Characterisation of the OTU domain deubiquitinase complement of Toxoplasma gondii

The phylum Apicomplexa contains several parasitic species of medical and agricultural importance. The ubiquitination machinery remains, for the most part, uncharacterised in apicomplexan parasites, despite the important roles that it plays in eukaryotic biology. Bioinformatic analysis of the ubiquitination machinery in apicomplexan parasites revealed an expanded ovarian tumour domain-containing (OTU) deubiquitinase (DUB) family in Toxoplasma, potentially reflecting functional importance in apicomplexan parasites. This study presents comprehensive characterisation of Toxoplasma OTU DUBs. AlphaFold-guided structural analysis not only confirmed functional orthologues found across eukaryotes, but also identified apicomplexan-specific enzymes, subsequently enabling discovery of a cryptic OTU DUB in Plasmodium species. Comprehensive biochemical characterisation of 11 Toxoplasma OTU DUBs revealed activity against ubiquitin- and NEDD8-based substrates and revealed ubiquitin linkage preferences for Lys6-, Lys11-, Lys48-, and Lys63-linked chain types. We show that accessory domains in Toxoplasma OTU DUBs impose linkage preferences, and in case of apicomplexan-specific TgOTU9, we discover a cryptic ubiquitin-binding domain that is essential for TgOTU9 activity. Using the auxin-inducible degron (AID) to generate knockdown parasite lines, TgOTUD6B was found to be important for Toxoplasma growth.

Chromosome-level genome of Schistosoma haematobium underpins genome-wide explorations of molecular variation

Urogenital schistosomiasis is caused by the blood fluke Schistosoma haematobium and is one of the most neglected tropical diseases worldwide, afflicting > 100 million people. It is characterised by granulomata, fibrosis and calcification in urogenital tissues, and can lead to increased susceptibility to HIV/AIDS and squamous cell carcinoma of the bladder. To complement available treatment programs and break the transmission of disease, sound knowledge and understanding of the biology and ecology of S. haematobium is required. Hybridisation/introgression events and molecular variation among members of the S. haematobium-group might effect important biological and/or disease traits as well as the morbidity of disease and the effectiveness of control programs including mass drug administration. Here we report the first chromosome-contiguous genome for a well-defined laboratory line of this blood fluke. An exploration of this genome using transcriptomic data for all key developmental stages allowed us to refine gene models (including non-coding elements) and annotations, discover ‘new’ genes and transcription profiles for these stages, likely linked to development and/or pathogenesis. Molecular variation within S. haematobium among some geographical locations in Africa revealed unique genomic ‘signatures’ that matched species other than S. haematobium, indicating the occurrence of introgression events. The present reference genome (designated Shae.V3) and the findings from this study solidly underpin future functional genomic and molecular investigations of S. haematobium and accelerate systematic, large-scale population genomics investigations, with a focus on improved and sustained control of urogenital schistosomiasis.

More than 100 million people are infected with the carcinogenic blood fluke Schistosoma haematobium, the aetiological agent of urogenital schistosomiasis—a neglected tropical disease (NTD). In spite of its major significance, little is known about this fluke, its interactions with the human and snail intermediate hosts and the pathogenesis of the urogenital form of schistosomiasis at the molecular and biochemical levels. To enable research in these areas, we report the first chromosome-level genome and markedly enhanced gene models for S. haematobium. Comparative genomic analyses also reveal evidence of past introgression events between or among closely related schistosome species. This present reference genome for S. haematobium and the findings from this study should underpin future functional genomic and molecular investigations of S. haematobium and accelerate systematic, large-scale population genomics investigations, with a focus on improved control of urogenital schistosomiasis.

Risk stratification of coronary revascularization patients by using clinical and angiographic data

AIM

Patients undergoing coronary artery bypass grafting (CABG) or percutaneous coronary intervention (PCI) are still at a substantial risk of death after their procedures. A core group of preoperative and preprocedural risk factors and conditions contributes the majority of inherent mid- and long-term mortality risk in these patients. Therefore, we sought to develop a classification tree model as a practical and user-friendly method of predicting mid-term survival after coronary revascularization procedures.

METHODS

We retrospectively analyzed data from a single, large-volume institution. Specifically, we examined all-cause three-year mortality in 3387 consecutive patients with multivessel or single proximal left anterior descending coronary artery disease who underwent either PCI with stenting or CABG.

RESULTS

Recursive partitioning indicated that the best single predictor of death within three years was a history of heart failure (HF), followed by a proximal left circumflex artery (pLCX) lesion and age greater than 65 years for patients with and without a history of HF, respectively. With these variables, patients were readily stratified into low-, intermediate-, and high-risk groups whose risks of death over three years ranged from 2.3% to 36.2%. Among patients with a history of HF, pLCX stenosis was an independent predictor of mid-term mortality after adjustment for other known risk factors (hazard ratio, 1.46; 95% CI, 1.04-2.03).

CONCLUSION

The constructed risk stratification scheme stratified patients into groups at low, intermediate, and high risk of death within three years. Stenosis of the pLCX seems to be an important prognostic factor for patients with a history of HF.

Prognostic value of myocardial perfusion imaging in patients with high exercise tolerance

BACKGROUND

Although high exercise tolerance is associated with an excellent prognosis, the significance of abnormal myocardial perfusion imaging (MPI) in patients with high exercise tolerance has not been established. This study retrospectively compares the utility of MPI and exercise ECG (EECG) in these patients.

METHODS AND RESULTS

Of 388 consecutive patients who underwent exercise MPI and reached at least Bruce stage IV, 157 (40.5%) had abnormal results and 231 (59.5%) had normal results. Follow-up was performed at 18+/-2.7 months. Adverse events, including revascularization, myocardial infarction, and cardiac death, occurred in 40 patients. Nineteen patients had revascularization related to the MPI results or the patient's condition at the time of MPI and were not included in further analysis. Seventeen patients (12.2%) with abnormal MPI and 4 (1.7%) with normal MPI had adverse cardiac events (P<0.001). Cox proportional-hazards regression analysis showed that MPI was an excellent predictor of cardiac events (global chi2=13.2; P<0.001; relative risk=8; 95% CI=3 to 23) but EECG had no predictive power (global chi2=0.05; P=0.8; relative risk=1; 95% CI=0.4 to 3.0). The addition of Duke's treadmill score risk categories did not improve the predictive power of EECG (global chi2=0.17). The predictive power of the combination of EECG (including Duke score categories) and MPI was no better than that of MPI alone (global chi2=13.5).

CONCLUSIONS

Unlike EECG, MPI is an excellent prognostic indicator for adverse cardiac events in patients with known or suspected CAD and high exercise tolerance.

Coronary artery ectasia in Egyptian patients with coronary artery disease

We conducted a retrospective study of 45 Egyptian patients with coronary artery ectasia who underwent coronary bypass grafting at our institution between 1980 and 1995. We examined the anatomic distribution and type of coronary ectasia and its association with coronary risk factors in these patients, and evaluated the severity of their coronary artery disease. We compared these findings with those from a group of 230 Egyptian patients who did not have coronary ectasia. These patients also underwent coronary artery bypass grafting between 1980 and 1995 at our institution. Obesity was present in 60% of the patients who had coronary artery ectasia, compared with 42% of patients who did not have ectasia (P < 0.01). Coronary artery ectasia was not related to any coronary risk factors other than obesity. However, patients who had ectasia did have a higher rate of triple-vessel coronary artery disease than did patients without ectasia (82% vs 67%, P < 0.05). Of the coronary vessels affected by ectasia, 43% were left anterior descending arteries. Diffuse disease was noted in 84% of all ectatic segments. We conclude that in this patient population, 2 conditions had a positive correlation with coronary ectasia: obesity and the severity of coronary artery disease.

Risk factor analysis among Egyptian patients who underwent coronary artery bypass surgery

We conducted a retrospective review of Egyptian patients who underwent coronary artery bypass graft surgery at our institution between 1980 and 1995. We examined the prevalence of coronary artery disease risk factors and evaluated the early postoperative results. We then compared these results with the corresponding data in a subset of American patients who underwent coronary artery bypass grafting at our institution in 1993. There were 290 Egyptian patients: 275 men and 15 women. The mean age was 54.5 years (range, 30 to 70 years). Angina was present in 258 (89%) of the Egyptian patients; of these, 186 (72.1%) were in Canadian Cardiovascular Society class 3 or 4. Risk factor analysis revealed a high prevalence of hyperlipidemia (69.7%), cigarette-smoking (66.6%), family history of coronary artery disease (53.1%), hypertension (46.9%), obesity (46.2%), and diabetes mellitus (32.4%). Comparisons between the 2 groups showed that the risk factors, except for hypertension, were significantly higher in the Egyptian patients, despite the older age of the Americans (mean, 65.5 years; range, 22 to 88 years). The prevalence of triple-vessel disease was 86.6% in the Egyptian patients and 51.0% in the American patients (p < 0.001). The operative morbidity rates in the Egyptian patients were low: these included arrhythmias (13.8%), bleeding (13.4%), infection (7.6%), low cardiac output (3.4%), myocardial infarction (3.4%), and cerebrovascular accident (1.4%). The hospital mortality rate was 1.4% for the Egyptians and 1.7% for the Americans (NS). These results show that, despite the high prevalence of risk factors among Egyptian patients with coronary artery disease, coronary artery bypass grafting can be performed with low operative morbidity and mortality rates.

Early and late mortality of patients undergoing aortic valve replacement after previous coronary artery bypass graft surgery

BACKGROUND

In a small number of patients who undergo coronary artery bypass graft surgery (CABG), a hemodynamically significant aortic valve lesion requiring aortic valve replacement (AVR) develops as they grow older. In a limited number of studies in small patient groups, high mortality has been shown in patients undergoing AVR after CABG. We undertook this study to determine the mortality risk factors for patients who undergo AVR after CABG procedures.

METHODS AND RESULTS

The outcome of 104 patients treated at our institution between January 1983 and December 1993 was retrospectively reviewed. The initial surgery was CABG in all patients. The patient population included 86 men (83%) and 18 women (17%); their mean age was 67 years. Overall, 70% of patients had congestive heart failure, and 96% had multivessel coronary artery disease. The diagnosis was aortic stenosis in 68% of patients, aortic insufficiency in 16%, and combined aortic stenosis and aortic insufficiency in 16%. Postoperative complications included worsening congestive heart failure (35%), perioperative myocardial infarction (13%), and bleeding (28%). The early mortality was 14%, and the late mortality was 17% (mean follow-up, 35 months). The risk factors for early mortality were number of diseased vessels (P = .028), renal failure (0.000), and prior myocardial infarction (P = .028). A perioperative predictor of early mortality was cardiopulmonary bypass time (P = .000). The risk factors for late mortality included preoperative diabetes mellitus (P = .007), postoperative acute respiratory distress syndrome (P = .011), and ventricular arrhythmias (P = .0001). The survival at 1, 5, and 10 years was 96%, 75%, and 49%, respectively.

CONCLUSIONS

Risk factors were identified for early and late mortality in patients undergoing AVR after previous CABG. Although early morbidity and mortality were high, the longterm outcome of the survivors was favorable.