Oral anticoagulation therapy in atrial fibrillation patients at high risk of bleeding: Clinical characteristics and treatment strategies based on data from the Polish multicenter register of atrial fibrillation (POL-AF)

BACKGROUND

Despite its benefits, oral anticoagulant (OAC) therapy in patients with atrial fibrillation (AF) is associated with hemorrhagic complications.

AIMS

We aimed to evaluate clinical characteristics of AF patients at high risk of bleeding and the frequency of OAC use as well as identify factors that predict nonuse of OACs in these patients.

METHODS

Consecutive AF patients hospitalized for urgent or planned reasons in cardiac centers were prospectively included in the registry in 2019. Patients with HAS-BLED ≥3 (high HAS-BLED group) were assumed to have a high risk of bleeding.

RESULTS

Among 3598 patients enrolled in the study, 29.2% were at high risk of bleeding (44.7% female; median [Q1-Q3] age 72 [65-81], CHA2DS2-VASc score 5 [4-6], HAS-BLED 3 [3-4]). In this group, 14.5% of patients did not receive OACs, 68% received NOACs, and 17.5% VKAs. In multivariable analysis, the independent predictors of nonuse of oral OACs were as follows: creatinine level (odds ratio [OR], 1.441; 95% confidence interval [CI], 1.174-1.768; P <0.001), a history of gastrointestinal bleeding (OR, 2.918; 95% CI, 1.395-6.103; P = 0.004), malignant neoplasm (OR, 3.127; 95% CI, 1.332-7.343; P = 0.009), and a history of strokes or transient ischemic attacks (OR, 0.327; 95% CI, 0.166-0.642; P = 0.001).

CONCLUSIONS

OACs were used much less frequently in the group with a high HAS-BLED score than in the group with a low score. Independent predictors of nonuse of OACs were creatinine levels, a history of gastrointestinal bleeding, and malignant neoplasms. A history of stroke or transient ischemic attack increased the chances of receiving therapy.

The role of pneumococcal vaccination in reducing cardiovascular risk in cardiac patients: Expert opinion of the Prevention Committee of the Polish Cardiac Society supported by the Polish Vaccinology Society

Respiratory diseases have been the fourth most common cause of death in Poland in recent years. Respiratory infection, especially pneumonia, can lead to exacerbation of chronic cardiovascular disease.Streptococcus pneumoniae is the most common bacterial pathogen causing community-acquired pneumonia. Pneumococci are also the most common pathogen complicating the course of infection with the influenza virus. Pneumonia, especially invasive pneumococcal disease, is associated with risk of death in the course of respiratory failure or sepsis and also with worsening of the prognosis for existing cardiovascular disease. Despite those facts, recommendations for pneumococcal vaccination are still not well established in cardiovascular guidelines. This expert opinion aims to summarize current knowledge on the importance of preventing invasive pneumococcal disease in cardiac patients.

Pharmacotherapy of heart failure A.D. 2023. Expert opinion of Working Group on Cardiovascular Pharmacotherapy, Polish Cardiac Society

Heart failure (HF) remains one of the most common causes of hospitalization and mortality among Polish patients. The position of the Section of Cardiovascular Pharmacotherapy presents the currently applicable options for pharmacological treatment of HF based on the latest European and American guidelines from 2021-2022 in relation to Polish health care conditions. Treatment of HF varies depending on its clinical presentation (acute/chronic) or left ventricular ejection fraction. Initial treatment of symptomatic patients with features of volume overload is based on diuretics, especially loop drugs. Treatment aimed at reducing mortality and hospitalization should include: drugs blocking the renin-angiotensin-aldosterone system (preferably angiotensin receptor antagonist/neprilisin inhibitor, i.e. sacubitril/valsartan, selected beta-blockers (no class effect - options include bisoprolol, metoprolol succinate, or vasodilatory beta-blockers - carvedilol and nebivolol), mineralocorticoid receptor antagonist and sodium-glucose cotransporter type 2 inhibitor (flozin), constituting the 4 pillars of pharmacotherapy. Their effectiveness of the above-mentioned has been confirmed in numerous prospective, randomized trials. The current HF treatment strategy is based on the fastest possible implementation of all four mentioned classes of drugs due to their independent, additive action. It is also important to individualize therapy according to comorbidities, blood pressure, resting heart rate, or presence of arrhythmia. The manuscript emphasizes cardio- and nephroprotective role of flozins in HF therapy, regardless of ejection fraction. We propose practical guidelines for the use of medicines, the profile of adverse reactions, drug interactions, as well as pharmacoeconomic aspects. The principles of treatment with ivabradine, digoxin, vericiguat, iron supplementation or antiplatelet and anticoagulant therapy were also discussed, along with recent novel drugs including omecamtiv mecarbil, tolvaptan or coenzyme Q10 as well as progress in the prevention and treatment of hyperkalemia. Based on the latest recommendations, treatment regimens for different types of HF were discussed.

New International Guidelines and Consensus on the Use of Lung Ultrasound

Following the innovations and new discoveries of the last 10 years in the field of lung ultrasound (LUS), a multidisciplinary panel of international LUS experts from six countries and from different fields (clinical and technical) reviewed and updated the original international consensus for point-of-care LUS, dated 2012. As a result, a total of 20 statements have been produced. Each statement is complemented by guidelines and future developments proposals. The statements are furthermore classified based on their nature as technical (5), clinical (11), educational (3), and safety (1) statements.

Metabolic associated fatty liver disease and cardiovascular risk: The expert opinion of the Working Group on Cardiovascular Pharmacotherapy of the Polish Cardiac Society

The diagnosis of metabolic associated fatty liver disease (MAFLD) is significant for patients' prognosis, as the disease accelerates the development of cardiovascular complications and, on the other hand, cardiometabolic conditions are risk factors for the development of fatty liver diseases. This expert opinion presents principles of MAFLD diagnosis and standards of management to reduce cardiovascular risks in patients with MAFLD.

Do Patients with Atrial Fibrillation and a History of Ischemic Stroke Overuse Reduced Doses of NOACs?-Results of the Polish Atrial Fibrillation (POL-AF) Registry

BACKGROUND

The aim of our study was to assess if patients with AF (atrial fibrillation) and a history of ischemic stroke (IS) excessively receive reduced doses of NOACs (non-vitamin K antagonist oral anticoagulants).

METHODS

The Polish AF (POL-AF) registry is a prospective, observational, multicenter study, including patients with AF from 10 cardiology hospital centers. In this study we focused on patients with IS in their past.

RESULTS

Among 3999 patients enrolled in the POL-AF registry, 479 (12%) had a previous history of IS. Compared to patients without IS history, post-stroke subjects had a higher CHA₂DS₂-VASc score (median score 7 vs. 4, p < 0.05). Of these subjects, 439 (92%) had anticoagulation therapy, 83 (18.9%) were treated with a vitamin K antagonist (VKA), 135 (30.8%) with rivaroxaban, 112 (25.5%) with dabigatran, and 109 (24.8%) with apixaban. There were a significant number of patients after IS with reduced doses of NOACs (48.9% for rivaroxaban, 45.5% for dabigatran, and 36.7% for apixaban). In many cases, patients were prescribed reduced doses of NOACs without any indication for reduction (28.8% of rivaroxaban use, 56.9% of dabigatran use, and 60.0% of apixaban use-out of reduced dosage groups, p = 0.06).

CONCLUSIONS

A significant proportion of AF patients received reduced doses of NOAC after ischemic stroke in a sizeable number of cases, without indication for dose reduction.

Characteristics and Treatment of Atrial Fibrillation with Respect to the Presence or Absence of Heart Failure. Insights from the Multicenter Polish Atrial Fibrillation (POL-AF) Registry

Background: We aimed to assess characteristics and treatment of AF patients with and without heart failure (HF). Methods: The prospective, observational Polish Atrial Fibrillation (POL-AF) Registry included consecutive patients with AF hospitalized in 10 Polish cardiology centers in 2019–2020. Results: Among 3999 AF patients, 2822 (71%) had HF (AF/HF group). Half of AF/HF patients had preserved ejection fraction (HFpEF). Compared to patients without HF (AF/non–HF), AF/HF patients were older, more often male, more often had permanent AF, and had more comorbidities. Of AF/HF patients, 98% had class I indications to oral anticoagulation (OAC). Still, 16% of patients were not treated with OAC at hospital admission, and 9%—at discharge (regardless of the presence of HF and its subtypes). Of patients not receiving OAC upon admission, 61% were prescribed OAC (most often apixaban) at discharge. AF/non–HF patients more often converted from AF at admission to sinus rhythm at discharge compared to AF/HF patients (55% vs. 30%), despite cardioversion performed as often in both groups. Class I antiarrhythmics were more often prescribed in AF/non–HF than in AF/HF group (13% vs. 8%), but still as many as 15% of HFpEF patients received them. Conclusions: Over 70% of hospitalized AF patients have coexisting HF. A significant number of AF patients does not receive the recommended OAC.

Symptomatic and Asymptomatic Patients in the Polish Atrial Fibrillation (POL-AF) Registry

BACKGROUND

Atrial fibrillation (AF) can cause severe symptoms, but it is frequently asymptomatic. We aimed to compare the clinical features of patients with asymptomatic and symptomatic AF.

METHODS

A prospective, observational, multicenter study was performed (the Polish Atrial Fibrillation (POL-AF) registry). Consecutive hospitalized AF patients over 18 years of age were enrolled at ten centers. The data were collected for two weeks during each month of 2019.

RESULTS

A total of 2785 patients were analyzed, of whom 1360 were asymptomatic (48.8%). Asymptomatic patients were more frequently observed to have coronary artery disease (57.5% vs. 49.1%, p < 0.0001), heart failure with preserved ejection fraction (39.8% vs. 26.5%, p < 0.0001), a previous thromboembolic event (18.2% vs. 13.1%, p = 0.0002), and paroxysmal AF (52.3% vs. 45.2%, p = 0.0002). In multivariate analysis, history of electrical cardioversion, paroxysmal AF, heart failure, coronary artery disease, previous thromboembolic event, and higher left ventricular ejection fraction were predictors of a lack of AF symptoms. First-diagnosed AF was a predictor of AF symptoms.

CONCLUSIONS

In comparison to symptomatic patients, more of those hospitalized with asymptomatic AF had been previously diagnosed with this arrhythmia and other cardiovascular diseases. However, they presented with better left ventricular function and were more frequently treated with cardiovascular medicines.

Antithrombotic therapy in patients with atrial fibrillation undergoing percutaneous coronary intervention, including compliance with current guidelines-data from the POLish Atrial Fibrillation (POL-AF) Registry

Background

Although triple antithrombotic therapy (TAT) is recommended in patients with atrial fibrillation (AF) undergoing percutaneous coronary intervention (PCI), guidelines allow an option of dual antithrombotic therapy (DAT). This study assesses the everyday practice of 10 cardiology departments in antithrombotic therapy in AF patients undergoing PCI and its agreement with current guidelines.

Methods

This analysis included medical data of AF patients enrolled in the prospective, observational registry (The POLish Atrial Fibrillation-POL-AF) that underwent PCI [elective or due to acute coronary syndrome (ACS)].

Results

Of the 3,999 consecutive subjects included, a final analysis was performed on 359 patients that underwent PCI: 148 with urgent PCI due to ACSand 211 patients with elective PCI. Eighty patients in the ACS-group and 120 patients in the elective-PCI group were treated with TAT, although guidelines also allowed DAT. Of 316 patients treated with oral anticoagulants as a part of combination therapy, 275 were on non-vitamin K antagonist oral anticoagulant (NOAC). Reduced doses of NOAC were used in 74 patients treated with rivaroxaban, 60 patients with dabigatran, and 54 patients with apixaban. The proportion of patients treated with reduced NOAC doses adequately to the guidelines was 29%, 100%, and 33% for rivaroxaban, dabigatran, and apixaban, respectively. Inappropriate low doses of NOACs were used in 71% of subjects on rivaroxaban and 67% on apixaban.

Conclusions

In patients with AF undergoing PCI, NOACs are definitely preferred over vitamin-K antagonists (VKAs) in TAT/DAT, and an aggressive antithrombotic strategy with TAT is frequently chosen even if DAT is permissible by the guidelines. Label adherence of using reduced NOAC dose during combination therapy is not satisfactory for apixaban and rivaroxaban and probably results from too cautious an approach to the known indications for reduced therapy. The study is registered in the database Clinical Trials-NCT04419012.

Two Strategies for the Dosage of Acenocoumarol Co-Administered with Rifampicin in Staphylococcal Prosthetic Valve Endocarditis

According to current European Society of Cardiology guidelines, for staphylococcal prosthetic valve endocarditis, rifampicin should be one of the drugs used. However, there is a concomitant need for vitamin K antagonists in patients with mechanical prostheses. It is widely known that rifampicin interacts with vitamin K antagonists (VKA), and this interaction makes it difficult to maintain the INR (international normalized ratio) value in the therapeutic range. We present two clinical cases of staphylococcal prosthetic valve endocarditis patients. Two different strategies for dealing with adverse drug interactions have been applied. In the first case, the dose of warfarin was up-titrated until the optimal INR value was obtained. In the second case, due to the history of labile INR values, a decision was made to modify the dosage of warfarin, taking into account pharmacological aspects of drug interactions.

Trends in the Prescription of Non-Vitamin K Antagonist Oral Anticoagulants for Atrial Fibrillation: Results of the Polish Atrial Fibrillation (POL-AF) Registry

Background: Current guidelines do not suggest in which groups of patients with atrial fibrillation (AF) individual non-vitamin K antagonist oral anticoagulants (NOACs) should be used for the prevention of thromboembolic complications. The aim of this study was to evaluate the frequency of use of apixaban, dabigatran, and rivaroxaban, and attempt to identify factors predisposing their administration. Methods: The Polish Atrial Fibrillation (POL-AF) registry is a prospective, non-interventional study, including consecutive patients with AF hospitalized in ten Polish cardiology centers during the period ranging from January to December 2019. In this study, all patients were treated with NOACs. Results: Among the 2971 patients included in the analysis, 40.4% were treated with rivaroxaban, 32% with apixaban, and 27.6% with dabigatran. The mean age of the total population was 72 ± 11.5 years and 43% were female. A reduced dose of NOAC was used in 35% of patients treated with apixaban, 39.7% of patients treated with dabigatran, and 34.4% of patients treated with rivaroxaban. Independent predictors of the use of apixaban were previous bleeding (OR 2.37, CI 1.67–3.38), GFR < 60 mL/min (OR 1.38, CI 1.25–1.64), heart failure (OR 1.38, CI 1.14–1.67) and age (per 5 years) (OR 1.14, CI 1.09–1.19). GFR < 60 mL/min (OR 0.79, CI 0.66–0.95), female (OR 0.8, CI 0.67–0.96) and age (per 5 years) (OR 0.95, CI 0.91–0.99) diminished the chance of using dabigatran. Previous bleeding (OR 0.43, CI 0.28–0.64), vascular disease (OR 0.84, CI 0.70–0.99), and age (per 5 years) (OR 0.94, CI 0.90–0.97) diminished the chance of choosing rivaroxaban. Conclusions: In hospitalized patients with AF, the most frequently chosen NOAC was rivaroxaban. Apixaban was chosen more often in patients after bleeding, and in those who were advanced in years, with heart failure and impaired renal function. Impaired renal function and female gender were factors that diminished the chance of using dabigatran. Previous bleeding and vascular disease was the factor that diminished the chance of using rivaroxaban. Dabigatran and rivaroxaban have been used less frequently in elderly patients.

Multi-Method Complex Approach for Hydration Assessment Does Not Detect a Hydration Difference in Hemodialysis versus Peritoneal Dialysis Patient

Assessment of hydration status is essential in monitoring the effectiveness of renal replacement therapy and is usually based on physical examination. However, comparisons of hydration status achieved with different dialysis methods are not conclusive. We compared the hydration status of patients on chronic hemodialysis (HD, n = 60) and peritoneal dialysis (PD, n = 20) in a comprehensive assessment including physical examination and additional methods. The mean age of the 80 chronically dialyzed patients (53 males, 27 females) was 58.1 ± 13.9 years. The clinical evaluation took into account the presence of peripheral edema, dyspnea, and crackling over the lung fields. Additional tests included lung ultrasound, electrical bioimpedance (performed in 79 patients), impedance cardiography, ultrasound assessment of large abdominal vessels (performed in 79 patients), select echocardiographic parameters (obtained in 78 patients), and serum NT-proBNP concentration. Residual diuresis volume was significantly higher in the PD group. We found no significant differences between the two groups in any other baseline characteristics or in the results of the clinical examination or additional tests. The use of different methods for assessing hydration does not allow differentiation of patients treated with dialysis in terms of the dialysis technique used. Therefore, it seems reasonable to use common algorithms to objectify the hydration status of these patients.

Lung ultrasound in the diagnosis of COVID-19 infection - A case series and review of the literature

COVID-19 pandemic caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and spreading worldwide has become a serious challenge for the entire health care system as regards infection prevention, rapid diagnosis, and treatment. Lung ultrasound (LUS) is a dynamically developing diagnostic method used in intensive care, cardiology and nephrology, it can also be helpful in diagnosing and monitoring pneumonia. Interstitial pneumonia appears to be the most common clinical manifestation of coronavirus infection. We present 4 case reports of COVID-19 involving the lungs, in which transthoracic lung ultrasound was successfully utilized as a constituent of bedside diagnostics and a review of the literature concerning potential use of LUS in COVID-19 diagnostics. The possibility to perform this examination repeatedly, its non-invasiveness and high sensitivity make it an important element of care provided for patients with viral pneumonia.

Polish recommendations for lung ultrasound in internal medicine (POLLUS-IM)

Objective

The aim of this study was to establish recommendations for the use of lung ultrasound in internal medicine, based on reliable data and expert opinions.

Methods

The bibliography from the databases (Pubmed, Medline, OVID, Embase) has been fully reviewed up to August 2017. Members of the expert group assessed the credibility of the literature data. Then, in three rounds, a discussion was held on individual recommendations (in accordance with the Delphi procedure) followed by secret voting.

Results

Thirty-eight recommendations for the use of lung ultrasound in internal medicine were established as well as discussed and subjected to secret voting in three rounds. The first 31 recommendations concerned the use of ultrasound in the diagnosis of the following conditions: pneumothorax, pulmonary consolidation, pneumonia, atelectasis, pulmonary embolism, malignant neoplastic lesions, interstitial lung lesions, cardiogenic pulmonary edema, interstitial lung diseases with fibrosis, dyspnea, pleural pain and acute cough. Furthermore, seven additional statements were made regarding the technical conditions of lung ultrasound examination and the need for training in the basics of lung ultrasound in a group of doctors during their specialization programs and medical students. The panel of experts established a consensus on all 38 recommendations.

[Difference in efficacy of dyslipidaemia treatment in obese and not obese women. Analysis of date from 3ST-POL study]

INTRODUCTION

Cardiovascular diseases remain the first cause of premature death in polish society. In Poland mortality concerned with cardiovascular diseases is higher in women than in men. Dyslipidemia is one of the most important and one of the most common risk factor of cardiovascular diseases. The efficacy of treatment of dyslipidaemia in Poland remains poor however there is lack of date as far as influence of sex and coexistence obesity on efficacy of treatment of dyslipidaemia is concerned.

AIM

Evaluation of difference in efficacy of treatment of dyslipidaemia in obese women and women with body mass index less than 30 kg/m2. Date from 3ST-POL Study.

METHODS

Post hoc analysis of date of 3ST-POL Study, conducted in 2007- 2008. The Study refers to efficacy of treatment of dyslipidaemia in ambulatory polish patients which remain under supervision of general practitioners, cardiologist or dialectologist.

RESULTS

Women comprise 53% (n=26099) of population of 3ST-POL Study. In 21769 of those it was possible to calculate body mass index (BMI). 16% of women ware obese. 70% of those in comparison of with 67.6% of women with BMI<30 kg/m2 were at high cardiovascular risk. (p<0.01). There was no difference in mean doses of statins between all groups (mean daily dose was 20 mg and 24 mg for atorvastatin and simvastatin respectively). LDL goal was reached in 9.67% vs, 15.8% of obese high risk and not at high risk women respectively (p<0.01). Total cholesterol goal was reached in 9.01% vs. 12.39% obese high risk and not at high risk women respectively (p<0.01). In group with BMI<30 kg/m2 LDL and total cholesterol goals in high risk and not at high risk women were reached in 10.02% vs. 14.46% and in 8.86% vs. 13.05% respectively (p<0.01 for both). Mean concentration of all lipids, except for triglycerides, was higher in non-obese women.

CONCLUSIONS

The efficacy of treatment of dyslipidaemia in women from 3ST-POL study was higher in patients with lower global cardiovascular risk. Obesity or lack of it has no influence of that difference. Nevertheless global efficacy was very poor as far as both – LDL and total cholesterol goals were concerned. Moreover there were now difference in mean statins doses between groups. This may be due to therapeutic inertia of physicians.

[Does cardiovascular comorbidities are important as far as ophthalmology treatment is concerned?]

Majority of patients with glaucoma, age-related maculopathy or diabetic macular edema is old. Therefore arterial hypertension, coronary arterial disease, diabetes and dyslipidemia are common finding in patients with sick eye. In this article some situations needing cooperation of cardiologist and ophthalmologist have been pointed. The influence of treatment of hypertension on glaucoma outcomes and the influence of intraocular injections of biological drugs on cardiovascular risk seems to be the most important issues.

[Predictors of efficacy initial low energy of external rectilinear biphasic cardioversion in persistent atrial fibrillation]

Rectilinear biphasic cardioversion (Bi-DC) has been shown to be very effective for restoration of sinus rhythm in patients with persistent atrial fibrillation (AF). There is, however, limited information on factors influencing effectiveness of the initial energy of 50 J for Bi-DC of atrial fibrillation.

AIM OF THE STUDY

Evaluation of efficacy of 50 J shock of Bi-DC for restoration sinus rhythm and development of point score system to predict high conversion rate of 50 J shock in persistent atrial fibrillation.

MATERIAL AND METHODS

The study group was composed of 502 consecutive Bi-DC in-patients with persistent atrial fibrillation who underwent cardioversion according to the standard protocol (50 J --> 1 J/kg m.c. --> 2 J/kg m.c. --> 200 J). Factors influencing effectiveness of 50 J shock were defined.

RESULTS

Rectilinear biphasic cardioversion of shock of 50 J was successful in 157 (31%) patients. In multivariate analysis independent factors associated with efficacy of 50 J shock were: atrial fibrillation duration < 7 months (OR: 14.3, CI: 5.83 - 35.2, p < 0.001), left ventricular ejection fraction--LVEF > 40% (OR: 5.67, CI: 1.22 - 26.3, p = 0.027), body weight < 78 kg (OR: 3.17, CI: 1.52 - 6.59, p = 0.002), permanent pacemaker (OR: 2.98, CI: 1.20 - 7.40, p = 0.018), LA diameter < 4.5 cm (OR: 2.80, CI: 1.19 - 6.58, p = 0.02). A simplified point score system was developed to predict the chance for termination of atrial fibrillation (the score gives 5 points for atrial fibrillation duration < 7 months; 2 points for EF > 40%; 1 point for pacemaker, body weight < 78 kg and LA < 4.5 cm, each). High effectiveness (65%) of 50 J shock was achieved in patients with > 9 points of scoring system and 80% in this group when atrial fibrillation duration is shorter than 3 months. Effectiveness of 50 J shock was very low in the remaining group (0 points--0%; 1-3 points--5%; 4-6 points--21%; 7-8 points--34%, respectively).

CONCLUSION

The efficacy of initial shock of 50 J for termination of atrial fibrillation is limited and is not recommended for general population of patients with atrial fibrillation referred for Bi-DC. 50 J might be considered in patients with pacemakers without factors associated with failure of 50 J to terminate atrial fibrillation: atrial fibrillation duration > 7 months, lower LVEF increased LA diameter, body weight > 78 kg. The shock of 50 J is effective in more than 60% of patients, if they achieved 9 or 10 points in proposed score. The highest efficacy of 50 J shock (80%) is possible to reach in this group if atrial fibrillation duration is shorter than 3 months.

Three-dimensional model of the potyviral genome-linked protein

The full sequence of the genome-linked viral protein (VPg) cistron located in the central part of potato virus Y (common strain) genome has been identified. The VPg gene codes for a protein of 188 amino acids, with significant homology to other known potyviral VPg polypeptides. A three-dimensional model structure of VPg is proposed on the basis of similarity of hydrophobic-hydrophilic residue distribution to the sequence of malate dehydrogenase of known crystal structure. The 5' end of the viral RNA can be fitted to interact with the protein through the exposed hydroxyl group of Tyr-64, in agreement with experimental data. The complex favors stereochemically the formation of a phosphodiester bond [5'-(O4-tyrosylphospho)adenylate] typical for representatives of picornavirus-like viruses. The chemical mechanisms of viral RNA binding to VPg are discussed on the basis of the model structure of protein-RNA complex.

Digoxigenin-labelled molecular probe for the simultaneous detection of three potato pathogens: potato spindle tuber viroid (PSTVd), potato virus Y (PVY), and potato leafroll virus (PLRV)

A molecular probe, p3POT, was constructed of PSTVd, PVY, PLRV cDNA fragments introduced into pUC18 vector. Sequencing of the inserts revealed that cloned fragments covered conservative parts of pathogenic genomes. Dot-blot hybridization of digoxigenin-labelled construct to crude extracts from plants infected with different potato viruses proved high sensitivity and specificity of the p3POT probe. This makes p3POT probe an useful tool for the routine testing, and selection of virus-free potatoes.

Detection of potato spindle tuber viroid (PSTV) in dormant potato tubers by concatameric cDNA probe

The 32P-labelled concatameric insert cut out from a plasmid pSPAv6.2(+), containing 6.2 copies of a full-length PSTV, was used to detect PSTV in dormant potato tubers by dot-blot hybridisation assay. The concatameric insert probe was 4 times more sensitive than the monomeric one. This allowed the detection of 0.5 pg of viroid RNA. The sensitivity makes th eoligomeric cDNA probe a useful alternative to cDNA probes.

Characterisation of synthetic DNA probe detecting potato spindle tuber viroid

Chemically synthesized DNA fragments complementary to selected regions of the potato spindle tuber viroid (PSTV) genome were cloned into Escherichia coli plasmid pUC9. One of the recombinant plasmids (pIBB4) with a 87 bp insert representing the central region of the PSTV genome (nucleotides 88 to 174) was used after labelling by nick translation for detecting PSTV by dot-blot hybridization. The molecular probe was almost as sensitive as the one carrying the full genomic PSTV copy (pAV401), detecting down to 20 pg of PSTV RNA in 8-15 micrograms of infected tissue. The specificity of the test was high; no signals were created by extracts from healthy plants or plants infected with a variety of common potato viruses. The probe is potentially useful in studies on mixed infections of potatoes with different viruses, and in selection of certified seed material.