Molecular-dynamics simulation methods for macromolecular crystallography

It is investigated whether molecular-dynamics (MD) simulations can be used to enhance macromolecular crystallography (MX) studies. Historically, protein crystal structures have been described using a single set of atomic coordinates. Because conformational variation is important for protein function, researchers now often build models that contain multiple structures. Methods for building such models can fail, however, in regions where the crystallographic density is difficult to interpret, for example at the protein-solvent interface. To address this limitation, a set of MD-MX methods that combine MD simulations of protein crystals with conventional modeling and refinement tools have been developed. In an application to a cyclic adenosine monophosphate-dependent protein kinase at room temperature, the procedure improved the interpretation of ambiguous density, yielding an alternative water model and a revised protein model including multiple conformations. The revised model provides mechanistic insights into the catalytic and regulatory interactions of the enzyme. The same methods may be used in other MX studies to seek mechanistic insights.

Treatment Outcomes of Newly Diagnosed Epilepsy: A Systematic Review and Meta-analysis

BACKGROUND AND OBJECTIVES

Understanding the multi-faceted treatment outcomes of newly diagnosed epilepsy is critical for developing rational therapeutic strategies. A meta-analysis was conducted to derive pooled estimates of a range of seizure outcomes in children and adults with newly diagnosed epilepsy commenced on antiseizure medication treatment, and to identify factors associated with different outcomes.

METHODS

PubMed/EMBASE were screened for eligible articles between 1 January, 1995 and 1 May, 2021 to include unselected cohort studies with a ≥ 12-month follow-up of seizure outcomes. Proportions of patients seizure free at different follow-up timepoints and their characteristics at the study population level were extracted. The patients were group-wise aggregated using a random-effects model. Primary outcomes were proportions of patients with cumulative 1-year seizure freedom (C1YSF), and 1-year and 5-year terminal seizure freedom (T1YSF and T5YSF). Secondary outcomes included the proportions of patients with early sustained seizure freedom, drug-resistant epilepsy and seizure-free off antiseizure medication at the last follow-up (off antiseizure medications). A separate random-effects meta-analysis was performed for nine predictors of importance.

RESULTS

In total, 39 cohorts (total n = 21,139) met eligibility criteria. They included 15 predominantly adult cohorts (n = 12,024), 19 children (n = 6569), and 5 of mixed-age groups (n = 2546). The pooled C1YSF was 79% (95% confidence interval [CI] 74-83). T1YSF was 68% (95% CI 63-72) and T5YSF was 69% (95% CI 62-75). Children had higher C1YSF (85% vs 68%, p < 0.001) and T1YSF than adult cohorts (74% vs 61%, p = 0.007). For secondary outcomes, 33% (95% CI 27-39) of patients achieved early sustained seizure freedom, 17% (95% CI 13-21) developed drug resistance, and 39% (95% CI 30-50) were off antiseizure medications at the last follow-up. Studies with a longer follow-up duration correlated with higher C1YSF (p < 0.001) and being off antiseizure medications (p = 0.045). Outcomes were not associated with study design (prospective vs retrospective), cohort size, publication year, or the earliest date of recruitment. Predictors of importance in newly diagnosed epilepsy include etiology, epilepsy type, abnormal diagnostics (neuroimaging, examination, and electroencephalogram findings), number of seizure types, and pre-treatment seizure burden.

CONCLUSIONS

Seizure freedom is achieved with currently available antiseizure medications in most patients with newly diagnosed epilepsy, yet this is often not immediate, may not be sustainable, and has not improved over recent decades. Symptomatic etiology, abnormal neuro-diagnostics, and increased pre-treatment seizure burden and seizure types are important predictors for unfavorable outcomes in newly diagnosed epilepsy. The study findings may be used as a quantitative benchmark on the efficacy of future antiseizure medication therapy for this patient population.

Great Safety and Efficacy of a New Drug-eluting-stent manufactured in a developing country at minimal cost: the VSTENT at 3 years follow-up

Background

In the care patients with coronary artery disease, a new drug-eluting stent, the VSTENT, covered with sirolimus was designed and manufactured in a developing country at minimal cost. Beside the clinical concern, from an engineering perspective, the questions were: Was this stent flexible? What was its radial strength? Did this stent brace itself against the wall with a strong strut network? What was the cell size and design?

Methods

From 6.2019 to 8.2020, 150 patients from 5 hospitals underwent PCI with a new VSTENT in 212 lesions. At the index PCI (D1), a subgroup of 61 patients (40%) was preselected to undergo additional imaging procedures including intravascular ultrasound (IVUS=41) or optical coherence tomography (OCT=20). All patients were followed-up clinically every month for one year. At 6 months (D180) they underwent digital subtraction angiography (DSA=143) or a second IVUS or OCT for the intravascular subgroup. The rate of invasive imaging follow-up was 95% for DSA, 92% for IVUS and 95% for OCT. The rate of major adverse cardiovascular events (MACE: mortality, in-stent restenosis (ISR), Target lesion revascularization (TLR) and data on radial strength, longitudinal flexibility, expansion and coverage were calculated.

Results

In all patients, the technical success was 100% (successful balloon inflation, complete stent expansion, uneventful balloon removal). The VSTENTs were deployed in arteries of all sizes: small with diameter (D) = 2.5mm in 11.3%, D= 2.75mm in 24.1%, and in large arteries D= or &gt;3mm in 66.6% of patients. The stent length varied from 15–38mm with 80% &gt;20mm. 92% had good apposition as evidenced by OCT or IVUS. There was no acute in-stent thrombus, no loss of side branch and no perforation. There was one cardiac arrest with successful resuscitation. The bench and angiographic data on radial strength, longitudinal flexibility, expansion and coverage were excellent

In Figure 1, The VSTENT design has open cells in the middle and closed cell at both distal segments. This design of mixed closed and open cell increases the radial strength at both ends while preventing the diametric difference (dog-boning effect)

In Figure 2, after deployment of a VSTENT, the size of the open cell design in the middle of the stent is approximately 3.40 mm2 while the size of the distal closed cells design is 1.7 mm2.

At 6 months, the rate of angiographic ISR inside the stent and within the 5 mm from the two ends was 3.5%. The rate of late lumen loss was 0.8mm in the in-stent segment and 0.07mm within 5mm of the two ends. The composite MACE was 4.7% with 1 mortality (0.7%) and 4 TLRs. At 36 months follow-up, only one TLR was reported.

Conclusions

At 3 years follow-up, the rate of angiographic ISR and TLR of the VSTENT was low. The data on radial strength, longitudinal flexibility, expansion and coverage were excellent. The VSTENT could be an affordable choice for interventional cardiology service in developing countries.

Funding Acknowledgement

Type of funding sources: Private company. Main funding source(s): United Healthcare

What are the ideal systolic and diastolic blood pressure which do not injure the intima of iliac and coronary arteries?

 

For patients with coronary artery disease, hypertension (HTN) is a major risk factor. How could uncontrolled HTN start atherosclerosis? In our prior research, laminar flow in coronary arteries prevented the formation of plaques while turbulent flow injured the intima and triggered atherosclerosis. In this present study our question was: Which blood pressure (BP) level is optimal in not producing turbulence and so not injuring the intima?

Methods

At first, a systolic BP&lt;120mmHg and diastolic BP&lt;75mmHg) were arbitrarily set as controlled (group A) while a BP of &gt;160/105mmHg as uncontrolled (group B). All patients underwent a dynamic coronary angiogram recorded at 15 images/second or 0.06 seconds per image. The first image was of the index artery completely filled with contrast. In subsequent images the blood in white color moved in over a background of black contrast (Figure 1A). In 1B, 0.06 seconds later, the blood arrived at the mid segment (white arrow). In 1C, the flood moved forward, however there was darker contrast hanging at the mid segment, marking the location of collision from the retrograde against the antegrade flow (white arrow). The reason was that in uncontrolled BP the contraction of the left ventricle was stronger so in systole, the coronary blood could reverse its course, run on a retrograde direction, collide against the antegrade flow and create turbulence (1C).

At the end, before deploying a vascular closure device, an iliac angiogram was performed. In Figure 2, on a black background of contrast, the blood in white color moved forward with a pointed tip of laminar flow. 0.06 seconds later, the laminar tip was stopped abruptly with all the layers recoiling on each other like a falling stack of dominoes. In the next image. a large swirl of disorganized mixing of blood and contrast suggested the presence of turbulence caused by the collision.

The data to be collected were (1) the duration of the antegrade and retrograde flow, (2) duration of the collision (turbulence at the collision site)

Results

In the group A (BP &lt;120/75 mmHg), 90% of 20 patients had no retrograde flow nor collision in the iliac and short collision in coronary arteries (&lt;0.12 secs). In 30 patients of group B (BP &gt;160/105 mmHg), the duration of retrograde flow and collision in the iliac artery were prolonged at &gt;0.24 msecs. In the coronary arteries, the duration was prolonged at 0.18 msecs (all p&lt;0.05 compared with group A). These locations of turbulence correlated with the location of plaques in our prior studies.

Conclusion

In patients with uncontrolled HTN, the retrograde flow was prolonged, and the turbulence was intense. In contrary, for patients with controlled BP, there was no retrograde flow and weaker collision in coronary arteries. The results suggest that a BP of &lt;120/75 mmHg may not trigger the atherosclerotic process. New clinical trials with larger number of patients should be performed in search for the lowest ideal blood pressure.

Funding Acknowledgement

Type of funding sources: None.

A PKA inhibitor motif within SMOOTHENED controls Hedgehog signal transduction

The Hedgehog (Hh) cascade is central to development, tissue homeostasis and cancer. A pivotal step in Hh signal transduction is the activation of glioma-associated (GLI) transcription factors by the atypical G protein-coupled receptor (GPCR) SMOOTHENED (SMO). How SMO activates GLI remains unclear. Here we show that SMO uses a decoy substrate sequence to physically block the active site of the cAMP-dependent protein kinase (PKA) catalytic subunit (PKA-C) and extinguish its enzymatic activity. As a result, GLI is released from phosphorylation-induced inhibition. Using a combination of in vitro, cellular and organismal models, we demonstrate that interfering with SMO-PKA pseudosubstrate interactions prevents Hh signal transduction. The mechanism uncovered echoes one used by the Wnt cascade, revealing an unexpected similarity in how these two essential developmental and cancer pathways signal intracellularly. More broadly, our findings define a mode of GPCR-PKA communication that may be harnessed by a range of membrane receptors and kinases.

Measuring the arterial phase of the right coronary artery in the patients suspected of coronary artery disease: a dual study by dynamic angiography and deep learning program

Funding Acknowledgements

Type of funding sources: None.

Background. In the diagnosis of coronary artery disease (CAD), coronary angiography (CA) plays a crucial role in determining the location and severity of the stenosis, the anatomical aspect of a lesion. It does not accurately reflect the flow dynamics in the coronary artery. This study aimed to evaluate the coronary flow abnormalities based on our new angiographic technique and Deep Learning (DL) program in patients suspected of CAD.

Methods. We randomly selected patients who were admitted with suspected CAD. All patients underwent our new technique of CA. After the index coronary artery was filled completely with contrast, we stopped the injection. At that time, the blood in white color flew in. The flow characteristics, the shape of the tip, borders, and direction could be clearly observed above a black background of the contrast. In this study, we measured the arterial phase (AP) from the beginning when the blood moved in until the end when all contrasts in black color washed out of the distal vasculature. In the DL protocol, the U-Net model combined with Dense-Net-121 and a binary image classification model are used to predict the beginning and ending frame. To obtain the best image for the DL program, we analyzed only the flow of the right coronary artery (RCA).

Results. 81 patients were enrolled. In patients with normal coronary angiography, the mean AP was 1.86s (27.4 +/- 5.4 frames). In patients with one significant lesion, the mean AP value was 2.35s (35.3 +/- 7.7 frames). The mean difference of the AP between the two groups was 0.49s (95% confidence interval: 0.295 to 0.694). This difference is statistically significant. Our DL has the mean root square error in predicting the AP was 0.34s.

Conclusion. In patients with CAD, the prolonged arterial phase could be accurately estimated using the DL program, reflecting the slow circulation of highly oxygenated blood. It could be used as a marker of coronary perfusion in future studies.

Germline and Mosaic Variants in PRKACA and PRKACB Cause a Multiple Congenital Malformation Syndrome

PRKACA and PRKACB code for two catalytic subunits (Cα and Cβ) of cAMP-dependent protein kinase (PKA), a pleiotropic holoenzyme that regulates numerous fundamental biological processes such as metabolism, development, memory, and immune response. We report seven unrelated individuals presenting with a multiple congenital malformation syndrome in whom we identified heterozygous germline or mosaic missense variants in PRKACA or PRKACB. Three affected individuals were found with the same PRKACA variant, and the other four had different PRKACB mutations. In most cases, the mutations arose de novo, and two individuals had offspring with the same condition. Nearly all affected individuals and their affected offspring shared an atrioventricular septal defect or a common atrium along with postaxial polydactyly. Additional features included skeletal abnormalities and ectodermal defects of variable severity in five individuals, cognitive deficit in two individuals, and various unusual tumors in one individual. We investigated the structural and functional consequences of the variants identified in PRKACA and PRKACB through the use of several computational and experimental approaches, and we found that they lead to PKA holoenzymes which are more sensitive to activation by cAMP than are the wild-type proteins. Furthermore, expression of PRKACA or PRKACB variants detected in the affected individuals inhibited hedgehog signaling in NIH 3T3 fibroblasts, thereby providing an underlying mechanism for the developmental defects observed in these cases. Our findings highlight the importance of both Cα and Cβ subunits of PKA during human development.

Getting to the bottom of bycatch: a GIS-based toolbox to assess the risk of marine mammal bycatch

Marine mammal bycatch poses a particular challenge in developing countries, where data to document bycatch and its effects are often lacking. Using the Bycatch Risk Assessment (ByRA) toolkit, based on InVEST open-source models, we chose 4 field sites in Southeast Asia with varying amounts of data on marine mammals and fishing occurrence: Trat province in the eastern Gulf of Thailand, the Sibu-Tinggi Islands and Kuching Bay, Malaysia, and Kien Giang Biosphere Reserve in southwestern Vietnam. These field sites have similar species of coastal marine mammals, small-scale and commercial fisheries, and support for research from universities and/or management. In Thailand and Kuching, results showed changing patterns of fishing and Irrawaddy dolphin Orcaella brevirostris habitat use across seasons, showing how bycatch risk could change throughout the year. Risk maps for dugongs Dugong dugon in peninsular Malaysia highlighted patterns of bycatch risk concentrated around a mainland fishing pier, and revealed high risk in a northern subregion. In Vietnam, first maps of bycatch risk for the Irrawaddy dolphin showed the highest risk driven by intensive use of gillnets and trawling gear. ByRA pinpointed areas of spatial and seasonal bycatch exposure, and estimated the consequence of bycatch on local species, providing managers with critical information on where to focus bycatch mitigation and meet new global standards for US Marine Mammal Protection Act and other international regulation (e.g. Official Journal of the European Union 2019; Regulation 2019/1241) compliance. The toolbox, a transferable open-source tool, can be used to guide fisheries management, marine mammal conservation, spatial planning, and further research.

Community-Based Antiretroviral Therapy (ART) Delivery for Female Sex Workers in Tanzania: 6-Month ART Initiation and Adherence

We conducted an implementation science study of a community-based ART distribution program for HIV-positive female sex workers (FSW) whereby clients received ART services through community-based mobile and home-based platforms. We compared 6-month treatment-related outcomes in the community-based ART arm (N = 256) to the standard facility-based ART delivery arm (N = 253). Those in the intervention arm were more likely to have initiated ART (100.0% vs. 71.5%; p = 0.04), be currently taking ART at the 6-month visit (100.0% vs. 95.0%; p < 0.01), and less likely to have stopped taking ART for more than 30 days continuously (0.9% vs. 5.7%; p = 0.008) or feel high levels of internalized stigma (26.6% vs. 39.9%; p = 0.001). In the adjusted regression model, internalized stigma (adjusted OR [aOR]: 0.5; 95% CI 0.28–0.83) and receiving community-based ART (aOR: 208.6; 95% CI 12.5–3479.0) were significantly associated with ART initiation. Community-based ART distribution model can improve linkage to and adherence to ART over standard facility-based ART programs for FSWs.

Two Cases of Inherited Triple Deficiency in a Large Kindred with Thrombotic Diathesis and Deficiencies of Antithrombin III, Heparin Cofactor II, Protein C and Protein S

Thirty-three subjects, belonging to a large family with functional antithrombin III (ATIII) deficiency (type IIa) and recurrent thromboembolism, were investigated for ATIII, heparin cofactor II (HCII), protein C (PC) and protein S (PS). We report the exceptional finding of two cases of triple deficiency: ATIII combined with HCII and PC in the first case aged 15 and ATIII combined with HCII and PS in the second case aged 27. Interestingly, both are asymptomatic thus far. Twenty-five other deficient members were found, among which seven are affected with a double deficiency. Totally, the results of our study show 38 deficiencies of four distinct antithrombotic protein: ATIII (n = 9), HCII (n = 9), PC (n = 7) or PS (n = 13). Two types of HCII deficiency were observed and type I PC deficiency was found. Functional PS deficiency was characterized by reduced levels of cofactor activity for activated PC. Our report demonstrates that combined deficiencies should be sought in a family already known to be deficient in one antithrombotic protein.

Abstract P1-11-04: Looking beyond the margins: Economic costs and complications associated with repeated breast-conserving surgeries

Background: Although considerable attention has been drawn to the problem of repeat breast-conserving surgery (BCS), the costs and complications due to these additional operations are not well-characterized. In this work, a retrospective review of insurance claims data for BCS patients was performed to assess complications and economic outcomes.

Methods: Private claims data were analyzed for 9,837 women undergoing BCS for breast carcinoma between January 2010 and December 2013. Patients enrolled in insurance plans in IL, TX, NM, and OK were included. Patients undergoing a second open breast surgery (mastectomy or BCS) within 90 days of the initial BCS were classified as having a repeat surgery. Complications were identified via a set of 8 CPT and 25 ICD9 diagnosis and procedure codes related to breast cancer treatment. The analysis included these complications and the total cost of all allowed healthcare claims within two years following diagnosis.

Results: 7,555/9,837 patients (77% ±0.8%, 95% confidence interval) had one BCS operation, and 2,282 patients (23% ±0.8%) had at least one repeat surgery. The mean patient age was 53 years. Women who underwent an additional operation waited an average of 24 days for the procedure.

The mean two-year total costs for patients undergoing a single BCS was $89,016 (±$1,884), and the cost for patients undergoing a repeat breast surgery was $105,088 (±$3,680; p &lt; 0.0001), $100,637 (±$4,219) for a second BCS and $115,292 (±$7,259) for subsequent mastectomy. The mean added cost due to a repeat surgery was $16,072.

The percentage of patients experiencing at least one complication was 23.6% (±1.0%) for those undergoing one BCS only and 34.8% (±2.0%) for those undergoing a repeat operation (p &lt; 0.0001). Patients undergoing repeated surgery were 88% more likely to experience multiple complications (5.5% ±0.5% vs. 10.4% ±1.3%) and nearly three times as likely to experience fat necrosis (2.5% ±0.4% vs. 7.2% ±1.1%). Infection, hematoma/seroma, and breast pain were the most common complications for patients who did not undergo a repeated surgery (9.9% ±0.7%, 8.7% ±0.6%, 6.9% ±0.6%). For patients undergoing a repeated surgery, infection, hematoma/seroma, and fat necrosis were the most common complications (15.3% ±1.5%, 13.9% ±1.4%, 7.2% ±1.1%).

Conclusions: For the 23% of women undergoing a second operation after BCS, complications were 48% more common, and the mean total cost of surgery was $16,072 more, demonstrating statistically-significant evidence of a patient-centered and fiscal imperative to reduce reoperations in BCS for breast cancer.Background: Although considerable attention has been drawn to the problem of repeat breast-conserving surgery (BCS), the costs and complications due to these additional operations are not well-characterized. In this work, a retrospective review of insurance claims data for BCS patients was performed to assess complications and economic outcomes.

Methods: Private claims data were analyzed for 9,837 women undergoing BCS for breast carcinoma between January 2010 and December 2013. Patients enrolled in insurance plans in IL, TX, NM, and OK were included. Patients undergoing a second open breast surgery (mastectomy or BCS) within 90 days of the initial BCS were classified as having a repeat surgery. Complications were identified via a set of 8 CPT and 25 ICD9 diagnosis and procedure codes related to breast cancer treatment. The analysis included these complications and the total cost of all allowed healthcare claims within two years following diagnosis.

Results: 7,555/9,837 patients (77% ±0.8%, 95% confidence interval) had one BCS operation, and 2,282 patients (23% ±0.8%) had at least one repeat surgery. The mean patient age was 53 years. Women who underwent an additional operation waited an average of 24 days for the procedure.

The mean two-year total costs for patients undergoing a single BCS was $89,016 (±$1,884), and the cost for patients undergoing a repeat breast surgery was $105,088 (±$3,680; p &lt; 0.0001), $100,637 (±$4,219) for a second BCS and $115,292 (±$7,259) for subsequent mastectomy. The mean added cost due to a repeat surgery was $16,072.

The percentage of patients experiencing at least one complication was 23.6% (±1.0%) for those undergoing one BCS only and 34.8% (±2.0%) for those undergoing a repeat operation (p &lt; 0.0001). Patients undergoing repeated surgery were 88% more likely to experience multiple complications (5.5% ±0.5% vs. 10.4% ±1.3%) and nearly three times as likely to experience fat necrosis (2.5% ±0.4% vs. 7.2% ±1.1%). Infection, hematoma/seroma, and breast pain were the most common complications for patients who did not undergo a repeated surgery (9.9% ±0.7%, 8.7% ±0.6%, 6.9% ±0.6%). For patients undergoing a repeated surgery, infection, hematoma/seroma, and fat necrosis were the most common complications (15.3% ±1.5%, 13.9% ±1.4%, 7.2% ±1.1%).

The impact of repeated breast-conserving surgeries BCS, No RepeatRepeat BCSConvert to MastectomyPatients76.8% (7,555)16.2% (1,589)7.0% (693)Mean Two-Year Cost Per Patient$89,016$100,637$115,292Patients with any Complication(s)23.6% (1,783)32.5% (516)40.3% (279)Patients with Infection9.9% (746)14.0% (222)18.3% (127)Patients with Hematoma/Seroma8.7% (655)12.8% (203)16.6% (115)Patients with Breast Pain6.9% (525)7.0% (111)6.1% (42)Patients with Fat Necrosis2.5% (187)7.6% (120)6.5% (45)

Conclusions: For the 23% of women undergoing a second operation after BCS, complications were 48% more common, and the mean total cost of surgery was $16,072 more, demonstrating statistically-significant evidence of a patient-centered and fiscal imperative to reduce reoperations in BCS for breast cancer.

Citation Format: Metcalf LN, Zysk AM, Underwood HR, Edelman G, Vu L, Cittadine AJ, Hyer KB, Thompson AM. Looking beyond the margins: Economic costs and complications associated with repeated breast-conserving surgeries [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P1-11-04.

Patient-derived xenotransplants can recapitulate the genetic driver landscape of acute leukemias

Genomic studies have identified recurrent somatic mutations in acute leukemias. However, current murine models do not sufficiently encompass the genomic complexity of human leukemias. To develop pre-clinical models, we transplanted 160 samples from patients with acute leukemia (AML, MLL, B-ALL and T-ALL) into immunodeficient mice. Of these, 119 engrafted with expected immunophenotype. Targeted sequencing of 374 genes and 265 frequently rearranged RNAs detected recurrent and novel genetic lesions in 48 paired primary tumor (PT) and patient-derived xenotransplant (PDX) samples. Overall, the frequencies of 274 somatic variant alleles correlated between PT and PDX samples, although the data were highly variable for variant alleles present at 0-10%. 17% of variant alleles were detected in either PT or PDX samples only. Based on variant allele frequency changes, 24 PT-PDX pairs were classified as concordant while the other 24 pairs showed various degree of clonal discordance. There was no correlation of clonal concordance with clinical parameters of diseases. Significantly more bone marrow samples than peripheral blood samples engrafted discordantly. These data demonstrate the utility of developing PDX banks for modeling human leukemia, and emphasize the importance of genomic profiling of PDX and patient samples to ensure concordance before performing mechanistic or therapeutic studies.

Factors influencing doctors' selection of dabigatran in non-valvular atrial fibrillation

RATIONALE, AIMS AND OBJECTIVES

This study was designed to examine the factors that influence doctors' decision in initiating or switching from warfarin to dabigratran.

METHOD

A survey questionnaire was sent to 181 doctors who were most likely to prescribe dabigatran (e.g. cardiologists and general internists) at the University of California, San Francisco Medical Center between November 2011 and February 2012. Survey participants were asked to complete an electronic or a paper version of the questionnaire, which consisted of 17 multiple-choice questions. Fisher's exact test and Cochran-Mantel-Haenszel test were used to compare survey responses between cardiologists and general internists.

RESULTS

A total of 65 survey responses were received (35.9% response rate). There were 13 cardiologists and 51 general internists who participated in the study. Cost (25%), renal function (21%) and CHADS2 score (18%) were the three factors doctors considered most often to determine a patient's eligibility for dabigatran in warfarin-naïve patients. On the other hand, histories of unstable international normalized ratio (37%) and missed appointments (17%) along with cost (19%) were most often considered in patients on warfarin. Cardiologists had prescribed dabigatran more often and had a significantly higher level of comfort with prescribing the drug than general internists (P = 0.003; 77% vs. 27%).

CONCLUSIONS

Cost was the most important factor influencing doctors' decision to prescribe dabigatran. Safety and effectiveness of dabigatran as well as patient preference were additional factors influencing their decision. General internists were less comfortable with prescribing dabigatran than cardiologists.

Population-based prevalence of hepatitis B and C virus, HIV, syphilis, gonorrhoea and chlamydia in male injection drug users in Lagos, Nigeria

There is little research on injecting drug use in Nigeria. We investigated the prevalence of HIV, hepatitis B and C, and sexually transmitted infections (STIs) among male injection drug users (IDUs) in Lagos. Male IDUs (N = 328) were recruited through respondent-driven sampling. Participants completed an interview about their sexual and injecting risk behaviours and were tested for hepatitis B surface antigen (HBV), hepatitis C antibody (HCV), HIV and syphilis, as well as genital chlamydia and gonorrhoea infections. Three-quarters of IDUs (74%) reported injecting drugs in the past one month although most did not share needles (92%) and the majority obtained sterile needles from pharmacists (87%). Estimated HBV, HCV, HIV, syphilis, gonorrhoea and chlamydia prevalences were 7.8%, 7.7%, 0.9%, 1.9%, 0.0%, and 3.7%, respectively. The burden of HIV is presently low among IDUs in Lagos. Changes in accessibility to sterile needles at pharmacists would likely have a deleterious effect on IDUs' health. HBV vaccination and HCV prevention programmes for IDUs are urgently needed.

Efficacy of three drugs for protecting against gentamicin-induced hair cell and hearing losses

BACKGROUND AND PURPOSE Exposure to an ototoxic level of an aminoglycoside can result in hearing loss. In this we study investigated the otoprotective efficacy of dexamethasone (DXM), melatonin (MLT) and tacrolimus (TCR) in gentamicin (GM)-treated animals and cultures. EXPERIMENTAL APPROACH Wistar rats were divided into controls (treated with saline); exposed to GM only (GM); and three GM-exposed groups treated with either DXM, MLT or TCR. Auditory function and cochlear surface preparations were studied. In vitro studies of oxidative stress, pro-inflammatory cytokine mRNA levels, the MAPK pathway and caspase-3 activation were performed in organ of Corti explants from 3-day-old rats. KEY RESULTS DXM, MLT and TCR decreased levels of reactive oxygen species in GM-exposed explants. The mRNA levels of TNF-α, IL-1β and TNF-receptor type 1 were significantly reduced in GM + DXM and GM + MLT groups. Phospho-p38 MAPK levels decreased in GM + MLT and GM + TCR groups, while JNK phosphorylation was reduced in GM + DXM and GM + MLT groups. Caspase-3 activation decreased in GM + DXM, GM + MLT and GM + TCR groups. These results were consistent with in vivo results. Local treatment of GM-exposed rat cochleae with either DXM, MLT or TCR preserved auditory function and prevented auditory hair cell loss. CONCLUSIONS AND IMPLICATIONS In organ of Corti explants, GM increased oxidative stress and initiated an inflammatory response that led to the activation of MAPKs and apoptosis of hair cells. The three compounds tested demonstrated otoprotective properties that could be beneficial in the treatment of ototoxicity-induced hearing loss.

Dexamethasone treatment of tumor necrosis factor-alpha challenged organ of Corti explants activates nuclear factor kappa B signaling that induces changes in gene expression that favor hair cell survival

The objective was to determine the role of nuclear factor kappa B (NFκB) in dexamethasone base (DXMb) protection of auditory hair cells from tumor necrosis factor-alpha (TNFα)-induced loss on gene expression and cell signaling levels. Organ of Corti (OC) explants from 3-day-old rats were cultured under one of the following conditions: (1) media only--no treatment; (2) media+TNFα; (3) media+TNFα+DXMb; (4) media+TNFα+DXMb+NFκB-Inhibitor (NFκB-I); or (5) media+TNFα+DXMb+NFκBI-Scrambled control (NFκBI-C). A total of 60 organ of Corti explants (OC) were stained with FITC-Phalloidin after 96 h in culture (conditions 1-5) for hair cell counts and imaging of surface characteristics. A total of 108 OC were used for gene expression studies (i.e. B-actin, Bax, Bcl-2, Bcl-xl, and TNFR1) after 0, 24, or 48 h in vitro (conditions 1-4). A total of 86 OC were cultured (conditions 1-3) for 48 h, 36 of which were used for phosphorylated NFκB (p-NFκB) ELISA studies and 50 for whole mount anti-p-NFκB immunostain experiments. TNFα+DXMb exposed cultures demonstrated significant upregulation in anti-apoptotic Bcl-2 and Bcl-xl genes and downregulation in pro-apoptotic Bax gene expression; DXMb treatment of TNFα explants also lowered the Bax/Bcl-2 ratio and inhibited TNFR1 upregulation. After inhibiting NFκB activity with NFκB-I, the gene expression profile following TNFα+DXMb treatment now mimics that of TNFα-challenged OC explants. The levels of p-NFκB and the degree of nuclear translocation are significantly greater in TNFα+DXMb exposed OC explants than observed in the TNFα and control groups in the middle+basal turns of OC explants. These findings were supported by the results of the hair cell counts and the imaging results obtained from the whole mount OC specimens. DXMb protects against TNFα-induced apoptosis of auditory hair cells in vitro via activation of NFκB signaling in hair cell nuclei, and regulation of the expression levels of anti- and pro-apoptotic genes and a pro-inflammatory gene.

RNA polymerase II elongation factors Spt4p and Spt5p play roles in transcription elongation by RNA polymerase I and rRNA processing

Previous investigations into the mechanisms that control RNA Polymerase (Pol) I transcription have primarily focused on the process of transcription initiation, thus little is known regarding postinitiation steps in the transcription cycle. Spt4p and Spt5p are conserved throughout eukaryotes, and they affect elongation by Pol II. We have found that these two proteins copurify with Pol I and associate with the rDNA in vivo. Disruption of the gene for Spt4p resulted in a modest decrease in growth and rRNA synthesis rates at the permissive temperature, 30 degrees C. Furthermore, biochemical and EM analyses showed clear defects in rRNA processing. These data suggest that Spt4p, Spt5p, and, potentially, other regulators of Pol I transcription elongation play important roles in coupling rRNA transcription to its processing and ribosome assembly.

Yeast RNA polymerase I enhancer is dispensable for transcription of the chromosomal rRNA gene and cell growth, and its apparent transcription enhancement from ectopic promoters requires Fob1 protein

At the end of the 35S rRNA gene within ribosomal DNA (rDNA) repeats in Saccharomyces cerevisiae lies an enhancer that has been shown to greatly stimulate rDNA transcription in ectopic reporter systems. We found, however, that the enhancer is not necessary for normal levels of rRNA synthesis from chromosomal rDNA or for cell growth. Yeast strains which have the entire enhancer from rDNA deleted did not show any defects in growth or rRNA synthesis. We found that the stimulatory activity of the enhancer for ectopic reporters is not observed in cells with disrupted nucleolar structures, suggesting that reporter genes are in general poorly accessible to RNA polymerase I (Pol I) machinery in the nucleolus and that the enhancer improves accessibility. We also found that a fob1 mutation abolishes transcription from the enhancer-dependent rDNA promoter integrated at the HIS4 locus without any effect on transcription from chromosomal rDNA. FOB1 is required for recombination hot spot (HOT1) activity, which also requires the enhancer region, and for recombination within rDNA repeats. We suggest that Fob1 protein stimulates interactions between rDNA repeats through the enhancer region, thus helping ectopic rDNA promoters to recruit the Pol I machinery normally present in the nucleolus.

Role of TATA binding protein (TBP) in yeast ribosomal dna transcription by RNA polymerase I: defects in the dual functions of transcription factor UAF cannot be suppressed by TBP

Initiation of ribosomal DNA (rDNA) transcription by RNA polymerase I (Pol I) in the yeast Saccharomyces cerevisiae involves upstream activation factor (UAF), core factor, the TATA binding protein (TBP), and Rrn3p in addition to Pol I. We found previously that yeast strains carrying deletions in the UAF component RRN9 switch completely to the use of Pol II for rRNA transcription, with no residual Pol I transcription. These polymerase-switched strains initially grow very slowly, but subsequent expansion in the number of rDNA repeats on chromosome XII leads to better growth. Recently, it was reported that TBP overexpression could bypass the requirement of UAF for Pol I transcription in vivo, producing nearly wild-type levels of growth in UAF mutant strains (P. Aprikian, B. Moorefield, and R. H. Reeder, Mol. Cell. Biol. 20:5269-5275, 2000). Here, we demonstrate that deletions in the UAF component RRN5, RRN9, or RRN10 lead to Pol II transcription of rDNA. TBP overexpression does not suppress UAF mutation, and these strains continue to use Pol II for rRNA transcription. We do not find evidence for even low levels of Pol I transcription in UAF mutant strains carrying overexpressed TBP. In diploid strains lacking both copies of the UAF component RRN9, Pol II transcription of rDNA is more strongly repressed than in haploid strains but TBP overexpression still fails to activate Pol I. These results emphasize that UAF plays an essential role in activation of Pol I transcription and silencing of Pol II transcription of rDNA and that TBP functions to recruit the Pol I machinery in a manner completely dependent on UAF.

Complete deletion of yeast chromosomal rDNA repeats and integration of a new rDNA repeat: use of rDNA deletion strains for functional analysis of rDNA promoter elements in vivo

Strains of Saccharomyces cerevisiae were constructed in which chromosomal rDNA repeats are completely deleted and their growth is supported by a plasmid carrying a single rDNA repeat, either a plasmid carrying the 35S rRNA gene transcribed from the native promoter by RNA polymerase I or a plasmid carrying the 35S rRNA gene fused to the GAL7 promoter for transcription by RNA polymerase II. This system has made it possible to assess the expression of rDNA by measuring the ability of synthesized rRNA to support cell growth as well as by measuring the actual rRNA synthesized rather than by the use of reporter mini-rDNA genes. Using this system, deletion analysis of the rDNA promoter confirmed the presence of two elements, the upstream element and the core promoter, and showed that basal transcription from the core promoter, if it takes place in vivo as was observed in vitro, is not sufficient to allow cell growth. We have also succeeded in integration of a rDNA repeat and its copy number expansion at the original chromosomal locus, which will allow future mutational analysis not only of rRNA but also other DNA elements involved in rRNA transcription, rDNA replication and recombination within a repeated rDNA structure.

Evidence for separable functions of Srp1p, the yeast homolog of importin alpha (Karyopherin alpha): role for Srp1p and Sts1p in protein degradation

Srp1p (importin alpha) functions as the nuclear localization signal (NLS) receptor in Saccharomyces cerevisiae. The srp1-31 mutant is defective in this nuclear localization function, whereas an srp1-49 mutant exhibits defects that are unrelated to this localization function, as was confirmed by intragenic complementation between the two mutants. RPN11 and STS1 (DBF8) were identified as high-dosage suppressors of the srp1-49 mutation but not of the srp1-31 mutation. We found that Sts1p interacts directly with Srp1p in vitro and also in vivo, as judged by coimmunoprecipitation and two-hybrid analyses. Mutants of Sts1p that cannot interact with Srp1p are incapable of suppressing srp1-49 defects, strongly suggesting that Sts1p functions in a complex with Srp1p. STS1 also interacted with the second suppressor, RPN11, a subunit of the 26S proteasome, in the two-hybrid system. Further, degradation of Ub-Pro-beta-galactosidase, a test substrate for the ubiquitin-proteasome system, was defective in srp1-49 but not in srp1-31. This defect in protein degradation was alleviated by overexpression of either RPN11 or STS1 in srp1-49. These results suggest a role for Srp1p in regulation of protein degradation separate from its well-established role as the NLS receptor.

Transcription factor UAF, expansion and contraction of ribosomal DNA (rDNA) repeats, and RNA polymerase switch in transcription of yeast rDNA

Strains of the yeast Saccharomyces cerevisiae defective in transcription factor UAF give rise to variants able to grow by transcribing endogenous ribosomal DNA (rDNA) by RNA polymerase II (Pol II). We have demonstrated that the switch to growth using the Pol II system consists of two steps: a mutational alteration in UAF and an expansion of chromosomal rDNA repeats. The first step, a single mutation in UAF, is sufficient to allow Pol II transcription of rDNA. In contrast to UAF mutations, mutations in Pol I or other Pol I transcription factors can not independently lead to Pol II transcription of rDNA, suggesting a specific role of UAF in preventing polymerase switch. The second step, expansion of chromosomal rDNA repeats to levels severalfold higher than the wild type, is required for efficient cell growth. Mutations in genes that affect recombination within the rDNA repeats, fob1 and sir2, decrease and increase, respectively, the frequency of switching to growth using Pol II, indicating that increased rDNA copy number is a cause rather than a consequence of the switch. Finally, we show that the switch to the Pol II system is accompanied by a striking alteration in the localization and morphology of the nucleolus. The altered state that uses Pol II for rDNA transcription is semistable and heritable through mitosis and meiosis. We discuss the significance of these observations in relation to the plasticity of rDNA tandem repeats and nucleolar structures as well as evolution of the Pol I machinery.

A prospective study of G-CSF effects on hemostasis in allogeneic blood stem cell donors

Granulocyte colony-stimulating factor (G-CSF) is used in healthy donors of peripheral blood stem cells (PBSC) for allogeneic transplantation. However, some data have recently suggested that G-CSF may induce a hypercoagulable state, prompting us to study prospectively 22 PBSC donors before and after G-CSF 5 microg/kg twice daily. We sought evidence for changes in the following parameters: platelet count, von Willebrand factor antigen (vWF:Ag) and activity (vWF activity), beta-thromboglobulin (beta-TG), platelet factor 4 (PF-4), platelet activation markers (GMP-140 and PAC-1), activated partial thromboplastin time (aPTT), prothrombin time (PT), coagulant factor VIII (FVIII:C), thrombin-antithrombin complex (TAT), prothrombin fragment 1+2 (F1+2), thrombomodulin (TM) and tissue plasminogen activator antigen (tPA:Ag) prior to G-CSF and immediately before leukapheresis. ADP-induced platelet aggregation studies were also performed. G-CSF administration produced only mild discomfort. We found a significant increase in vWF:Ag (from 0.99 +/- 0.32 U/ml to 1.83 +/- 0.69 U/ml; P < 0.001), in vWF activity (from 1.04 +/- 0.34 U/ml to 1.78 +/- 0.50 U/ml; P < 0.001) and in FVIII:C (from 1.12 +/- 0.37 U/ml to 1.73 +/- 0.57 U/ml; P < 0.001) after G-CSF. Of note, four donors with low baseline vWF had a two- to three-fold increase after receiving G-CSF. G-CSF had no impact on the platelet count, beta-TG, PF-4, GMP-140 or PAC-1. The final% of platelet aggregation decreased from 73 +/- 22% to 37 +/- 26% after G-CSF (P < 0.001). We found a significant decrease in aPTT after G-CSF (29.9 +/- 3.1 s to 28.3 +/- 3.3 s; P = 0.004), but the PT was unaffected. In addition, we also observed a significant increase in TAT, F1+2 and TM, but not in tPA:Ag. Our data suggest that G-CSF may possibly induce a hypercoagulable state by increasing levels of FVIII:C and thrombin generation. In contrast to this information, we found reduced platelet aggregation after G-CSF administration. The clinical implications of these findings remain unclear and larger studies are definitely required.

RNA polymerase switch in transcription of yeast rDNA: role of transcription factor UAF (upstream activation factor) in silencing rDNA transcription by RNA polymerase II

Transcription factor UAF (upstream activation factor) is required for a high level of transcription, but not for basal transcription, of rDNA by RNA polymerase I (Pol I) in the yeast Saccharomyces cerevisiae. RRN9 encodes one of the UAF subunits. We have found that rrn9 deletion mutants grow extremely slowly but give rise to faster growing variants that can grow without intact Pol I, synthesizing rRNA by using RNA polymerase II (Pol II). This change is reversible and does not involve a simple mutation. The two alternative states, one suitable for rDNA transcription by Pol I and the other favoring rDNA transcription by Pol II, are heritable not only in mitosis, but also in meiosis. Thus, S. cerevisiae has an inherent ability to transcribe rDNA by Pol II, but this transcription activity is silenced in normal cells, and UAF plays a key role in this silencing by stabilizing the first state.

Mutational analysis of the structure and localization of the nucleolus in the yeast Saccharomyces cerevisiae

The nucleolus in Saccharomyces cerevisiae is a crescent-shaped structure that makes extensive contact with the nuclear envelope. In different chromosomal rDNA deletion mutants that we have analyzed, the nucleolus is not organized into a crescent structure, as determined by immunofluorescence microscopy, fluorescence in situ hybridization, and electron microscopy. A strain carrying a plasmid with a single rDNA repeat transcribed by RNA polymerase I (Pol I) contained a fragmented nucleolus distributed throughout the nucleus, primarily localized at the nuclear periphery. A strain carrying a plasmid with the 35S rRNA coding region fused to the GAL7 promoter and transcribed by Pol II contained a rounded nucleolus that often lacked extensive contact with the nuclear envelope. Ultrastructurally distinct domains were observed within the round nucleolus. A similar rounded nucleolar morphology was also observed in strains carrying the Pol I plasmid in combination with mutations that affect Pol I function. In a Pol I-defective mutant strain that carried copies of the GAL7-35S rDNA fusion gene integrated into the chromosomal rDNA locus, the nucleolus exhibited a round morphology, but was more closely associated with the nuclear envelope in the form of a bulge. Thus, both the organization of the rDNA genes and the type of polymerase involved in rDNA expression strongly influence the organization and localization of the nucleolus.

Short-term insulin-induced glycogen formation in primary hepatocytes as a screening bioassay for insulin action

We describe a novel bioassay to measure specific insulin-like activity in primary cultures of rat hepatocytes by determination of [3H]glycogen from d-[6-3H]glucose. The dose-response curve of insulin in this assay exhibited an EC50 of 0.42 (+/-0.04) nM, which is comparable to the dissociation constant of insulin from its receptor in hepatocytes. We used this assay to examine possible residual insulin-like activity of the four major fragments formed upon insulin degradation by insulin protease. Fragments A1-13B1-9, A1-14B1-9,and A14-21B14-30 showed no measurable activity. Although preparations of fragment A14-21B10-30 displayed dose-dependent agonist activity with an EC50 of 380 (+/-40) nM, we conclude that this was due to an insulin-like impurity since the chemically synthesized fragment showed no such activity. In summary, this bioassay demonstrates the action of insulin on glycogen formation in hepatocytes and provides a rapid and sensitive measurement of insulin-like activity which could facilitate screening studies.

Interaction of TATA-binding protein with upstream activation factor is required for activated transcription of ribosomal DNA by RNA polymerase I in Saccharomyces cerevisiae in vivo

Previous in vitro studies have shown that initiation of transcription of ribosomal DNA (rDNA) in the yeast Saccharomyces cerevisiae involves an interaction of upstream activation factor (UAF) with the upstream element of the promoter, forming a stable UAF-template complex; together with TATA-binding protein (TBP), UAF then recruits an essential factor, core factor (CF), to the promoter, forming a stable preinitiation complex. TBP interacts with both UAF and CF in vitro. In addition, a subunit of UAF, Rrn9p, interacts with TBP in vitro and in the two-hybrid system, suggesting the possible importance of this interaction for UAF function. Using the yeast two-hybrid system, we have identified three mutations in RRN9 that abolish the interaction of Rrn9p with TBP without affecting its interaction with Rrn10p, another subunit of UAF. Yeast cells containing any one of these individual mutations, L110S, L269P, or L274Q, did not show any growth defects. However, cells containing a combination of L110S with one of the other two mutations showed a temperature-sensitive phenotype, and this phenotype was suppressed by fusing the mutant genes to SPT15, which encodes TBP. In addition, another mutation (F186S), which disrupts both Rrn9p-TBP and Rrn9p-Rrn10p interactions in the two-hybrid system, abolished UAF function in vivo, and this mutational defect was suppressed by fusion of the mutant gene to SPT15 combined with overexpression of Rrn10p. These experiments demonstrate that the interaction of UAF with TBP, which is presumably achieved by the interaction of Rrn9p with TBP, is indeed important for high-level transcription of rDNA by RNA polymerase I in vivo.

Effects of [norleucine27]growth hormone-releasing hormone (GHRH) (1-29)-NH2 administration on the immune system of aging men and women

Aging in humans is associated with the decline of functional activities of the GH-insulin-like growth factor I (IGF-I) axis and the immune system. Because lymphocytes express GH-IGF-I, as well as GHRH and their respective receptors, restoration of this axis in age-advanced individuals, by the administration of GHRH, may enhance immune cell function. This hypothesis was tested by a single blind randomized placebo-controlled trial of 5 months duration, in which healthy elderly subjects (10 women, 9 men) self-administered sc nightly placebo for 4 weeks, followed by 16 weeks of [norleucine27]GHRH (1-29)-NH2 at a dose of 10 micrograms/kg. Fasting (0800 h-0900 h) blood samples were obtained for immune studies and for measurements of serum concentrations of IGF-I and soluble interleukin (IL)-2 receptor. GH pulsatility was determined in blood samples obtained at 10-min intervals for 12 h (2000 h-0800 h). Freshly isolated peripheral lymphocytes were analyzed by flow cytometric analysis for determination of lymphocyte subsets and monocytes. Mitogen stimulation responses, natural killer cell number and cytotoxicity, basal and stimulated IL-2 secretion from cultured lymphocytes, and IL-2 and IL-2R messenger RNA expression were measured. These studies were conducted at baseline, after placebo, and during GHRH analog administration at 4 and 16 weeks. Treatment with GHRH analog resulted in a significant increase (107 and 70% in men and women, respectively) in the 12-h integrated GH secretion (P < .05) and serum IGF-I levels (28%) (P < .001) in both men and women by 4 weeks and lasted 12 weeks for IGF-I and 16 weeks for GH. Activation of the immune system occurred in both sexes within 4 weeks. A 30% increase (P < .001) in lymphocytes expressing the transferrin receptor (CD71) and in monocytes (CD14) (P < .05) occurred within 4 weeks. By 16 weeks, there was a significant increase (30%) in B cells (CD20) (P < .01), in cells expressing the T cell receptor alpha/beta (20%) (P < .01), and T cell receptor gamma/delta (40%) (P < .0001). There were no changes in the number of T cells (CD3), T cell subsets (CD4, CD8), or natural killer cell (CD57) over the treatment period. The increase in B cell number was associated with enhanced responsiveness (50%) to the B cell mitogens: pokeweed mitogen (P < .01 or better) and Staphylococus aureus cells (P < .001), and a transient increase at 4 weeks in circulating IgG (P < .0001), IgM, and IgA (P < .001). T cells were functionally activated, as evidenced by a 50% increase in responsiveness to phytohemagglutinin (P < .01 or better), 70% increase in the number of lymphocytes expressing the IL-2 receptor (IL-2R) (CD25) (P < .001), and enhanced IL-2R messenger RNA expression and basal IL-2 secretion (50%) (P < .05) at 16 weeks of treatment. Furthermore, circulating soluble IL-2 receptor rose significantly (15%) (P < .05) within 4 weeks of treatment and remained elevated for the duration of the study. There were no sex differences in the immune response to GHRH analog and no adverse effects. These results indicate that GHRH analog administration has profound immune-enhancing effects and may be of therapeutic benefit in states of compromised immune function.

Role of the pharmacist in childhood immunizations

OBJECTIVE

Fewer than half of the 2-year-old children in the United States are fully immunized. This article reviews the literature on barriers to immunization in children and examines how pharmacists can promote childhood immunizations by acting as an educational resource and providing increased access to vaccines.

DATA SOURCES

Published data were collected from the literature. Anecdotal data were collected from unstructured interviews with parents and health care professionals at two childhood immunization clinics in Des Moines, Iowa.

DATA SYNTHESIS

Data from the literature were compared with data informally collected in the clinics. Both the literature and interviews indicated a variety of structural and personal barriers that may prevent parents from having children vaccinated.

CONCLUSION

By collecting and documenting adequate vaccination histories, pharmacists can be a resource for parents and health care professionals who are unsure of a child's immunization status. Pharmacists may wish to establish immunization clinics in their pharmacies as a method to increase access to vaccines.

Development of an isotope dilution assay for precise determination of insulin, C-peptide, and proinsulin levels in non-diabetic and type II diabetic individuals with comparison to immunoassay

We describe the application of a stable isotope dilution assay (IDA) to determine precise insulin, C-peptide, and proinsulin levels in blood by extraction from serum and quantitation by mass spectrometry using analogues of each target protein labeled with stable isotopes. Insulin and C-peptide levels were also determined by immunoassay, which gave consistently higher results than by IDA, the relative difference being larger at low concentrations. Insulin, C-peptide, and proinsulin levels were all shown by IDA to be higher in type II diabetics than in non-diabetics, with mean values rising from 22 (+/- 2) to 92 (+/- 8), 335 (+/- 11) to 821 (+/- 24), and 6 (+/- 1) to 37 (+/- 3) pM, respectively. Interestingly, the ratio between IDA and immunoassay values for insulin levels increased from 1.3 in non-diabetics to 1.7 in type II diabetics. The ratio between proinsulin and insulin levels by IDA increased from 0.24 in non-diabetics to 0.36 in type II diabetics, whereas the ratio between C-peptide and insulin levels by IDA decreased from 17.6 to 10.7. This disproportionate change in protein levels between different types of individuals has implications for the metabolism of insulin in the diabetics studied (type II) and suggests that C-peptide levels are not always a reliable guide as to pancreatic insulin secretion. In addition, levels of the 33-residue C-peptide (partially trimmed form) were shown to be less than 10% that of the fully trimmed 31-residue C-peptide levels, and we tested IDA in a clinical context by two post-pancreatic graft studies. IDA was shown to give direct, positive identification of the target protein with unrivaled accuracy, avoiding many of the problems associated with present methodology for protein determination.

Phosphorylation of Srp1p, the yeast nuclear localization signal receptor, in vitro and in vivo

Srp1p, the protein encoded by SRP1 of the yeast Saccharomyces cerevisiae, is a yeast nuclear localization signal (NLS) receptor protein. We have previously reported isolation of a protein kinase from yeast extracts that phosphorylates Srp1p complexed with NLS peptides/proteins. From partial amino acid sequences of the four subunits of the purified kinase, we have now identified this protein kinase to be identical to yeast casein kinase II (CKII). It was previously thought that autophosphorylation of the 36 kDa subunit of the yeast enzyme was stimulated by the substrate, GST-Srp1p. However, with the use of a more refined system, no stimulation of autophosphorylation of the 36 kDa subunit of yeast CKII was observed. Biochemical and mutational analyses localized the in vitro phosphorylation site of Srp1p by CKII to serine 67. It was shown that, in the absence of NLS peptides/proteins, phosphorylation of the intact Srp1p protein is very weak, but deletion of the C-terminal end causes great stimulation of phosphorylation without NLS peptides/proteins. Thus, the CKII phosphorylation site is apparently masked in the intact protein structure by the presence of a C-terminal region, probably between amino acids 403 and 516. Binding of NLS peptides/proteins most likely causes a change in protein conformation, exposing the CKII phosphorylation site. Mutational alterations of serine 67, the CKII phosphorylation site, to valine (S67V) and aspartic acid (S67D) were not found to cause any significant deleterious effects on cell growth. Analysis of in vivo phosphorylation showed that at least 30% of the wild type Srp1p molecules are phosphorylated in growing cells, and that the phosphorylation is mostly at the serine 67 CKII site. The ability of Srp1p purified from E coli and treated with calf intestinal phosphatase to bind a SV40 T-antigen NLS peptide was compared with that of Srp1p which was almost fully phosphorylated by CKII. No significant difference was observed. It appears that NLS binding does not require any phosphorylation of Srp1p, either by CKII or by some other protein kinase.

Activation of immune function by dehydroepiandrosterone (DHEA) in age-advanced men

BACKGROUND

Substantial data from animal studies have demonstrated a stimulatory effect of dehydroepiandrosterone (DHEA) on immune function. However, little is known about the effects of DHEA on the human immune system. Since aging is associated with a decline in immune function and in DHEA production, we proposed that oral administration of DHEA to elderly men would result in activation of their immune system.

METHODS

Nine healthy age-advanced men (mean age of 63 years) with low DHEA-sulfate levels participated in this study. They were treated nightly with an oral placebo for 2 weeks followed by DHEA (50 mg) for 20 weeks. Fasting (0800h-0900h) blood samples were obtained at 4- to 8-week intervals for immune function studies and hormone determinations. Freshly isolated peripheral lymphocytes were used for flow cytometric identification of lymphocyte subsets, cells expressing the IL-2 receptor (IL-2R), mitogen stimulation studies, and for determining natural killer (NK) cell number and cytotoxicity. Levels of interleukin-2 (IL-2) and IL-6 secreted from cultured lymphocytes were determined under basal and mitogen stimulated conditions. Sera were analyzed for soluble IL-2 Receptor (sIL-2R) levels, insulin-like growth factor-I (IGF-I) and IGF binding protein-I (IGFBP-I) concentrations.

RESULTS

Baseline levels of serum DHEA sulfate (DHEAS), a stable marker of circulating DHEA levels, were 2 standard deviations below young adult values and increased 3-4 fold within 2 weeks. These levels were sustained throughout the duration of DHEA administration. When compared with placebo, DHEA administration resulted in a 20% increase (p < .01) in serum IGF-I, a decreasing trend in IGFBP-I, and a 32% increase in the ratio of IGF-I/IGFBP-I (p < .01). Activation of immune function occurred within 2-20 weeks of DHEA treatment. The number of monocytes increased significantly (p < .01) after 2 (45%) and 20 (35%) weeks of treatment. The population of B cells fluctuated with increases (p < .05) at 2 (35%) and 10 (29%) weeks of treatment. B cell mitogenic response increased 62% (p < .05) by 12 weeks unaccompanied by changes in serum IgG, IgA, and IgM levels. Total T cells and T cell subsets were unaltered. However, a 40% increase (p < .05) in T cell mitogenic response, 39% increase in cells expressing the IL-2R (CD25+) (p < .05), and 20% increase in serum sIL-2R levels (p < .01) were found at 12-20 weeks of DHEA treatment, suggesting a functional activation of T lymphocytes occurred. In vitro mitogen stimulated release of IL-2 and IL-6 was enhanced 50% (p < .05) and 30% (p < .01) respectively by 20 weeks of treatment without basal secretion being affected. NK cell number showed a 22-37% increase (p < .01) by 18-20 weeks of treatment with a concomitant 45% increase (p < .01) in cytotoxicity. There were no adverse effects noted with DHEA administration.

CONCLUSION

Administration of oral DHEA at a daily dose of 50 mg to age-advanced men with low serum DHEAS levels significantly activated immune function. The mechanism(s) to account for the immunoenhancing properties of DHEA are unclear. Consideration is given to the potential role of an increase in bioavailable IGF-I, which by virtue of its mitogenic effects on immune cell function, may mediate the DHEA effects. While extended studies are required, our findings suggest potential therapeutic benefits of DHEA in immunodeficient states.

A stable isotope dilution assay for the in vivo determination of insulin levels in humans by mass spectrometry

Insulin levels in humans were measured by a new assay, the isotope dilution assay (IDA), based on stable isotope dilution mass spectrometry. A known amount of a deuterated analog of insulin was used as an internal standard and added to the serum samples before sample processing. After isolation by immunoaffinity chromatography and solid phase extraction, followed by a purification step on reversed-phase microbore high-performance liquid chromatography (HPLC), the insulin-containing fraction was analyzed by mass spectrometry. The relative intensity of the signals due to insulin and its deuterated analog in the mass spectrum was used to determine the concentration of insulin in the sample. Using serum samples of 0.5-2.0 ml, we were able to measure insulin levels in the range of 3-1700 pmol/l in several clinical samples from type II diabetic patients. The basal level of endogenous insulin was also determined in two normal subjects and found to be approximately 20 pmol/l. Insulin secretion was followed after the ingestion of 75 g glucose in one healthy volunteer. Finally, the determination of the insulin level of one hemolyzed post-mortem blood sample, for which immunoassays gave inconsistent results, was performed to help forensic investigations. Our results showed a good correlation with standard immunoassay data, except in six samples where much lower values were obtained by our stable isotope dilution assay, suggesting an overestimation of insulin levels by immunoassay in some cases. As it is not subject to immunological interferences by insulin-related compounds, this new assay has a major clinical advantage in that it avoids confusions related to hyperinsulinemia.

Physical and kinetic characterization of recombinant human cholesteryl ester transfer protein

Cholesteryl ester transfer protein (CETP) mediates the exchange of triglycerides (TGs), cholesteryl esters (CEs) and phospholipids (PLs) between lipoproteins in the plasma. In order to better understand the lipid transfer process, we have used recombinant human CETP expressed in cultured mammalian cells, purified to homogeneity by immunoaffinity chromatography. Purified recombinant CETP had a weight-average relative molecular mass (MW) of 69561, determined by sedimentation equilibrium, and a specific absorption coefficient of 0.83 litre.g-1.cm-1. The corresponding hydrodynamic diameter (Dh) of the protein, determined by dynamic light scattering, was 14 nm, which is nearly twice the expected value for a spheroidal protein of this molecular mass. These data suggest that CETP has a non-spheroidal shape in solution. The secondary structure of CETP was estimated by CD to contain 32% alpha-helix, 35% beta-sheet, 17% turn and 16% random coil. Like the natural protein from plasma, the recombinant protein consisted of several glycoforms that could be only partially deglycosylated using N-glycosidase F. Organic extraction of CETP followed by TLC showed that CE, unesterified cholesterol (UC), PL, TG and fatty acids (FA) were associated with the pure protein. Quantitative analyses verified that each mol of CETP contained 1.0 mol of cholesterol, 0.5 mol of TG and 1.3 mol of PL. CETP mediated the transfer of CE, TG, PL, and UC between lipoproteins, or between protein-free liposomes. In dual-label transfer experiments, the transfer rates for CE or TG from HDL to LDL were found to be proportional to the initial concentrations of the respective ligands in the donor HDL particles. Kinetic analysis of CE transfer was consistent with a carrier mechanism, having a Km of 700 nM for LDL particles and of 2000 nM for HDL particles, and a kcat of 2 s-1. The Km values were thus in the low range of the normal physiological concentration for each substrate. The carrier mechanism was verified independently for CE, TG, PL and UC in 'half-reaction' experiments.

Multiprotein transcription factor UAF interacts with the upstream element of the yeast RNA polymerase I promoter and forms a stable preinitiation complex

Like most eukaryotic rDNA promoters, the promoter for rDNA in Saccharomyces cerevisiae consists of two elements: a core element, which is essential, and an upstream element, which is not essential but is required for a high level of transcription. We have demonstrated that stimulation of transcription by the upstream element is mediated by a multiprotein transcription factor, UAF (upstream activation factor) which contains three proteins encoded by RRN5, RRN9, and RRN10 genes, respectively, and probably two additional uncharacterized proteins. The three genes were originally defined by mutants that show specific reduction in the transcription of rDNA. These genes were cloned and characterized. Epitope tagging of RRN5 (or RRN9), combined with immunoaffinity purification was used to purify UAF, which complemented all three (rrn5, rrn9, and rrn10) mutant extracts. Using rrn10 mutant extracts, a large stimulation by UAF was demonstrated for template containing both the core element and the upstream element but not for a template lacking the upstream element. In the absence of UAF, the mutant extracts showed the same weak transcriptional activity regardless of the presence or absence of the upstream element. We have also demonstrated that UAF alone makes a stable complex with the rDNA template, committing that template to transcription. Conversely, no such template commitment was observed with rrn10 extracts without UAF. By using a series of deletion templates, we have found that the region necessary for the stable binding of UAF corresponds roughly to the upstream element defined previously based on its ability to stimulate rDNA transcription. Differences between the yeast UAF and the previously studied metazoan UBF are discussed.

Gene RPA43 in Saccharomyces cerevisiae encodes an essential subunit of RNA polymerase I

Yeast RNA polymerase I contains 14 distinct polypeptides, including A43, a component of about 43 kDa. The corresponding gene, RPA43, encodes a 326-amino acid polypeptide matching the peptidic sequence of two tryptic fragments isolated from A43. Gene inactivation leads to a lethal phenotype that is rescued by a plasmid containing the 35S ribosomal RNA gene fused to the GAL7 promoter, which allows the synthesis of 35S rRNA by RNA polymerase II in the presence of galactose. A screening for mutants rescued by the presence of GAL7-35SrDNA identified a nonsense rpa43 allele truncating the protein at amino acid position 217. [3H]Uridine pulse labeling showed that this mutation abolishes 35S rRNA synthesis without significant effects on the synthesis of 5 S RNA and tRNAs. These properties establish that A43 is an essential component of RNA polymerase I. This highly hydrophilic phosphoprotein has a strongly acidic carboxyl-terminal domain, and shows no homology to entries in current sequence data banks, including all the genetically identified components of the other two yeast RNA polymerases. RPA43 mapped next to RPA190, encoding the largest subunit of polymerase I. These genes are divergently transcribed and may thus share upstream regulatory elements ensuring their co-regulation.