Inhibitory effect of thymoquinone from Nigella sativa against SARS-CoV-2 main protease. An in-silico study

Abstract Nigella sativa is known for the safety profile, containing a wealth of useful antiviral compounds. The main protease (Mpro, 3CLpro) of severe acute respiratory syndrome 2 (SARS-CoV-2) is being considered as one of the most attractive viral target, processing the polyproteins during viral pathogenesis and replication. In the current investigation we analyzed the potency of active component, thymoquinone (TQ) of Nigella sativa against SARS-CoV-2 Mpro. The structures of TQ and Mpro was retrieved from PubChem (CID10281) and Protein Data Bank (PDB ID 6MO3) respectively. The Mpro and TQ were docked and the complex was subjected to molecular dynamic (MD) simulations for a period 50ns. Protein folding effect was analyzed using radius of gyration (Rg) while stability and flexibility was measured, using root means square deviations (RMSD) and root means square fluctuation (RMSF) respectively. The simulation results shows that TQ is exhibiting good binding activity against SARS-CoV-2 Mpro, interacting many residues, present in the active site (His41, Cys145) and also the Glu166, facilitating the pocket shape. Further, experimental approaches are needed to validate the role of TQ against virus infection. The TQ is interfering with pocket maintaining residues as well as active site of virus Mpro which may be used as a potential inhibitor against SARS-CoV-2 for better management of COVID-19.

Molecular docking, dynamics, and quantum chemical study of vanillylacetone and beta-hydroxy ketone derivatives against Mpro of SARS-CoV-2

This study is carried out to find novel active drug candidates which can effectively bind to key residues of main protease (Mpro) of SARS-CoV-2. We performed molecular docking of fifty-seven (57) ligands from two classes: vanillylacetone and its derivatives and beta-hydroxy ketone derivatives against Mpro of SARS-CoV-2. We also docked three antiviral drugs as reference/benchmark drugs including remdesivir (RDV), chloroquine (CQ), and hydroxychloroquine (HCQ) against Mpro for comparison of inhibition tendencies of selected ligands. Binding energies of our reference drugs are as: CQ = -5.1 kcal mol-1 (with predicted inhibition constant (Ki pred) = 177 μmol), HCQ = -5.7 kcal mol-1 (Ki pred = 64.07 μmol) and RDV -6.3 kcal mol-1 (Ki pred = 13.95 μmol). We got remarkable results for our docked ligands as 79% of total ligands indicated binding energies better than CQ, 39 % better than both HCQ and CQ, and 19 % better than all reference drugs. More interestingly interaction analysis of eight best-docked ligands showed that they interacted with desired key residues of Mpro. We further selected the four best-docked ligands L1 = -6.6 kcal mol-1 (Ki pred =13.95 μmol), L6 = -7.0 kcal mol-1 (Ki pred = 7.08 μmol), L34 = -6.0 kcal mol-1 (Ki pred = 38.54 μmol), and L50 = -6.6 kcal mol-1 (Ki pred =13.95 umol) for further analysis by quantum chemical study, molecular dynamic (MD) simulations and ADMET analysis. We have also carried out MD-simulations of six more docked ligand L2, L14, L20, L36, L46 and L48 some of which were showing weak binding affinities and some average binding affinities to check their simulation behavior. Their RMSD, RMSF and binding free energy results were also quite satisfying. We believe the current investigation will evoke the scientific community and highlights the potential of selected compounds for potential use as antiviral compounds against Mpro of SARS-CoV-2.

Longitudinal stability of molecular alterations and drug response profiles in tumor spheroid cell lines enables reproducible analyses

The utility of patient-derived tumor cell lines as experimental models for glioblastoma has been challenged by limited representation of the in vivo tumor biology and low clinical translatability. Here, we report on longitudinal epigenetic and transcriptional profiling of seven glioblastoma spheroid cell line models cultured over an extended period. Molecular profiles were associated with drug response data obtained for 231 clinically used drugs. We show that the glioblastoma spheroid models remained molecularly stable and displayed reproducible drug responses over prolonged culture times of 30 in vitro passages. Integration of gene expression and drug response data identified predictive gene signatures linked to sensitivity to specific drugs, indicating the potential of gene expression-based prediction of glioblastoma therapy response. Our data thus empowers glioblastoma spheroid disease modeling as a useful preclinical assay that may uncover novel therapeutic vulnerabilities and associated molecular alterations.

A threefold approach including quantum chemical, molecular docking and molecular dynamic studies to explore the natural compounds from Centaurea jacea as the potential inhibitors for COVID-19

In the current report, we studied the possible inhibitors of COVID-19 from bioactive constituents of Centaurea jacea using a threefold approach consisting of quantum chemical, molecular docking and molecular dynamic techniques. Centaurea jacea is a perennial herb often used in folk medicines of dermatological complaints and fever. Moreover, anticancer, antioxidant, antibacterial and antiviral properties of its bioactive compounds are also reported. The Mpro (Main proteases) was docked with different compounds of Centaurea jacea through molecular docking. All the studied compounds including apigenin, axillarin, Centaureidin, Cirsiliol, Eupatorin and Isokaempferide, show suitable binding affinities to the binding site of SARS-CoV-2 main protease with their binding energies -6.7 kcal/mol, -7.4 kcal/mol, -7.0 kcal/mol, -5.8 kcal/mol, -6.2 kcal/mol and -6.8 kcal/mol, respectively. Among all studied compounds, axillarin was found to have maximum inhibitor efficiency followed by Centaureidin, Isokaempferide, Apigenin, Eupatorin and Cirsiliol. Our results suggested that axillarin binds with the most crucial catalytic residues CYS145 and HIS41 of the Mpro, moreover axillarin shows 5 hydrogen bond interactions and 5 hydrophobic interactions with various residues of Mpro. Furthermore, the molecular dynamic calculations over 60 ns (6×106 femtosecond) time scale also shown significant insights into the binding effects of axillarin with Mpro of SARS-CoV-2 by imitating protein like aqueous environment. From molecular dynamic calculations, the RMSD and RMSF computations indicate the stability and dynamics of the best docked complex in aqueous environment. The ADME properties and toxicity prediction analysis of axillarin also recommended it as safe drug candidate. Further, in vivo and in vitro investigations are essential to ensure the anti SARS-CoV-2 activity of all bioactive compounds particularly axillarin to encourage preventive use of Centaurea jacea against COVID-19 infections.

Payment for ecosystem services (PES): a holistic tool for sustainable forest management-a case study from Pakistan

Economic valuation of ecosystem services is a new concept in forest management. Economic valuation provides basis for payment for ecosystem services (PES). Therefore, objective of this study was to evaluate eco-tourism and carbon stock services of the Maindam valley, District Swat, Pakistan. For the carbon stock calculation, a sample size of 155 plots of 0.1 hectare (Ha) was taken using preliminary survey at 95% confidence interval and 10% allowable error. The data for tourism services was collected from owners of all the hotels, 100 tourists and key informants of the area at 10% sampling intensity on pretested questionnaire for twenty years period (1997-2017). Results showed that Miandam valley has carbon stock worth US$ 16,306,000 while the value of eco-tourism was US$ 1,578,458 on annual basis. The results also showed that trend of tourism has drastically declined after the 9/11 incident for foreigners and locals and the situation was further deteriorated during the era of Talibanization or militancy from 2008-2011. This study recommends implementation of PES strategy at the rate of 5%, thus a total of US$ 78,922 can be earned from eco-tourism and carbon crediting in the study area annually, which could play important role in sustainable forest management.

MTT Heterogeneity in Perfusion CT Imaging as a Predictor of Outcome after Aneurysmal SAH

BACKGROUND AND PURPOSE

Impairment of tissue oxygenation caused by inhomogeneous microscopic blood flow distribution, the so-called capillary transit time heterogeneity, is thought to contribute to delayed cerebral ischemia after aneurysmal SAH but has so far not been systematically evaluated in patients. We hypothesized that heterogeneity of the MTT, derived from CTP parameters, would give insight into the clinical course of patients with aneurysmal SAH and may identify patients at risk of poor outcome.

MATERIALS AND METHODS

We retrospectively analyzed the heterogeneity of the MTT using the coefficient of variation in CTP scans from 132 patients. A multivariable logistic regression model was used to model the dichotomized mRS outcome. Linear regression was used to eliminate variables with high linear dependence. T tests were used to compare the means of 2 groups. Furthermore, the time of the maximum coefficient of variation for MTT after bleeding was evaluated for correlation with the mRS after 6 months.

RESULTS

On average, each patient underwent 5.3 CTP scans during his or her stay. Patients with high coefficient of variation for MTT presented more often with higher modified Fisher (P = .011) and World Federation of Neurosurgical Societies grades (P = .014). A high coefficient of variation for MTT at days 3-21 after aneurysmal SAH correlated significantly with a worse mRS score after 6 months (P = .016). We found no correlation between the time of the maximum coefficient of variation for MTT after bleeding and the patients' outcomes after 6 months (P = .203).

CONCLUSIONS

Heterogeneity of MTT in CTP after aneurysmal SAH correlates with the patients' outcomes. Because the findings are in line with the pathophysiologic concept of the capillary transit time heterogeneity, future studies should seek to verify the coefficient of variation for MTT as a potential imaging biomarker for outcome.

Bioaccumulation of heavy metals in the tissues of Schizothorax plagiostomus at River Swat

Snow trout (Schizothorax plagiostomus) is an economically important freshwater fish, mostly found in northern areas of water reservoirs of Pakistan. The current study was conducted in River Swat to analyze the bioaccumulation of heavy metals (Pb, Cr, Ni, and Zn) in tissues of Schizothorax plagiostomus. Tissues were extracted and dissolved in perchloric acid (HClO4) and nitric acid (HNO3) along with hotplate. The heavy metals, zinc (Zn), lead (Pb), chromium (Cr), and Nickel (Ni) were determined using Perkin Elmer 2380 atomic absorption spectrophotometer. Results shows great variation in the content of the metal related to tissue type and sampling sites. A high concentration of bioaccumulation was reported at Charbagh, whereas lowest at Odigram: Charbagh>Landakai>Odigram. In the same way, Cr was the most accumulated heavy metal followed by lead, nickel, and Zinc.

Effect of different protein based feed on the growth of mahseer

For the proper growth of fish, it is necessary to feed the fish with a proper and balanced diet. A study was conducted to find out the effect of different protein-based diets on fingerlings of Tor putitora (mahseer). A feed with dietary protein levels of 35%, 40%, 45%, and 50% were prepared. The effect of different protein-based feed on weight gain, standard growth rate (SGR), food conversion ratio (FCR), percent weight gain, food conversion efficiency (FCE), and protein efficiency ratio (PER) was studied. An increase was observed in the growth rate with an increase in protein concentration up to 45%. The fingerlings fed a 45% protein diet shown the highest growth, followed by 50%, 40%, and 35%. The SGR value was greatest for 45% protein diet (8.56) followed by 50% and 40%, while the least values were observed for 35% protein feed (1.57). The same trend was observed for FCE. The highest PER values was observed in fishes fed 45% protein-based feed (0.65) followed by 50% (0.56), 40% (0.38) and35% (0.17). The food conversion ratio was lowest for 45% protein diet (3.41), while the greatest for 35% protein feed (16.85). It was concluded that a 45% protein-based diet was the best feed formulation for higher production of Tor putitora. However, research on the same percentage of protein diet is recommended for yearlings.

First-principles study of the electronic structures and optical and photocatalytic performances of van der Waals heterostructures of SiS, P and SiC monolayers

Designing van der Waals (vdW) heterostructures of two-dimensional materials is an efficient way to realize amazing properties as well as open up opportunities for applications in solar energy conversion, nanoelectronic and optoelectronic devices. The electronic structures and optical and photocatalytic properties of SiS, P and SiC van der Waals (vdW) heterostructures are investigated by (hybrid) first-principles calculations. Both binding energy and thermal stability spectra calculations confirm the stability of these heterostructures. Similar to the corresponding parent monolayers, SiS–P (SiS–SiC) vdW heterostructures are found to be indirect type-II bandgap semiconductors. Furthermore, absorption spectra are calculated to understand the optical behavior of these systems, where the lowest energy transitions lie in the visible region. The valence and conduction band edges straddle the standard redox potentials of SiS, P and SiC vdW heterostructures, making them promising candidates for water splitting in acidic solution.

The electronic structures and optical and photocatalytic properties of SiS, P and SiC van der Waals (vdW) heterostructures are investigated by (hybrid) first-principles calculations.

Stacking effects in van der Waals heterostructures of blueP and Janus XYO (X = Ti, Zr, Hf: Y = S, Se) monolayers

Using first-principles calculations, the geometry, electronic structure, optical and photocatalytic performance of blueP and XYO (X = Ti, Zr, Hf; Y = S, Se) monolayers and their corresponding van der Waal heterostructures in three possible stacking patterns, are investigated. BlueP and XYO (X = Ti, Zr, Hf; Y = S, Se) monolayers are indirect bandgap semiconductors. A tensile strain of 8(10)% leads to TiSeO(ZrSeO) monolayers transitioning to a direct bandgap of 1.30(1.61) eV. The calculated binding energy and AIMD simulation show that unstrained(strained) blueP and XYO (X = Ti, Zr, Hf; Y = S, Se) monolayers and their heterostructures are thermodynamically stable. Similar to the corresponding monolayers, blueP-XYO (X = Ti, Zr, Hf: Y = S, Se) vdW heterostructures in three possible stacking patterns are indirect bandgap semiconductors with staggered band alignment, except blueP-TiSeO vdW heterostructure, which signifies straddling band alignment. Absorption spectra show that optical transitions are dominated by excitons for blueP and XYO (X = Ti, Zr, Hf; Y = S, Se) monolayers and the corresponding vdW heterostructures. Both E VB and E CB in TiSO, ZrSO, ZrSeO and HfSO monolayers achieve energetically favorable positions, and therefore, are suitable for water splitting at pH = 0, while TiSeO and HfSeO monolayers showed good response for reduction and fail to oxidise water. All studied vdW heterostructures also show good response to any produced O2, while specific stacking reduces H+ to H2.

Co2YZ (Y= Cr, Nb, Ta, V and Z= Al, Ga) Heusler alloys under the effect of pressure and strain

Full Heuslers alloys are a fascinating class of materials leading to many technological applications. These have been studied widely under ambient conditions. However, less attention been paid to study them under the effect of compression and strain. Here in this work Co₂YZ (Y= Cr, Nb, Ta, V and Z = Al, Ga) Heusler alloys have been studied comprehensively under pressure variations. Calculated lattice constants are in reasonable agreement with the available data. It is determined that lattice constant deceases with the increase in tensile stress and increases by increasing pressure in reverse direction. Band profiles reveals the half metallic nature of the studied compounds. The bond length decreases while band gap increases in compressive strain. The compounds are found to be reflective in visible region, as characteristics of the metals. The magnetic moments reveal the half-mettalic ferromagnetic nature of the compounds.

Assessment of Tumor Angiogenesis by Expression of CD 105 in Ameloblastoma, Odontogenic Keratocyst and Central Giant Cell Lesion

Background:

Angiogenesis is critical for tumor growth and reflects the aggressive behavior of invasive odontogenic lesions [like amelogenesis (AM) (AM), Odontogenic Keratocyst (OKC) and Central giant cell lesion (CGCL)]. Mean vascular density (MVD) shows the angiogenic potential and CD105 is an ideal endothelial biomarker due to its specificity to new blood vessels for MVD detection. The aim of the study was to compare the MVD (angiogenic potential) among AM, OKC and CGCL in comparison to Pyogenic Granuloma (PG) using CD105 biomarker.

Methods:

Sixty-four primary cases of odontogenic invasive tumors (AM, OKC and CGCL) and PG, diagnosed clinically and histologically were included in the study, with 16 samples in each group. Tissue samples of peripheral AM, Peripheral GCL of jaws, malignant AM, and specimen with insufficient tissue were excluded. Tissue sections were embedded, processed and stained using Hematoxylin and Eosin (H and E). Immunohistochemistry was performed using antibodies against CD105, with positive brown cytoplasmic staining in the endothelial cells of neo-vasculature. Distinct countable, positively stained endothelial cell or clusters were evaluated under light microscope for identification of MVD. ANOVA and t-test were applied for statistical analysis of data.

Results:

Highest MVD was displayed in CGCL (32.99±0.77) and the minimum was observed in OKC (7.21± 0.75) respectively. CGCL showed significantly higher MVD to AM, OKC and PG lesions (p<0.05). AM (8.07± 0.36) and Odontogenic Keratocyst (7.21± 0.75) showed comparable MVD, which was lower than PG (14.7± 0.96) and CGCL vascular density (p < 0.01) respectively.

Conclusion:

CGCL was most aggressive, with highest MVD among the investigated odontogenic lesions (OKC, AM and PG). The proliferative aggressive behavior of Odontogenic Keratocyst is comparable to AM due to comparable mean vascular density.

Ultrasound guided percutaneous nephrostomy: Experience at ahmadu bello university teaching hospital, Zaria

BACKGROUND

Obstructive uropathy is a common problem in urologic practice; temporary relief of obstruction in the upper tract poses a significant challenge. Ultrasound-guided percutaneous nephrostomy (PCN) is an option for upper tract drainage; compared to fluoroscopic guidance, it is readily available, affordable, and not associated with radiation exposure. We present our experience with ultrasound-guided PCN.

PATIENTS AND METHODS

We studied all patients who had ultrasound-guided PCN in our center between January 2013 and January 2017. Information obtained included the patients' demographics, clinical details, primary pathology, indications, outcome, and complications within 30 days. Relevant data were extracted and analyzed using descriptive statistics.

RESULTS

A total number of 35 PCNs were performed in 26 patients within the period of study. The median age was 44.5 years. There were 17 females and 9 males. About 88.2% of the females had ureteric obstruction from advanced carcinoma of the cervix while the predominant cause of obstruction in the males was advanced carcinoma of the bladder. Kidney access under ultrasound guidance required well dilated collecting systems for success and ease of puncture. The most common complication was hematuria, which resolved within 24-48 h in all patients uneventfully.

CONCLUSION

PCN is an important and common procedure for temporary relief of upper urinary tract obstruction. While fluoroscopic guidance provides superior image guidance, ultrasound guidance is comparatively reliable, albeit with a longer learning curve. Adequate training, careful patients selection, and patience are key to success.

Characterization of the water diffusion in GEM foil material

Systematic studies on the GEM foil material are performed to measure the moisture diffusion rate and saturation level. These studies are important because the presence of this compound inside the detector’ s foil can possibly change its mechanical and electrical properties, and in such a way, the detector performance can be affected. To understand this phenomenon, a model is developed with COMSOL Multiphysics v. 4.3 [1], which described the adsorption and diffusion within the geometry of GEM foil, the concentration profiles and the time required to saturate the foil. The COMSOL model is verified by experimental observations on a GEM foil sample. This note will describe the model and its experimental verification results.

Candidate eco-friendly gas mixtures for MPGDs

Modern gas detectors for detection of particles require F-based gases for optimal performance. Recent regulations demand the use of environmentally unfriendly F-based gases to be limited or banned. This review studies properties of potential eco-friendly gas candidate replacements.

Quality control for the first large areas of triple-GEM chambers for the CMS endcaps

The CMS Collaboration plans to equip the very forward muon system with triple-GEM detectors that can withstand the environment of the High-Luminosity LHC. This project is at the final stages of R&D and moving to production. An unprecedented large area of several 100 m2 are to be instrumented with GEM detectors which will be produced in six different sites around the world. A common construction and quality control procedure is required to ensure the performance of each detector. The quality control steps will include optical inspection, cleaning and baking of all materials and parts used to build the detector, leakage current tests of the GEM foils, high voltage tests, gas leak tests of the chambers and monitoring pressure drop vs. time, gain calibration to know the optimal operation region of the detector, gain uniformity tests, and studying the efficiency, noise and tracking performance of the detectors in a cosmic stand using scintillators.

A novel application of Fiber Bragg Grating (FBG) sensors in MPGD

We present a novel application of Fiber Bragg Grating (FBG) sensors in the construction and characterisation of Micro Pattern Gaseous Detector (MPGD), with particular attention to the realisation of the largest triple (Gas electron Multiplier) GEM chambers so far operated, the GE1/1 chambers of the CMS experiment at LHC. The GE1/1 CMS project consists of 144 GEM chambers of about 0.5 m2 active area each, employing three GEM foils per chamber, to be installed in the forward region of the CMS endcap during the long shutdown of LHC in 2108-2019. The large active area of each GE1/1 chamber consists of GEM foils that are mechanically stretched in order to secure their flatness and the consequent uniform performance of the GE1/1 chamber across its whole active surface. So far FBGs have been used in high energy physics mainly as high precision positioning and re-positioning sensors and as low cost, easy to mount, low space consuming temperature sensors. FBGs are also commonly used for very precise strain measurements in material studies. In this work we present a novel use of FBGs as flatness and mechanical tensioning sensors applied to the wide GEM foils of the GE1/1 chambers. A network of FBG sensors have been used to determine the optimal mechanical tension applied and to characterise the mechanical tension that should be applied to the foils. We discuss the results of the test done on a full-sized GE1/1 final prototype, the studies done to fully characterise the GEM material, how this information was used to define a standard assembly procedure and possible future developments.

Renal point-of-care testing: collaboration between biomedical scientists and community pharmacists

The incidence of chronic kidney disease (CKD) is increasing with the prevalence of obesity, diabetes mellitus, elevated blood pressure and other cardiovascular-renal risk factors. Wider point-of-care testing (POCT) strategies in the community setting are needed to prevent CKD and delay progressive loss of renal function. Since publication of the Institute of Biomedical Science (IBMS) Point of Care Testing (Near-Patient Testing) Guidance on the Involvement of the Clinical Laboratory, the biomedical scientist can now provide enhanced services including tests for blood glucose, cholesterol, and monitor blood pressure. Under the current pharmacy contract, community pharmacies are now often equipped with sophisticated record access systems and interfaces to monitor drug interactions in suspect/high-risk CKD patients. Current facilities can be utilised further allowing pharmacists more clinical involvement based on community need. Further development of POCT in the community involving collaborations between biomedical scientists and community pharmacists would allow wider service availability in primary care and might be advantageous in suspect/high-risk patients.

Nephrotoxic nephritis and glomerulonephritis: animal model versus human disease

Glomerulonephritis (GN) encompasses a range of immune-mediated disorders that cause inflammation within the glomerulus of the kidney. The pathogenesis of GN is complex. Intricacy arises from factors such as autoimmunity, cancer and structural abnormalities within the kidney. Studies using animal models have highlighted crucial interaction between inflammatory cells and cells intrinsic to the kidney, both of which are fundamental to the pathogenesis of GN. This review aims to provide insight on a 'suitable' model for nephrotoxic nephritis and glomerulonephritis (NTN GN) and relate its experimental validity to humans. The BALB/c NTN murine model and Wistar Kyoto (WKY) rat have held experimental validity in the study of GN in humans. The chemokine receptor CXCR3 also mediates renal T-cell recruitment and subsequent tissue injury in NTN. It is noteworthy to consider CXCR3 blockade in Th1-mediated renal inflammation as future therapeutic options for patients with GN and subsets thereof. Currently used immunosuppressive therapies for GN are not always uniformly effective and are frequently associated with serious side-effects. Corticosteroids are effective in several types of GN owing to their ability to inhibit the pro-inflammatory effects of cytokines known to promote glomerular inflammation. Differences between experimental and human GN complicate translation of experimental therapies into practice. More research is required to translate animal model research into a better comprehension of human GN disease. However, the complexity of GN research makes findings a challenge to replicate.

A cross sectional survey of newborn care practices in rural Sindh, Pakistan: implications for research and policy

INTRODUCTION

Of annual four million neonatal deaths, majority in the developing world, approximately three-quarters die within the first week of life. Pakistan has one of the highest newborn mortality rates.

STUDY DESIGN

We conducted a cross sectional study to assess knowledge, attitudes and practices of women of reproductive age in rural Pakistan.

RESULTS

Of 1490 mothers interviewed, prevalence of newborn care practices ranged between 32% (early bathing of newborn) and 69% (use of traditional cord applications). Uptake of antenatal care services was identified as a strong predictor of good newborn care after controlling for skilled birth attendance, socio-economic status, age of mother and sex of infant (OR = 1.26; 95% CI: 1.00-1.57).

CONCLUSIONS

The association of uptake of antenatal care services with good newborn care highlights the necessity to improve coverage of services with the integration of counseling about newborn care in order to reduce the burden of neonatal morbidity and mortality.

Testicular abscess caused by Salmonella para-typhi

This case is the first report of a bacteriologically proven testicular abscess in a child caused by Salmonella paratyphi 'A' in Pakistan that clinically simulates a testicular tumour. The case also emphasises that a course of 2 weeks antibiotic is sufficient for testicular abscess if complete surgical debridement is done.

Expression of the kcnk3 potassium channel gene lessens the injury from cerebral ischemia, most likely by a general influence on blood pressure

We examined the possible protective effect of TASK-1 (TWIK-related acid-sensitive potassium channel-1, kcnk3) and -3 potassium channels during stroke. TASK-1 and TASK-3, members of the two pore domain (K2P or kcnk) potassium channel family, form hetero or homodimers and help set the resting membrane potential. We used male TASK-1 and TASK-3 knockout mice in a model of focal cerebral ischemia, permanent middle cerebral artery occlusion (pMCAO). Infarct volume was measured 48 h after pMCAO. The TASK-1 knockout brains had larger infarct volumes (P=0.004), and those in TASK-3 knockouts were unchanged. As the TASK-1 gene is expressed in adrenal gland, heart and possibly blood vessels, the higher infarct volumes in the TASK-1 knockout mice could be due to TASK-1 regulating blood vessel tone and hence blood pressure or influencing blood vessel microarchitecture and blood flow rate. Indeed, we found that male TASK-1 knockout mice had reduced blood pressure, likely explaining the increased brain injury seen after pMCAO. Thus to make precise conclusions about how TASK-1 protects neurons, neural- or organ-specific deletions of the gene will be needed. Nevertheless, a consequence of having TASK-1 channels expressed (in various non-neuronal tissues and organs) is that neuronal damage is lessened when stroke occurs.

Contribution of proton-translocating proteins to the virulence of Salmonella enterica serovars Typhimurium, Gallinarum, and Dublin in chickens and mice

We investigated the attenuating effects of a range of respiratory chain mutations in three Salmonella serovars which might be used in the development of live vaccines. We tested mutations in nuoG, cydA, cyoA, atpB, and atpH in three serovars of Salmonella enterica: Typhimurium, Dublin, and Gallinarum. All three serovars were assessed for attenuation in their relevant virulence assays of typhoid-like infections. Serovar Typhimurium was assessed in 1-day-old chickens and the mouse. Serovar Gallinarum 9 was assessed in 3-week-old chickens, and serovar Dublin was assessed in 6-week-old mice. Our data show variation in attenuation for the nuoG, cydA, and cyoA mutations within the different serovar-host combinations. However, mutations in atpB and atpH were highly attenuating for all three serovars in the various virulence assays. Further investigation of the mutations in the atp operon showed that the bacteria were less invasive in vivo, showing reduced in vitro survival within phagocytic cells and reduced acid tolerance. We present data showing that this reduced acid tolerance is due to an inability to adapt to conditions rather than a general sensitivity to reduced pH. The data support the targeting of respiratory components for the production of live vaccines and suggest that mutations in the atp operon provide suitable candidates for broad-spectrum attenuation of a range of Salmonella serovars.

Rectal excision with coloanal anastomosis for superficial distal third rectal cancer: survival and local recurrence

OBJECTIVE

Appropriate surgical treatment of distal third rectal cancer limited to bowel wall (i.e. T1 or T2) in medically operable patients is controversial. Transanal excision can deprive some patients of accurate pathological staging, prognosis and cure. In contrast abdominoperineal resection has considerable practical and psychosocial problems largely related to a permanent colostomy. We hypothesize that superficial distal rectal tumours can be effectively treated with rectal excision and coloanal anastomosis.

SUBJECTS AND METHODS

Prospective oncological study of 80 patients with distal third superficial rectal carcinomas treated by complete rectal excision with coloananl anastomosis from December 1977 to January 1993 was carried out. The resected specimens were examined for depth of spread and number of histologically positive nodes. The actuarial local recurrence and survival rates for superficial node-negative and node-positive tumours were analysed independently.

RESULTS

Seventy-eight patients had complete postoperative assessment. Thirty-one percent had received low-dose preoperative neo-adjuvant radiotherapy (3500 rads). Mean follow-up time in all patients was 70 months on average. The lymph node involvement rate for T1 and T2 tumours was 12.5 and 15.6%, respectively. The local recurrence rates for patients with (T1/T2) N0 and (T1/T2) N1 were 1.5 and 16.7%, respectively, and the five year actuarial survival rates were 96.6 and 90%, respectively. The overall local recurrence was 3.8% with five-year actuarial survival of 95.8%.

CONCLUSIONS

Lymph node involvement in superficial tumours is not rare. Rectal excision with coloanal anastomosis results in a high cure rate especially for node-positive superficial tumours. This treatment strategy avoids the psychological trauma of colostomy following abdominoperineal resection and the potential risk of undertreatment by local excision.

A phylogenetically conserved NAD+-dependent protein deacetylase activity in the Sir2 protein family

The yeast Sir2 protein, required for transcriptional silencing, has an NAD(+)-dependent histone deacetylase (HDA) activity. Yeast extracts contain a NAD(+)-dependent HDA activity that is eliminated in a yeast strain from which SIR2 and its four homologs have been deleted. This HDA activity is also displayed by purified yeast Sir2p and homologous Archaeal, eubacterial, and human proteins, and depends completely on NAD(+) in all species tested. The yeast NPT1 gene, encoding an important NAD(+) synthesis enzyme, is required for rDNA and telomeric silencing and contributes to silencing of the HM loci. Null mutants in this gene have significantly reduced intracellular NAD(+) concentrations and have phenotypes similar to sir2 null mutants. Surprisingly, yeast from which all five SIR2 homologs have been deleted have relatively normal bulk histone acetylation levels. The evolutionary conservation of this regulated activity suggests that the Sir2 protein family represents a set of effector proteins in an evolutionarily conserved signal transduction pathway that monitors cellular energy and redox states.

Partitioning of serpin-proteinase reactions between stable inhibition and substrate cleavage is regulated by the rate of serpin reactive center loop insertion into beta-sheet A

The serpin family of serine proteinase inhibitors is a mechanistically unique class of naturally occurring proteinase inhibitors that trap target enzymes as stable covalent acyl-enzyme complexes. This mechanism appears to require both cleavage of the serpin reactive center loop (RCL) by the proteinase and a significant conformational change in the serpin structure involving rapid insertion of the RCL into the center of an existing beta-sheet, serpin beta-sheet A. The present study demonstrates that partitioning between inhibitor and substrate modes of reaction can be altered by varying either the rates of RCL insertion or deacylation using a library of serpin RCL mutants substituted in the critical P(14) hinge residue and three different proteinases. We further correlate the changes in partitioning with the actual rates of RCL insertion for several of the variants upon reaction with the different proteinases as determined by fluorescence spectroscopy of specific RCL-labeled inhibitor mutants. These data demonstrate that the serpin mechanism follows a branched pathway, and that the formation of a stable inhibited complex is dependent upon both the rate of the RCL conformational change and the rate of enzyme deacylation.

[Surgical management of periocular basal cell carcinoma using frozen section control and immediate plastic reconstruction--indications and methods in 106 patients]

PURPOSE

To review our first experiences with the surgical removal of basal cell carcinoma (BCC) utilizing frozen section control and immediate plastic reconstruction.

PATIENTS AND METHODS

We analyzed the accuracy of clinical diagnosis, methods of surgical excision, plastic repair and recurrence rates in 162 consecutive patients who underwent surgical excision utilizing either frozen section (n = 106) or biomicroscopic control (n = 56) between January 1991 and June 1996. Specimens used for intraoperative frozen-section monitoring were also fixed, processed, and sectioned for permanent sections and served as postoperative controls for the frozen sections (n = 43).

RESULTS

The accuracy of clinical diagnosis was 86% (n = 189). In 106 patients with BCC excised with frozen section control, there were no recurrences reported after a mean follow-up of 2.9 years. The mean surgical defect measured 55% of total eyelid length (range 10%-100%). The incidence of morphea pattern was 34%. Intraoperative re-excisions due to frozen sections positive for tumor were necessary in 31% of cases. Permanent postoperative sections of the tissue that had been used for intraoperative frozen sections confirmed in 97.5% of patients (n = 43) the preliminary findings made with frozen sections. In 56 patients with BCC excised with biomicroscopic control, three tumors recurred (5%) after a mean follow-up of 4.4 years. The mean surgical defect measured 42% of total eyelid length (range 16%-100%). The incidence of morphea type was 23%.

CONCLUSION

Surgical removal utilizing frozen section control and immediate plastic repair appears to represent a reliable and effective option in the management of selected patients with periocular BCC.

Is rectal intussusception a cause of idiopathic incontinence?

PURPOSE

The cause of rectal intussusception in patients primarily dominated by symptoms of anal incontinence has not been fully elucidated, especially for patients with idiopathic incontinence.

METHODS

Between 1991 and 1996, 51 patients referred with a diagnosis of idiopathic incontinence were prospectively evaluated by standard questionnaire, clinical examination, defecography, and anal manometry. Fourteen female patients were identified with rectal intussusception and were treated by transabdominal rectopexy. Postoperatively, clinical assessment and anal manometry were performed at regular intervals.

RESULTS

Continence was improved after rectopexy (P < 0.01). The postoperative increases in the anal resting pressure, maximum squeeze pressure, and maximum tolerated volume were not statistically significant.

CONCLUSIONS

Rectopexy improved anal incontinence in patients with rectal intussusception. The cause of rectal intussusception in anal incontinence could not be explained by functional improvement of the internal anal sphincter tone or an increase in the maximum tolerated volume. Rectal intussusception may be a cause of idiopathic incontinence in patients; however, larger prospective studies are required to support this concept.

Plasminogen activator inhibitor-1 contains a cryptic high affinity binding site for the low density lipoprotein receptor-related protein

Much of the controversy surrounding the binding of plasminogen activator inhibitor-1 (PAI-1) to the low density lipoprotein receptor-related protein (LRP) may be due to the labile structure of PAI-1 and the distinct conformations that it can adopt. To examine this possibility and to test the hypothesis that PAI-1 contains a specific high affinity binding site for LRP, a sensitive and quantitative assay for PAI-1 binding to LRP was developed. This assay utilizes a unique PAI-1 mutant that was constructed with a hexapeptide tag at the NH2 terminus, which is recognized by the protein kinase, heart muscle kinase and can be specifically labeled with 32P. Our results show that only 32P-PAI-1 in complex with a proteinase binds LRP with high affinity and is efficiently endocytosed by cells, indicating that a high affinity site for LRP is generated on PAI-1 only when in complex with a proteinase. In addition, PAI-1 in complex with different proteinases is shown to cross-compete for LRP binding, demonstrating that the binding site is independent of the proteinase and therefore must reside on the PAI-1 portion of the complex. Finally, mutagenesis of PAI-1 results in loss of LRP binding, confirming that the high affinity binding site is located on PAI-1 and suggesting that the LRP binding site lays within a region of PAI-1 previously shown to contain the heparin binding domain.

Prospective, randomized study comparing clinical results between small and large colonic J-pouch following coloanal anastomosis

PURPOSE

Improved functional results can be obtained by construction of a colonic J-pouch after coloanal anastomosis. Variability in pouch size following coloanal anastomosis is prevalent in current literature. In this study, the authors compare clinical bowel function after complete rectal excision with coloanal anastomosis for patients with rectal carcinoma using either a small 6-cm or a large 10-cm colonic J-pouch anastomosis. The clinical outcome is assessed both at short-term and long-term follow-up.

METHODS

Fifty-nine consecutive patients with rectal cancers 4 to 8 cm from the anal verge were recruited into the study. Patients were randomized intraoperatively to either a 6-cm J-pouch group or a 10-cm J-pouch group. Clinical assessments were performed prospectively at 3, 6, 12, and 24 months postoperatively, following colostomy closure. Clinical parameters such as frequency, urgency, continence, and laxative and enema use were assessed and compared between the two groups.

RESULTS

There was no statistical differences in the mean defecation frequency, urgency, and fecal continence between the two groups at 3, 6, 12, and 24 months. In the first year, laxative and enema use between the two groups was negligible; however at two years, 30 percent of patients with a large reservoir compared with 10 percent of patients in the small-pouch group required laxative and/or enema for constipation and evacuation of bowels.

CONCLUSION

Similar clinical results can be expected from patients with either small or large reservoirs at one year. However, with long-term follow-up, patients with a large reservoir are more likely to require medication for constipation and evacuation. To avoid these inconveniences a small reservoir is advocated for patients undergoing coloanal anastomosis.