Salivary protein changes in response to acute stress in medical residents performing advanced clinical simulations: a pilot proteomics study

CONTEXT

Quantitative changes of salivary proteins due to acute stress were detected.

OBJECTIVE

To explore protein markers of stress in saliva of eight medical residents who performed emergency medicine simulations.

MATERIALS AND METHODS

Saliva was collected before the simulations, after the simulations, and following morning upon waking. Proteins were separated by sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE), identified by mass spectrometry (MS), and relatively quantified by densitometry.

RESULTS

Salivary alpha-amylase and S-type cystatins significantly increased, while the ∼26 kDa and low-molecular weight (MW) (<10 kDa) SDS-PAGE bands exhibited changes after stress.

DISCUSSION AND CONCLUSION

Alpha-amylase and cystatins are potential salivary markers of acute stress, but further validation should be performed using larger sample populations.

Reasons Why Herbal Users Do or Do Not Tell Their Physicians about Their Use: A Survey of Adult Ohio Residents

Background:

Several studies have reported lack of patient–physician communication regarding herbal use. However, reasons for this lack of communication are not well understood.

Objective:

To determine, explore, and identify reasons for lack of patient–physician communication about herbal use.

Methods:

Using a cross-sectional design, a systematic sample of 1,000 adult Ohio residents was surveyed through a 29 item questionnaire. Survey items were adapted from earlier instruments evaluating complementary and alternative use. Descriptive and univariate statistics were run using SPSS version 10.0.

Results:

Of 210 usable responses, almost half (47.6%) of the participants reported that they were either currently using herbal products or had used them in the past, with 1 in 16 using herbal products daily. Forty-eight percent of these respondents indicated that they had never had a discussion with their physician about using herbal medicines. A similar percentage (45%) of individuals using herbal agents had not told their physicians about any of the products they used. The top 3 reasons for informing physicians of herbal use were that the physician needs to be aware of all of the products used, the physician may know whether herbals work, and the physician understands the interactions of herbals with prescribed drugs. The main reason that patients did not supply the information was that the physician did not ask them about it.

Conclusions:

Many patients do not inform their physicians about their use of herbal products unless asked. Physicians and other healthcare providers should therefore integrate inquiry about herbal product use as part of medication history.

Effect of changing NAVA levels on peak inspiratory pressures and electrical activity of the diaphragm in premature neonates

BACKGROUND

Neurally adjusted ventilator assist (NAVA) uses electrical activity of the diaphragm (Edi) to provide patient-directed ventilatory support. The NAVA level determines the proportional amount of ventilatory support. Systematically increasing NAVA level initially increases peak inspiratory pressure (PIP) while maintaining a constant Edi until a breakpoint (BrP) is reached. Further increases in NAVA level reduce the Edi, while the PIP plateaus. This study was performed to establish whether premature neonates have intact neural feedback systems allowing them to have a BrP.

METHOD

NAVA level was increased by 0.5 cm H2O μV(-1) every 3 min from 0.5 to 4.0 cm H2O μV(-1). PIP, Edi, mean blood pressure, heart rate, respiratory rate, oxygen saturation and FIO2 were recorded. Statistics: Non-linear regression was done for PIP and Edi. Linear regression was done for the other variables. The data from the trials were combined by normalizing to NAVA levels above and below the BrP.

RESULT

Nine neonates were studied on NAVA and 12 on non-invasive NAVA. PIP increased until the BrP was reached and then remained unchanged. Edi decreased after the BrP was reached. All other variables remained unchanged.

CONCLUSION

Neonates demonstrated a BrP suggesting intact neural feedback mechanisms that may protect lungs from over distention with NAVA ventilation.

Electrical activity of the diaphragm (Edi) values and Edi catheter placement in non-ventilated preterm neonates

OBJECTIVE

The electrical activity of the diaphragm (Edi) reflects neural respiratory drive. Edi peak correlates with inspiratory drive and Edi minimum (Edi min) correlates with the tonic activity of the diaphragm. Edi data in non-ventilated preterm neonates have not been determined.The primary aim of this study was to determine Edi values in non-ventilated preterm neonates throughout postnatal maturation and with various types of noninvasive respiratory support. The secondary aim was to evaluate the success or complications of placement of the Edi catheter in premature neonates.

STUDY DESIGN

This was a prospective observational study of non-ventilated neonates <33 weeks gestation. Data were collected weekly using an Edi catheter placed in neonates on highflow nasal cannula (HFNC), nasal cannula (NC) or room air (RA). Clinical stability was determined by measuring heart rate (HR), respiratory rate (RR) and oxygen saturation (Sats). Success and adverse events of Edi catheter placement was monitored. Statistics were obtained by analysis of variance, P<0.05 was considered significant.

RESULT

Seventeen neonates were enrolled at 26 to 33 weeks postmenstrual age and studied from 1 to 10 weeks in duration. Overall Edi peak was 10.8±3.7 mcV (range 3.7 to 18.7) and Edi min was 2.8±1.1 mcV (range 0.8 to 7.6). There was no difference in Edi peak and min over postmenstrual ages within or between neonates, and no difference between those neonates on HFNC, NC or RA. HR, RR and Sats were not different over postmenstrual age or between any groups. The Edi catheter was placed successfully in 100% of these neonates. There were no adverse events noted.

CONCLUSION

In clinically stable neonates, the inspiratory drive (Edi peak) and tonic activity (Edi min) do not change with postnatal maturation or with the level of noninvasive respiratory support. The Edi catheter can be placed successfully in these premature neonates. These Edi data have the potential to guide ventilatory management of premature neonates.

Does it matter what you call it? A randomized trial of language used to describe palliative care services

INTRODUCTION

Integration of palliative care into oncology practice remains suboptimal. Misperceptions about the meaning of palliative care may negatively impact utilization.

PURPOSE

We assessed whether the term and/or description of palliative care services affected patient views.

METHODS

2x2 between-subject randomized factorial telephone survey of 169 patients with advanced cancer. Patients were randomized into one of four groups that differed by name (supportive care vs. palliative care) and description (patient-centered vs. traditional). Main outcomes (0-10 Likert scale) were patient understanding, impressions, perceived need, and intended use of services.

RESULTS

When compared to palliative care, the term supportive care was associated with better understanding (7.7 vs. 6.8; p = 0.021), more favorable impressions (8.4 vs. 7.3; p = 0.002), and higher future perceived need (8.6 vs. 7.7; p = 0.017). There was no difference in outcomes between traditional and patient-centered descriptions. In adjusted linear regression models, the term supportive care remained associated with more favorable impressions (p = 0.003) and higher future perceived need (p = 0.022) when compared to palliative care.

CONCLUSIONS

Patients with advanced cancer view the name supportive care more favorably than palliative care. Future efforts to integrate principles of palliative medicine into oncology may require changing impressions of palliative care or substituting the term supportive care.

Do-not-resuscitate orders and predictive models after intracerebral hemorrhage

OBJECTIVE

To quantify the accuracy of commonly used intracerebral hemorrhage (ICH) predictive models in ICH patients with and without early do-not-resuscitate orders (DNR).

METHODS

Spontaneous ICH cases (n = 487) from the Brain Attack Surveillance in Corpus Christi study (2000-2003) and the University of California, San Francisco (June 2001-May 2004) were included. Three models (the ICH Score, the Cincinnati model, and the ICH grading scale [ICH-GS]) were compared to observed 30-day mortality with a chi(2) goodness-of-fit test first overall and then stratified by early DNR orders.

RESULTS

Median age was 71 years, 49% were female, median Glasgow Coma Scale score was 12, median ICH volume was 13 cm(3), and 35% had early DNR orders. Overall observed 30-day mortality was 42.7% (95% confidence interval [CI] 38.3-47.1), with the average model-predicted 30-day mortality for the ICH Score, Cincinnati model, and ICH-GS at 39.9% (p = 0.005), 40.4% (p = 0.007), and 53.9% (p < 0.001). However, for patients with early DNR orders, the observed 30-day mortality was 83.5% (95% CI 78.0-89.1), with the models predicting mortality of 64.8% (p < 0.001), 57.2% (p < 0.001), and 77.8% (p = 0.02). For patients without early DNR orders, the observed 30-day mortality was 20.8% (95% CI 16.5-25.7), with the models predicting mortality of 26.6% (p = 0.05), 31.4% (p < 0.001), and 41.1% (p < 0.001).

CONCLUSIONS

ICH prognostic model performance is substantially impacted when stratifying by early DNR status, possibly giving a false sense of model accuracy when DNR status is not considered. Clinicians should be cautious when applying these predictive models to individual patients.

A synergism model for PPARalpha and PXR agonist effects on HDL-cholesterol and apoA1

Synergism between gemfibrozil and CDD 3540, drugs used to elevate mouse serum HDL cholesterol and apoprotein A1, is modeled using nonlinear response surface techniques. This approach employs a common simple pharmacological model to describe the dose-response function. Its parameters are modeled as functions of drug mixture fractions using models borrowed from mixture experiment analysis methods. This study advances previous in vitro synergy studies in three key areas. First, it was in vivo, with the associated additional variability. Second, the sample size was much smaller than in previous studies. Finally, this was the first specially designed study with this type of statistical analysis in mind. The design consisted of replicated observations along each of five rays at combination amounts chosen employing the principles of D-optimality. Also, the observed in vivo synergism of the combined use of these drugs, elevated levels of HDL-C and apoA1, and the experimental results and statistical models may provide important clues regarding the biological mechanisms of action of the two compounds.

Developmental selenomethionine and methylmercury exposures affect zebrafish learning

Methylmercury (MeHg) is a ubiquitous environmental pollutant and has been shown to affect learning in vertebrates following relatively low exposures. Zebrafish were used to model long-term learning deficits after developmental MeHg exposure. Selenomethionine (SeMet) co-exposure was used to evaluate its role in neuroprotection. Embryos were exposed from 2 to 24h post fertilization to (1) MeHg without SeMet, (2) SeMet without MeHg and (3) in combination of MeHg and SeMet. In case (1), the levels of MeHg were 0.00, 0.01, 0.03, 0.06, 0.10, and 0.30 microM. In case (2), the levels of SeMet were 0.00. 0.03, 0.06, 0.10, and 0.30 microM. In case (3), co-exposure levels of (MeHg, SeMet) were (0.03, 0.03), (0.03, 0.06), (0.03, 0.10), (0.03, 0.30), (0.10, 0.03), (0.10, 0.06), (0.10, 0.10), and (0.10, 0.30) microM. Learning functions were tested in individual adults, 4 months after developmental exposure using a spatial alternation paradigm with food delivery on alternating sides of the aquarium. Low levels of MeHg (<0.1 microM) exposure delayed learning in treated fish; fish exposed to higher MeHg levels were unable to learn the task; SeMet co-exposure did not prevent this deficit. These data are consistent with findings in laboratory rodents. The dorsal and lateral telencephalon are the primary brain regions in fish involved in spatial learning and memory. Adult telencephalon cell body density decreased significantly at all MeHg exposures >0.01 microM MeHg. SeMet co-exposure ameliorated but did not prevent changes in telencephalon cell body density. In summary, MeHg affected both learning and brain structure, but SeMet only partially reversed the latter.

Modeling the combination of amphotericin B, micafungin, and nikkomycin Z against Aspergillus fumigatus in vitro using a novel response surface paradigm

Response surface methods for the study of multiple-agent interaction allow one to model all of the information present in full concentration-effect data sets and to visualize and quantify local regions of synergy, additivity, and antagonism. In randomized wells of 96-well plates, Aspergillus fumigatus was exposed to various combinations of amphotericin B, micafungin, and nikkomycin Z. The experimental design was comprised of 91 different fixed-ratio mixtures, all performed in quintuplicate. After 24 h of drug exposure, drug effect on fungal viability was assessed using the tetrazolium salt 2,3-bis {2-methoxy-4-nitro-5-[(sulfenylamino) carbonyl]-2H-tetrazolium-hydroxide} (XTT) assay. First, we modeled each fixed-ratio combination alone using the four-parameter Hill concentration-effect model. Then, we modeled each parameter, including the 50% inhibitory concentration (IC(50)) effect, versus the proportion of each agent using constrained polynomials. Finally, we modeled the three-agent response surface overall. The overall four-dimensional response surface was complex, but it can be explained in detail both analytically and graphically. The grand model that fit the best included complex polynomial equations for the slope parameter m and the combination index (equivalent to the IC(50) for a fixed-ratio concentration, but with concentrations normalized by the respective IC(50)s of the drugs alone). There was a large region of synergy, mostly at the nikkomycin Z/micafungin edge of the ternary plots for equal normalized proportions of each drug and extending into the center of the plots. Applying this response surface method to a huge data set for a three-antifungal-agent combination is novel. This new paradigm has the potential to significantly advance the field of combination antifungal pharmacology.

Verapamil, but not probenecid, co-administration can convert desloratadine to a sedating antihistamine in mice

The possibility that non-sedating antihistamines could elicit sedation in mice due to drug-induced inhibition of brain PgP was evaluated by measuring the ability of desloratadine alone or in combination with verapamil to cause ataxia in mice. Also, the concentrations of desloratadine in plasma and in brain homogenates were measured by liquid chromatography-mass spectrometry. Relative to methylcellulose (control) treatment, verapamil plus desloratadine decreased rotarod performance of mice. Plasma concentrations of desloratadine appeared comparable in the mice treated with either desloratadine or verapamil plus desloratadine, however the rate of decline of desloratadine from brain tissue was slower in mice treated with verapamil plus desloratadine compared to mice treated with desloratadine only. These data suggest that inhibition of brain PgP can convert desloratadine to a sedating antihistamine in mice.

Exotic meson decay to omegapi0pi-

A partial-wave analysis of the mesons from the reaction pi(-)p --> pi(+)pi(-)pi(-)pi(0)pi(0)p has been performed. The data show b(1)pi decay of the spin-exotic states pi(1)(1600) and pi(1)(2000). Three isovector 2(-+) states were seen in the omegarho(-) decay channel. In addition to the well known pi(2)(1670), signals were also observed for pi(2)(1880) and pi(2)(1970).

A New Nonlinear Mixture Response Surface Paradigm for the Study of Synergism: A Three Drug Example

A flexible approach to response surface modeling for the study of the joint action of three active anticancer agents is used to model a complex pattern of synergism, additivity and antagonism in an in vitro cell growth assay. The method for determining a useful nonlinear response surface model depends upon a series of steps using appropriate scaling of drug concentrations and effects, raw data modeling, and hierarchical parameter modeling. The method is applied to a very large in vitro study of the combined effect of Trimetrexate (TMQ), LY309887 (LY), and Tomudex (TDX) on inhibition of cancer cell growth. The base model employed for modeling dose-response effect is the four parameter Hill equation [1]. In the hierarchical aspect of the final model, the base Hill model is treated as a function of the total amount of the three drug mixture and the Hill parameters, background B, dose for 50% effect D50, and slope m, are understood as functions of the three drug fractions. The parameters are modeled using the canonical mixture polynomials from the mixture experiment methodologies introduced by Scheff [2]. We label the model generated a Nonlinear Mixture Amount model with control observations, or zero amounts, an "NLMAZ" model. This modeling paradigm provides for the first time an effective statistical approach to modeling complex patterns of local synergism, additivity, and antagonism in the same data set, the possibility of including additional experimental components beyond those in the mixture, and the capability of modeling three or more drugs.

Provision of drug information to patients by pharmacists: the impact of the Omnibus Budget Reconciliation Act of 1990 a decade later

Drug-related illness in the United States factors substantially in health care costs, although often these illnesses and their attendant costs are preventable. One strategy for minimizing adverse drug reactions is to provide drug information to consumers in the form of prescription counseling at pharmacies. The Omnibus Budget Reconciliation Act of 1990 (OBRA 1990) contained provisions for mandating such counseling to Medicaid patients. OBRA 1990 was implemented in 1993, but most states acted quickly to extend counseling services to all patients receiving prescription drugs. We looked at the extent and quality of prescription counseling available in community pharmacies 1 decade after OBRA 1990 was written. We evaluated the counseling services afforded at large chain pharmacies, independent community pharmacies, and on-line pharmacies for a hydrochlorothiazide prescription. We found that most (69%) pharmacies offered to provide prescription counseling service, and that average counseling index scores, a measure of the quality or extent of information provided as determined by a Rasch analysis, were generally satisfactory. Our observations based on a single prescription for hydrochlorothiazide, along with other studies, suggest that there is a positive upward trend in the number of pharmacies providing prescription drug information, and that the extent of information provided suggests that the objectives of OBRA 1990 and related legislation to reduce ADRs are being fundamentally satisfied.

Herbal and nonherbal alternative medicine use in Northwest Ohio

OBJECTIVE

To determine the prevalence and characteristics of herbal and nonherbal alternative medicine use among adults living in northwest Ohio.

DESIGN

Cross-sectional survey.

SETTING

Three grocery store intercepts in northwest Ohio.

SUBJECTS

A consecutive sample of 326 English-speaking persons > or =18 years old.

METHODS

A 26-item survey self-administered to participants over a 6-month period.

OUTCOME MEASURES

Prevalence of herbal remedy use.

RESULTS

Forty percent of respondents have used an herbal remedy during the last 12 months. The average number of herbs used was 2.3 per person. Herbal remedy use was not associated with specific sociodemographic variables. Desire to improve general health was the most common reason for use of an herbal remedy (16%). Herbal users cited "herbals are natural" as the most common benefit. Magazines (17%), health food stores (16%), and friends (14%) were the most common sources of herbal remedy information. Only 50% of the population informed their physician of such use. Forty-one percent used an herbal remedy sometimes to always to self-treat before seeking medical care from a physician. Fifteen percent of adults treated their children with herbs. Nearly all (86%) respondents believed the herb was helpful or very helpful.

CONCLUSIONS

A significant number of the adults surveyed in the Toledo metropolitan area commonly used complementary and alternative medicine (CAM). There were no independent factors associated with herbal remedy use. It is important for healthcare providers to acknowledge this growing trend of CAM therapy use and begin to incorporate open discussion about CAM into the patient-provider relationship.

Observation of exotic meson production in the reaction pi- p --> eta'pi- p at 18 GeV/c

An amplitude analysis of an exclusive sample of 5765 events from the reaction pi- p-->eta'pi- p at 18 GeV/c is described. The eta'pi- production is dominated by natural parity exchange and by three partial waves: those with J(PC) = 1(-+), 2(++), and 4(++). A mass-dependent analysis of the partial-wave amplitudes indicates the production of the a2(1320) meson as well as the a4(2040) meson, observed for the first time decaying to eta'pi-. The dominant, exotic (non- qq) 1(-+) partial wave is shown to be resonant with a mass of 1.597+/-0.010(+0.045)(-0.010) GeV/c2 and a width of 0.340+/-0.040+/-0.050 GeV/c2. This exotic state, the pi1(1600), is produced with a t dependence which is different from that of the a2(1320) meson, indicating differences between the production mechanisms for the two states.

Instituting organizational learning for quality improvement through strategic planning nominal group processes

Healthcare managers are faced with unprecedented challenges as characterized by managed care constraints, downsizing, increased client needs, and a society demanding more responsive services. Managers must initiate change for quality, efficiency, and survival. This article provides information and strategies for (a) assessing the change readiness of an organization, (b) conducting an organizational diagnosis, (c) instituting a team culture, (d) developing a change strategy, (e) integrating the strategy with a quality improvement process, and (f) identifying the leadership skills to implement organization renewal. Nominal group processes, namely, SWOT and the Search Conference, are described, and case examples are provided. The implementation strategies have been used successfully in a variety of milieus; practical advice for success is described in detail.

Is The Barley Endosperm a Water Reservoir for the Embryo When Germinating Seeds Are Dried?

The water content of germinating seeds fluctuates in response to water potential changes in the surrounding environment. We tested the hypothesis that the endosperm functions as a water reservoir when imbibed seeds experience drying, and we characterized water uptake and movement within barley (Hordeum vulgare cv. Triumph) caryopses (hereafter referred to as seeds). Water movement into and through germinating barley seeds during imbibition and drying was determined gravimetrically and with the fluorescent dye trisodium 8-hydroxy-1,3,6-pyrenetrisulfonate (PTS). During imbibition, embryo tissues hydrated more rapidly and reached a higher water content (g H20/g dry weight) than did the endosperm, although the endosperm eventually contained nine times as much total water. When barley seeds that had imbibed for 12 h were exposed to moderate (-4 MPa) drying, PTS solution moved from the endosperm into the shoot meristem, radicle, and scutellum, but not vice versa. Radicle emergence and elongation proceeded for up to 8 h. With harsh (-150 MPa) drying, PTS concentrated almost exclusively in the radicle. These data illustrate that the endosperm is at least a temporary water storage compartment external to the embryo itself. We speculate that water supplied by the endosperm may be important in reducing the harmful effects of drying during the critical transition period when a germinating seed changes from a desiccation-tolerant to a desiccation-intolerant organism.

What is quality, who wants it, and why?

The health services literature is replete with examples of the failure of total quality management to produce significant change in organizational performance. Some authors suggest that incremental quality improvement be abandoned in favor of structural reengineering. However, these naysayers ignore the critical impact of environmental change, managed care, and customer service as primary organizational drivers that demand an enhanced focus on continuous quality improvement. Coupled with these factors is the movement towards the creation of learning organizations. At the core of any learning organization is a commitment to quality and the empowerment of employees to identify and improve quality.

Fairy Rings in Turf Associated with the Bird's Nest Fungus Cyathus stercoreus

During the summer of 1998, several fairy rings with the fruiting bodies of a bird's nest fungus were observed on two greens at the University of Minnesota turf plots in St. Paul. Both greens, a 3-year-old annual bluegrass green and a 2-year-old creeping bentgrass green, were constructed of a 90% sand: 10% reed sedge peat soil mix. The fungus was identified as Cyathus stercoreus (Schwein.) de Toni (Nidulariaceae) (1). The fruiting bodies were approximately 15 mm tall and 8 mm wide. The fairy rings were irregular in shape, with a diameter of up to 50 cm, and contained up to 120 fruiting bodies per ring. On annual bluegrass, chlorotic and necrotic grass was observed at the edge of the rings in July but those damaged areas recovered in August. No symptoms were associated with the rings in creeping bentgrass. Rings were first discovered in June and early July and expanded by about 10 cm in 30 days. New fruiting bodies appeared during July and August as the rings expanded. The application of the fungicide chorothalanil did not affect the rings. This is the first report of a bird's nest fungus associated with fairy ring in turf. Reference: (1) H. J. Brodie. 1975. The Bird's Nest Fungi. University of Toronto Press, Toronto.

The formulatiion development and stability of spironolactone suspension

The purpose of this study was to extemporaneously formulate a liquid dosage form from commercially available tablets and establish the chemical stability of the drug. A suspension of spironolactone (5mg/mL) was formulated from 25-mg spironolactone tablets. Stability-indicating, high perfpromance liquid chromatography assay procedures were used to analyze the concentration of the drug. Chemical stability was predicted using accelerated stability studies. The stability studies were conducted at four temperatures, namely 5*, 30*, and 50*, and 60*C. The spironolactone suspension showed less than 10% degradation at all four temperatures for a period of three months. It appears that the formulation may be stable for longer periods of time; however, the investigation did not extend past this timeline and no recommendation should be implied.

Standard error and sample size determination for estimation of probabilities based on a test variable

A method of sample size determination for estimation of probabilities based on a test variable is presented. Applications to estimation of sensitivity and specificity of medical tests are the focus of this research, although the methods can be applied to other areas of study such as engineering reliability. Examples are given for determining sample sizes required for the classification of patients with cutaneous lupus erythematosus based on the incidence of several markers. In this example, the test variable is the number of markers present. The methodology employs a weighted average of model-based and non-model-based estimates of the probability with the weights determined by the closeness to or the confidence in the given model. Formulas and charts required for determining sample size are provided for test variables that can be modeled by the binomial, Poisson, or normal distributions, i.e., for the most commonly encountered distributions for counting events (binomial and Poisson) and for measurements (normal). However, the methods given can be applied to any distribution, including multivariate. Especially when relatively small probabilities (the rare events) are being estimated, the techniques provided assistance in safeguarding against undersampling brought on by unwarranted confidence in a test variable distribution and against oversampling required for high accuracy in non-model-based probability estimators.

Comparison of tobramycin pharmacokinetics after administration by CRIS and a traditional intravenous piggyback infusion

OBJECTIVE

To compare the administration pharmacokinetics of a 30-minute intravenous piggyback (ivpb) infusion of tobramycin with those of controlled-release infusion system (CRIS) using a 20-mL vial at rates of 60 and 120 mL/h.

DESIGN

Randomized, controlled, crossover, prospective, open-label trial.

SETTING

Medical college-affiliated hospital.

PARTICIPANTS

Eight healthy volunteer men between the ages of 22 and 24 years weighing between 60 and 90 kg.

INTERVENTIONS

Volunteers received, in random order, tobramycin sulfate 2 mg/kg i.v. on 3 occasions separated by 1 week. The drug was administered using a 50-mL ivpb infusion at 100 mL/h for 30 minutes, and with the CRIS using a 20-mL vial with flow rates of 60 mL/h for 1 hour (slow) and 120 mL/h for 1 hour (fast).

MAIN OUTCOME MEASURES

Primary endpoints were area under the time-concentration curve (AUC), time to reach maximum concentration (tmax), and maximum concentration (Cmax). Secondary endpoints were elimination rate constant (ke), clearance (Cl), and half-life (t1/2).

RESULTS

Six volunteers successfully completed the trial. The tmax values observed following fast CRIS and ivpb were 28 +/- 8 and 32 +/- 4 minutes, respectively, and not significantly different from each other. Both occurred significantly earlier than the tmax associated with slow CRIS (44 +/- 7 min). The Cmax values observed following ivpb (11.2 +/- 1.5 mg/L) and slow CRIS (10.9 +/- 0.9 mg/L) administration were not significantly different from each other, but both were significantly lower than that of fast CRIS (13.4 +/- 1.5 mg/L). The AUCs of slow and fast CRIS were 29.8 +/- 4.8 and 31.2 +/- 3.8 mg/L.h, respectively, and were not significantly different from each other. The AUC of fast CRIS was significantly greater than that observed with ivpb (27.4 +/- 4.3 mg/L.h). No significant difference in ke (fast CRIS 0.32 +/- 0.03 h-1; slow CRIS 0.33 +/- 0.04 h-1; ivpb 0.34 +/- 0.0 h-1) was observed among any of the methods.

CONCLUSIONS

CRIS administration of tobramycin resulted in higher AUCs than did ivpb administration. Compared with ivpb, fast CRIS resulted in a higher Cmax, but the tmax values of fast CRIS and ivpb administration were not statistically different. Compared with ivpb, slow CRIS resulted in a more delayed tmax, but the Cmax values of slow CRIS and ivpb were not statistically different.

Modified tension band wiring of medial malleolar ankle fractures

Twenty-two displaced medial malleolar ankle fractures that were treated surgically using the modified tension band method of Cleak and Dawson were retrospectively reviewed at an average follow-up of 25 months. The technique involves the use of a screw to anchor a figure-of-eight wire. There were no malreductions and all fractures healed. Problems with the technique included technical errors with hardware placement, medial ankle pain, and asymptomatic wire migration. Despite this, modified tension band wiring remains an acceptable method for fixation of selected displaced medial malleolar fractures. It is especially suited for small fracture fragments and osteoporotic bone.

Investigation of how different halos influence pin forces

STUDY DESIGN

This study investigated the effect of the size and material of halo rings on the pin force produced at the halo pin-calvarium complex.

SUMMARY OF BACKGROUND DATA

Loosening of halo pins has been a problem with using the halo-vest apparatus to stabilize cervical spine fractures.

METHODS

One standard halo pin and seven different halo rings were used to test the anterior pin hole of each ring at a constant torque of 8 inch-pounds (0.9 Nm).

RESULTS

Pin force fluctuated from halo to halo, and decreased as the nut was tightened.

CONCLUSIONS

Identical torques applied to different halos will not guarantee the same magnitude of pin force for halo fixation.

Evaluation of hypothesis testing for comparing two populations using NONMEM analysis

In a simulation study of inference on population pharmacokinetic parameters, two methods of performing tests of hypotheses comparing two populations using NONMEM were evaluated. These two methods are the test based upon 95% confidence intervals and the likelihood ratio test. Data were simulated according to a monoexponential model and, in that context, power curves for each test were generated for (i) the ratio of mean clearance and (ii) the ratio of the population standard deviations of clearance. To generate the power curves, a range of these parameters was employed; other pharmacokinetic parameters were selected to reflect the variability typically present in a Phase II clinical trial. For tests comparing the means, the confidence interval tests had approximately the same power as the likelihood ratio tests and were consistently more faithful to the nominal level of significance. For comparison of the standard deviations, and when the volume of information available was relatively small, however, the likelihood ratio test was more able to detect differences between the two groups. These results were then compared to results on parameter estimation in order to gain insight into the question of power. As an example, the nonnormality of estimates of the ratio of standard deviations plays an important role in explaining the low power for the confidence interval tests. We conclude that, except for the situation of modeling standard deviations with only sparse information, NONMEM produces tests of significance that are effective at detecting clinically significant differences between two populations.

An evaluation of point and interval estimates in population pharmacokinetics using NONMEM analysis

In a simulation study of the estimation of population pharmacokinetic parameters, including fixed and random effects, the estimates and confidence intervals produced by NONMEM were evaluated. Data were simulated according to a monoexponential model with a wide range of design and statistical parameters, under both steady state (SS) and non-SS conditions. Within the range of values for population parameters commonly encountered in research and clinical settings, NONMEM produced parameter estimates for CL, V, sigma CL, and sigma epsilon which exhibit relatively small biases. As the range of variability increases, these biases became larger and more variable. An important exception was bias in the estimate for sigma V which was large even when the underlying variability was small. NONMEM standard error estimates are appropriate as estimates of standard deviation when the underlying variability is small. Except in the case of CL, standard error estimates tend to deteriorate as underlying variability increases. An examination of confidence interval coverage indicates that caution should be exercised when the usual 95% confidence intervals are used for hypothesis testing. Finally, simulation-based corrections of point and interval estimates are possible but corrections must be performed on a case-by-case basis.

Treatment of a syngeneic rat tumor with magnetically responsive albumin microspheres labeled with doxorubicin or protein A

The tumoricidal activity of magnetically responsive albumin microspheres tagged with either doxorubicin or Staphylococcal protein A was tested against an induced mammary adenocarcinoma, 13762, implanted subcutaneously in the tail of female Fischer-344 rats. Magnetically responsive albumin microspheres containing Fe3O4 particles were prepared by an emulsion polymerization method incorporating either doxorubicin or protein A into the albumin matrix. Microspheres were produced with an average diameter of 1 micron (0.2 to 1.5 micron) in a concentration of 10(9) microspheres/mg. Microspheres were injected either directly into the tail artery and localized to the implanted tumor using a permanent bipolar adjustable gap magnet with a field strength of 8000 Oe, or directly into the femoral vein with no magnetic localization. Control groups consisted of animals treated with intravenously or intraarterially administered microspheres containing no active agent, and a no-treatment group. Survival was significantly greater in both the doxorubicin- and protein A-treated animals than in the control groups. First appearance of local metastases was prolonged in only the intraarterial magnetically localized doxorubicin-treated group of animals. Tumor growth rate was significantly depressed in both intraarterially magnetically localized treatment groups when compared to intravenously administered nonlocalized treatment groups. Magnetically responsive albumin microspheres appear to be an effective delivery system for cytotoxic agents and biologic response modifiers. Significant tumoricidal activity can be produced with a one-time administration of these agents utilizing this drug delivery system.

Mercury compounds reduce photosynthesis by plankton

Concentrations of organomercurial fungicides as low as 0.1 part per billion in water reduced photosynthesis and growth in laboratory cultures of one species of marine diatom and several natural phytoplankton communities from Florida lakes. The acute toxicity of mercury compounds to phytoplankton is dependent on the chemical nature of the mercury compound and on cell concentrations.