Annual mpMRI surveillance: PI-RADS upgrading and increasing trend correlated with patients who harbor clinically significant disease.

INTRODUCTION: Prostate cancer screening has routinely identified men with very low- or low-risk disease, per the National Comprehensive Cancer Network guidelines. Current literature has demonstrated that the most appropriate management strategy for these patients is active surveillance (AS). The mainstay of AS includes periodic biopsies and biannual prostate-specific antigen tests. However, multiparametric magnetic resonance imaging (mpMRI) is uniquely posed to improve patient surveillance. This study aimed to evaluate the utility of an annual mpMRI in patients on AS, focusing on radiologic upgrading and Prostate Imaging-Reporting and Data System (PI-RADS) trends as indicators of clinically significant disease. METHODS: This prospective, single intuition, study enrolled 208 patients on AS who had at least two biopsies and 1 mpMRI with a median follow-up of 5.03 years. The main outcome variable was time to Gleason grade (GG) reclassification. RESULTS: After delineating patients on their initial PI-RADS score, men with score 3 and 5 lesions at first MRI had comparable GG reclassification-free survival to their counterparts. Conversely, men with initial PI-RADS 4 lesions showed a lower 5-year GG reclassification-free survival compared to those with PI-RADS score 1-2. The cohort was then subset to 70 patients who obtained ≥2 mpMRIs on protocol. Men experiencing uptrending mpMRI scores had an increased risk of GG reclassification, with a 35.4% difference in 5 year GG reclassification-free survival probability on the Kaplan-Meier curve analysis. CONCLUSION: In conclusion, this study demonstrates that for men on AS with stable recapitulated disease, an annual MRI may replace repeat biopsies after confirmatory sampling has been obtained. On the other hand, men who initiate AS with PI-RADS 4 and/or who display uptrending mpMRI scores require periodic biopsies along with repeat imaging. This study highlights the utility of integrating an annual MRI into AS protocols, thus promising a more effective approach to management.

Research Note: Modified serum fluorescein isothiocyanate dextran (FITC-d) assay procedure to determine intestinal permeability in poultry fed diets high in natural or synthetic pigments.

Oral administration of fluorescein isothiocyanate dextran (FITC-d) has been used as an indicator for intestinal permeability in poultry research for several years. Under healthy conditions, tight junctions in the intestinal wall will not allow the 4-6kDa FITC-d to enter the bloodstream. Detection of FITC-d in serum (1-hour post-oral administration of FITC-d) has proven to be a reliable indicator of leaky gut syndrome (increased intestinal inflammation and disruption of tight junctions). Administration of supplementary phytobiotics in feed, particularly products with high beta-carotene levels or other pigments, has resulted in strong serum background fluorescence, which can render this assay unreliable. To account for this increase in background autofluorescence, the FITC-d assay procedure has been modified to accommodate these particular serum samples by including pre-administration serum collection from each treatment group to remove background fluorescence. The modified FITC-d procedure detailed will allow for analysis of intestinal permeability in pigmented serum.

Enhanced Photocatalytic Hydrogen Production by Hybrid Streptavidin-Diiron Catalysts.

Hybrid protein-organometallic catalysts are being explored for selective catalysis of a number of reactions, because they utilize the complementary strengths of proteins and of organometallic complex. Herein, we present an artificial hydrogenase, StrepH2, built by incorporating a biotinylated [Fe-Fe] hydrogenase organometallic mimic within streptavidin. This strategy takes advantage of the remarkable strength and specificity of biotin-streptavidin recognition, which drives quantitative incorporation of the biotinylated diironhexacarbonyl center into streptavidin, as confirmed by UV/Vis spectroscopy and X-ray crystallography. FTIR spectra of StrepH2 show characteristic peaks at shift values indicative of interactions between the catalyst and the protein scaffold. StrepH2 catalyzes proton reduction to hydrogen in aqueous media during photo- and electrocatalysis. Under photocatalytic conditions, the protein-embedded catalyst shows enhanced efficiency and prolonged activity compared to the isolated catalyst. Transient absorption spectroscopy data suggest a mechanism for the observed increase in activity underpinned by an observed longer lifetime for the catalytic species FeI Fe0 when incorporated within streptavidin compared to the biotinylated catalyst in solution.

Exploration, Explanation, and Parent-Child Interaction in Museums.

Young children develop causal knowledge through everyday family conversations and activities. Children's museums are an informative setting for studying the social context of causal learning because family members engage together in everyday scientific thinking as they play in museums. In this multisite collaborative project, we investigate children's developing causal thinking in the context of family interaction at museum exhibits. We focus on explaining and exploring as two fundamental collaborative processes in parent-child interaction, investigating how families explain and explore in open-ended collaboration at gear exhibits in three children's museums in Providence, RI, San Jose, CA, and Austin, TX. Our main research questions examined (a) how open-ended family exploration and explanation relate to one another to form a dynamic for children's learning; (b) how that dynamic differs for families using different interaction styles, and relates to contextual factors such as families' science background, and (c) how that dynamic predicts children's independent causal thinking when given more structured tasks. We summarize findings on exploring, explaining, and parent-child interaction (PCI) styles. We then present findings on how these measures related to one another, and finally how that dynamic predicts children's causal thinking. In studying children's exploring we described two types of behaviors of importance for causal thinking: (a) Systematic Exploration: Connecting gears to form a gear machine followed by spinning the gear machine. (b) Resolute Behavior: Problem-solving behaviors, in which children attempted to connect or spin a particular set of gears, hit an obstacle, and then persisted to succeed (as opposed to moving on to another behavior). Older children engaged in both behaviors more than younger children, and the proportion of these behaviors were correlated with one another. Parents and children talked to each other while interacting with the exhibits. We coded causal language, as well as other types of utterances. Parents' causal language predicted children's causal language, independent of age. The proportion of parents' causal language also predicted the proportion of children's systematic exploration. Resolute behavior on the part of children did not correlate with parents' causal language, but did correlate with children's own talk about actions and the exhibit. We next considered who set goals for the play in a more holistic measure of parent-child interaction style, identifying dyads as parent-directed, child-directed, or jointly-directed in their interaction with one another. Children in different parent-child interaction styles engaged in different amounts of systematic exploration and had parents who engaged in different amounts of causal language. Resolute behavior and the language related to children engaging in such troubleshooting, seemed more consistent across the three parent-child interaction styles. Using general linear mixed modeling, we considered relations within sequences of action and talk. We found that the timing of parents' causal language was crucial to whether children engaged in systematic exploration. Parents' causal talk was a predictor of children's systematic exploration only if it occurred prior to the act of spinning the gears (while children were building gear machines). We did not observe an effect of causal language when it occurred concurrently with or after children's spinning. Similarly, children's talk about their actions and the exhibit predicted their resolute behavior, but only when the talk occurred while the child was encountering the problem. No effects were found for models where the talk happened concurrently or after resolving the problem. Finally, we considered how explaining and exploring related to children's causal thinking. We analyzed measures of children's causal thinking about gears and a free play measure with a novel set of gears. Principal component analysis revealed a latent factor of causal thinking in these measures. Structural equation modeling examined how parents' background in science related to children's systematic exploration, parents' causal language, and parent-child interaction style, and then how those factors predicted children's causal thinking. In a full model, with children's age and gender included, children's systematic exploration related to children's causal thinking. Overall, these data demonstrate that children's systematic exploration and parents' causal explanation are best studied in relation to one another, because both contributed to children's learning while playing at a museum exhibit. Children engaged in systematic exploration, which supported their causal thinking. Parents' causal talk supported children's exploration when it was presented at certain times during the interaction. In contrast, children's persistence in problem solving was less sensitive to parents' talk or interaction style, and more related to children's own language, which may act as a form of self-explanation. We discuss the findings in light of ongoing approaches to promote the benefit of parent-child interaction during play for children's learning and problem solving. We also examine the implications of these findings for formal and informal learning settings, and for theoretical integration of constructivist and sociocultural approaches in the study of children's causal thinking.

Effects of the selective EET antagonist, 14,15-EEZE, on cardioprotection produced by exogenous or endogenous EETs in the canine heart.

Previously, we demonstrated (17) that 11,12- and 14,15-epoxyeicosatrienoic acids (EETs) produce marked reductions in myocardial infarct size. Although it is assumed that this cardioprotective effect of the EETs is due to a specific interaction with a membrane-bound receptor, no evidence has indicated that novel EET antagonists selectively block the EET actions in dogs. Our goals were to investigate the effects of 11,12- and 14,15-EET, the soluble epoxide hydrolase inhibitor, 12-(3-adamantan-1-yl-ureido)-dodecanoic acid (AUDA), and the putative selective EET antagonist, 14,15-epoxyeicosa-5(Z)-enoic acid (14,15-EEZE), on infarct size of barbital anesthetized dogs subjected to 60 min of coronary artery occlusion and 3 h of reperfusion. Furthermore, the effect of 14,15-EEZE on the cardioprotective actions of the selective mitochondrial ATP-sensitive potassium channel opener diazoxide was investigated. Both 11,12- and 14,15-EET markedly reduced infarct size [expressed as a percentage of the area at risk (IS/AAR)] from 21.8 +/- 1.6% (vehicle) to 8.7 +/- 2.2 and 9.4 +/- 1.3%, respectively. Similarly, AUDA significantly reduced IS/AAR from 21.8 +/- 1.6 to 14.4 +/- 1.2% (low dose) and 9.4 +/- 1.8% (high dose), respectively. Interestingly, the combination of the low dose of AUDA with 14,15-EET reduced IS/AAR to 5.8 +/- 1.6% (P < 0.05), further than either drug alone. Diazoxide also reduced IS/AAR significantly (10.2 +/- 1.9%). In contrast, 14,15-EEZE had no effect on IS/AAR by itself (21.0 +/- 3.6%), but completely abolished the effect of 11,12-EET (17.8 +/- 1.4%) and 14,15-EET (19.2 +/- 2.4%) and AUDA (19.3 +/- 1.6%), but not that of diazoxide (10.4 +/- 1.4%). These results suggest that activation of the EET pathway, acting on a putative receptor, by exogenous EETs or indirectly by blocking EET metabolism, produced marked cardioprotection, and the combination of these two approaches resulted in a synergistic effect. These data also suggest that 14,15-EEZE is not blocking the mitochondrial ATP-sensitive potassium channel as a mechanism for antagonizing the cardioprotective effects of the EETs.

Retrometabolic syntheses of astaxanthin (3,3'-dihydroxy-beta,beta-carotene-4,4'-dione) conjugates: a novel approach to oral and parenteral cardio-protection.

Disodium disuccinate astaxanthin has potent cardioprotective effects in animals, with demonstrated preclinical efficacy in the rat, rabbit, and canine models of experimental infarction. It has been effective in subchronic and acute dosing regimens after parenteral administration, and recently published data in rats demonstrate that oral cardioprotection is also readily achieved. Myocardial salvage in the canine can reach 100% with a 4-day subchronic dosing regimen; single-dose I.V. cardioprotection, when given 2 hours before experimental coronary occlusion, is on average two-thirds of that achieved with the subchronic regimen in dogs. In conscious animals, no effects on hemodynamic parameters have been observed. Recently, the beneficial properties of this prototypical astaxanthin conjugate have been extended to include second- and third-generation compounds with improved pharmacokinetic and/or potency profiles. The primary mechanism of cardioprotection appears to be antioxidant activity: potent direct scavenging of the lynchpin radical in ischemia-reperfusion injury, superoxide anion, has been documented in appropriate model systems. In addition, modulation of serum complement activity, reduction of the levels of deposition of C-reactive protein (CRP) and the membrane attack complex (MAC) in infarcted tissue, and reduction in oxidative stress markers from the arachidonic acid and linoleic acid pathways also suggest a significant anti-inflammatory component to the mechanism of cardioprotection. Favorable plasma protein binding has been demonstrated in vitro for several astaxanthin conjugates; this binding capacity overcomes the supramolecular assembly of the compounds that occurs in aqueous solution, which in itself improves the stability and shelf-life of aqueous formulations. Astaxanthin readily populates cardiac tissue after metabolic hydrolysis of both oral and parenteral administration of the astaxanthin ester derivates, providing a reservoir of cardioprotective agent with a significant half-life due to favorable ADME in mammals. Due to the well-documented safety profile of astaxanthin in humans, disodium disuccinate astaxanthin may well find clinical utility in cardiovascular applications in humans following successful completion of preclinical and clinical pharmacology and toxicology studies in animals and humans, respectively.

Effect of N-methyl-d-aspartate receptor blockade on plasticity of frontal cortex after cholinergic deafferentation in rat.

Cholinergic projections from the nucleus basalis play a critical role in cortical plasticity. For instance, cholinergic deafferentation increases dendritic spine density and expression of the GluR1 subunit of the alpha-amino-3-hydroxy-5-methylisoxazole-4-propionate receptor in frontal cortex. Acetylcholine modulates glutamatergic activity in cortex, and the N-methyl-d-aspartate subtype of glutamate receptor plays a role in many forms of synaptic plasticity. To assess whether N-methyl-d-aspartate receptors mediate the increase in GluR1 and spine density resulting from cholinergic deafferentation, we examined the effect of N-methyl-d-aspartate receptor blockade on nucleus basalis lesion-induced upregulation of GluR1 and dendritic spines. Rats received unilateral sham or 192 IgG saporin lesions of the nucleus basalis. Half of the rats in each group were treated with the N-methyl-d-aspartate antagonist MK-801 or phosphate-buffered saline. Two weeks later, brains were processed for either immunohistochemical staining of the GluR1 subunit or Golgi histology. In layer II-III of frontal cortex, neuronal GluR1 expression was assessed using an unbiased stereological technique, and spine density was assessed on basilar branches of pyramidal neurons. GluR1 expression was increased after nucleus basalis lesion, but this increase was prevented with MK-801. Similarly, nucleus basalis-lesioned animals had significantly higher spine densities, and this effect was also prevented by treatment with MK-801. Thus, N-methyl-d-aspartate receptor blockade prevented both GluR1 and spine density upregulation following cholinergic deafferentation, suggesting that these effects are N-methyl-d-aspartate receptor-mediated.

Seven day oral supplementation with Cardax (disodium disuccinate astaxanthin) provides significant cardioprotection and reduces oxidative stress in rats.

In the current study, the improved oral bioavailability of a synthetic astaxanthin derivative (Cardax; disodium disuccinate astaxanthin) was utilized to evaluate its potential effects as a cardioprotective agent after 7-day subchronic oral administration as a feed supplement to Sprague-Dawley rats. Animals received one of two concentrations of Cardax in feed (0.1 and 0.4%; approximately 125 and 500 mg/kg/day, respectively) or control feed without drug for 7 days prior to the infarct study carried out on day 8. Thirty minutes of occlusion of the left anterior descending (LAD) coronary artery was followed by 2 h of reperfusion prior to sacrifice, a regimen which resulted in a mean infarct size (IS) as a percentage (%) of the area at risk (AAR; IS/AAR,%) of 61 +/- 1.8%. The AAR was quantified by Patent blue dye injection, and IS was determined by triphenyltetrazolium chloride (TTC) staining. Cardax at 0.1 and 0.4% in feed for 7 days resulted in a significant mean reduction in IS/AAR,% to 45 +/- 2.0% (26% salvage) and 39 +/- 1.5% (36% salvage), respectively. Myocardial levels of free astaxanthin achieved after 7-day supplementation at each of the two concentrations (400 +/- 65 nM and 1634 +/- 90 nM, respectively) demonstrated excellent solid-tissue target organ loading after oral supplementation. Parallel trends in reduction of plasma levels of multiple lipid peroxidation products with disodium disuccinate astaxanthin supplementation were observed, consistent with the documented in vitro antioxidant mechanism of action. These results extend the potential utility of this compound for cardioprotection to the elective human cardiovascular patient population, for which 7-day oral pre-treatment (as with statins) provides significant reductions in induced periprocedural infarct size.

Lipid metabolite profiles and milk production for Holstein and Jersey cows fed rumen-protected choline during the periparturient period.

Choline is important for assembly of very low density lipoproteins to export triglyceride from liver; however, studies to assess the effect of rumen-protected choline (RPC) supplementation on blood lipid metabolites in periparturient dairy cows have not been conducted. Thirty-two multiparous Holstein and 10 multiparous Jersey cows were randomly assigned to control or RPC treatments. A close-up diet was fed from approximately 3 wk before parturition through parturition, followed by a lactation diet from parturition through 49 d postpartum. For RPC, diets were top-dressed once daily with 60 g of a RPC product (25% choline as choline chloride) from 21 d before expected parturition through 21 d postpartum. Treatment did not affect dry matter intake either prepartum (12.0 vs. 12.1 kg/d for RPC and control, respectively) or during the first 3 wk postpartum (14.8 vs. 15.7 kg/d, respectively). Daily yields of 3.5% fat-corrected milk (39.4 vs. 37.4 kg/d), fat (1.46 vs. 1.38 kg/d), and protein (1.09 vs. 1.05 kg/d) did not differ statistically by treatment (RPC vs. control, respectively). Jersey cows in the control group had lower concentrations of nonesterified fatty acids and beta-hydroxybutyrate in plasma during d 1 to 10 postpartum than did other breed and treatment combinations. Cows fed RPC tended to have greater serum triglycerides prepartum (17.0 vs. 14.7 mg/dL) and lower plasma phospholipid at parturition (65.2 vs. 78.1 mg/dL) than control cows. Treatment did not affect cholesterol and phospholipid at other time points, but concentrations followed patterns of dry matter intake pre- and postpartum. Cows were in moderate body condition score (mean = 3.3) at the start of the study and did not lose excessive condition by 3 wk postpartum (mean body condition score loss = 0.5); therefore, cows might not have been at great risk for hepatic lipid accumulation. Additionally, calculated Met balance was negative postpartum; supplemental RPC might not have spared enough Met to produce a physiological benefit. More research is needed to determine how choline affects prevention or alleviation of fatty liver syndrome and to confirm potential differences between Holstein and Jersey cows.

Hydrogen peroxide generated extracellularly by receptor-ligand interaction facilitates cell signaling.

Reactive oxygen species (ROS) are key components of postreceptor intracellular signaling pathways; however, the role of ROS in signal initiation is uncertain. We discovered that receptor-ligand interaction caused the generation of hydrogen peroxide (H2O2). Using members of the hematopoietin receptor superfamily, as well as EGF receptor, we show that H2O2 is generated by specific receptor-ligand interaction in cells and in cell-free systems. With cognate ligand, the extracellular domain of the receptor was sufficient for H2O2 generation. We also found that production of H2O2 was diminished in a granulocyte-macrophage colony-stimulating factor receptor mutant unable to bind ligand. Exogenously added H2O2 induced signaling in the absence of ligand, whereas catalase and a membrane-bound peroxiredoxin inhibited ligand-dependent signaling. Our results suggest that H2O2 produced by receptor-ligand interaction is involved as a chemical mediator that facilitates cell signaling.

Effects of yeast culture (Saccharomyces cerevisiae) on prepartum intake and postpartum intake and milk production of Jersey cows.

Yeast cultures (Saccharomyces cerevisiae; YC) have been added to diets for dry and lactating dairy cows to attempt to improve ruminal fermentation, potentially increasing dry matter intake (DMI) and milk yield. Jersey cows (14 primigravid and 25 multigravid) were fed total mixed rations prepartum and postpartum that were either supplemented or not supplemented with YC. The YC was a dried product that was top-dressed at 60 g/d for approximately 21 d prepartum and 140 d postpartum. The DMI was increased by YC during both the last 7 d prepartum (9.8 vs. 7.7 kg) and during the first 42 d of lactation (13.7 vs. 11.9 kg). The treatment-by-day interaction was significant for DMI during the first 21 d postpartum, indicating that cows supplemented with YC increased DMI more rapidly than did nonsupplemented cows. A significant treatment-by-day interaction indicated that cows supplemented with YC lost body weight less rapidly postpartum than did non-supplemented cows. A significant interaction of treatment by day indicated that cows supplemented with YC reached peak milk production more quickly than did nonsupplemented cows. However, total milk produced during the first 140 d of lactation did not differ. Concentrations of fat, protein, lactose, total solids, and urea N in milk, as well as somatic cell count, were not significantly affected by YC. Supplementation of YC increased DMI during the transition period and increased DMI postpartum.

Beyond the good prognosis. Examination of an inception cohort of patients with chronic low back pain.

STUDY DESIGN: A 22-month prospective cohort study. OBJECTIVES: To describe the course of an inception cohort of patients with chronic low back pain. SUMMARY OF BACKGROUND DATA: Chronic low back pain is a debilitating condition with great medical and social cost. METHODS: A cohort of 1246 patients with acute low back pain who sought treatment from 208 North Carolina providers was observed. Patients who developed chronic low back pain were identified. Entry criteria were back pain of less than 10 weeks' duration, no previous care for this episode of low back pain, no previous spine surgery, not pregnant, no nonskin malignancy, and access to a telephone. The providers were of four types: primary care medical doctors, doctors of Chiropractic, orthopedic surgeons, and health maintenance organization-based primary care providers. Patients were contacted by telephone shortly after enrollment and at 2, 4, 8, 12, and 24 weeks, with a final interview at 22 months. Patient functional status, care-seeking, and satisfaction were evaluated. RESULTS: Ninety-six patients had chronic, continuous symptoms for 3 months, forming the inception cohort of chronic low back pain. A valid, reliable measure of back-specific functional disability also was used. Predictors of the development of chronicity were poor baseline functional status and sciatica. A more powerful predictor of chronicity was poor functional status at 4 weeks. Two thirds of patients with chronic low back pain at 3 months had functionally disabling symptoms at 22 months, and a majority of these were employed. Satisfaction with care was low. Forty-six patients (2.6% of the entire cohort) underwent surgery, with no statistically significant difference in surgical rates among initial provider strata. Patients who underwent surgery after 3 months had a Roland disability score at 22 months of 10 (7.7, 12.3). Forty-one percent of patients with chronic low back pain see an orthopedic or neurologic surgeon. Chronic low back pain occurs in 7.7% of patients who seek care for acute low back pain, with unremitting pain for 22 months in 4.7%. CONCLUSION: Once established, chronic low back pain is persistent. Most patients with chronic low back pain seek little care, and a majority are employed. Future research should emphasize maintenance of employment and function.

Patterns and determinants of multiple provider use in patients with acute low back pain.

OBJECTIVE: To describe the patterns of provider use associated with an acute episode of nonspecific low back pain and their impact on cost. METHODS: The analysis is based on a prospective cohort study of patients with acute low back pain followed until they recovered completely or to 6 months. Patients were followed after an initial visit to one of four provider types: private primary care physician, chiropractor, orthopedic surgeon, or HMO primary care physician. Follow-up interviews were conducted at baseline, 2, 4, 8, 12, and 24 weeks; 1,580 (97%) of the participants completed the 6-month follow-up. MAIN RESULTS: Seventy-nine percent of patients saw only the initial provider who began their care for low back pain. Logistic regression revealed that duration of pain prior to initial visit, sciatica, higher Roland disability score, days to functional recovery, interval to complete recovery, referral by initial provider, disk attribution, satisfaction, and the type of index provider were significantly (p < .05) associated with seeking care from multiple provider types. Age, race, gender, and education were not significant. The adjusted proportions of multiple provider type use were 14% (95% confidence interval [CI] 11%, 17%) for the private primary care provider stratum; 19% (95% CI 16%, 23%) for the chiropractic stratum; 30% (95% CI 23%, 37%) for the orthopedic stratum; and 9% (95% CI 5%, 14%) for the HMO primary care physician stratum. Cost of seeing only the index provider was $439 (95% CI $404, $475), and cost of seeing multiple provider types was $1,137 (95% CI $1,064, $1,211) based on the adjusted model. CONCLUSIONS: Use of multiple provider types, is associated with several factors, one of which is the initial provider type. The cost of such use is significant.

Patterns of ordering diagnostic tests for patients with acute low back pain. The North Carolina Back Pain Project.

BACKGROUND: Low back pain is a common reason for visiting a physician. Authors of guidelines and insurance payers are currently scrutinizing use of radiography and computed tomography (CT) or magnetic resonance imaging (MRI). OBJECTIVE: To study the determinants of the use of lumbar spine radiography and either CT or MRI in patients with acute low back pain. DESIGN: Prospective cohort study. SETTING: Community-based practices in North Carolina in six strata: urban primary care physicians, rural primary care physicians, urban chiropractors, rural chiropractors, orthopedic surgeons, and practitioners at a group-model health maintenance organization. PATIENTS: 1580 patients with acute low back pain. MEASUREMENTS: Telephone interviews done after the index office visit and at 2, 4, 8, 12, and 24 weeks or until complete recovery; survey of practitioners; and chart abstraction. RESULTS: During the acute back pain episode, 46% of patients had radiography and 9% had CT or MRI. Patient variables related to use of radiography included pain that began more than 2 weeks before the index visit and no previous episodes of low back pain. Practitioner variables associated with use of radiography were being a chiropractor or orthopedic surgeon and having a solo practice. Use of CT or MRI was associated with white race, neurologic deficit at baseline, sciatica, poor functional status at baseline, and small group-practice size. Practitioners' responses to clinical vignettes were associated with aggregate practitioner behavior: In the vignettes and in real life, practitioners were more likely to order CT for patients with sciatica. However, a practitioner's response to a vignette did not predict that practitioner's use of CT or MRI for similar patients in his or her own practice. CONCLUSION: Radiography is commonly used as a diagnostic test for patients with acute back pain. Clinical factors and provider specialty are major correlates of the use of imaging studies.

Photodynamic therapy (PDT) of the ciliary body with silicon naphthalocyanine (SINc) in rabbits.

BACKGROUND AND OBJECTIVE: To investigate silicone naphthalocyanine (SINc; 0.5 mg/kg) for photodynamic therapy (PDT) of the ciliary body in pigmented rabbits. STUDY DESIGN/MATERIALS AND METHODS: SINc was dissolved in canola oil by heating, emulsified with Tween-80, and given by ear vein. Pharmacokinetics were studied in frozen sections by fluorescence microscopy using a CCD camera-based, low light detection system with digital image processing at 1 hr and 24 hr (12 rabbits, 24 eyes total). A Ti:Sapphire laser delivered light at 770 nm by contact fiberoptic (1,000 microns; 80 mW/cm2;20,40 and 80 J/cm2). Controls (5 rabbits), received laser light at 770 nm without SINc. For comparison, eyes received continuous wave Nd:YAG laser by fiberoptic contact (0.8-1.2 J). RESULTS: Localization studies showed intravascular distribution shifting to a ciliary body distribution at 24 hr. PDT at 1 hr and 24 hr postinjection showed a more selective destruction of the ciliary body at 24 hr. Ciliary processes treated at 24 hr showed infarction and marked edema with sparing of iris. Tissue thermal damage was minimal in PDT controls. Eyes treated with the Nd:YAG laser exhibited full-thickness thermal necrosis of iris, ciliary processes, and a fibrinous iridocyclitis. In contrast, eyes treated by PDT were quiet with thrombosis of superficial blood vessels. CONCLUSION: Tissue photon penetration is good at 770 nm and thermal effects from the exciting laser alone were minimal. The ciliary processes of pigmented rabbits exhibit a selective retention of SINc and on that basis can be selectively destroyed with a minimum on thermal damage to nontarget tissues.

Calcitonin-secreting cells of the thyroid express an extracellular calcium receptor gene.

Calcitonin (CT) secretion by parafollicular cells of the thyroid (C cells) is regulated by small changes in the concentration of extracellular calcium ([Ca2+]e). Elevation of [Ca2+]e elicits a rise in the C cell cytoplasmic calcium concentration and stimulates CT release. The molecular entity through which C cells detect changes in [Ca2+]e and modulate hormone secretion is unknown. Recently, an extracellular calcium-sensing receptor (CaR) complementary DNA was isolated from bovine parathyroid gland. To assess whether parathyroid cells and C cells use similar mechanisms to detect changes in ambient Ca2+, rat, human, and sheep C cells were examined for expression of the parathyroid CaR or a related receptor isoform. Reverse transcription-polymerase chain reaction analysis identified CaR transcripts in rat and human thyroid gland. Northern blot analysis demonstrated CaR messenger RNA (mRNA) in rat thyroid gland, a human medullary thyroid carcinoma (MTC) isolate, and a highly enriched preparation of sheep C cells. Rat MTC 44-2 cells, a cell line responsive to changes in [Ca2+]e, express abundant levels of CaR mRNA. Human TT cells, a C cell line lacking the extracellular calcium-sensing function, have undetectable levels of CaR mRNA by Northern blot analysis. Western blot analysis, using antiserum specific to the parathyroid CaR, detected CaR protein in rMTC 44-2, but not TT cells. Immunostaining of both dispersed sheep C cells and rat thyroid gland sections identified C cell-specific expression of the CaR protein, and in situ hybridization analysis confirmed the C cell-specific expression of CaR mRNA in the intact rat thyroid. The nucleotide sequence of the coding region of the rMTC 44-2 CaR transcripts was found to encode the same CaR protein as that expressed in the parathyroid and kidney. The results demonstrate that C cells express the same extracellular calcium-sensing receptor that is found in parathyroid and kidney, and the presence of this receptor protein in C cell lines correlates with the extracellular calcium-sensing function. This CaR is likely to represent the primary molecular entity through which C cells detect changes in [Ca2+]e and control CT release, suggesting that activation of the same receptor can either stimulate or inhibit hormone secretion in different cell types.

The outcomes and costs of care for acute low back pain among patients seen by primary care practitioners, chiropractors, and orthopedic surgeons. The North Carolina Back Pain Project.

BACKGROUND: Patients with back pain receive quite different care from different types of health care practitioners. We performed a prospective observational study to determine whether the outcomes of and charges for care differ among primary care practitioners, chiropractors, and orthopedic surgeons. METHODS: Two hundred eight practitioners in North Carolina were randomly selected from six strata: urban primary care physicians (n = 39), rural primary care physicians (n = 48), urban chiropractors (n = 32), rural chiropractors (n = 32), orthopedic surgeons (n = 29), and primary care providers at a group-model health maintenance organization (HMO) (n = 28). The practitioners enrolled consecutive patients with acute low back pain. The patients were contacted by telephone periodically for up to 24 weeks to assess functional status, work status, use of health care services, and satisfaction with the care received. RESULTS: The status at six months was ascertained for 1555 of the 1633 patients enrolled in the study (95 percent). The times to functional recovery, return to work, and complete recovery from low back pain were similar among patients seen by all six groups of practitioners, but there were marked differences in the use of health care services. The mean total estimated outpatient charges were highest for the patients seen by orthopedic surgeons and chiropractors and were lowest for the patients seen by HMO and primary care providers. Satisfaction was greatest among the patients who went to the chiropractors. CONCLUSIONS: Among patients with acute low back pain, the outcomes are similar whether they receive care from primary care practitioners, chiropractors, or orthopedic surgeons. Primary care practitioners provide the least expensive care for acute low back pain.

Pancuronium infusion for neuromuscular block in children in the pediatric intensive care unit.

When neuromuscular blockade becomes necessary in the intensive care unit, there are several options available in regard to both the drug and the mode of delivery (continuous versus intermittent administration). Despite extensive experience with intermediate acting drugs such as atracurium or vecuronium, these muscle relaxants are costly and may account for a significant portion of the pharmacy charges. We undertook an open label study to evaluate the efficacy and dosing requirements for a less costly drug, pancuronium. The study group included 25 patients ranging in age from 3 mo to 17 yr and in weight from 3.2 to 68 kg. If the patient had not previously received neuromuscular blocking agents (NMBAs), pancuronium was administered as a bolus dose of 0.1 mg/kg followed by a continuous infusion of 0.05 mg.kg-1.h-1. A nerve stimulator was applied to either the ulnar or peroneal nerve and a standard train-of-four (TOF) was monitored every 2 h. In patients that had previously received other NMBAs, no bolus dose of pancuronium was administered and the infusion was started at 0.05 mg.kg-1.h-1. The pancuronium infusion was increased or decreased by increments of 0.01 mg.kg-1.h-1 to maintain one to two twitches of the TOF. In patients that required an increase in the infusion rate, an additional bolus dose equivalent to the current hourly rate was administered and then followed by the increase in the infusion rate.(ABSTRACT TRUNCATED AT 250 WORDS)

Characterization of AAT1: a gene involved in the regulation of amino acid transport in Saccharomyces cerevisiae.

A new class of Saccharomyces cerevisiae mutants (aat1 - amino acid transport) has been identified. These mutants are unable to grow on rich medium or on minimal medium supplemented with certain amino acids (isoleucine, methionine, phenylalanine, tyrosine or valine). This phenotype is directly linked to the presence of the leu2 allele in these strains: aat1 LEU2 organisms grow normally on all media tested. Leucine uptake through the leucine-specific permease is inhibited to less than 35% of wild-type levels in aat1 cells preincubated in nonpermissive media, and the activity of the general amino acid permease is also low in these conditions. aat1 cells are therefore unable to grow on rich media because they cannot take up enough leucine to supplement their auxotrophic requirement.

Effects of ovariectomy on GnRH mRNA, proGnRH and GnRH levels in the preoptic hypothalamus of the female rat.

Experiments were carried out to investigate the effects of ovariectomy on gonadotropin-releasing hormone (GnRH) messenger RNA (mRNA), proGnRH and GnRH peptide levels in the hypothalamus of female rats. Intact proestrous female rats and female rats, which had been ovariectomized for 2 weeks, were sacrificed at 9.00 h and the preoptic area (POA) and basal hypothalamus (BH) were dissected out and frozen on dry ice. One group of tissues from proestrous control and ovariectomized females were extracted in acetic acid, centrifuged at 13,000 g and the supernatant purified on a C18 column. The purified extract was then radioimmunoassayed for proGnRH, using a specific antiserum to rat proGnRH (ARK-2), and for GnRH using the E1-14 antiserum. Total cellular RNA was isolated from another group of tissues and prepared as Northern blots. Hybridization with 32P-labeled GnRH cRNA was used to detect GnRH mRNA. A third group of proestrous and ovariectomized female rats were perfused, and 50 microns vibratome sections were cut. These were immunostained with proGnRH or GnRH antiserum, followed by in situ hybridization with 35S-labeled GnRH cRNA to detect GnRH mRNA. Based on the histochemical staining, mRNA was colocalized to the cell soma of neurons containing proGnRH and GnRH throughout the POA and BH. Based on the radioimmunoassay, proGnRH levels were 2 times higher in the POA versus the BH, but GnRH levels were 6-7 times higher in the BH. Ovariectomy significantly decreased proGnRH levels in both the POA and BH, while GnRH decreased in the BH. In contrast, quantitative Northern blot analysis demonstrated that ovariectomy had no effect on mRNA levels in the POA and BH. These data indicate that the effects of ovariectomy on proGnRH and GnRH levels are a result of altered translation, posttranslational processing and/or secretion of GnRH.