Preliminary findings on diagnostic performance of computed tomography perfusion images for intracranial arterial stenosis: a retrospective study

OBJECTIVES

Computed tomographic perfusion (CTP) can play an auxiliary role in the selection of patients with acute ischemic stroke for endovascular treatment. However, data on CTP in non-stroke patients with intracranial arterial stenosis are scarce. We aimed to investigate images in patients with asymptomatic intracranial arterial stenosis to determine the detection accuracy and interpretation time of large/medium-artery stenosis or occlusion when combining computed tomographic angiography (CTA) and CTP images.

METHODS

We retrospectively reviewed 39 patients with asymptomatic intracranial arterial stenosis from our hospital database from January 2021 to August 2023 who underwent head CTP, head CTA, and digital subtraction angiography (DSA). Head CTA images were generated from the CTP data, and the diagnostic performance for each artery was assessed. Two readers independently interpreted the CTA images before and after CTP, and the results were analyzed.

RESULTS

After adding CTP maps, the accuracy (area under the curve) of diagnosing internal carotid artery (R1: 0.847 vs. 0.907, R2: 0.776 vs. 0.887), middle cerebral artery (R1: 0.934 vs. 0.933, R2: 0.927 vs. 0.981), anterior cerebral artery (R1: 0.625 vs. 0.750, R2: 0.609 vs. 0.750), vertebral artery (R1: 0.743 vs. 0.764, R2: 0.748 vs. 0.846), and posterior cerebral artery (R1: 0.390 vs. 0.575, R2: 0.390 vs. 0.585) occlusions increased for both readers (p < 0.05). Mean interpretation time (R1: 72.4 ± 6.1 s vs. 67.7 ± 6.4 s, R2: 77.7 ± 3.8 s vs. 72.6 ± 4.7 s) decreased when using a combination of both images both readers (p < 0.001).

CONCLUSIONS

The addition of CTP images improved the accuracy of interpreting CTA images and reduced the interpretation time in asymptomatic intracranial arterial stenosis. These findings support the use of CTP imaging in patients with asymptomatic intracranial arterial stenosis.

Efficacy and safety of intravenous thrombolysis in mild ischemic stroke

Background: Intravenous thrombolysis is the preferred clinical treatment for ultra-early (<4.5 h) ischemic stroke. However, whether intravenous thrombolysis should be used in patients with mild stroke remains controversial. This study reports a systematic review and meta-analysis of the efficacy and safety of intravenous thrombolysis in acute mild stroke. Methods: The PubMed, Cochrane Library, MEDLINE, Embase and CBM disc databases were searched for studies on intravenous thrombolysis versus nonthrombolysis in acute mild stroke. All studies published in English prior to March 2022 were retrieved. The studies were screened and selected based on the inclusion and exclusion criteria. Then, the data were extracted and recorded by trained researchers. RevMan 5.4 statistical software was used to analyze the data on the efficacy (mRS score, stroke recurrence rate and mortality at 90 days) and safety (intracranial hemorrhage, symptomatic intracranial hemorrhage) of the patients with acute mild stroke in the intravenous thrombolysis and nonthrombolysis groups. Results: A total of 14 high-quality studies containing 86,063 patients with acute mild stroke (8,824 in the intravenous thrombolysis group; 77,239 in the nonthrombolysis group) were included in this meta-analysis. The meta-analysis results were as follows: (1) Efficacy: There were significant differences in mRS scores of 0~1 and 0~2 between the intravenous thrombolysis and nonthrombolysis groups (mRS 0-1, OR= 1.53, 95% CI: 1.31~1.79, Z=5.40, P <0.00001; mRS 0-2, OR= 1.33, 95% CI: 1.07~1.65, Z=2.59, P =0.01). (2) Safety: There was no significant difference in the recurrence rate of stroke or mortality between the two groups ( recurrence rate, OR= 0.62, 95% CI: 0.35~1.08, Z=1.68, P =0.09; mortality, OR=0.89, 95% CI: 0.45~1.77, Z=0.33, P =0.74). There were more patients with intracranial hemorrhage in intravenous thrombolysis group than in nonthrombolysis group (asymptomatic intracranial hemorrhage, OR= 2.39, 95% CI:1.19~4.80, Z=2.45, P =0.01; symptomatic intracranial hemorrhage, OR= 7.65, 95% CI:3.07~19.05, Z=4.37, P <0.0001). Conclusion: Intravenous thrombolysis significantly improved the functional outcomes but did not reduce mortality at 90 days in patients with acute mild stroke and had a higher risk of intracranial hemorrhage.

[Investigation and analysis of underground noise in Sichuan coal mines]

Objective: To understand the harm degree of underground noise and provide basis for noise control. Methods: In November 2019, 13 typical coal mines in Sichuan Province were selected as the research objects, and a total of 1203 sites and 609 jobs of noise exposure were investigated. Results: The noise intensity P75 >80 dB (A) was measured. The noise intensity of the inspection place of the air compressor is >86 dB (A) , the noise intensity of the inspection place of the gas drainage and the operation place of the main fan is between 80-85 dB (A) . Conclusion: Besides the harm of dust, noise exposure should also be paid attention to, and the measures of sound absorption and sound insulation should be taken or personal protection should be strengthened.

[Association between a novel regulatory genetic variants and lung cancer risk in Chinese: a two-stage case-control study]

Objective: Regulatory quantitative trait loci (regQTL) theory can help to evaluate the regulation function of single nucleotide polymorphisms (SNPs) on crucial biological signals from a three-dimensional perspective. The aim of this study was to investigate the effect of these regQTL-SNPs on the susceptibility of lung cancer. Methods: Based on the regQTL theory, using the database of identified lung cancer regQTL-SNPs, we screened the SNPs that may function as regQTL in the reported susceptible regions of lung cancer by genome-wide association study(GWAS), and a two-stage case-control study was conducted (screening stage: 2 331 lung cancer cases and 3 077 healthy controls; validation stage: 626 lung cancer cases and 667 healthy controls) to definite the association of related regQTL-SNPs with the susceptibility of lung cancer. Results: A total of 8 regQTL-SNPs were screened in the reported susceptible regions of lung cancer by GWAS. Among which, 3 SNPs were significantly associated with the risk of lung cancer (P<0.05) in the screening stage. Further validation results indicated that the variant T allele of rs6998591 in ADRA1A was significantly associated with increased risk of lung cancer (additive model: OR=1.33, 95%CI:1.01-1.74, P=0.040). In addition, the variant G allele of rs11202916 in ACTA2 was significantly associated with decreased risk of lung cancer (recessive model: OR=0.71, 95%CI:0.52-0.96, P=0.026). Stratified analysis indicated that the variant T allele of rs6998591 significantly increased lung squamous cell carcinoma risk (additive model: OR=1.53, 95%CI: 1.01-2.32, P=0.043), while the variant G allele of rs11202916 significantly decreased lung adenocarcinoma risk (additive model: OR=0.83, 95%CI: 0.69-0.98, P=0.031). Gene-environment interaction analysis indicated that the risk of developing lung cancer increased by 235% in smoking individuals carrying rs6998591 variant T allele compared with those non-smoking individuals carrying no rs6998591 variant T allele(OR=3.35,95%CI:2.10-5.34,P<0.001). Conclusion: There are two regQTL-SNPs that could significantly affect the susceptibility of lung cancer in the GWAS reported susceptible regions of lung cancer.

[Study on the value of serum des-γ-carboxy prothrombin in predicting hepatocellular carcinoma recurrence after liver transplantation]

Objective: To explore the clinical value of serum des-γ-carboxy prothrombin (DCP) in predicting hepatocellular carcinoma recurrence after liver transplantation. Methods: A total of 115 cases with hepatocellular carcinoma who underwent liver transplantation in Zhongshan Hospital Affiliated to Fudan University from October 2016 to December 2018 were retrospectively analyzed. Receiver operating characteristic curve analysis, Mann-Whitney U test, Kaplan-Meier method, Log-Rank test, χ2 test, univariate and multivariate Cox regression analysis and other statistical methods were used to explore the value of DCP in predicting tumor recurrence after liver transplantation and its correlation with clinicopathological characteristics. Results: The preoperative serum DCP level in recurrent population after liver transplantation was significantly higher than that in non-recurrent population (P < 0.001). The optimal cut-off value of preoperative DCP for predicting recurrence was 200mAU/ml with the use of receiver operating characteristic curve. The sensitivity, specificity, Youden's index and the receiver operating characteristic curve was 87.90%, 57.30%, 0.452, and 0.726, respectively. Survival analysis results grouped by this cut-off value showed that patients with preoperative DCP ≥200mAU/ml had a higher probability of recurrence (P < 0.001). Further, subgroup survival analysis showed that patients with preoperative DCP≥200 mAU/ ml had a higher probability of recurrence than other cases of alpha-fetoprotein negative subgroup, cumulative tumor diameter ≤ 9 cm subgroup and Milan criteria subgroup (P < 0.05). Cox regression analysis showed that preoperative DCP≥200 mAU/ ml (P = 0.017) and cumulative tumor diameter > 9 cm (P = 0.014) was an independent risk factor for recurrence after liver transplantation. χ (2) test results showed that preoperative serum DCP level was correlated with gender, serum gamma glutamyltransferase level, serum alpha fetoprotein level, cumulative tumor diameter, vascular invasion, tumor differentiation and liver cancer transplant criteria (P < 0.05). Conclusion: Preoperative serum DCP can be used as a supplement to the existing liver cancer transplant criteria to predict hepatocellular carcinoma recurrence after liver transplantation. In addition, the accurate screening of patients with low risk of HCC recurrence after liver transplantation can improve the prognosis and efficacy of liver transplant patients.

Induction therapy for clinical stage T2N0M0 esophageal cancer: A systematic review and meta-analysis

OBJECTIVE

It is still controversial whether patients with clinical T2N0M0 (cT2N0M0) esophageal cancer are treated with induction therapy. The aim of this study was to determine the effect of induction therapy on cT2N0M0 esophageal cancer.

METHODS AND MATERIALS

We searched PubMed, Embase, the Cochrane Library, and Medline databases from inception up to May 1, 2017. This meta-analysis was performed to compare odds ratios (OR) for 5-year overall survival (OS), pathologically understaged and overstaged after esophagectomy.

RESULTS

Eight retrospective studies of 2646 patients were included in the meta-analysis. Data showed that no statistically significant difference in 5-year over survival was observed between induction therapy group and direct operation group. The pooled OR and 95% confidence interval (CI) for 5-year OS were 0.92 (95% CI = 0.72-1.18; P = .52). Whereas, compared with induction therapy group, direct operation group had more pathologically understaged and less overstaged after esophagectomy.

CONCLUSIONS

Currentclinical staging for T2N0M0 esophageal carcinoma remains inaccurate. In this study, we found that direct operation group had more pathologically understaged and less overstaged after esophagectomy compared with induction therapy group. Induction therapy could degrade the tumor staging but not improve the patient's survival.

[Focus on the controversial problems of orbital decompression in the treatment of dysthyroid optic neuropathy]

Dysthyroid optic neuropathy (DON) is the most common cause of visual loss in thyroid associated ophthalmopathy, for which steroid pulse therapy and orbital decompression are the common treatments currently. While steroid pulse therapy was recommended as the first-choice for DON, orbital decompression remained as an indispensable therapy although controversies on such treatment still exist. The mechanism, approaches and outcomes of orbital decompression, as well as its advantages and disadvantages over steroid pulse therapy were retrospectively reviewed, and it was suggested that the combination therapy of steroid pulse therapy and surgical decompression might be the better choice for the treatment of DON. (Chin J Ophthalmol, 2018, 54: 488-490).

Remnant lymph node metastases after neoadjuvant therapy and surgery in patients with pathologic T0 esophageal carcinoma impact on prognosis: A systematic review and meta-analysis

BACKGROUND

The aim of this study was to evaluate the outcomes of patients with pathologic T0 esophageal carcinoma after neoadjuvant therapy and surgery.

METHODS

We searched PubMed, Embase, Cochrane Library, and Medline databases from inception up to November 12, 2016. The meta-analysis was performed to compare odds ratios (OR) for overall survival (OS), disease-free survival (DFS), local control (LC), and distant control (DC).

RESULTS

Eight published studies of 837 patients were included in the meta-analysis. Data showed that the ypT0N1 group was associated with worse outcomes compared with the ypT0N0 group. The pooled OR and 95% confidence interval (CI) for 3-year and 5-year OS were 3.08 [2.07, 4.57] and 4.27 [2.76, 6.59], respectively. Whereas, the pooled OR and 95% CI for 3-year and 5-year DFS were 3.90 [2.08, 7.34] and 5.17 [1.93, 13.87], respectively. The pooled OR and 95% CI for LR and DR were 4.52 [1.72, 11.91] and 2.65 [1.38, 5.09], respectively.

CONCLUSIONS

Remnant lymph node metastases after neoadjuvant therapy and surgery in patients with pathologic T0 esophageal carcinoma portend poor survival, and it is an important prognostic factor.

Laparoscopic Heller myotomy is not superior to pneumatic dilation in the management of primary achalasia: Conclusions of a systematic review and meta-analysis of randomized controlled trials

BACKGROUND

Achalasia is an esophageal motility disorder, of unknown cause, which results in increased lower esophageal sphincter tone and symptoms of difficulty swallowing. Current major therapeutic options include laparoscopic Heller myotomy (LHM) and pneumatic dilation (PD). We undertake a systematic review comparing the efficacy and safety of these 2 treatments in the treatment of esophageal achalasia.

METHODS

PubMed, Embase, and Cochrane Central Register of Controlled Trials were searched for randomized controlled trial investigating LHM versus PD in the treatment of primary achalasia. The primary outcome was symptom remission rates. The Mantel-Haenszel method with fixed-effect or random-effects model was used to calculate relative risks and 95% confidence intervals (CIs).

RESULTS

Five studies involving 498 participants were included. The cumulative remission rate was significantly higher with LHM at 3 months and 1 year (short-term), with a risk ratio of 1.16 (95% CI 1.01-1.35, P = 0.04) and 1.14 (95% CI 1.02-1.27, P = 0.02), respectively. There were no significant differences between LHM and PD in 2-year and 5-year remission rate (long-term), with a risk ratio of 1.05 (95% CI 0.91-1.22, P = 0.49) and 1.17 (95% CI 0.84-1.64, P = 0.34), respectively. Rates of major mucosal tears requiring subsequent intervention with LHM were significantly lower than those of esophageal perforation with PD requiring postprocedural medical or surgical therapy, with a risk ratio of 0.25 (95% CI 0.08-0.81, P = 0.02). Postprocedural rates of gastroesophageal reflux, lower esophageal sphincter pressures, and quality of life scores did not differ in trials with sufficient data.

CONCLUSIONS

There were no significant differences between LHM and PD in 2-year and 5-year remission rate. This study indicates that either treatment can be proposed as initial treatment for achalasia.

Association between MDR1 C3435T polymorphism and refractory epilepsy in the Chinese population: a systematic review and meta-analysis

The association between the C3435T polymorphism in the MDR1 gene and refractory epilepsy remains controversial. The association appears to be influenced by ethnicity and region. We have performed a systematic review and meta-analysis to assess the link between the MDR1 C3435T polymorphism and refractory epilepsy in the Chinese population. We searched the Cochrane Library, MIDLINE, EMBASE, CBM disc, CNKI, VIP, and WANFANG databases for literature published through August 2013 for case-control studies that evaluated the association between the MDR1 C3435T polymorphism and refractory epilepsy. Twenty-one case-control studies involving 4269 patients (1863 cases in the group with drug-resistant epilepsy and 2406 in the group with drug-responsive epilepsy) were included in the systematic review and meta-analysis. The analysis showed that there were significantly more cases with the MDR1 3435 CC genotype in the group with drug-resistant epilepsy than in the group with drug-responsive epilepsy [odds ratio (OR)=1.50, 95% confidence interval (CI)=1.09-2.06, P=0.01]. In a subanalysis of patients from the southern regions of China, the correlation was not significant [odds ratio (OR)=1.2, 95% confidence interval (CI)=0.89-1.64, P=0.24]. The relationship established in a subset of the Chinese population between the MDR1 C3435T polymorphism and refractory epilepsy will guide epilepsy treatment and development of new AEDs.

Non-vitamin K antagonist oral anticoagulants in cardiovascular disease management: evidence and unanswered questions

WHAT IS KNOWN AND OBJECTIVE

Anticoagulation is important in the management of cardiovascular disorders; however, traditional anticoagulants such as heparins and vitamin K antagonists (VKAs) have limitations, including parenteral administration with the former and the need for coagulation monitoring and dose adjustments with the latter. Three non-VKA oral anticoagulants (OACs), dabigatran, rivaroxaban and apixaban, are available for the prevention of stroke in patients with atrial fibrillation (AF) and may change clinical practice. This article reviews current knowledge and important unanswered questions on the use of these agents in patients with cardiovascular disease.

METHODS

A literature search was performed using PubMed and the search terms dabigatran, rivaroxaban, apixaban, AF and acute coronary syndrome (ACS). Peer-reviewed, published clinical trials, review articles, relevant treatment guidelines and prescribing information documents were identified and reviewed for relevance.

RESULTS AND DISCUSSION

Dabigatran is an oral direct thrombin inhibitor; rivaroxaban and apixaban are oral direct Factor Xa inhibitors. These agents have a quicker onset and offset of action, more predictable pharmacokinetic and pharmacodynamic profiles, and fewer drug-drug interactions than VKAs, allowing use of fixed doses. For the prevention of stroke in patients with AF, the non-VKA OACs were either non-inferior or superior to warfarin with similar or improved bleeding profiles, particularly with respect to reductions in intracranial haemorrhage. In patients with ACS receiving dual antiplatelet therapy, the addition of rivaroxaban significantly reduced the rate of death from cardiovascular causes, myocardial infarction or stroke without increasing fatal bleeding, but led to higher rates of major bleeding. Dose reductions with non-VKA OACs are mandated in certain circumstances in patients with AF, such as moderate renal impairment. Contraindications include creatinine clearance <15 mL/min (<30 mL/min for dabigatran in Europe and Canada) and moderate or severe hepatic impairment, but patients can be transitioned to other anticoagulants if appropriate. It is unknown which non-VKA OAC is optimal for stroke prevention in patients with AF, although factors such as co-medications (e.g. dabigatran may be preferred if a patient is taking a co-medication that is a strong cytochrome P450 3A4 inhibitor) and renal function (rivaroxaban and apixaban depend less on renal clearance than dabigatran) will be important for individual patients. Addition of rivaroxaban to antiplatelet therapy for prevention of recurrent events in patients with recent ACS is approved in Europe for patients at the highest risk (with elevated cardiac biomarkers) and must take into account the increased risk of major bleeding. Although routine coagulation monitoring is not required, an understanding of which assays are appropriate for each non-VKA OAC and how they are affected is important. In a bleeding emergency, non-specific prohaemostatic agents are suggested to reverse the action of the non-VKA OACs, but more clinical data are needed.

WHAT IS NEW AND CONCLUSION

Non-VKA OACs provide similar or improved efficacy and, on current evidence, improved safety. They provide greater convenience, compared with traditional anticoagulants for the prevention of stroke in patients with AF. Rivaroxaban may be of benefit to selected high-risk patients with ACS. Selection of the most appropriate non-VKA OAC will depend on individual patient factors.

Long-term donor health and its relationship with outcome of allogeneic hematopoietic stem cell transplantation

Data on long-term follow-up of donors for hematopoietic stem cell transplantation (HSCT) are limited. Donors of 612 adult allogeneic HSCT were studied, at a median of 81 (14-181) months post-HSC donation. Nine donors had severe health problems. Five donors died from aggressive malignancies or terminal illness, at a median of 41 (16-57) months post-donation. Notably, all their recipients had leukemic relapses. In contrast, donors of recipients in remission were all living. This observation might be due to an inherent depressed immunosurveillance in the donors, or selection of donors with suboptimal health for desperate patients with poor risks pre-HSCT.

Embryonic expression of pituitary adenylyl cyclase-activating polypeptide and its selective type I receptor gene in the frog Xenopus laevis neural tube

The genes encoding pituitary adenylyl cyclase-activating peptide (PACAP) and its selective type I receptor (PAC1) are expressed in the embryonic mouse neural tube, where they may be involved in neurogenesis and neural tube development. We examined here the early expression and potential actions of PACAP and PAC1 in the vertebrate developmental model Xenopus laevis. PACAP and PAC1 mRNAs were first detected by RT-PCR in stage 16-18 embryos (18 hours after fertilization). Two distinct PACAP precursor mRNAs were identified. One encoded both growth hormone-releasing hormone and PACAP, whereas the other encoded only full-length PACAP. Unlike that in the adult, the latter represented the predominant embryonic PACAP mRNA species. In situ hybridization revealed that PACAP and PAC1 mRNAs were restricted to neural cells. PAC1 gene expression was observed mainly in the ventricular zone in the ventral parts of the prosencephalon, mensencephalon, rhombencephalon, and anterior spinal cord. In contrast, PACAP mRNA was localized exclusively in postmitotic cells in the dorsolateral parts of the rhombencephalon and entire spinal cord. Most PACAP mRNA-containing cells were characterized as Rohon-Beard neurons. Exposure of early embryos to UV irradiation, which ventralizes embryos and inhibits neural induction, reduced the expression of PACAP and PAC1 genes. These results suggest that PACAP may be involved in the early development of the embryonic Xenopus neural tube.

The solution structure of [d(CGC)r(amamam)d(TTTGCG)]2

The solution structure and hydration of a DNA.RNA hybrid chimeric duplex [d(CGC)r(amamam)d(TTTGCG)]2 in which the RNA adenines were substituted by 2'-O-methylated riboadenines was determined using two-dimensional NMR, simulated annealing, and restrained molecular dynamics. Only DNA residue 7T in the 2'-OMe-RNA.DNA junction adopted an O4'-endo sugar conformation, while the other DNA residues including 3C in the DNA.2'-OMe-RNA junction, adopted C1'-exo or C2'-endo conformations. The observed NOE intensity of 2'-O-methyl group to H1' proton of 4am at the DNA.2'-OMe-RNA junction is much weaker than those of 5am and 6am. The 2'-O-methyl group of 4am was found to orient towards the minor groove in the trans domain while the 2'-O-methyl groups of 5am and 6am were found to be in the gauche (+) domain. In contrast to the long-lived water molecules found close to the RNA adenine H2 and H1' protons and the methyl group of 7T in the RNA-DNA junction of [d(CGC)r(aaa)d(TTTGCG)]2, there were no long-lived water molecules found in [d(CGC)r(amamam)d(TTTGCG)]2. This is probably due to the hydrophobic enviroment created by the 2'-O-methylated riboadenines in the minor groove or due to the wider minor groove width in the middle of the structure. In addition, the 2'-O-methylation of riboadenines in pure chimeric duplex increses its melting temperature from 48.5 degrees C to 51.9 degrees C. The characteristic structural features and hydration patterns of this chimeric duplex provide a molecular basis for further therapeutic applications of DNA.RNA hybrid and chimeric duplexes with 2'-modified RNA residues.

Fenoldopam in the prevention of contrast media-induced acute renal failure

OBJECTIVE

To examine the role of fenoldopam in prevention of contrast media-induced acute renal failure (ARF).

DATA SOURCES

A literature search of MEDLINE (from 1966 to October 2000) was performed using the following title search terms: fenoldopam, contrast, and renal failure.

STUDY SELECTION

English-language human studies, abstracts, and pertinent animal data were reviewed.

DATA SYNTHESIS

Small trials using animals with artificially induced ARF receiving fenoldopam demonstrated improvement in renal function. Preliminary trials in healthy humans have also demonstrated similar results using doses not affecting systemic blood pressure.

CONCLUSIONS

Fenoldopam may have a role in the management of ARF induced by contrast dye. However, due to the lack of a large-scale study it cannot be routinely recommended.

Recognition, pathophysiology, and management of acute myocardial infarction

New insights into the pathophysiology of atherosclerotic plaques leading to acute myocardial infarction (MI) are discussed, along with new diagnostic and treatment strategies. Ischemic heart disease represents a continuum from stable angina to unstable angina to non-Q-wave MI to Q-wave MI. Patients whose angina becomes unstable are classified as having acute coronary syndrome (ACS). It was formerly believed that thrombosis leading to critical occlusion of coronary arteries at the site of atherosclerotic plaque rupture was the common cause of ischemic heart disease. It is now thought that even lesions that do not critically occlude coronary arteries can cause MI. ACS can be caused by the rupture of an unstable atherosclerotic plaque. Vulnerable plaques are usually those causing only mild to moderate stenosis and having a lipid-rich core and a thin, macrophage-dense, collagen-poor fibrous cap. Factors affecting plaque rupture include mechanical injury, circadian rhythm, inflammation, and infection. Progressive thrombosis and vasospasm may follow plaque rupture. The diagnosis of MI starts with the recognition of symptoms of myocardial ischemia that are new or different from the usual pattern. Agents used to prevent or treat plaque rupture and its complications include thrombolytics, antiplatelet agents, antithrombotics, beta-blockers, angiotensin-converting-enzyme (ACE) inhibitors, and nitrates. Once patients survive the acute phase of MI, long-term therapy for prevention of future events begins. Post-MI patients should receive aspirin, beta-blockers, and an ACE inhibitor indefinitely; modification of cardiovascular risk factors is also important. Greater understanding of the pathophysiology of ACS has led to strategies to limit the progression of atherosclerosis and to improve survival and function after an acute event.

Patient-reported adherence to guidelines of the Sixth Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure

OBJECTIVES

To compare antihypertensive drug compliance with treatment guidelines established by the Sixth Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure (JNC VI), and to identify patient adherence to antihypertensive drugs and factors affecting prescribing patterns.

METHODS

Patients filling antihypertensive drug prescriptions in metropolitan New York area pharmacies were enrolled. Pharmacy externs collected patient-reported demographics, medical and drug histories, and blood pressure measurements. Compliance with JNC VI guidelines was assessed.

RESULTS

Eight hundred twenty-one patients from 102 pharmacies participated. Blood pressure was controlled in 61% of patients at the time of the study. The most prescribed class of antihypertensive agents was angiotensin-converting enzyme inhibitors, followed by diuretics and beta-blockers. Over the study period, compliance with JNC VI guidelines decreased significantly from 85% to 64% (p<0.05). Thirty-seven percent of patients reported consistent adherence to their antihypertensive regimens. Patients' education level was the only factor found to correlate positively with the appropriateness of antihypertensive agents prescribed.

CONCLUSION

Compliance with JNC VI guidelines decreased over time, and patient adherence to drug therapy was suboptimal. Continuing-education efforts to reinforce optimal blood pressure management are necessary.

Tenecteplase: a review

BACKGROUND

Certain shortcomings of the available thrombolytic agents have prompted the search for a more fibrin specific fibrinolytic agent with a longer half-life. Such properties would allow bolus administration, possibly leading to faster reperfusion of occluded arteries.

OBJECTIVE

This article focuses on the new thrombolytic agent tenecteplase, reviewing its mechanism of action, pharmacokinetic characteristics, clinical efficacy, tolerability, and potential for drug interactions in the management of acute myocardial infarction.

METHODS

English-language articles for inclusion in this review were identified through searches of MEDLINE, EMBASE, and International Pharmaceutical Abstracts from 1966 to April 2001. The search terms used included tenecteplase, myocardial infarction, TNK, and TNK-tPA. Abstracts from recent conferences and symposia were also consulted.

RESULTS

Tenecteplase is a variant of the native tissue-type plasminogen activator (tPA) molecule that has 14-fold greater fibrin specificity than alteplase, a longer half-life, slower plasma clearance, and 80-fold greater resistance to inhibition by plasminogen activator inhibitor type 1. Its half-life of approximately 18 minutes allows single-bolus administration. In comparative clinical trials, tenecteplase was found to have equivalent efficacy to recombinant tPA (alteplase). The rate of intracranial hemorrhage with tenecteplase was similar to that with alteplase, and tenecteplase was associated with fewer noncerebral complications and less need for blood transfusions.

CONCLUSIONS

Tenecteplase appears to be as effective and well tolerated as alteplase in the management of acute myocardial infarction and offers the convenience of single-bolus administration.

L-arginine in the management of cardiovascular diseases

OBJECTIVE

To examine the role of L-arginine in the management of cardiovascular diseases.

DATA SOURCES

A MEDLINE search (1966-April 2000) of review articles, using the search terms arginine, nitric oxide, and cardiovascular diseases, was conducted. After reviewing these articles, primary studies using the search terms arginine, hypercholesterolemia, hypertension, diabetes, smoking, ischemic heart disease, and heart failure were reviewed.

STUDY SELECTION

English-language human studies were selected and evaluated based on quality of review.

DATA SYNTHESIS

Small-scale studies have demonstrated that intravenous L-arginine augments endothelial function by enhancing vasodilation and reducing monocyte adhesion. Oral supplementation demonstrated similar effects as well as improvement of exercise ability in patients with cardiovascular diseases.

CONCLUSIONS

L-arginine improves the management of multiple cardiovascular diseases. However, most published human studies are small. Before therapy can be routinely recommended, larger, well-designed studies are required to confirm its effect.

New recommendations from the 1999 American College of Cardiology/American Heart Association acute myocardial infarction guidelines

OBJECTIVE

To review literature relating to significant changes in drug therapy recommendations in the 1999 American College of Cardiology (ACC)/American Heart Association (AHA) guidelines for treating patients with acute myocardial infarction (AMI).

DATA SOURCES

1999 ACC/AHA AMI guidelines, English-language clinical trials, reviews, and editorials researching the role of drug therapy and primary angioplasty for AMI that were referenced in the guidelines were included. Additional data published in 2000 or unpublished were also included if relevant to interpretation of the guidelines.

STUDY SELECTION

The articles selected influence AMI treatment recommendations.

DATA SYNTHESIS

Many clinicians and health systems use the ACC/AHA AMI guidelines to develop treatment plans for AMI patients. This review highlights important changes in AMI drug therapy recommendations by reviewing the results of recent clinical trials. Insights into evolving drug therapy strategies that may impact future guideline development are also described.

CONCLUSIONS

Several changes in drug therapy recommendations were included in the 1999 AMI ACC/AHA guidelines. There is emphasis on administering fibrin-specific thrombolytics secondary to enhanced efficacy. Selection between fibrin-specific agents is unclear at this time. Low response rates to thrombolytics have been noted in the elderly, women, patients with heart failure, and those showing left bundle-branch block on the electrocardiogram. These patient groups should be targeted for improved utilization programs. The use of glycoprotein (GP) IIb/IIIa receptor inhibitors in non-ST-segment elevation MI was emphasized. Small trials combining reduced doses of thrombolytics with GP IIb/IIIa receptor inhibitors have shown promise by increasing reperfusion rates without increasing bleeding risk, but firm conclusions cannot be made until the results of larger trials are known. Primary percutaneous coronary intervention (PCI) trials suggest lower mortality rates for primary PCI when compared with thrombolysis alone. However, primary PCI, including coronary angioplasty, is only available at approximately 13% of US hospitals, making thrombolysis the preferred strategy for most patients. Clopidogrel has supplanted ticlopidine as the recommended antiplatelet agent for patients with aspirin allergy or intolerance following reports of a better safety profile. The recommended dose of unfractionated heparin is lower than previously recommended, necessitating a separate nomogram for patients with acute coronary syndromes. Routine use of warfarin, either alone or in combination with aspirin, is not supported by clinical trials; however, warfarin remains a choice for antithrombotic therapy in patients intolerant to aspirin. Beta-adrenergic receptor blockers continue to be recommended, and emphasis is placed on improving rates of early administration (during hospitalization), even in patients with moderate left ventricular dysfunction. New recommendations for drug treatment of post-AMI patients with low high-density lipoprotein cholesterol and/or elevated triglycerides are included, with either niacin or gemfibrozil recommended as an option. Supplementary antioxidants are not recommended for either primary or secondary prevention of AMI, with new data demonstrating lack of efficacy vitamin E in primary prevention. Estrogen replacement therapy or hormonal replacement therapy should not be initiated solely for prevention of cardiovascular disease, but can be continued in cardiovascular patients already taking long-term therapy for other reasons. Bupropion has been added as a new treatment option for smoking cessation. As drug therapy continues to evolve in treating AMI, more frequent updates of therapy guidelines will be necessary.

Beneficial effects of statins in coronary artery disease--beyond lowering cholesterol

OBJECTIVE

To review the benefits of statins in coronary artery disease management beyond their cholesterol-lowering effects.

DATA SOURCES

A MEDLINE search (1966-May 2000) was conducted using the following terms: lovastatin, pravastatin, simvastatin, atorvastatin, fluvastatin, cerivastatin, endothelium, plaque stabilization, antithrombotic effects.

STUDY SELECTION

English-language human studies and case reports.

DATA EXTRACTION

Studies published demonstrating other mechanisms of statins' clinical beneficial effects were evaluated and reviewed.

DATA SYNTHESIS

The understanding of the pharmacologic effects of statins has led to the realization that the benefits of these agents extend beyond simply lowering cholesterol. These properties include beneficial effects on vessel endothelial tissue; decreased low-density lipoprotein oxidation and inflammation; ability to stabilize atherosclerotic plaques and perhaps promote regression; proliferative effects on smooth-muscle growths, possibly strengthening atherosclerotic plaques; antithrombotic effects by inhibiting platelet aggregation and stimulation of fibrinolytic factors; and improvement of blood viscosity and flow. With these actions, statins may benefit the situation of long-term atherosclerotic plaque formation and the setting of acute coronary syndrome.

CONCLUSIONS

Further large-scale studies are needed to determine the clinical importance and validity of these postulated beneficial effects of statins.

Predictive performance study of two digoxin assays in subjects with various degrees of renal function

This prospective study was conducted to compare the predictive performance of fluorescence polarization immunoassay (FPIA, Abbott TDx Digoxin II) and radioimmunoassay (RIA, Kallestad Labs) with combined low-pressure liquid chromatography/RIA (LPLC/RIA) digoxin assay in measuring 15-17 serum digoxin concentrations (SDC) obtained after a single 10 microg/kg intravenous digoxin dose in patients with various degrees of renal function and at different SDC ranges. Eighteen men and women were stratified into 3 age- and gender-matched groups based upon renal function [N = 6 in each, group I (Cl(cr) < 10 mL/min), group II (Cl(cr) = 10-50 mL/min), and group III (Cl(cr) > 50 mL/min)]. Serum digoxin concentrations were measured at time zero; at 0.25, 0.5, 0.75, 1, 2, 3, 4, 6, 8, and 12 hours; and at 2, 3, 4, and 5-7 days after the digoxin dose, using the three different digoxin assays. TDx Digoxin II was unbiased [mean error -0.09 (95% CI -0.19, 0.01)] and RIA biased [mean error -0.29 (95% CI -0.36, -0.21)] to over-predict SDC by 14.2%. In group I patients, the analysis revealed a bias to over-predict SDC by 6.0% for TDx Digoxin II [mean error -0.16 (95% CI -0.29, -0.07)] and an unbiased performance by RIA. In groups II and III, both TDx Digoxin II and RIA showed biased performance, the mean magnitude of bias was low (< 20%). For intermediate SDC range (> 0.5 ng/mL and < or = 3.0 ng/mL), TDx Digoxin II was unbiased in predicting SDC, whereas RIA was biased to under-predict SDC [mean error 0.13 (95% CI 0.10, 0.16)] by 9.9%. The magnitude of bias observed in all cases was less than 20%. Both assays, TDx Digoxin II and RIA, imprecisely measured SDC for all samples combined, different groups and SDC ranges. In all time-paired samples, TDx Digoxin II (FPIA) performed better than the RIA. In conclusion, the magnitude of bias observed with either assay at different groups and SDC ranges was not likely to be clinically relevant. Therefore, either assay may be used to measure SDC in clinical practice.

Stability and peptide binding specificity of Btk SH2 domain: molecular basis for X-linked agammaglobulinemia

X-linked agammaglobulinemia (XLA) is caused by mutations in the Bruton's tyrosine kinase (Btk). The absence of functional Btk leads to failure of B-cell development that incapacitates antibody production in XLA patients leading to recurrent bacterial infections. Btk SH2 domain is essential for phospholipase C-gamma phosphorylation, and mutations in this domain were shown to cause XLA. Recently, the B-cell linker protein (BLNK) was found to interact with the SH2 domain of Btk, and this association is required for the activation of phospholipase C-gamma. However, the molecular basis for the interaction between the Btk SH2 domain and BLNK and the cause of XLA remain unclear. To understand the role of Btk in B-cell development, we have determined the stability and peptide binding affinity of the Btk SH2 domain. Our results indicate that both the structure and stability of Btk SH2 domain closely resemble with other SH2 domains, and it binds with phosphopeptides in the order pYEEI > pYDEP > pYMEM > pYLDL > pYIIP. We expressed the R288Q, R288W, L295P, R307G, R307T, Y334S, Y361C, L369F, and 1370M mutants of the Btk SH2 domain identified from XLA patients and measured their binding affinity with the phosphopeptides. Our studies revealed that mutation of R288 and R307 located in the phosphotyrosine binding site resulted in a more than 200-fold decrease in the peptide binding compared to L295, Y334, Y361, L369, and 1370 mutations in the pY + 3 hydrophobic binding pocket (approximately 3- to 17-folds). Furthermore, mutation of the Tyr residue at the betaD5 position reverses the binding order of Btk SH2 domain to pYIIP > pYLDL > pYDEP > pYMEM > pYEEI. This altered binding behavior of mutant Btk SH2 domain likely leads to XLA.

The association of infection and coronary artery disease: an update

Numerous studies have reported an association of coronary atherosclerosis and restenosis with certain bacterial and viral infections. This article reviews the pathophysiology of atherosclerosis, the role of infectious agents (cytomegalovirus, Chlamydia pneumoniae and Helicobacter pylori) in atherogenesis and studies supporting the potential beneficial effects of antibiotics or antiviral agents in the management of atherosclerotic disease. The interactions of cytomegalovirus and the arterial wall have been extensively studied. However, despite the successful preliminary therapeutic trials with the use of macrolides in augmenting possible C. pneumoniae-induced cardiovascular events, the exact mechanisms of how C. pneumoniae enters the arterial wall remains unknown at this point. For H. pylori, regardless of the large number of studies performed to assess the association between H. pylori and coronary artery disease, no definitive conclusion could be made at this time, due to contradictory results. Before one can widely adopt the use of antibiotics or antiviral agents as treatment for atherosclerosis, further studies must be designed to address some important issues. In vivo animal models need to be established to further examine the various hypotheses regarding the interaction of infectious agents and atherosclerosis and restenosis. Large-scale prospective cohort studies should be designed to relate evidence of infection to future risk of cardiovascular diseases. Confounding variables, such as other cardiovascular risk factors and socio-economic status, should be controlled in order to strengthen the association. Further interventional studies are also required to establish the best antibiotic or antiviral regimen to maximise efficacy and minimise side effects.

Molecular cloning of growth hormone-releasing hormone/pituitary adenylyl cyclase-activating polypeptide in the frog Xenopus laevis: brain distribution and regulation after castration

Pituitary adenylyl cyclase-activating peptide (PACAP) appears to regulate several neuroendocrine functions in the frog, but its messenger RNA (mRNA) structure and brain distribution are unknown. To understand the potential role of PACAP in the male frog hypothalamic-pituitary-gonadal axis, we cloned the frog Xenopus laevis PACAP mRNA and determined its distribution in the brain. We then analyzed the castration-induced alterations of mRNA expression for PACAP and its selective type I receptor (PAC1) in the hypothalamic anterior preoptic area, a region known to regulate reproductive function. The PACAP mRNA encodes a peptide precursor predicted to give rise to both GH-releasing hormone and PACAP. The deduced peptide sequence of PACAP-38 was nearly identical to that of human PACAP with one amino acid substitution. Abundant PACAP mRNA was detected in the brain, but not several other tissues, including the testis. In situ hybridization revealed strong expression of the PACAP gene in the dorsal pallium, ventral hypothalamus, and nuclei of cerebellum. PACAP mRNA signals were weak to moderate in the hypothalamic anterior preoptic area and were absent in the pituitary. Castration induced an increase in the expression of PACAP and PAC1 receptor mRNAs in the hypothalamic anterior preoptic area after 3 days. Replacement with testosterone prevented the castration-induced changes. These results provide a molecular basis for studying the physiological functions of PACAP in frog brain and suggest that PACAP may be involved in the feedback regulation of hypothalamic-pituitary-gonadal axis.

Use of direct thrombin inhibitors in acute coronary syndrome

OBJECTIVE

This paper examines the rationale for using direct thrombin inhibitors in the management of acute coronary syndrome (ACS).

BACKGROUND

With traditional management of ACS using aspirin and unfractionated heparin (UH), refractory angina and new myocardial infarction (MI) continue to develop. Growing understanding of the pathophysiology of ACS has led to the search for more effective therapies directed toward preventing formation of fibrin- and platelet-rich thrombi in the coronary arteries. Current pharmacologic approaches include use of direct thrombin inhibitors (lepirudin, desirudin, and bivalirudin).

METHODS

We reviewed all published clinical trials abstracted in MEDLINE from 1966 to April 2000, excluding pilot studies enrolling <500 patients.

RESULTS

Use of lepirudin at medium doses (0.4-mg/kg bolus + 0.15 mg/kg/h) resulted in lower rates of death, new MI, and refractory angina at 7 days compared with UH (3.0% vs 6.5%; P = 0.047), although the incidence of minor bleeding was increased (7.6% vs 4.5%; P < 0.05). Bivalirudin was as effective as UH in preventing complications after percutaneous coronary intervention (11.4% vs 12.2%; NS) and carried a lower bleeding risk (7.8% vs 19.2%; NS); however, its use in the management of ACS has not been studied. Desirudin used at low doses (0.1-mg/kg bolus + 0.1 mg/kg/h) in large-scale clinical trials in patients with acute MI treated with alteplase or streptokinase appeared to be at least as effective as UH (8.9% vs 9.8% at 30 days; NS). However, its therapeutic index was narrow, since it was associated with significantly more moderate bleeding (8.8% vs 7.7%; P < 0.05).

CONCLUSIONS

All clinical trials to date have studied relatively short-term use (3-5 days) of direct thrombin inhibitors, and long-term benefits on morbidity and mortality have not been demonstrated. Until further data are available, direct thrombin inhibitors should be restricted to use as a possible alternative in patients who require anticoagulant therapy but experience UH-induced thrombocytopenia.

Solution structure of an N-capping peptide from the N-terminal leucine-repeat region of hepatitis delta antigen

Hepatitis delta virus (HDV) is a satellite virus of the hepatitis B virus (HBV) which provides the surface antigen for the viral coat. The RNA genome of HDV encodes two proteins, the small delta antigen and the large delta antigen, which differ only with the latter having an additional 19 amino acids at the C-terminus. Previously, we have shown that dAg24-50, a synthetic peptide corresponding to residues 24-50 of the N-terminal leucine-repeat region of hepatitis delta antigen, binds to the viral RNA and forms an alpha-helical conformation in TFE-containing solution. However, it exhibited low alpha-helicity (less than 5%) in the absence of TFE. In order to obtain biologically active delta antigen peptides with higher structural stability in solution, an N-capping 21-residue polypeptide corresponding to residues 24-38 of hepatitis delta antigen (dAg(Cap24-38am)) was synthesized and, surprisingly, its solution structure was found to be a stable alpha-helix (64%) by circular dichroism and 1H NMR techniques. Moreover, the structure of the capping box shows the characteristic L-shaped bend perpendicular to the helix axis. This structural knowledge provides a molecular basis for understanding the role of the N-terminal leucine-repeat region of hepatitis delta antigen and has a significant potential for the development of diagnostic and therapeutic methods for HDV.

Cytochrome p450-mediated cardiovascular drug interactions

Numerous cardiovascular agents are substrates, inhibitors, or inducers of cytochrome P450 (CYP450) enzymes. The growing understanding of the CYP450 enzyme family allows us to predict potential drug interactions. This review discusses CYP450-mediated cardiovascular drug interactions with selected examples reported in the literature. The principles of predicting drug interactions are also discussed. Studies evaluating in vivo drug interaction and case reporting by clinicians are necessary to establish the clinical significance of these interactions, which will in turn help to develop strategies to prevent and manage the potentially devastating effects they might have on patients.

Solution structure of the human BTK SH3 domain complexed with a proline-rich peptide from p120cbl

X-linked agammaglobulinemia (XLA), an inherited disease, is caused by mutations in the Bruton's tyrosine kinase (BTK). The absence of functional BTK leads to failure of B cell differentiation which incapacitates antibody production in XLA patients leading to, sometimes lethal, bacterial infections. Point mutation in the BTK gene that leads to deletion of C-terminal 14 aa residues of BTK SH3 domain was found in one patient family. To understand the role of BTK in B cell development, we have determined the solution structure of BTK SH3 domain complexed with a proline-rich peptide from the protein product of c-cbl protooncogene (p120cbl). Like other SH3 domains, BTK SH3 domain consists of five beta-strands packed in two beta-sheets forming a beta-barrel-like structure. The rmsd calculated from the averaged coordinates for the BTK SH3 domain residues 218-271 and the p120cbl peptide residues 6-12 of the complex was 0.87 A (+/-0.16 A) for the backbone heavy atoms (N, C, and Calpha) and 1.64 A (+/-0.16 A) for all heavy atoms. Based on chemical shift changes and inter-molecular NOEs, we have found that the residues located in the RT loop, n-Src loop and helix-like loop between beta4 and beta5 of BTK SH3 domain are involved in ligand binding. We have also determined that the proline-rich peptide from p120cbl binds to BTK SH3 domain in a class I orientation. These results correlate well with our earlier observation that the truncated BTK SH3 domain (deletion of beta4, beta5 and the helix-like loop) exhibits weaker affinity for the p120cbl peptide. It is likely that the truncated SH3 domain fails to present to the ligand the crucial residues in the correct context and hence the weaker binding. These results delineate the importance of the C-terminus in the binding of SH3 domains and also indicate that improper folding and the altered binding behavior of mutant BTK SH3 domain likely lead to XLA.

The solution structure of [d(CGC)r(aaa)d(TTTGCG)](2): hybrid junctions flanked by DNA duplexes

The solution structure and hydration of the chimeric duplex [d(CGC)r(aaa)d(TTTGCG)](2), in which the central hybrid segment is flanked by DNA duplexes at both ends, was determined using two-dimensional NMR, simulated annealing and restrained molecular dynamics. The solution structure of this chimeric duplex differs from the previously determined X-ray structure of the analogous B-DNA duplex [d(CGCAAATTTGCG)](2)as well as NMR structure of the analogous A-RNA duplex [r(cgcaaauuugcg)](2). Long-lived water molecules with correlation time tau(c)longer than 0.3 ns were found close to the RNA adenine H2 and H1' protons in the hybrid segment. A possible long-lived water molecule was also detected close to the methyl group of 7T in the RNA-DNA junction but not with the other two thymines (8T and 9T). This result correlates with the structural studies that only DNA residue 7T in the RNA-DNA junction adopts an O4'-endo sugar conformation, while the other DNA residues including 3C in the DNA-RNA junction, adopt C1'-exo or C2'-endo conformations. The exchange rates for RNA C2'-OH were found to be approximately 5-20 s(-1). This slow exchange rate may be due to the narrow minor groove width of [d(CGC)r(aaa)d(TTTGCG)](2), which may trap the water molecules and restrict the dynamic motion of hydroxyl protons. The minor groove width of [d(CGC)r(aaa)d(TTTGCG)](2)is wider than its B-DNA analog but narrower than that of the A-RNA analog. It was further confirmed by its titration with the minor groove binding drug distamycin. A possible 2:1 binding mode was found by the titration experiments, suggesting that this chimeric duplex contains a wider minor groove than its B-DNA analog but still narrow enough to hold two distamycin molecules. These distinct structural features and hydration patterns of this chimeric duplex provide a molecular basis for further understanding the structure and recognition of DNA. RNA hybrid and chimeric duplexes.

Hydration of [d(CGC)r(aaa)d(TTTGCG)](2)

We have studied the hydration and dynamics of RNA C2'-OH in a DNA. RNA hybrid chimeric duplex [d(CGC)r(aaa)d(TTTGCG)](2). Long-lived water molecules with correlation time tau(c) larger than 0.3 ns were found close to the RNA adenine H2 and H1' protons in the hybrid segment. A possible long-lived water molecule was also detected close to the methyl group of 7T in the RNA-DNA junction but not to the other two thymine bases (8T and 9T). This result correlates with the structural studies that only DNA residue 7T in the RNA-DNA junction adopts an O4'-endo sugar conformation (intermediate between B-form and A-form), while the other DNA residues including 3C in the DNA-RNA junction, adopt C1'-exo or C2'-endo conformations (in the B-form domain). Based on the NOE cross-peak patterns, we have found that RNA C2'-OH tends to orient toward the O3' direction, forming a possible hydrogen bond with the 3'-phosphate group. The exchange rates for RNA C2'-OH were found to be around 5-20 s(-1), compared to 26.7(+/-13.8) s(-1) reported previously for the other DNA.RNA hybrid duplex. This slow exchange rate may be due to the narrow minor groove width of [d(CGC)r(aaa)d(TTTGCG)](2), which may trap the water molecules and restrict the dynamic motion of hydroxyl protons. The distinct hydration patterns of the RNA adenine H2 and H1' protons and the DNA 7T methyl group in the hybrid segment, as well as the orientation and dynamics of the RNA C2'-OH protons, may provide a molecular basis for further understanding the structure and recognition of DNA.RNA hybrid and chimeric duplexes.

The role of vasopressin in the treatment of vasodilation in shock states

OBJECTIVE

To review the role of vasopressin in the treatment of vasodilatory shock.

DATA SOURCES

A MEDLINE search on published reports (1966-April 1999) was conducted.

STUDY SELECTION

English-language studies and case reports were selected and evaluated based on quality of review of vasopressin in the treatment of vasodilatory shock.

DATA SYNTHESIS

In patients with end-stage vasodilatory shock, baroreceptor reflex is impaired and vasopressin stores are depleted. Persistent elevation of catecholamines may lead to down-regulation of beta-adrenergic receptors and reduces smooth-muscle response to catecholamines, leading to inability of maintaining organ perfusion. Small-scale studies and case reports have demonstrated vasopressin's efficacy in maintaining blood pressure in patients with septic shock, cardiac arrest, and end-stage heart failure, refractory to other vasopressor therapies.

CONCLUSIONS

Vasopressin may be a reasonable alternative for patients in vasodilatory shock. However, larger-scale controlled dinical trials are warranted before its routine use can be recommended.

Solution structure and dynamics of G1TE, a nonphosphorylated cyclic peptide inhibitor for the Grb2 SH2 domain

The solution structure and dynamics of G1TE, a nonphosphorylated cyclic peptide inhibitor for the Grb2 SH2 domain, was determined using two-dimensional NMR and simulated annealing methods. G1TE consists of 10 amino acids and a C-terminal Cys cyclized through its side-chain sulfur atom by a thioether linkage to its N terminus. The results indicate that G1TE assumes a circle-like shape in solution in which all the side chains are protruding outside, and none of the residues are involved in intramolecular hydrogen bonding. The average root-mean-square deviations were found to be 0.41 +/- 0.11 A for the backbone heavy atoms C, Calpha, and N, and 1.03 +/- 0.14 A for all heavy atoms in a family of 10 structures. (15)N relaxation measurements indicate that G1TE has rather restricted dynamics in the fast time scale within its backbone. However, residues Tyr3, Val6, and Gly7 may be involved in a possible conformational exchange. The structural comparison between G1TE in solution and the BCR-Abl phosphopeptide bound to Grb2 SH2 domain revealed that G1TE may form a larger circle-like binding surface than the BCR-Abl phosphopeptide in the bound form. Also, the restricted backbone dynamics of G1TE may result in a reduced loss of entropy and can compensate for the absence of a phosphate group at the Tyr3 position. These structural and dynamic properties of G1TE may provide a molecular basis for understanding its interactions with the Grb2 SH2 domain.

Solution structure and RNA-binding activity of the N-terminal leucine-repeat region of hepatitis delta antigen

Hepatitis delta virus (HDV) is a satellite virus of the hepatitis B virus (HBV) which provides the surface antigen for the viral coat. The RNA genome of HDV encodes two proteins: the small delta antigen and the large delta antigen. The two proteins resemble each other except for the presence of an additional 19 amino acids at the C terminus of the latter species. We have found that the N-terminal leucine-repeat region of hepatitis delta antigen (HDAg) binds to the autolytic domain of HDV genomic RNA and attenuates its autolytic activity. A 27-residue polypeptide corresponding to residues 24-50 of HDAg, designated dAg(24-50), was synthesized, and its solution structure was found to be an alpha-helix by circular dichroism and (1)H-nuclear magnetic resonance (NMR) techniques. Binding affinity of dAg(24-50) with HDV genomic RNA was found to increase with its alpha-helical content, and it was further confirmed by modifying its N- and C-terminal groups. Furthermore, the absence of RNA binding activity in the mutant peptides, dAgM(24-50am) and dAgM(Ac24-50am), in which Lys38, Lys39, and Lys40 were changed to Glu, indicates a possible involvement of these residues in their binding activity. Structural knowledge of the N-terminal leucine-repeat region of HDAg thus provides a molecular basis for the understanding of its role in the interaction with RNA. Proteins 1999;37:121-129.

Cilostazol

Cilostazol is a phosphodiesterase III inhibitor that has been shown to be effective for treatment of symptomatic intermittent claudication. It is generally well tolerated, but is contraindicated in patients with severe heart failure because of the potential detrimental effects demonstrated by other agents in the same class. Additional studies are required to examine the long-term benefits of cilostazol therapy.

Structural studies of symmetric DNA undecamers containing non-symmetrical sheared (PuGAPu):(PyGAPy) motifs

Interstrand purine-purine stacks originate from tandem sheared purine.purine pairing and represent one of the most important motifs in both DNA and RNA structures. Several RNA and DNA structures, solved recently in both solution and the solid state, contain these special motifs, which greatly increase the structural diversity of nucleic acid molecules. The direct evidence for the sheared purine-purine pairing at neutral pH in solution remains, however, elusive. In this manuscript, we have used high resolution NMR methods to study a series of symmetrical DNA duplexes containing two non-symmetrical 5'-(PuGAPu)/(PyGAPy)-3' motifs. Many strong- and medium-strength NOEs across the G.A base pair were detected in the H2O-NOESY spectra collected at a relatively low temperature (-5 degrees C). These NOEs, especially those from A-6NH2 to G-H1', G-H4', and G-2NH2, clearly define the proposed side-by-side sheared G.A pairing nature. Another interesting feature is the strong NOEs exhibited by the unpaired G-imino proton in the G.A pair to its own G-2NH2, which implies that G-2NH2 is involved in H-bonding with a base in the minor groove edge. The finding that non-symmetrical (PuGAPu):(PyGAPy) motif also form similarly stable structures loosens the requirement for a more restricted (PyGAPu)2 motif in forming the interstrand purine-purine stacks.

Infection and atherosclerosis--focus on cytomegalovirus and Chlamydia pneumoniae

BACKGROUND AND OBJECTIVE

Numerous studies have reported an association of coronary atherosclerosis and restenosis with certain bacterial and viral infections. This article reviews the pathophysiology of atherosclerosis, the role of infectious agents (i.e, cytomegalovirus and Chlamydia pneumoniae) in atherogenesis, and studies supporting the potential beneficial effects of antibiotics or antiviral agents in the management of atherosclerotic disease.

DATA SOURCES

English-language clinical studies, abstracts, and review articles pertaining to infectious agents and coronary atherosclerosis.

STUDY SELECTION AND DATA EXTRACTION

Relevant seroepidemiologic and pathologic studies and animal models evaluating the role of cytomegalovirus or C. pneumoniae in coronary atherosclerosis.

DATA SYNTHESIS

Studies evaluating the possible role of cytomegalovirus and C. pneumoniae in the pathogenesis of atherosclerosis, as well as studies examining the use of antimicrobial and antiviral agents for reduction of cardiovascular events, are reviewed and critiqued.

CONCLUSIONS

Current data do not allow us to determine whether infection is a cause or a cofactor of atherosclerosis. These uncertainties can be resolved by larger scale seroepidemiologic, pathologic, and interventional studies. Such efforts will contribute to identifying populations that are appropriate for particular surveillance or specific interventions, such as antibiotics or antiviral therapy.

Local helix content and RNA-binding activity of the N-terminal leucine-repeat region of hepatitis delta antigen

Hepatitis delta virus (HDV) is a satellite virus of the hepatitis B virus (HBV) which provides the surface antigen for the viral coat. Our results show that the N-terminal leucine-repeat region of hepatitis delta antigen (HDAg), encompassing residues 24-50, binds to the autolytic domain of HDV genomic RNA and attenuates its autolytic activity. The solution conformation of a synthetic peptide corresponding to residues 24-50 of HDAg as determined by two-dimensional 1H NMR and circular dichroism techniques is found to be an alpha-helix. The local helix content of this peptide was analyzed by NOEs and coupling constants. Mutagenesis studies indicate that Lys38, Lys39, and Lys40 within this alpha-helical peptide may be directly involved in RNA binding. A structural knowledge of the N-terminal leucine-repeat region of HDAg thus provides a molecular basis for understanding its role in the interaction with RNA.

Main-chain dynamics of cardiotoxin II from Taiwan cobra (Naja naja atra) as studied by carbon-13 NMR at natural abundance: delineation of the role of functionally important residues

Cardiotoxin analogue II (CTX II) is an all beta-sheet, small molecular mass (6.8 kDa), basic protein possessing a wide array of biological properties. Nearly complete assignment of the protonated carbon resonances has been achieved by heteronuclear NMR experiments. The study shows that the correlation between the carbon-13 chemical shifts and CTX II structure is good in general, but interesting deviations are also noticed. To characterize the internal dynamics of CTX II, longitudinal, transverse relaxation rates and heteronuclear 13C{1H} NOEs were measured for alpha-carbons at natural abundance by two-dimensional NMR spectroscopy. Relaxation measurements were obtained in a 14.1 T spectrometer for 50 residues, which are evenly spread along the CTX II polypeptide chain. Except for five alpha-carbons, all data were analyzed from a simple two-parameter spectral density function using the model free approach of Lipari and Szabo. The microdynamical parameters (S2, taue, and Rex) were calculated with an overall rotational correlation time (taum) for the protein of 4.8 ns. For most residues, the alpha-carbons exhibit fast (taue < 30 ps) restricted libration motions (S2 = 0.79-0.89). The present study reveals that the functionally important residues located at the tips of the three loops are flexible, and the flexibility of residues in this region could be important in the binding of cardiotoxins to their putative "receptors" which are postulated to be located on the erythrocyte membrane. In addition, the results obtained in the present study support the earlier predictions on the relative role of the lysine residues in the erythrocyte lytic activity of cardiotoxins.

Current perspective on the use of angiotensin-converting enzyme inhibitors in the management of coronary (atherosclerotic) artery disease

OBJECTIVE

To review the pathophysiology of atherosclerosis, the role of the renin-angiotensin system in atherogenesis, and studies supporting the potential beneficial effects of angiotensin-converting enzyme (ACE) inhibitors in reducing cardiovascular events with long-term use.

BACKGROUND

Through its action in converting angiotensin I to angiotensin II and by degrading bradykinin, local tissue ACE exerts many effects that can contribute to the development of atherosclerosis. Therefore, the use of ACE inhibitors can possibly result in antiatherogenic effects. Possible mechanisms for antiatherogenic effects of ACE inhibitors include: (1) reduction of blood pressure; (2) antiproliferative and antimigratory effects on vascular smooth muscle cells, neutrophils, and monocytes; (3) restoration of endothelial function; (4) stabilization of fatty plaque by preventing vasoconstriction; (5) antiplatelet effects; and (6) enhancement of endogenous fibrinolysis.

DATA SOURCES

English-language clinical studies, abstracts, and review articles pertaining to the use of ACE inhibitors and atherosclerosis.

STUDY SELECTION AND DATA EXTRACTION

Relevant human studies examining the role of ACE inhibitors and atherosclerosis.

DATA SYNTHESIS

Studies evaluating the possible beneficial effects of ACE inhibitors in the development of atherosclerosis are reviewed and critiqued. Design of ongoing studies with clinical and surrogate end points are discussed.

CONCLUSIONS

Based on current published studies, recommendations are made regarding the use of ACE inhibitors in atherosclerosis. Therapeutic monitoring parameters for efficacy and adverse effects are also reviewed.

SH3 domain of Bruton's tyrosine kinase can bind to proline-rich peptides of TH domain of the kinase and p120cbl

X-linked agammaglobulinemia (XLA), an inherited disease, is caused by mutations in the Bruton's tyrosine kinase (BTK). The absence of functional BTK leads to failure of B-cell differentiation; this incapacitates antibody production in XLA patients, who suffer from recurrent, sometimes lethal, bacterial infections. BTK plays an important role in B-cell development; it interacts with several proteins in the context of signal transduction. Point mutation in the BTK gene that leads to deletion of C-terminal 14 aa residues of BTK SH3 domain was found in a patient family. To understand the role of BTK, we studied binding of BTK SH3 domain (aa 216-273, 58 residues) and truncated SH3 domain (216-259, 44 residues) with proline-rich peptides; the first peptide constitutes the SH3 domain of BTK, while the latter peptide lacks 14 amino acid residues of the C terminal. Proline-rich peptides selected from TH domain of BTK and p120cbl were studied. It is known that BTK TH domain binds to SH3 domains of various proteins. We found that BTK SH3 domain binds to peptides of BTK TH domain. This suggests that BTK SH3 and TH domains may associate in inter- or intramolecular fashion, which raises the possibility that the kinase may be regulating its own activity by restricting the availability of both its ligand-binding modules. We also found that truncated SH3 domain binds to BTK TH domain peptide less avidly than does normal SH3 domain. Also, we show that the SH3 and truncated SH3 domains bind to peptide of p120cbl, but the latter domain binds weakly. It is likely that the truncated SH3 domain fails to present to the ligand the crucial residues in the correct context, hence the weaker binding. These results delineate the importance of C-terminal in binding of SH3 domains and indicate also that improper folding and the altered binding behavior of mutant BTK SH3 domain likely leads to XLA.

Calcium channel blockers: association with myocardial infarction, mortality, and cancer

The purpose of this study was to review the results of trials assessing the association between the use of calcium channel blockers (CCBs) and mortality, myocardial infarction (MI), and cancer. Possible mechanisms of such relationships are discussed and recommendations regarding the use of CCBs made. Since 1995, 10 controversial studies have been published that associate the use of CCBs with an increased risk of mortality, MI, and cancer; these findings have caused widespread anxiety and frustration among patients and physicians. For health care professionals to properly advise patients, the facts surrounding this controversy should be reviewed. To do this, we reviewed and assessed English-language clinical studies, abstracts, editorials, and review articles pertaining to the use of CCBs and mortality, MI, and cancer in humans. The designs of ongoing prospective, randomized studies are discussed. Based on current published studies, the US Food and Drug Administration has agreed to a label warning against off-label use of short-acting nifedipine in patients with hypertension, acute MI, or nonvasospastic unstable angina. Practitioners should exercise caution when prescribing CCBs, especially to high-risk patients (e.g., those with congestive heart failure or clinical or subclinical coronary artery disease). When possible, long-acting CCBs should be used.

Patient preferences for thrombolytic therapy in acute myocardial infarction

BACKGROUND

Despite extensive professional debate regarding the optimal thrombolytic therapy strategy in acute myocardial infarction (AMI), patient preferences have not been explored.

METHODS

Preferences among patients with known or suspected coronary artery disease for treatment with tissue plasminogen activator (tPA) or streptokinase (SK) for AMI were determined using a questionnaire presenting GUSTO-1 trial and drug cost data. Preferences were based on consideration of 30-day mortality (M) alone, hemorrhagic stroke rate (SR) alone, overall preference (M + SR), drug acquisition costs, and the estimated annual costs of using a single agent to treat all AMIs. Cost-related responses were provided under payer designations of self, third-party insurance, and federal government.

RESULTS

The response rate was 81% (101/125 patients). tPA was preferred by 84%, and SK by 66%, for M alone and SR alone, respectively (chi 2, p < 0.01). Overall preference (M + SR) favored tPA (78%, p < 0.01). tPA preference decreased to 43% considering drug acquisition costs under the self-pay option (p < 0.01 vs M + SR). Similar trends of lesser magnitude were also observed for the third-party and government-payer options.

CONCLUSIONS

Under conditions of zero cost and consideration of mortality plus stroke-risk data, tPA were preferred overall due to its lower mortality. Introduction of drug-cost data significantly shifted the preference toward SK, particularly under the self-payer designation. Patient preferences for thrombolytic therapy in AMI indicate tradeoffs between clinical attributes and costs, and should assist in framing medical debate and decision making.

Immunolocalization of the pseudorabies virus immediate-early protein IE180 by immunoperoxidase staining

The immediate-early (1E) gene of pseudorabies virus (PRV) expresses immediately upon infection, a phosphorylated protein (immediate-early protein, IE180) that can transactivate viral other genes and plays an essential role in regulating viral gene expression. In order to detect and localize IE180 in infected cells early on, this gene was cloned for overexpression, and the expressed products were applied to generate specific antibodies against IE180 protein. Two recombinant expression plasmids pN and pNB were constructed by cloning the IE gene onto pET 30a(+) expression vector via NcoI and BamHI sites. Plasmid pN contains the 1.8-kb NcoI-NcoI fragment of IE gene coding for the N-terminus of 616 amino acid residues, while pNB contains the 2.8-kb NcoI-Bam HI fragment coding for the rest of the IE180 protein. Both pN and pNB were transformed, respectively, into E. coli cells and produced large amounts of IE protein products during induction with 1 mM IPTG. The expressed IE proteins for pN and pNB were 60 kDa and 100 kDa in size, respectively. These expression products were purified and then used as antigens to immunize mice for preparing specific antibodies against PRV IE180 protein. The specificities of the mice immune sera were confirmed by their abilities to react with IE180 protein present in the PRV infected cells in the Western immunoblotting assay. Furthermore, immunoperoxidase staining of PRV infected cells undertaken with these antisera revealed the subcellular distribution of the IE proteins in the infected cells and also demonstrated their transportation from the cytoplasm to the nucleus during infection.

Is the volume of distribution of digoxin reduced in patients with renal dysfunction? Determining digoxin pharmacokinetics by fluorescence polarization immunoassay

STUDY OBJECTIVE

To determine digoxin pharmacokinetics in subjects with different degrees of renal function using fluorescence polarization immunoassay (FPIA), which is associated with less interference from digoxin-like immunoreactive substances (DLIS) than radioimmunoassay.

SETTING

University hospital clinical research center.

PARTICIPANTS

Eighteen subjects (mean age 44 yrs) with different degrees of renal function: group 1, creatinine clearance (Clcr) below 10 ml/minute; group 2, Clcr 10-50 ml/minute; and group 3, Clcr greater than 50 ml/minute (6 patients in each group).

INTERVENTION

Over 5-7 days, 15 serum samples were collected after a single intravenous dose of digoxin 7 or 10 micrograms/kg actual body weight (WT) for serum concentration measurements by FPIA. Two-compartment pharmacokinetic parameters (zero-time intercept of the concentration-time curve of the initial distribution phase [A], zero-time intercept of the concentration-time curve of the terminal elimination phase [B], initial distribution phase constant [alpha], terminal elimination rate constant [beta], volume of distribution in the central compartment [Vc] and at steady state [Vss], total body clearance [Cl], mean residence time [MRT], area under the concentration-time curve [AUC]) were determined using a nonlinear least squares regression program.

MEASUREMENTS AND MAIN RESULTS

No significant differences were found among groups for A, B, alpha, beta, beta-half-life Vc/WT, MRT, AUC, and Cl/WT. Significant differences were observed in Vss/WT (4.8 +/- 1.0, 6.6 +/- 0.5, 6.4 +/- 0.7 L/kg) between group 1 versus group 2 and group 1 versus group 3 (p < 0.01). Measured Clcr was correlated with Cl (r2 = 0.40, p < 0.01), Cl/WT (r2 = 0.29, p < 0.05), Vss (r2 = 0.35, p = 0.01), and Vss/WT (r2 = 0.24, p < 0.05).

CONCLUSION

This study confirmed that Vss is smaller in patients with chronic renal failure (Clcr < 10 ml/min) than those without chronic renal failure. Therefore, previous recommendations that lower digoxin loading doses should be administered in patients with renal failure are applicable to digoxin serum concentration monitoring using FPIA.

Hairpin loops consisting of single adenine residues closed by sheared A.A and G.G pairs formed by the DNA triplets AAA and GAG: solution structure of the d(GTACAAAGTAC) hairpin

The DNA undecamers GTACAAAGTAC (AAA 11-mer) and GTACGAGGTAC (GAG 11-mer) have been studied in solution by high-resolution NMR spectroscopy. Both duplexes form stable hairpins containing single deoxyadenosine loops and stems containing five base-pairs that are closed at the loop end by sheared AxA and GxC pairs, respectively. These molecules thus contain new AAA and GAG loop turn motifs. All protons, including the chiral H5'/H5" protons of the loop residues, were assigned using NOESY, DQF-COSY and heteronuclear 1H-31P COSY experiments. The backbone torsion angles were constrained using experimental data from NOE crosspeaks, three-bond 1H-1H coupling constants and four-bond 1H-31P coupling constants and four-bond 1H-31P coupling constants. The AAA and GAG 11-mers form similar structures in solution. The detailed structure of the AAA 11-mer was determined by the combined use of NMR, distance geometry and energy minimization methods. This structure exhibits good stacking of the loop adenosine base on the closing 5Ax7A sheared pair, with the 6A base stacking on the 5A base and the 6A deoxyribose stacking with the 7A base. All sugars in the AAA 11-mer hairpin adopt the typical DNA C2'-endo conformation and a sharp backbone turn occurs between residues 6A and 7A. This loop turn is brought about mainly by a change in the backbone phosphate torsion angles from zeta(g-) alpha(g-) to zeta(g+) alphat(g+) at the turn. The gamma torsion angle of residue 7A in the closing sheared pair also changes from gauche+ to trans. In Pu1NPu2 loop turns of the GCA, AAA and GAG types, the chemical shift of the H4' proton of the loop deoxyribose depends on the nature of Pu2; this reflects the stacking of the loop sugar on the Pu2 base and the different ring current effects of A or G in this position.

Stability and folding of the SH3 domain of Bruton's tyrosine kinase

Bruton's tyrosine kinase (BTK) plays an important role in B cell development. Deletion of C-terminal 14 amino acids of the SH3 domain of BTK results in X-linked agammaglobulinemia (XLA), an inherited disease. We report here on the stability and folding of SH3 domain of BTK. Peptides corresponding to residues 216-273 (58 residues) and 216-259 (44 residues) of BTK SH3 domain were synthesized by solid phase methods; the first peptide constitutes the entire SH3 domain of BTK while the latter peptide lacks 14 amino acid residues of the C-terminal. The 58 amino acid peptide forms mainly a beta-barrel type folding unit. Although small and lacking disulfide bonds, this peptide is extremely stable to thermal denaturation. Based on circular dichroism measurements, its melting temperature was found to be high, 82 degrees C at pH 6.0. However, the Gibbs free energy (delta GH2O) of the intrinsic stability and thermodynamic spontaneity of unfolding were found to be low, 2.6 kcal/mol by Gdn.HCl denaturation experiments, as compared to 12 kcal/mol obtained for larger single domain proteins, indicating poor stability of SH3 domain. Addition of 500 mM of Na2SO4 increased the free energy change delta GH2O to 4.0 kcal/mol, suggesting an ionic strength effect. The truncated peptide fails to fold correctly and adopts random coil conformation in contrast to 58 amino acid beta-barrel peptide, which exhibits high thermal stability but normal or low stability at ambient temperature. These results, to our knowledge the first to delineate the importance of C-terminal in structural integrity of SH3 domains, indicate also that improper folding and/or poor stability of mutant SH3 domain in BTK likely causes XLA.