of adsorbed model antigens from aluminium-containing adjuvants by interstitial proteins

Vaccines prepared by adsorbing an antigen onto an aluminium-containing adjuvant are usually administered by intramuscular or subcutaneous injection. The vaccine then comes in contact with interstitial fluid which contains proteins. In vitro displacement studies were performed to determine whether antigens, which are adsorbed to aluminium-containing adjuvants, can be displaced by interstitial proteins. It was found that when previously adsorbed model antigens such as lysozyme or myoglobin were exposed to interstitial proteins such as albumin or fibrinogen that extensive displacement occurred. A factorial study of the displacement of myoglobin from aluminium hydroxide adjuvant by albumin was performed. The displacement occurred rapidly with the majority of the displacement occurring in less than 15 min. Whether the concentration of the adsorbed myoglobin was above or below the adsorptive capacity of the aluminium hydroxide adjuvant affected the amount which could be displaced. Less myoglobin was displaced when the concentration was below the adsorptive capacity. The age of the model vaccine (1, 2 or 7 days) prior to exposure to the interstitial protein did not influence the amount of myoglobin that was displaced. The affinity of model antigens and interstitial proteins for aluminium hydroxide or aluminium phosphate adjuvant was characterized by the adsorption coefficient in the Langmuir equation. In every case studied, the protein having the larger adsorption coefficient was able to displace the protein with the smaller adsorption coefficient.

Stability of aluminium-containing adjuvants to autoclaving

Aluminium phosphate adjuvant remained amorphous when autoclaved for 30 or 60 min at 121 degrees C. However, deprotonation and dehydration reactions occurred as evidenced by a decrease in the pH. The protein adsorption capacity, rate of acid neutralization at pH 2.5 and point of zero charge also decreased indicating that the deprotonation/dehydration reactions resulted in a decreased surface area. Autoclaving aluminium hydroxide adjuvant increased the degree of crystallinity as measured by the width at half height of the major band in the X-ray diffractogram. The pH decreased during autoclaving suggesting that the same deprotonation/dehydration reactions which reduced the surface area of aluminium phosphate adjuvant were responsible for the increased degree of crystallinity. These reactions also resulted in a reduced surface area as both the protein adsorption capacity and viscosity decreased following autoclaving.

Selective type III phosphodiesterase inhibition prevents elevated compartment pressure after ischemia/reperfusion injury

BACKGROUND

A new synthetic cyclic adenosine monophosphate phosphodiesterase inhibitor, cilostazol, has been shown to inhibit platelet aggregation and act synergistically with endogenous prostaglandin I2 to enhance smooth-muscle cell vasodilitation. The effect of cilostazol in ischemia/reperfusion injury-induced compartment syndrome was investigated.

METHODS

Sixteen rabbits underwent femoral artery occlusion after ligation of branches from the terminal aorta to the femoral artery. After 7 hours of ischemia, reperfusion was established with heparinized polyethylene shunts. Experimental animals (n = 8) received cilostazol (3.0 mg/kg) and control animals (n = 8) received normal saline as an intravenous infusion 10 minutes before shunt placement. During reperfusion, anterior compartment pressure was continuously monitored in the left lower extremity, and femoral artery blood flow was measured by laser Doppler fluorometry. To quantitate skeletal muscle oxidative metabolism and viability, triphenyltetrazolium chloride (TTC) reduction (micrograms of TTC per milligram of protein) of tibialis anterior muscle from the right lower extremity was measured at femoral artery occlusion, 7 hours of ischemia, and 2 hours of reperfusion. To assess tissue edema, dry/wet weight ratios were also determined at these intervals. Data were expressed as means +/- SE. Comparisons within groups were performed by analysis of variance, and comparisons between groups with two-tailed unpaired t tests.

RESULTS

At 2 hours of reperfusion, the difference between controls and cilostazol-treated animals was extremely significant (p = 0.0008). Preischemia and 2-hour reperfusion TTC and dry/wet weight ratios were not significantly different within or between experimental groups, nor was femoral artery blood flow during reperfusion.

CONCLUSION

Cilostazol inhibits the increase in compartment pressure central to the development of the compartment syndrome. The mechanism appears to be independent of altered tissue permeability or oxidative metabolism.

Ubiquinone binding capacity of the Rhodobacter capsulatus cytochrome bc1 complex: effect of diphenylamine, a weak binding QO site inhibitor

Diphenylamine (DPA), a known inhibitor of polyene and isoprene biosynthesis, is shown to inhibit flash-activatable electron transfer in photosynthetic membranes of Rhodobacter capsulatus. DPA is specific to the QO site of ubihydroquinone:cytochrome c oxidoreductase, where it inhibits not only reduction of the [2Fe-2S]2+ cluster in the FeS subunit and subsequent cytochrome c reduction but also heme bL reduction in the cytochrome b subunit. In both cases, the kinetic inhibition constant (Ki) is 25 +/- 10 microM. A novel aspect of the mode of action of DPA is that complete inhibition is established without disturbing the interaction between the reduced [2Fe-2S]+ cluster and the QO site ubiquinone complement, as observed from the electron paramagnetic resonance (EPR) spectral line shape of the reduced [2Fe-2S] cluster, which remained characteristic of two ubiquinones being present. These observations imply that DPA is behaving as a noncompetitive inhibitor of the QO site. Nevertheless, at higher concentrations (>10 mM), DPA can interfere with the QO site ubiquinone occupancy, leading to a [2Fe-2S] cluster EPR spectrum characteristic of the presence of only one ubiquinone in the QO site. Evidently, DPA can displace the more weakly bound of the two ubiquinones in the site, but this is not requisite for its inhibiting action.

Wellness Wednesdays: Health Promotion and Service Learning on Campus

The Wellness Wednesdays program has shown itself to be an effective method for providing community-based service learning opportunities in a setting that is convenient for participants, students, and faculty. As the program continues to grow, it will provide opportunities for interdisciplinary collaboration with other health-related departments on campus. It also will provide a setting for faculty and student research in multiple areas related to management, health promotion, disease prevention, and health behavior motivation.

Ticks and tick-borne diseases in Oklahoma

Tick-borne diseases are common in Oklahoma, especially the eastern part of the state where tick prevalence is highest. Three species of hard ticks are present in Oklahoma that are known vectors of human disease--the American dog tick (Rocky Mountain spotted fever; RMSF), the lone star tick (ehrlichiosis) and the black-legged tick (Lyme disease). Oklahoma consistently ranks among the top states in numbers of reported RMSF cases, and Ehrlichiosis may be as prevalent as RMSF. Although Lyme disease is frequently reported in Oklahoma, over-diagnosing of this disease due to false-positive test results is common; positive or equivocal screening tests should be confirmed by Western immunoblot. At present, it is unclear whether the disease seen here is Lyme disease or another Lyme-like disease. If true Lyme disease is present in the state, it is probably rare. Physicians should be aware of the most recent recommendations for diagnosis, therapy and prevention of tick-borne diseases.

Differential sensory block: spinal vs epidural with lidocaine

PURPOSE

In this study we sought to determine if and when a difference exists with regards to differential sensory blockade between spinal and epidural anaesthesia using lidocaine.

METHODS

Ten healthy volunteers were randomly assigned to receive both spinal and epidural anaesthesia. Non-epinephrine containing solutions of lidocaine, 100 mg lidocaine 5% with 7.5% dextrose (spinal) and 600 mg lidocaine 2% (epidural), were used to establish sensory blockade. At five minute intervals, for a total of 65 min, the following sensory modalities were tested: anaesthesia (complete loss of sensation to pinprick), analgesia (loss of an equally sharp sensation to pinprick compared with that at an unblocked dermatome), cold sensation (complete loss of cold temperature discrimination).

RESULTS

At all times, except at time = 0 during spinal anaesthesia, the levels of analgesia and cold sensation were more cephalad than the level of anaesthesia for both spinal and epidural anaesthesia. Multiple comparison testing among the three dermatomal response levels showed that, during epidural anaesthesia, the level of analgesia was more cephalad than the level of cold sensation at the following times: 25 min, 30 min, and from 40 to 60 min. In contrast, the level of analgesia was not different from the level of cold sensation during spinal anaesthesia.

CONCLUSIONS

Spinal and epidural anaesthesia with lidocaine produce a similar degree of differential sensory blockade. Epidural anaesthesia produces a detectable difference between the level of analgesia and cold sensation at various times, whereas spinal anaesthesia did not reliably do so in this study.

Effect of pH on the Elution of Model Antigens from Aluminum-Containing Adjuvants

The effect of adjusting the pH of a model ovalbumin (iep = 4.7) and aluminum hydroxide adjuvant (iep = 11.5) vaccine or a model lysozyme (iep = 11.4) and aluminum phosphate adjuvant (iep = 5.0) vaccine to values ranging from 3 to 11 was studied. The model vaccine prepared at pH 7.4 served as the reference. Additional adsorption of ovalbumin occurred in the pH range 7.4 to 4.1. Elution of ovalbumin occurred when the pH was adjusted to values above 7.4 or below 4.1. Maximum elution occurred at pH 2.9 and 11.0. Elution of lysozyme from aluminum phosphate adjuvant occurred when the pH was adjusted to any value other than the reference pH of 7.4. More lysozyme was eluted at pH 2.9 than at pH 11.0. The adsorption/elution behavior could be explained by the effect of pH on: (1) the ionization state of the protein, 2) the solubility of the adjuvant, and (3) the electrostatic interaction between the protein and adjuvant. Copyright 1998 Academic Press.

Elutability of Proteins from Aluminum-Containing Vaccine Adjuvants by Treatment with Surfactants

The elutability of proteins from adjuvants in model vaccines composed of ovalbumin adsorbed by aluminum hydroxide adjuvant or lysozyme adsorbed by aluminum phosphate adjuvant following treatment with surfactant solutions was studied. Nonionic (Triton X-100, lauryl maltoside), zwitterionic (lauryl sulfobetaine), anionic (sodium dodecyl sulfate), and cationic (cetylpyridinium chloride, dodecyltrimethylammonium chloride) surfactants were investigated. Cetylpyridinium chloride produced the greatest degree of elution (60%) of ovalbumin from aluminum hydroxide adjuvant. Sodium dodecyl sulfate completely eluted lysozyme from aluminum phosphate adjuvant. The effectiveness of surfactants in removing preadsorbed proteins was directly related to their ability to denature the protein. Micellar solubilization and electrostatic repulsion may also contribute to desorption. Copyright 1998 Academic Press. Copyright 1998Academic Press

Exploiting methyl groups as motional labels for structure analysis in solid polymers

We report results of magic-angle spinning (MAS) nuclear Overhauser experiments on solid polymers. Specifically, the focus of this work is to demonstrate that methyl groups provide unique motional labels in crystalline and amorphous materials that may be exploited to provide spatial information. The motivation for this work stems from the fact that recently developed techniques for distance determination in organic solids, e.g. REDOR and related spin-echo methods, typically require isotopic labelling. Comparison of heteronuclear MAS 13C-1H NOE growth rates for bis-phenol A (a crystalline organic solid), polycarbonate, chloral polycarbonate, polystyrene, poly(4-methylstyrene), and poly(alpha-methylstyrene) confirms that methyl groups are the only sources of cross-relaxation in these rigid polymers. The experiments are straightforward, and have the advantage that no isotopic labelling is required. In general, decreased growth rates and increased induction periods for carbons distant from methyl groups are observed. Critical analysis of the data suggests that the rates are sensitive to packing density, and we address the contribution of intrachain and interchain interactions to the observed rates. We expect that methyl-stimulated NOE's are general to all rigid solids, and that these experiments could prove useful for local structure characterization of polymers in cases where isotopic labelling is not practical.

Sympathetic block during spinal anesthesia in volunteers using lidocaine, tetracaine, and bupivacaine

BACKGROUND AND OBJECTIVES

Spinal anesthesia to high thoracic dermatomes is alleged to result in almost complete block of all sympathetic efferent nerves. To examine the degree of sympathectomy during spinal anesthesia, the sympathetic response to a cold pressor test (CPT) applied to unblocked dermatomes before and during spinal anesthesia was measured with use of three different local anesthetics.

METHODS

Twelve healthy volunteers were studied in a randomized and double-blind fashion on three separate occasions. In random order, each volunteer received approximately equipotent spinal doses of tetracaine 15 mg, bupivacaine 15 mg, and lidocaine 100 mg in hyperbaric solutions. Prior to and 30 minutes after spinal injection of local anesthetic, a CPT was applied for 2 minutes, and changes from baseline resting conditions in five physiologic variables were measured.

RESULTS

The CPT 1 given before anesthetic administration resulted in an increase in heart rate, mean arterial pressure, cardiac index, and plasma concentrations of norepinephrine and epinephrine. Spinal anesthesia to a median level of T3 resulted in a decrease in mean arterial pressure by 10-12% but did not significantly decrease the other variables. Spinal anesthesia did not change the increase in heart rate or cardiac index in response to the second CPT, but the increase in mean arterial pressure was attenuated compared to the CPT before anesthesia. No increase in norepinephrine or epinephrine concentration was observed during the CPT given during spinal anesthesia. There was no significant relationship between level of analgesia and sympathetic response to stress.

CONCLUSIONS

Spinal anesthesia with hyperbaric solutions of tetracaine 15 mg, bupivacaine 15 mg, and lidocaine 100 mg attenuated sympathetic function but did not produce complete sympathectomy. The effects were independent of the local anesthetic used.

In vivo absorption of aluminium-containing vaccine adjuvants using 26Al

Aluminium hydroxide (AH) and aluminium phosphate (AP) adjuvants, labelled with 26Al, were injected intramuscularly (i.m.) in New Zealand White rabbits. Blood and urine samples were collected for 28 days and analysed for 26Al using accelerator mass spectrometry to determine the absorption and elimination of AH and AP adjuvants. 26Al was present in the first blood sample (1 h) for both adjuvants. The area under the blood level curve for 28 days indicates that three times more aluminium was absorbed from AP adjuvant than AH adjuvant. The distribution profile of aluminium to tissues was the same for both adjuvants (kidney > spleen > liver > heart > lymph node > brain). This study has demonstrated that in vivo mechanisms are available to eliminate aluminium-containing adjuvants after i.m. administration. In addition, the pharmacokinetic profiles of AH and AP adjuvants are different.

Effect of sorbitol on the phosphate adsorptive capacity of ferrihydrite suspensions

The purpose of this study was to stabilize the phosphate adsorptive capacity of aqueous suspensions of ferrihydrite, a potential phosphate binder. Ferrihydrite was precipitated by the addition of 1 N NaOH to 1 M FeCl3 until pH 8.0 was reached. The ferrihydrite suspension was divided into three portions and an amount of sorbitol was added to produce sorbitol concentrations of 0, 1, or 5% w/v, respectively. The phosphate adsorptive capacity and X-ray diffraction pattern were periodically determined during aging at room temperature. The phosphate adsorptive capacity of the ferrihydrite suspension containing 0% sorbitol decreased steadily from 0.012 mgP/mg to 0.007 mgP/mg during the 1-year aging period. In contrast, suspensions containing 1 or 5% sorbitol exhibited constant phosphate adsorptive capacities during this period. X-ray diffraction patterns revealed that ferrihydrite transformed to hematite and goethite during aging of the control suspension. The presence of 1 or 5% sorbitol prevented the transformation of ferrihydrite to more crystalline iron oxides. This study suggests that the phosphate adsorptive capacity of ferrihydrite suspensions can be stabilized by the incorporation of small amounts of sorbitol into the formulation.

Role of the electrostatic attractive force in the adsorption of proteins by aluminum hydroxide adjuvant

The fact that both aluminum hydroxide adjuvant and proteins have a pH dependent surface charge means that electrostatic forces play a role in the adsorption of proteins by aluminum hydroxide adjuvant during the preparation of vaccines. The objective of this study was to examine the contribution of the electrostatic attractive force in the adsorption of proteins by aluminum hydroxide adjuvant. Since the surface charge characteristics of aluminum hydroxide adjuvant can be modified by the adsorption of phosphate anion, a series of aluminum hydroxide adjuvants were prepared by treatment with various concentrations of phosphate anion. The isoelectric points (iep) of these adjuvants ranged from 11.0 to 4.6 and the electrophoretic mobilities at pH 7.4 ranged from 2.0 to -3.3 microns cm/V s. The line broadening of the (020) band of the X-ray diffraction pattern indicated that treatment with phosphate anion did not change the primary crystallite dimension. Adsorption at pH 7.4 of positively charged lysozyme (iep = 11.1) was directly related to the negative surface charge of the adjuvant. No adsorption occurred when the surface charge was positive. In contrast, negatively charged ovalbumin (iep = 4.6) was adsorbed by all of the adjuvants at pH 7.4, although the adsorptive capacity was the greatest when the surface charge was positive. The results indicate that adsorptive forces in addition to the electrostatic attractive force play an important role in the adsorption of some proteins by aluminum hydroxide adjuvant. It is believed the structurally flexible proteins, like ovalbumin, exhibit more complex adsorption behavior than structurally rigid proteins, like lysozyme, for which adsorptive behavior can be explained by electrostatic forces.

The Effect of Humidity on the Physical and Chemical Stability of Spray-Dried Aluminum Hydroxycarbonate

The moisture sorption isotherm of amorphous spray-dried aluminum hydroxycarbonate (SDAHC) at 25&deg;C revealed that moisture sorption increased sharply when the relative humidity exceeded 80%. The physical and chemical stability of SDAHC was studied for 1 year at 25&deg;C and 0, 11, 54, 84, or 100% RH. The results were interpreted to reveal that two mechanisms affect the properties of SDAHC at 25&deg;C. The sample stored at 0% RH did not exhibit any significant changes during the 1-year study period. The surface area and rate of acid neutralization decreased when samples were stored at 11 or 54% RH, but the material remained amorphous. This change is believed to be due to aggregation and cementation of particles. Much larger changes in surface area and the rate of acid neutralization occurred in the samples aged at 84 or 100% RH. Under these humidity conditions, polymorphic transformations occurred in addition to aggregation and cementation. X-ray diffraction indicated that microcrystalline boehmite was an intermediate phase. The stable polymorph was bayerite, which is believed to form due to the high surface pH produced by water sorption at 84 or 100% RH. The moisture sorption isotherm was useful in identifying the humidity conditions which resulted in high moisture sorption. Polymorphic transformations were only detected when the SDAHC was aged under these humidity conditions.

Treatment of aluminium hydroxide adjuvant to optimize the adsorption of basic proteins

Aluminium hydroxide adjuvant has an isoelectric point (i.e.p.) of ca 11 and is a good adsorbent for acidic proteins due to the contribution of electrostatic attractive forces. However, electrostatic repulsive forces reduce its ability to adsorb basic proteins. Pretreatment of aluminium hydroxide adjuvant with carefully selected concentrations of phosphate anion reduces the positive surface charge which exists at pH 7.4. Treatment with higher concentrations of phosphate anion produces a negative surface charge. The adsorption of lysozyme (i.e.p = 11.1) was found to be directly related to the concentration of phosphate anion used to pretreat the aluminium hydroxide adjuvant.