Knowledge, attitudes, and practices towards COVID-19 and COVID-19 vaccines among Obstetrician-Gynaecologists

INTRODUCTION AND OBJECTIVE

The article assesses the knowledge, attitudes, and practices of Obstetrician-Gynaecologists (OB/GYNs) in Israel regarding COVID-19, its impact on fertility, pregnancy and childbirth, and their positions on COVID-19 vaccines.

MATERIAL AND METHODS

A cross-sectional anonymous survey was employed, and the data analyzed using logistic regression models.

RESULTS

A total of 172 OB/GYN participants aged 44.9 years, primarily female (59.7%), mostly attending physicians (60.4%), had a mean knowledge score of 75.62%, with 81.1% having sufficient knowledge about general COVID-19 information, 11.9% having specific knowledge about pregnancy, birth, and breastfeeding, and 40.3% having knowledge about COVID-19 vaccination. Notably, only 27% of participants correctly identified the increased risk of preeclampsia in pregnant women with COVID-19. Nevertheless, all OB/GYN participants recommended the COVID-19 vaccination during pregnancy. The majority (65.1%) recommended vaccination across all trimesters, while a smaller percentage recommended it only in the second (25%) or third (6%) trimesters, and very few in the first trimester (4%). The study found that attitudes towards vaccination were influenced by workplace, role, religion, religious observance, and marital status.

CONCLUSIONS

The study showed a good level of knowledge regarding COVID-19 vaccines which contributed to OB/GYNs' recommendations to their patients. These findings can be valuable for designing future COVID-19 vaccination campaigns.

Uncovering the effects of COVID-19 on in-hospital cardiac arrest - a living systematic review and meta-analysis

INTRODUCTION AND OBJECTIVE

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) caused a global pandemic and had a negative impact on the entire health care system. To understand the effect of COVID-19 on outcomes of in-hospital cardiac arrest (IHCA), a systematic review and meta-analysis of studies was designed to compare the pre- and intra-pandemic periods of adult patients who suffered cardiac arrest, and additionally by performing a sub-analysis related to COVID-19 positive vs. negative patients in the same group of patients.

MATERIAL AND METHODS

To evaluate the impact of COVID-19 on IHCA outcomes a systematic review and meta-analysis was performed. Pubmed (MEDLINE), Scopus, Embase, Web of Science, and Cochrane database were searched for articles published from 1 January 2020 - 8 April 2023.

RESULTS

Return of spontaneous circulation events among IHCA patients in pre-COVID-19 and COVID-19 pandemic periods varied and amounted to 64.0% vs. 60.0%, respectively (OR=1.23; 95%CI: 1.19 to 1.26; p<0.001). Re-arrest occurrence was 4.5% vs. 4.9%, respectively (OR=1.24; 95%CI: 1.00 to 1.53; p=0.05). Survival to hospital discharge (SHD) was 25.1% compared to 20.9% for COVID-19 period (OR = 1.17; 95%CI: 0.96 to 1.41; p=0.12). During the COVID-19 period, SHD in COVID-19 positive patients was 14.0% compared to 25.9% for patients without COVID-19 (OR=0.72; 95%CI: 0.28 to 1.86; p=0.50). 30-day survival rate among COVID-19 positive vs. negative patients was 62.6% vs. 58.3%, respectively (OR =0.99; 95%CI: 0.23 to 4.24; p=0.99).

CONCLUSIONS

Patients with SARS-CoV-2 infection had reduced rates of ROSC and SDH, as well as poorer neurologic outcomes and increased in hospital re-arrests during the COVID-19 period. However, the 30-day survival rate was similar in SARS-CoV-2 positive and negative patients.

ETView SL versus Macintosh Direct Laryngoscope for Endotracheal Intubation Amid Simulated COVID-19 Cardiac Arrest: A Randomized Crossover Study

Airway management procedures, such as endotracheal intubation (ETI), pose a significant risk of aerosol generation, requiring robust personal protective equipment (PPE) against aerosol-generating procedures (AGP). This study aimed to assess the impact of PPE-AGP on intubation success rates, time to intubation, and glottic visualization using ETView and a standard Macintosh laryngoscope (MAC). A total of 52 physicians participated in this prospective, observational, randomized crossover study conducted in a medical simulation setting. Participants included COVID-19 patients with cardiac arrest scenarios with and without PPE-AGP who were intubated with ETView and MAC. During intubation without PPE-AGP, ETView showed a similar first-pass success rate (FPS) but had a shorter intubation time and better glottal hydration compared to MAC. In scenario B (with PPE-AGP), ETView outperformed MAC in FPS, initiation time, and glottic visualization. The use of PPE-AGP had little impact on ETView's performance. However, it negatively affected the Macintosh laryngoscope, reducing FPS and glottic visibility. Participants found intubation with ETView easier in both scenarios. In conclusion, as compared to the Macintosh laryngoscope, ETView demonstrated higher performance under the circumstances of the simulation, especially when PPE-AGP was used.

A comprehensive review and meta-analysis of suPAR as a predictor of acute kidney injury

INTRODUCTION AND OBJECTIVE

The global impact of acute kidney injury (AKI) has not been thoroughly investigated. With the development of new techniques, soluble urokinase plasminogen activator receptor (suPAR) has become increasingly important in the diagnosis of AKI. Therefore, a systematic review and meta-analysis was carried out to evaluate the predictive value of suPAR for AKI.

MATERIAL AND METHODS

The review and meta-analysis investigated the relationship between suPAR levels and acute kidney injury. Pubmed, Scopus, Cochrane Controlled Register of Trials, and Embase were searched for relevant studies from inception to 10 January 2023. Stata (Ver. 16 StataCorp, College Station, TX, USA) was used for all statistical analyses. A random effects model using the Mantel-Haenszel approach was employed, and odds ratios (OR) and standard mean differences (SMD) with 95% confidence intervals (CI) were calculated for binary and continuous outcomes, respectively.

RESULTS

Nine studies reported suPAR levels among patients with and without AKI. Pooled analysis showed that suPAR levels in patients with and without AKI varied and amounted to 5.23 ± 4.07 vs. 3.23 ±0.67 ng/mL (SMD = 3.19; 95%CI: 2.73 to 3.65; p<0.001). The results from the sensitivity analysis did not alter the direction.

CONCLUSIONS

This results show that increasing suPAR levels are associated with the occurrence of AKI. SuPAR might act as a novel biomarker for CI-AKI in clinical practice.

Effect of SARS-CoV-2 infection on out-of-hospital cardiac arrest outcomes - systematic review and meta-analysis

INTRODUCTION AND OBJECTIVE

The COVID-19 pandemic caused by the SARS-CoV-2 virus has recently presented the world with an unprecedented challenge. The purpose of this systematic review and meta-analysis is to investigate the relationship between SARS-CoV-2 infection and out-of-hospital cardiac arrest (OHCA) by comparing data from infected and non-infected individuals. The study adds to our understanding of the broader effects of the pandemic on public health and emergency care by examining the influence of COVID-19 on OHCA.

MATERIAL AND METHODS

A comprehensive systematic literature search was performed using PubMed, EMBASE, Scopus, Web of Science, the Cochrane Library and Google Scholar from 1 January 2020 - 24 May 2023. Incidence rates and odds ratios (ORs) or mean differences (MDs) with 95% confidence intervals (CIs) for risk factors were recorded from individual studies, and random-effects inverse variance modelling used to generate pooled estimates.

RESULTS

Six studies, involving 5,523 patients, met the criteria for inclusion in the meta-analysis. Survival to hospital admission, defined as admission to the emergency department with sustained return of spontaneous circulation (ROSC), among patients with and without on-going infection was 12.2% and 20.1%, respectively (p=0.09). Survival to hospital discharge/30-day survival rate was 0.8% vs. 6.2% (p<0.001). Two studies reported survival to hospital discharge in good neurological condition; however, the difference was not statistically significant (2.1% vs. 1.8%; p=0.37).

CONCLUSIONS

Compared to the non-infected patients, the ongoing SARS-CoV-2 infection was associated with worse OHCA outcomes.

Prediction value of soluble urokinase plasminogen activator receptor (suPAR) in COVID-19 patients - a systematic review and meta-analysis

INTRODUCTION AND OBJECTIVE

In COVID-19, the rapid prediction of the severity of a patient's condition using modern biomarkers can accelerate the implementation of appropriate therapy, and thus improve the patient's prognosis.

MATERIAL AND METHODS

A meta-analysis was conducted of data available in the literature on the differences in baseline suPAR blood concentration between patients (1) who tested positive and negative for COVID-19, (2) who had severe and non-severe COVID-19, and (3) COVID-19 survivors and non-survivors.

RESULTS

SuPAR levels in SARS-CoV-2 negative and positive patients varied and amounted to 3.61±1.59 ng/ml vs. 6.45±3.13 ng/ml, respectively (MD = -3.18; 95%CI: -4.71 to -1.66; p<0.001). suPAR levels among non-severe and severe COVID-19 patients were 7.06±2.64 ng/ml and 5.06±3.16 ng/ml (MD = 0.18; 95%CI: -2.48 to 2.83; p=0.90), respectively. Pooled analysis showed that suPAR levels between severe versus critical COVID-19 patients to be 5.59±1.54 ng/ml and 6.49±1.43 ng/ml, respectively (MD = -1.00; 95%CI: -1.31 to -0.70; p<0.001). The suPAR levels between ICU survivors versus non-survivors amounted to 5.82±2.33 ng/ml and 8.43±4.66 ng/ml (MD = -3.59; 95%CI: -6.19 to -1.00; p=0.007). In the case of in-hospital mortality, the mean suPAR level among survivors to hospital discharge was 5.63±1.27 ng/ml, compared to 7.85±2.61 ng/ml for patients who did not survive (MD = -3.58; 95%CI: -5.42 to -1.74; p<0.001).

CONCLUSIONS

SuPAR levels are significantly elevated in severe COVID-19 illness and maybe useful in predicting mortality. Further studies are needed to determine cut-off points and clarify the association of suPAR levels with disease progression. This is of utmost importance given the ongoing pandemic and overburdened health care systems.

The effect of zinc supplementation on the course of COVID-19 - A systematic review and meta-analysis

INTRODUCTION AND OBJECTIVE

Zinc is a trace element that plays a role in stimulating innate and acquired immunity. The aim of the study was to determine the antiviral effect of the administration of zinc in COVID-19 patients.

MATERIAL AND METHODS

A literature search was performed in P Web of Science, PubMed, Scopus and Cochrane databases from 1 January 2020 - 22 August 2022. In addition, reference lists of the included articles and their related citations in PubMed were also reviewed for additional pertinent studies.

RESULTS

A total of 9 eligible studies were identified. In-hospital mortality in zinc supplementation patients, and patients treated without zinc, varied and amounted to 21.6% vs. 23.04% difference (OR=0.71; 95%CI: 0.62-0.81; p<0.001). 28-day to 30-day mortality in patients treated with zinc was 7.7%, compared to 11.9% for patients treated without zinc (OR=0.61; 95%CI: 0.35-1.06; p=0.08). In-hospital adverse events among patients treated with and without COVID-19 did not show any statistically significant differences in relation to acute kidney injury occurrence (12.8% vs. 12.4%, respectively; OR=0.63; 95%CI: 0.19-2.12; p=0.45, as well as need for mechanical ventilation (13.2% vs. 14.1%; OR=0.83; 95%CI: 0.52-1.32; p=0.43).

CONCLUSIONS

Zinc supplementation is associated with lower COVID-19 in-hospital mortality. Additionally, it is risk-free in COVID-19 patients since there have been no negative side effects, such as acute renal damage or the requirement for mechanical ventilation compared to patients without COVID-19. Due to scientific evidence and the role it represents in the human body, zinc supplementation should be taken into consideration for COVID-19 patients as an adjunct therapy.

The Influence of COVID-19 on Out-Hospital Cardiac Arrest Survival Outcomes: An Updated Systematic Review and Meta-Analysis

Cardiopulmonary resuscitation in patients with out-of-hospital cardiac arrest (OHCA) is associated with poor prognosis. Because the COVID-19 pandemic may have impacted mortality and morbidity, both on an individual level and the health care system as a whole, our purpose was to determine rates of OHCA survival since the onset of the SARS-CoV2 pandemic. We conducted a systematic review and meta-analysis to evaluate the influence of COVID-19 on OHCA survival outcomes according to the PRISMA guidelines. We searched the literature using PubMed, Scopus, Web of Science and Cochrane Central Register for Controlled Trials databases from inception to September 2021 and identified 1775 potentially relevant studies, of which thirty-one articles totaling 88,188 patients were included in this meta-analysis. Prehospital return of spontaneous circulation (ROSC) in pre-COVID-19 and COVID-19 periods was 12.3% vs. 8.9%, respectively (OR = 1.40; 95%CI: 1.06-1.87; p < 0.001). Survival to hospital discharge in pre- vs. intra-COVID-19 periods was 11.5% vs. 8.2% (OR = 1.57; 95%CI: 1.37-1.79; p < 0.001). A similar dependency was observed in the case of survival to hospital discharge with the Cerebral Performance Category (CPC) 1-2 (6.7% vs. 4.0%; OR = 1.71; 95%CI: 1.35-2.15; p < 0.001), as well as in the 30-day survival rate (9.2% vs. 6.4%; OR = 1.63; 95%CI: 1.13-2.36; p = 0.009). In conclusion, prognosis of OHCA is usually poor and even worse during COVID-19.

Efficacy and Safety of Video-Laryngoscopy versus Direct Laryngoscopy for Double-Lumen Endotracheal Intubation: A Systematic Review and Meta-Analysis

The available meta-analyses have inconclusively indicated the advantages of video-laryngoscopy (VL) in different clinical situations; therefore, we conducted a systematic review and meta-analysis to determine efficacy outcomes such as successful first attempt or time to perform endotracheal intubation as well as adverse events of VL vs. direct laryngoscopes (DL) for double-lumen intubation. First intubation attempt success rate was 87.9% for VL and 84.5% for DL (OR = 1.64; 95% CI: 0.95 to 2.86; I² = 61%; p = 0.08). Overall success rate was 99.8% for VL and 98.8% for DL, respectively (OR = 3.89; 95%CI: 0.95 to 15.93; I² = 0; p = 0.06). Intubation time for VL was 43.4 ± 30.4 s compared to 54.0 ± 56.3 s for DL (MD = −11.87; 95%CI: −17.06 to −6.68; I² = 99%; p < 0.001). Glottic view based on Cormack–Lehane grades 1 or 2 equaled 93.1% and 88.1% in the VL and DL groups, respectively (OR = 3.33; 95% CI: 1.18 to 9.41; I² = 63%; p = 0.02). External laryngeal manipulation was needed in 18.4% cases of VL compared with 42.8% for DL (OR = 0.28; 95% CI: 0.20 to 0.40; I² = 69%; p < 0.001). For double-lumen intubation, VL offers shorter intubation time, better glottic view based on Cormack–Lehane grade, and a lower need for ELM, but comparable first intubation attempt success rate and overall intubation success rate compared with DL.

Vitamin D supplementation to treat SARS-CoV-2 positive patients. Evidence from meta-analysis

BACKGROUND

Vitamin D is a likely candidate for treatment as its immune modulating characteristics have effects on coronavirus disease 2019 (COVID-19) patients. It was sought herein, to summarize the studies published to date regarding the vitamin D supplementation to treat severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) positive patients.

METHODS

A systematic review and meta-analysis were performed following Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement. The primary outcome were 14-day and in-hospital mortality reported as an odds ratio (OR) with the associated 95% confidence interval (CI).

RESULTS

Eight articles were included in the review with a combined total of 2,322 individual patients, 786 in the vitamin D supplementation group and 1,536 in the control group. The use of vitamin D compared to the group without vitamin D supplementation was associated with a lower 14-day mortality (18.8% vs. 31.3%, respectively; OR = 0.51; 95% CI: 0.12-2.19; p = 0.36), a lower in-hospital mortality (5.6% vs. 16.1%; OR = 0.56; 95% CI: 0.23-1.37; I2 = 74%; p = 0.20), the rarer intensive care unit admission (6.4% vs. 23.4%; OR = 0.19; 95% CI: 0.06-0.54; I2 = 77%; p = 0.002) as well as rarer mechanical ventilation (6.5% vs. 18.9%; OR = 0.36; 95% CI: 0.16-0.80; I2 = 0.48; p = 0.01).

CONCLUSIONS

Vitamin D supplementation in SARS-CoV-2 positive patients has the potential to positively impact patients with both mild and severe symptoms. As several high-quality randomized control studies have demonstrated a benefit in hospital mortality, vitamin D should be considered a supplemental therapy of strong interest. Should vitamin D prove to reduce hospitalization rates and symptoms outside of the hospital setting, the cost and benefit to global pandemic mitigation efforts would be substantial.

Meta-analysis of chest compression-only versus conventional cardiopulmonary resuscitation by bystanders for adult with out-of-hospital cardiac arrest

BACKGROUND

According to the guidelines of cardiopulmonary resuscitation (CPR) conducted by bystanders, two methods of CPR are feasible: standard CPR (sCPR) with mouth-to-mouth ventilations and continuous chest compression-only CPR (CCC) without rescue breathing. The goal herein, was to evaluate the effect of sCPR (30:2) and CCC on resuscitation outcomes in patients with out-of-hospital cardiac arrest (OHCA) patients.

METHODS

This study was a systematic review and meta-analysis. Using standardized criteria, Pub- Med, Web of Science, Scopus, EMBASE and Cochrane Collaboration were searched for trials assessing the effect of sCPR vs. CCC on resuscitation outcomes after adult OHCA. Random-effects model meta-analysis was applied to calculate the mean deviation (MD), odds ratio (OR) and 95% confidence interval (CI).

RESULTS

Overall, 3 randomized controlled trials and 12 non-randomized trials met the inclusion criteria. Survival to hospital discharge with sCPR was 10.2% compared to 9.3% in the CCC group (OR = 1.04; 95% CI: 0.93-1.16; p = 0.46). Survival to hospital discharge with good neurological outcome measured with the cerebral performance category (CPC 1 or 2) was 6.5% for sCPR vs. 5.8% for CCC (OR = 1.00; 95% CI: 0.84-1.20; p = 0.98). Prehospital return of spontaneous circulation (ROSC) in sCPR and CCC groups was 15.9% and 14.8%, respectively (OR = 1.13; 95% CI: 0.91-1.39; p = 0.26). Survival to hospital admission with ROSC occurred in 29.5% of the sCPR group compared to 28.4% in CCC group (OR = 1.20; 95% CI: 0.89-1.63; p = 0.24).

CONCLUSIONS

This systematic review and meta-analysis concluded that there were no significant differences in the resuscitation outcomes between the use of standard cardiopulmonary resuscitation and chest compression only.

12-month interim results of a prospective study of patients with mild to moderate open-angle glaucoma undergoing combined viscodilation of Schlemm's canal and collector channels and 360° trabeculotomy as a standalone procedure or combined with cataract surgery

PURPOSE

To characterize clinical outcomes of combined viscodilation of Schlemm's canal and collector channels and 360° trabeculotomy as a standalone procedure or combined with cataract surgery in eyes with mild to moderate open-angle glaucoma (OAG).

METHODS

In this prospective case series, the OMNI glaucoma surgical platform (Sight Sciences, Menlo Park, CA) was utilized to perform the procedure either combined with phacoemulsification or as a standalone procedure. Changes from baseline in intraocular pressure (IOP) and IOP-lowering medications were evaluated through the first 12 months of a planned 24-month follow-up period.

RESULTS

Among 17 eyes of 15 subjects, mean IOP was reduced from 20.4 mmHg to 12.7-13.7 mmHg through 12 months of follow-up (p < 0.001 at every time point) and mean medications reduced from 2.5 to 0.1-0.6 (p < 0.001 at every time point). IOP reductions in eyes undergoing standalone surgery were approximately 2-4 mmHg greater at each time point compared to eyes undergoing surgery combined with phacoemulsification; this may be related to a higher baseline IOP in the former eyes (22.1 vs 18.5 mmHg). Six eyes developed hyphema, of which three required washout for elevated IOP on the first postoperative day; six additional eyes had IOP elevations that resolved with medical management.

CONCLUSION

Viscodilation of Schlemm's canal and collector channels paired with ab interno trabeculotomy performed with a single integrated instrument (OMNI), whether as standalone or combined with phacoemulsification, effectively lowers both IOP and the need for IOP-lowering medications through 12 months of follow-up.

Platelet Factor 4 (PF4) Release during Human Platelet Aggregation in Diabetic Patients

The release of platelet factor 4 during platelet aggregation was investigated in diabetic patients. We observed an increased release of platelet factor 4 in diabetic patients.

The authors suggest that the increased release of platelet factor 4 may play an essential role in pathogenesis of thromboembolic complications in diabetes mellitus.

Effects of arachidonyl-2'-chloroethylamide (ACEA) on the protective action of various antiepileptic drugs in the 6-Hz corneal stimulation model in mice

Accumulating evidence indicates that cannabinoid CB₁ receptor ligands play a pivotal role in seizures, not only in preclinical studies on animals, but also in clinical settings. This study was aimed at characterizing the influence of arachidonyl-2′-chloroethylamide (ACEA–a selective cannabinoid CB₁ receptor agonist) co-administered with phenylmethylsulfonyl fluoride (PMSF) on the anticonvulsant potency of various antiepileptic drugs (clobazam, lacosamide, levetiracetam, phenobarbital, tiagabine and valproate) in the 6-Hz corneal stimulation model. Psychomotor seizures in male albino Swiss mice were evoked by a current (32 mA, 6 Hz, 3 s stimulus duration) delivered via corneal electrodes. Potential adverse effects produced by the antiepileptic drugs in combination with ACEA+PMSF were assessed using the chimney test (motor performance), passive avoidance task (remembering and acquisition of learning), and grip-strength test (muscular strength). Brain concentrations of antiepileptic drugs were measured by HPLC to exclude any pharmacokinetic contribution to the observed effect. ACEA (5 mg/kg, i.p.) + PMSF (30 mg/kg, i.p.) significantly potentiated the anticonvulsant potency of levetiracetam (P<0.05), but not that of clobazam, lacosamide, phenobarbital, tiagabine or valproate in the 6-Hz corneal stimulation model. Moreover, ACEA+PMSF did not significantly affect total brain concentrations of levetiracetam in mice. No behavioral side effects were observed in animals receiving combinations of the studied antiepileptic drugs with ACEA+PMSF. In conclusion, the combined administration of ACEA+PMSF with levetiracetam is associated with beneficial anticonvulsant pharmacodynamic interaction in the 6-Hz corneal stimulation model. The selective activation of cannabinoid CB₁ receptor-mediated neurotransmission in the brain may enhance levetiracetam-related suppression of seizures in epilepsy patients, contributing to the efficacious treatment of epilepsy in future.

Gold and gold-iron modified zeolites--towards the adsorptive deodourisation

Zeolites exhibiting different structures (Y, Beta, and ZSM-5) were modified with gold and iron and applied for odour adsorption from the air containing dibutyl sulphide (Bu(2)S) used as a representative odour producing compound. The structure of the zeolites used determines the rate of adsorption (higher on Y type zeolites and smaller on two other zeolites), whereas hydrophilicity affects the selectivity towards Bu(2)S adsorption increasing in the order: Y<Beta<ZSM-5. For the same zeolite structure, Bu(2)S adsorption selectivity depends on the total acidity of zeolites which increases after iron modification. The texture and surface properties of the modified zeolites were studied by XRD, XPS, UV-vis, TEM, pyridine adsorption and FTIR, test reactions (acetonylacetone cyclisation, isopropanol decomposition).

Changes in the content of health-promoting compounds and antioxidant activity of broccoli after domestic processing

The effect of water- and steam-cooking on the content of vitamin C, polyphenols, carotenoids, tocopherols and glucosinolates, as well as on the antioxidant activity of broccoli, are reported. Flavonoids, phenolic acids, vitamins C and E, beta-carotene, lutein, and glucosinolates in domestically processed broccoli were quantified using high-performance liquid chromatography (HPLC) methods; total polyphenols were determined with Folin-Ciocalteu reagent. The antioxidant capacities of broccoli extracts were evaluated using the Trolox equivalent antioxidant capacity (TEAC) and 2,2-diphenyl-1-picrylhydrazyl (DPPH) methods. The results indicated that steam-cooking of broccoli results in an increase in polyphenols, as well as the main glucosinolates and their total content as compared with fresh broccoli, whereas cooking in water has the opposite effect. Steam-cooking of broccoli has no influence on vitamin C, whereas cooking in water significantly lowers its content. Both, water- and steam-cooking of broccoli results in an increase in beta-carotene, lutein, and alpha- and gamma-tocopherols as compared with fresh broccoli. Similar effects of steaming and water-cooking of broccoli on their antioxidant activity were observed.

Liposomal cargo unloading induced by pH-sensitive peptides

Amphiphilic peptides designed to have a pH-dependent conformational change and membrane activity are described. At physiologic pH, the peptides would exist in a random coil conformation, but at endosomal pH values they would switch to amphiphilic alpha-helices, disrupt membranes, and release liposomal contents. A series of peptides have been investigated that contain a high percentage of Glu residues for the pH-induced conformational switch, and Leu residues for optimal lipid binding. Circular dichroism (CD) results in aqueous and liposomal environments were performed and demonstrate a pH-dependent shift to helicity upon acidification. Liposomal release data at neutral and acidic pH, also document the success of this design strategy.

Probing essential residues for cellular uptake with a cationic nuclear localization signal sequence

The nuclear localization signal sequence (NLS) of the transcription factor NF-kappaB is a cationic peptide with the ability to cross the cytoplasmic membrane and facilitate the delivery of attached cargo, such as DNA and proteins, to cells. Previous research had pointed to the essential role of cationic residues, therefore, the importance of residues within the NLS of NF-kappaB was evaluated for cellular uptake using an alanine replacement strategy. Although it was expected that removal of the cationic groups would have the greatest effect on membrane translocation, the most significant decreases in cellular uptake occurred with the replacement of the hydrophilic Q6 (80%) and the hydrophobic L8 (70%) residues. Replacement of the positively charged residues resulted in 30-40% decrease in cellular uptake, indicating that electrostatic interactions are not the primary driving force for membrane translocation.

Alpha-lactose monohydrate single crystals as hosts for matrix isolation of guest biopolymers

Single crystals of alpha-lactose monohydrate show a remarkable tendency to include biopolymers, such as proteins, oligonucleotides and dextrans, within the growing lattice. Glycosylation increased the amount of protein contained within the crystals. The guest molecules were found only within the (010) growth sector of the hatchet shaped crystals, thereby binding preferentially to one of the seven developed crystal faces. The topographical features of the active surface are described.

DNA binding properties of basic helix-loop-helix fusion proteins of Tal and E47

The basic helix-loop-helix (bHLH) transcription factor Tal has been shown to form heterodimers with the ubiquitously expressed bHLH transcription factor E47 and thereby modulate gene expression. The absence of homodimeric Tal-DNA complexes had been attributed to the inability of Tal to homodimerize, but subsequent studies have shown that the bHLH region of Tal does homodimerize. In order to correlate the contributions of both the basic region and the helix-loop-helix (HLH) domain to the lack of DNA binding by Tal homodimers, mutant and fusion proteins based on Tal and E47 were designed and synthesized. Size-exclusion chromatography established that all mutant and fusion proteins were dimeric. Point mutations were made within the basic region of Tal based on residues within E47 that are essential for DNA binding, but an affinity for DNA was not observed. Even complete replacement of the basic region in Tal with the basic region of E47, in an E47-Tal fusion protein, did not confer DNA binding upon the protein. However, when the dimerization domain in Tal was replaced with its E47 counterpart, in a Tal-E47 fusion protein, sequence specific DNA binding was observed with an apparent dissociation constant of 3.6 x 10(-9) M2. Furthermore, circular dichroism studies showed that the basic region of Tal in the Tal-E47 fusion protein underwent a random coil to helix transition in the presence of a specific DNA probe. These experimental observations indicate that the inability of Tal homodimers to recognize DNA stems from a misalignment of its basic region with respect to the HLH domain, rather than an intrinsic inability of the Tal basic region to bind DNA.

The design of self-replicating helical peptides

The self-assembly of helical peptides and information transfer through autocatalysis and cross-catalysis are the foundation of peptide-based molecular evolution models. Many fundamental properties of living systems, such as environmental sensitivity, chiroselectivity, cross-catalysis, dynamic error correction and conditional selection, are exhibited by various self-replicating peptide systems. Recently, advances have been made in the design of peptide systems with autocatalytic and cross-catalytic properties.

Targeting the dimerization interface for irreversible inhibition of HIV-1 protease

A novel strategy was used to irreversibly inhibit HIV-1 protease. The inhibitor was designed to form a disulfide bond with Cys95, present at the dimerization interface of HIV-1 protease. The inhibitor was shown to be active against HIV-1 protease with K(inact) = 3.7 microM and V(inact) = 0.012 min(-1).

Uncoiling c-Jun coiled coils: inhibitory effects of truncated Fos peptides on Jun dimerization and DNA binding in vitro

c-Jun is an oncoprotein that comprises a portion of the AP-1 transcription factor and belongs to the basic-leucine zipper (bZIP) DNA binding protein family. Using peptides derived from the leucine zipper region of Fos, we have developed agents that inhibit Jun's DNA binding in the low micromolar range. Fos peptides that were effective inhibitors in the DNA binding assay were also found to inhibit cellular Jun binding to an AP-1 site in a luciferase reporter plasmid in MCF-7 cells. Size exclusion studies confirmed that peptides that inhibit the DNA binding of Jun also inhibit its dimerization. These peptides were found to have a cytotoxic effect on the MCF-7 cell line when delivered with the transfecting agent Tfx-50, possibly due to their role as transcription factor regulators.

A pH-tunable peptide ligase

A chemical ligation system is reported, in which a highly acidic coiled-coil peptide was used to template two basic peptide fragments and catalyze their condensation, in a pH-tunable fashion, to generate a coiled-coil product. This template showed a high catalytic efficiency (with single turnover) under neutral conditions. Under acidic conditions, however, its catalytic efficiency was reduced by approximately 4500-fold.

Helical peptide and protein design

The design of dimeric coiled-coils has ultimately led to novel applications, such as self-replicating peptide systems, whereas the structural features of the less common trimeric coiled-coil continue to be elucidated. Novel topologies have been discovered in designed proteins, as exemplified by the right-handed tetrameric coiled-coil and the inverted U four-helix bundle, and a single switch of two amino acids within a protein has been shown to be sufficient to designate a new protein fold. Conformational switching from helix to sheet has been observed for designed peptides and transcription factors, whereas peptides designed from beta-amino acids have been found to adopt a helical conformation in aqueous solution.

Probing the role of interfacial residues in a dimerization inhibitor of HIV-1 protease

The importance of each side chain of a cross-linked interfacial peptide inhibitor of HIV-1 protease was evaluated using an alanine scanning approach. Whereas the parent inhibitor has an IC50 value of 350 nM, values for the mutations reported here range from 280-9200 nM. The relative importance or each residue was thus assigned and correlated to the solvent accessible surface area (SASA) exposed upon mutation.

Structure-function relationship in a beta-sheet peptide inhibitor of E47 dimerization and DNA binding

A beta-sheet peptide inhibitor, 2H10, has been developed that inhibits the dimerization of the transcription factor E47. Inhibition of E47 dimerization has been demonstrated to also inhibit the DNA binding of this transcription factor. Truncated peptides based on 2H10 have demonstrated that the beta-sheet content of these peptides directly correlates with their inhibitory properties. Individual residues within 2H10 were identified that were responsible for the beta-sheet secondary structure by employing an alanine replacement strategy. The beta-sheet character of the alanine mutants also correlated well with their inhibition of E47 DNA binding. These results provide further evidence that interactions between the interfacial peptide inhibitors of E47 and the transcription factor itself are mediated by a beta-sheet structure.

Selective amplification by auto- and cross-catalysis in a replicating peptide system

Self-replication has been demonstrated in synthetic chemical systems based on oligonucleotides, peptides and complementary molecules without natural analogues. However, within a living cell virtually no molecule catalyses its own formation, and the search for chemical systems in which both auto- and cross-catalysis can occur has therefore attracted wide interest. One such system, consisting of two self-replicating peptides that catalyse each other's production, has been reported. Here we describe a four-component peptide system that is capable of auto- and cross-catalysis and allows for the selective amplification of one or more of the products by changing the reaction conditions. The ability of this system selectively to amplify one or more molecules in response to changes in environmental conditions such as pH or salt concentration supports the suggestions that self-replicating peptides may have played a role in the origin of life.

Restricting the flexibility of crosslinked, interfacial peptide inhibitors of HIV-1 protease

Interfacial peptides of HIV-1 protease were crosslinked with varying length alkyl-chains containing either a single cis or trans double bond, or a triple bond to remove degrees of freedom within the tethers. The synthesis of these compounds and their effects on the activity of HIV-1 protease are described.

A beta-sheet peptide inhibitor of E47 dimerization and DNA binding

BACKGROUND

Many transcription factors are active only in their dimeric form, including the basic-helix-loop-helix (bHLH) family of transcription factors. The disruption of the dimer therefore presents a means of inhibiting the biological functions of such transcription factors. E47 is a homodimeric bHLH transcription factor with a four-helix bundle dimerization interface. Here, we investigate the concept of dimerization inhibition using peptides derived from the dimerization domain of E47.

RESULTS

We have synthesized several peptides corresponding to the E47 dimerization interface that inhibit E47 DNA-binding activity with IC50 values in the range of 3.6-120 mM. Interestingly, helix II; a peptide corresponding to the carboxy-terminal helix of the E47 dimerization interface, adopted a beta-sheet structure in solution, as shown using circular dichroism (CD), and inhibited the binding of E47 to DNA at equimolar concentrations. Size-exclusion chromatography, analytical ultracentrifugation and cross-linking experiments verified that this peptide prevented E47 dimerization. Furthermore, CD experiments provided evidence that helix II could induce a beta-sheet secondary structure upon the highly alpha-helical E47 bHLH domain.

CONCLUSIONS

This study is the first demonstration of dissociative inhibition in the bHLH class of transcription factors and also provides an example of beta-sheet induction in an alpha-helical protein. Future experiments will prove the structural determinants of the beta-sheet secondary structure in helix II and investigate the generality of the dissociative strategy in other transcription factor families.

Inhibiting the dimeric restriction endonuclease EcoRI using interfacial helical peptides

BACKGROUND

Many enzymes are active only in a dimeric form, including a variety of type II restriction endonucleases. Disruption of subunit interactions is therefore a potential method for multimeric enzyme inhibition. EcoRI is a homodimeric restriction endonuclease, the dimeric interface of which consists of a four-helix bundle. We set out to design helical peptides to interact with this interface and block dimer formation, thus rendering EcoRI inactive.

RESULTS

Here we describe two synthetic, helical peptides based on the interfacial region of EcoRI. Both peptides inhibit the enzyme, but the peptide derived from the alpha 4 helix of EcoRI had both a higher helical content and better efficacy than a variant peptide, alpha 4(Leu), that has three Ile-->Leu mutations (IC50 values of 27 microM and 90 microM, and helical contents of 29% and 10%, respectively). Size-exclusion chromatography confirmed that the alpha 4 peptide disrupted dimerization of EcoRI, and circular dichroism indicated that EcoRI remained folded upon binding to alpha 4. Inhibition with alpha 4 and alpha 4(Leu) was shown to be specific for EcoRI, as the dimeric restriction enzyme PvuII was not affected by the peptides.

CONCLUSIONS

Interfacial peptide inhibitors of the dimeric EcoRI were obtained that both inhibit dimerization and endonuclease activity. The peptide sequence with a preference for a helical conformation was a more effective inhibitor, presumably because the more preorganized state enhanced interactions with the helical interface of EcoRI. The specific nature of this endonuclease-peptide interaction was also confirmed. The potential of this strategy for inhibiting other enzyme classes is currently being addressed.

Endothiopeptide inhibitors of HIV-1 protease

Endothiopeptide inhibitors of HIV-1 protease were synthesized by chemical and enzymatic methods to individually replace each backbone amide bond in 1 with a thioamide-linkage. Interestingly, agent 7, which contains a thioamide-linkage between the P2' and P3' positions of 1, was the most potent, competitive inhibitor of HIV-1 protease with a Ki of 3.4 microM.

Inhibiting the assembly of protein-protein interfaces

Protein-protein association is found throughout mechanisms of cellular growth and differentiation, and viral replication. Inhibiting the assembly of protein complexes, therefore, presents itself as a novel means of inhibition for a wide variety of cellular and viral events. Peptides and small molecules that modify the overall quaternary structure of a selection of receptor-ligand interactions and oligomeric viral enzymes have been developed recently.

Subtilisin-catalyzed religation of proteolyzed hen egg-white lysozyme: investigation of the role of disulfides

BACKGROUND

The use of proteases to form, instead of break, peptide bonds has expanded the repertoire of techniques available for protein semisynthesis. Several groups have previously reported the use of proteases in aqueous-organic solvents to form single amide bonds within proteins, but low yields and lengthy reaction times make this an impractical approach to protein synthesis. We recently found that proteolyzed triose phosphate isomerase can be re-ligated rapidly and efficiently by subtilisin, in mixed aqueous-organic solvent systems.

RESULTS

We now report the use of subtilisin to resynthesize hen egg-white lysozyme from a mixture of its proteolyzed fragments in high yield and with rapid reaction times. This enzymatic religation can also be achieved after reduction of the four disulfide bonds present in lysozyme, with the same efficiency as that observed for the disulfide-containing proteolysis mixture.

CONCLUSIONS

For egg-white lysozyme, the subtilisin religation reaction can be used to re-synthesize a proteolyzed protein even after reduction of disulfide bonds. The utility of this reaction in more generalized protein semisynthesis reactions is currently being explored.

Synthesis of the basic-helix-loop-helix region of the immunoglobulin enhancer binding protein E47 and evaluation of its structural and DNA binding properties

The basic-helix-loop-helix (bHLH) region of the immunoglobulin enhancer binding protein E47 (IEB E47) was prepared in high yield by a solid-phase peptide synthesis methodology. Size-exclusion chromatography, sedimentation equilibrium and cross-linking data showed that the synthetic bHLH protein, 1, was dimeric, and higher-order aggregates of trimer and tetramer were also observed. The circular dichroism spectrum of 1 showed a high helical content, which increased upon addition of DNA containing the kappa E2 sequence. Gel mobility shift experiments showed that protein 1 bound sequence specifically to the kappa E2 sequence with a binding constant of 10(-10) M2, and had an affinity for other E box sequences as well. Comparisons between the co-crystal structure of IEB E47 with DNA and structural studies in solution showed lower helical contents in solution as would have been predicted from the crystal structure.

The rational design of highly stable, amphiphilic helical peptides

A computer algorithm was devised for the evaluation of helical stability of potentially amphiphilic peptide sequences of specified length containing a set number of leucines in the hydrophobic region. All possible combinations of Glu, Lys and Gln in the hydrophilic region are rated using a set of empirical rules for salt bridge formation in alpha-helices, and the sequences which rate the highest are displayed. The rules for salt bridge formation were largely derived from published studies on the effects of salt bridges on helical stability. The algorithm was tested by redesigning a known amphiphilic alpha-helical peptide, alpha 1B or 1, which has been shown to aggregate into four-helix bundles. Comparison of the circular dichroism spectra of two peptides, 2 and 3, to 1 demonstrated that the redesigned peptide with the highest priority score from the algorithm, 2, was more helical when aggregated and slightly more helical as a monomer, whereas the peptide with the low priority score, 3, was somewhat less helical when aggregated and much less helical when monomeric. These results support the design of the algorithm, although conclusions based on aggregation data are complicated by the importance of interhelix contacts in the bundle. Further studies are underway to examine the reliability of the algorithm's predictions regarding the design of other helical peptides.

Chromosome numbers of goldenrods, Euthamia and Solidago (Compositae-Astereae)

Chromosome number determinations were made from 227 populations of 43 taxa of Euthamia and Solidago. Nearly all were confirmations of previous reports. The majority of the populations sampled were from Ontario. First report: Solidago hispida Muhl. var. tonsa Fern., 2n = 18.

[Supraventricular subarachnoid cysts]

Five patients with supraventricular subarachnoid cysts are described. In most patients epilepsy was the presenting sign. Cerebral angiography showed in all cases only an avascular lesion and and the correct diagnosis was established only during the operation. In only one case recurrent filling of the cyst was observed.