The effects of systemic immunomodulatory treatments on COVID-19 outcomes in patients with atopic dermatitis: Results from the global SECURE-AD registry

BACKGROUND

Limited data are available on the effects of systemic immunomodulatory treatments on COVID-19 outcomes in patients with atopic dermatitis (AD).

OBJECTIVE

To investigate COVID-19 outcomes in patients with AD treated with or without systemic immunomodulatory treatments, using a global registry platform.

METHODS

Clinicians were encouraged to report cases of COVID-19 in their patients with AD in the Surveillance Epidemiology of Coronavirus Under Research Exclusion for Atopic Dermatitis (SECURE-AD) registry. Data entered from 1 April 2020 to 31 October 2021 were analysed using multivariable logistic regression. The primary outcome was hospitalization from COVID-19, according to AD treatment groups.

RESULTS

442 AD patients (mean age 35.9 years, 51.8% male) from 27 countries with strongly suspected or confirmed COVID-19 were included in analyses. 428 (96.8%) patients were treated with a single systemic therapy (n = 297 [67.2%]) or topical therapy only (n = 131 [29.6%]). Most patients treated with systemic therapies received dupilumab (n = 216). Fourteen patients (3.2%) received a combination of systemic therapies. Twenty-six patients (5.9%) were hospitalized. No deaths were reported. Patients treated with topical treatments had significantly higher odds of hospitalization, compared with those treated with dupilumab monotherapy (odds ratio (OR) 4.65 [95%CI 1.71-14.78]), including after adjustment for confounding variables (adjusted OR (aOR) 4.99 [95%CI 1.4-20.84]). Combination systemic therapy which did not include systemic corticosteroids was associated with increased odds of hospitalization, compared with single agent non-steroidal immunosuppressive systemic treatment (OR 8.09 [95%CI 0.4-59.96], aOR 37.57 [95%CI 1.05-871.11]). Hospitalization was most likely in patients treated with combination systemic therapy which included systemic corticosteroids (OR 40.43 [95%CI 8.16-207.49], aOR 45.75 [95%CI 4.54-616.22]).

CONCLUSIONS

Overall, the risk of COVID-19 complications appears low in patients with AD, even when treated with systemic immunomodulatory agents. Dupilumab monotherapy was associated with lower hospitalization than other therapies. Combination systemic treatment, particularly combinations including systemic corticosteroids, was associated with the highest risk of severe COVID-19.

Outer Membrane Vesicles: An Emerging Vaccine Platform

Vaccine adjuvants are substances that improve the immune capacity of a recombinant vaccine to a great extent and have been in use since the early 1900s; they are primarily short-lived and initiate antigen activity, mainly an inflammatory response. With the developing technologies and innovation, early options such as alum were modified, yet the inorganic nature of major vaccine adjuvants caused several side effects. Outer membrane vesicles, which respond to the stressed environment, are small nano-sized particles secreted by gram-negative bacteria. The secretory nature of OMV gives us many benefits in terms of infection bioengineering. This article aims to provide a detailed overview of bacteria's outer membrane vesicles (OMV) and their potential usage as adjuvants in making OMV-based vaccines. The OMV adjuvant-based vaccines can be a great benefactor, and there are ongoing trials for formulating OMV adjuvant-based vaccines for SARS-CoV-2. This study emphasizes engineering the OMVs to develop better versions for safety purposes. This article will also provide a gist about the advantages and disadvantages of such vaccines, along with other aspects.

Reactive oxygen species: the root cause of nanoparticle-induced toxicity in Drosophila melanogaster

Nanotechnology is a rapidly developing technology in the twenty-first century. Nanomaterials are extensively used in numerous industries including cosmetics, food, medicines, industries, agriculture, etc. Along with its wide application toxicity is also reported from studies of various model organisms including Drosophila. The toxicity reflects cytotoxicity, genotoxicity, and teratogenicity. The current study correlates the toxicity as a consequence of reactive oxygen species (ROS) generated owing to the presence of nanoparticles with the living cell. ROS mainly includes hydroxyl ions, peroxide ions, superoxide anions, singlet oxygen, and hypochlorous acids. An elevated level of ROS can damage the cells by various means. To protect the body from excess ROS, living cells possess a set of antioxidant enzymes which includes peroxidase, glutathione peroxidase, and catalase. If the antioxidant enzymes cannot nullify the elevated ROS level than DNA damage, cell damage, cytotoxicity, apoptosis, and uncontrolled cell regulations occur resulting in abnormal physiological and genotoxic conditions. Herewith, we are reporting various morphological and physiological defects caused after nanoparticle treatment as a function of redox imbalance.

Seasonal variation in photosynthetic rates and satellite-based GPP estimation over mangrove forest

In view of increasing anthropogenic influences and global changes, quantification of carbon assimilation through photosynthesis has gained tremendous significance. Precise estimation of Gross Primary Productivity (GPP) is essential for several ecosystem models and is typically done using coarser scale satellite data. The mangrove ecosystem, which offers significant protection to the coastal environment, is one of the critical habitats from a global change point of view. Light use efficiency (LUE) was measured using diurnal in situ photosynthetic rate observations for 13 dominant mangrove species for 3 seasons at each of the three mangrove dominant test-sites situated along the east and west coast of India. Variations in photosynthetic rates among these species were studied for 3 seasons that indicated varying responses of mangrove ecosystem at each site. Among all species, Rhizophora mucronata and Sonneratia apetala indicated higher values at two of the test-sites. IRS Resourcesat-2 LISS-IV datasets were used for the estimation of GPP. Mean GPP for all the sites varied from 1.2 to 7.7 g C m^-2 day^-1 with maximum value of 14.4 g C m^-2 day^-1. Mean values of GPP varied across the sites, based on its maximum LUE values and available photosynthetically active radiation (PAR). The results provide GPP values at much better spatial resolution for a threatened habitat like mangroves that typically survive in a narrow habitat along the coasts.

Formulation and development of floating multiple-unit minitablets of Nimodipine without using a gas-generating agent: in vitro and in vivo characterization

Background

Floating drug delivery systems have been reported for different active pharmaceutical ingredients as single-unit tablets with gas-generating agents. In this present research, the formulation of floating multiple-unit minitablets of Nimodipine without using gas-generating agent was attempted with an objective of increased residence time, sustain-release and improved oral bioavailability. Solid dispersion with different ratios (1:0.5, 1:1, 1:1.5, 1:2, 1:2.5) of drug with the lipophilic carrier such as Compritol ATO 888, Gelucire 43/01, G39/01 and Precirol ATO 05 was formulated using melt granulation technique. The adsorbent Sylysia 350 to lipophilic carrier is maintained at 1:1. The granules were compressed into minitablets weighing 15 mg and were filled into a ‘0’ size capsule.

Results

Differential scanning calorimetry study justified no interaction of the drug with excipients. The formulations which exhibited desirable flow property, floating lag time less than 1 min and floating time of 12 h were further characterized for various post-compression parameters. The optimized single-dose (capsule) of floating multiple-unit minitablets of Nimodipine consisting of 60 mg of drug, 120 mg of G43/01 and 120 mg of Sylysia 350 showed an average of floating lag time within 24.48 s, floating time of 14.32 h and sustained-release up to 12 h. Pharmacokinetic study of the optimized formulation (F9) showed nearly 2.5 times increase in area under the curve with increased residence time in comparison to aqueous suspension of Nimodipine. The stability study revealed no significant change in various parameters before and after storage.

Conclusion

Hence, gelucire 43/01-based multiple-unit minitablets of Nimodipine can be considered a promising approach for sustaining the drug release with gastric retention for 12 h without using gas-generating agent.

An Investigation on the Coinfection of Measles and HSV-1 in Hospitalized Acute Encephalitis Syndrome Patients in Eastern India

Acute encephalitis syndrome (AES) is a clinical condition that occurs due to infectious and noninfectious agents- however, viruses are considered to be the dominant pathogen. agents- however, viruses are considered to be the dominant pathogen. In this study, suspected AES cases were enrolled and tested for viral etiology through serology and polymerase chain reaction (PCR)/reverse transcriptase PCR from August 2012-July 2013. During this period, 820 cases were investigated and 96 cases were diagnosed to have a viral etiology whereas 20 patients had IgM antibodies for measles in serum and HSV-1 DNA in cerebrospinal fluid. All 20 of the patients were children below 14 years of age. The median hospital stay was 15 days (IQR: 14.2-17 days) and median GCS score was 7(IQR: 6-8) and were significantly different with patients with co-infections when comapred with patients having HSV-1 infection only. It may be suspected that the measles infection may have a role in the pathogenesis and thus an impact on the prognosis of the AES when present with HSV-1.

Molecular and phylogenetic analysis of the dengue strains circulating in Odisha, India

Dengue has emerged as a major public health challenge in terms of both changing clinical pattern and epidemiological features. The state of Odisha reported first dengue epidemic in the year 2010 and this continued each year in epidemic form during post monsoon period gradually becoming an endemic phenomenon. Present study depicts the changing epidemiological and clinical pattern of dengue with reference to its serotypes and genotypes. The study included 5320 suspected dengue cases from different health facilities of the state during 2010-2017. Dengue NS1 antigen and IgM antibody was done through ELISA. Serotyping was done through RTPCR by amplifying a part of core-pre-membrane gene (CprM) followed by sequencing and phylogenetic analysis. Dengue IgM antibody in 17.7% cases and NS1 antigen in 53.20% cases was detected. Dengue serotype 2 (DEN-2) was the only serotype detected in 2010 and 2011 where as all four serotypes 1, 2, 3, 4 were detected in 2012-2017, DEN-2 being dominant but in 2017 DEN-3 was found to be dominant. Phylogenetic analysis revealed genotype IV of DEN-2 and genotype III of DEN-1 and DEN-3 circulating in this region. In 6 cases involvement of DEN-2 in clinically evident encephalitis cases is an important observation in this region and needs public health attention. High prevalence of dengue was observed without any previous reported outbreaks in the state with increased number of cases from 2010 to 2012 affecting both urban and rural areas. High incidence in 2012 was due to co-circulation of more than one serotype which continued in the following years. Severity in some cases was associated with mixed infection but in most cases it was mild indicating the endemic nature of the virus in most parts of Odisha.

Software Defect Prediction Using Hybrid Distribution Base Balance Instance Selection and Radial Basis Function Classifier

Software is an important part of human life and with the rapid development of software engineering the demands for software to be reliable with low defects is increasingly pressing. The building of a software defect prediction model is proposed in this article by using various software metrics with publicly available historical software defect datasets collected from several projects. Such a prediction model can enable the software engineers to take proactive actions in enhancing software quality from the early stages of the software development cycle. This article introduces a hybrid classification method (DBBRBF) by combining distribution base balance (DBB) based instance selection and radial basis function (RBF) neural network classifier to obtain the best prediction compared to the existing research. The experimental results with post-hoc statistical significance tests shows the effectiveness of the proposed approach.

Hybrid Data Mining Approach for Image Segmentation Based Classification

Evolutionary harmony search algorithm is used for its capability in finding solution space both locally and globally. In contrast, Wavelet based feature selection, for its ability to provide localized frequency information about a function of a signal, makes it a promising one for efficient classification. Research in this direction states that wavelet based neural network may be trapped to fall in a local minima whereas fuzzy harmony search based algorithm effectively addresses that problem and able to get a near optimal solution. In this, a hybrid wavelet based radial basis function (RBF) neural network (WRBF) and feature subset harmony search based fuzzy discernibility classifier (HSFD) approaches are proposed as a data mining technique for image segmentation based classification. In this paper, the authors use Lena RGB image; Magnetic resonance image (MR) and Computed Tomography (CT) Image for analysis. It is observed from the obtained simulation results that Wavelet based RBF neural network outperforms the harmony search based fuzzy discernibility classifiers.

Hybrid Data Mining Approach for Image Segmentation Based Classification

Evolutionary harmony search algorithm is used for its capability in finding solution space both locally and globally. In contrast, Wavelet based feature selection, for its ability to provide localized frequency information about a function of a signal, makes it a promising one for efficient classification. Research in this direction states that wavelet based neural network may be trapped to fall in a local minima whereas fuzzy harmony search based algorithm effectively addresses that problem and able to get a near optimal solution. In this, a hybrid wavelet based radial basis function (RBF) neural network (WRBF) and feature subset harmony search based fuzzy discernibility classifier (HSFD) approaches are proposed as a data mining technique for image segmentation based classification. In this paper, the authors use Lena RGB image; Magnetic resonance image (MR) and Computed Tomography (CT) Image for analysis. It is observed from the obtained simulation results that Wavelet based RBF neural network outperforms the harmony search based fuzzy discernibility classifiers.

Non-Volatile Flash Memory Characteristics of Tetralayer Nickel-Germanide Nanocrystals Embedded Structure

Formation of tetralayer memory structure having nickel-germanide nanocrystals using a Ge/Ni multilayers is proposed. X-ray diffraction study shows the NiGe (002) phase formation after proper annealing. Cross sectional HRTEM clearly shows the sharpness and the size (~4-6 nm) of the stacked nanocrystals embedded in the oxide matrix. A large anti-clockwise hysteresis memory win- dow of 13.4 Volt at ± 15 Volt is observed for the optimized samples. This large memory window indicates for the MLC applications. Frequency independent C-V curve confirms about the charge storage in the nanocrystals. A good charge retention and endurance characteristics are exhibited upto 125 °C for the nonvolatile memory application.

Bayesian analysis of two diagnostic methods for paediatric ringworm infections in a teaching hospital

Quantitatively, conventional methods of diagnosis of tinea capitis or paediatric ringworm, microscopic and culture tests were evaluated with Bayes rule. This analysis would help in quantifying the pervasive errors in each diagnostic method, particularly the microscopic method, as a long-term treatment would be involved to eradicate the infection by the use of a particular antifungal chemotherapy. Secondly, the analysis of clinical data would help in obtaining digitally the fallible standard of the microscopic test method, as the culture test method is taken as gold standard. Test results of 51 paediatric patients were of 4 categories: 21 samples were true positive (both tests positive), and 13 were true negative; the rest samples comprised both 14 false positive (microscopic test positivity with culture test negativity) and 3 false negative (microscopic test negativity with culture test positivity) samples. The prevalence of tinea infection was 47.01% in the population of 51 children. The microscopic test of a sample was efficient by 87.5%, in arriving at a positive result on diagnosis, when its culture test was positive; and, this test was efficient by 76.4%, in arriving at a negative result, when its culture test was negative. But, the post-test probability value of a sample with both microscopic and culture tests would be correct in distinguishing a sample from a sick or a healthy child with a chance of 71.5%. However, since the sensitivity of the analysis is 87.5%, the microscopic test positivity would be easier to detect in the presence of infection. In conclusion, it could be stated that Trychophyton rubrum was the most prevalent species; sensitivity and specificity of treating the infection, by antifungal therapy before ascertaining by the culture method remain as 0.8751 and 0.7642, respectively. A correct/coveted diagnostic method of fungal infection would be could be achieved by modern molecular methods (matrix-assisted laser desorption ionisation-time of flight mass spectrometry or fluorescence in situ hybridization or enzyme-linked immunosorbent assay [ELISA] or restriction fragment length polymorphism or DNA/RNA probes of known fungal taxa) in advanced laboratories.

Postinfectious glomerulonephritis: Is there a role for steroids?

The role of steroids in treatment of postinfectious glomerulonephritis (PIGN) has been controversial. The reason for such controversy is the risk of infection relapse associated with steroid therapy. Steroids may have a place in the treatment of resistant cases where renal function does not improve despite aggressive antibiotic therapy as well as in patients with crescentic form of PIGN. We report a case of a 39 year-old Caucasian man who was diagnosed with methicillin-resistant Staphylococcus aureus (MRSA) bacteremia resulting in acute IgA dominant PIGN that failed to respond to antibiotic treatment alone, but responded significantly to steroids in addition to antibiotics. This anecdotal experience suggests that steroids could be considered in conjunction with antibiotic therapy for the treatment of refractory cases of PIGN or crescentic form of PIGN. More studies with long-term follow-up of patients treated with steroids in addition to antimicrobial agents are required to quantify the risk of infection relapse with steroid therapy.

Removal of hexavalent chromium by biosorption process in rotating packed bed

Removal of hexavalent chromium ions from an aqueous solution by crude tamarind (Tamarindus indica) fruit shell was examined in a rotating packed bed contactor by continuously recirculating a given volume of solution through the bed. Reduction of Cr(VI) to Cr(III) within the biosorbent appeared to be the removal mechanism. Depletion rate of Cr(VI) from, and release of reduced Cr(III) ions into the aqueous phase, was influenced by mass transfer resistance besides pH and packing depth. A mathematical model considering the reduction reaction to be irreversible and incorporating intraparticle and external phase mass transfer resistances represented the experimental data adequately. The study indicated that the limitations of fixed bed contactor operating under terrestrial gravity in intensifying mass transfer rates for this system can be overcome with rotating packed bed due to liquid flow under centrifugal acceleration.

[Relapse after surgical treatment of mycobacterium ulcerans infection (buruli ulcer): study of risk factors in 84 patients in the Democratic Republic of the Congo]

OBJECTIVE

To identify risk factors for relapse after exclusively surgical treatment of Mycobacterium ulcerans infection (Buruli ulcer).

METHODS

Study was carried out in 102 patients treated exclusively by surgery for Buruli ulcer at various care facilities in the Congo from January 1, 2000 to January 1, 2005.

RESULTS

Outcomes included relapse in 22 patients (21.5%), cure in 62 (60.7%), and unknown in 18 (17.6%). Statistical analysis identified the following variables as independent risk factors for relapse after exclusively surgical treatment: incomplete surgical excision (OR = 91.83; P = 0.0000; IC to 95%), age under 16 years (OR = 14.80; P = 0.0000; IC to 95%) and pre-ulcerative Buruli lesions (edema and plaque) (OR = 3.18; P = 0.0215; IC to 95%).

CONCLUSION

Quality of excision, patient age, and clinical form of lesion are the main predictors of relapse after isolated surgical treatment of Buruli ulcer.

HIV, hepatitis B and C infection status of the blood donors in a blood bank of a tertiary health care centre of Orissa

A record based retrospective study was conducted at the blood bank of SCB Medical College, Cuttack. All the donors who had donated blood from June to December 2005 were considered. 91.7%of the donors were males and majority belonged to 21-30 years age group. 1.98% of the donors were positive for hepatitis C, 1.13% for hepatitis B and 0.35% for HIV. For HBV infection, majority belonged to 31-40 years age group. But for HCV and HIV infection more were in the 21-30 year age group. Significantly more number of exchange donors was positive for HBV and HCV in comparison to voluntary donors in blood bank and camp. No voluntary donors from the camp were HIV positive.

Recruitment of governing elements for electron transfer in the nitric oxide synthase family

At least three building blocks are responsible for the molecular basis of the modulation of electron transfer in nitric oxide synthase (NOS) isoforms: the calmodulin-binding sequence, the C-terminal extension, and the autoregulatory loop in the reductase domain. We have attempted to impart the control conferred by the C termini of NOS to cytochrome P450 oxidoreductase (CYPOR), which contains none of these regulatory elements. The effect of these C termini on the properties of CYPOR sheds light on the possible evolutionary origin of NOS and addresses the recruitment of new peptides on the development of new functions for CYPOR. The C termini of NOSs modulate flavoprotein-mediated electron transfer to various electron acceptors. The reduction of the artificial electron acceptors cytochrome c, 2,6-dichlorophenolindophenol, and ferricyanide was inhibited by the addition of any of these C termini to CYPOR, whereas the reduction of molecular O(2) was increased. This suggests a shift in the rate-limiting step, indicating that the NOS C termini interrupt electron flux between flavin mononucleotide (FMN) and flavin adenine dinucleotide (FAD) and/or the electron acceptors. The modulation of CYPOR by the addition of the NOS C termini is also supported by flavin reoxidation and fluorescence-quenching studies and antibody recognition of the C-terminal extension. These experiments support the origin of the NOS enzymes from modules consisting of a heme domain and CYPOR or ferredoxin-NADP(+) reductase- and flavodoxin-like subdomains that constitute CYPOR, followed by further recruitment of smaller modulating elements into the flavin-binding domains.

Structural effects on the formation of proton and alkali metal ion adducts of apolar, neutral peptides: electrospray ionization mass spectrometry and Ab initio theoretical studies

Apolar, neutral peptides have been shown to ionize extremely well under the conditions used for electrospray ionization mass spectrometry (ESIMS). Peptides for which the conformations have been independently determined in solution and in crystals have been examined by ESIMS. Studies of peptide helices ranging from 7 to 18 residues reveal that shorter helices yield exclusively singly charged ions, while in larger helices multiply charged species are detectable. Multiple sites for protonation/metallation are introduced in the helix by proline insertion or by changing the chirality in the residue. The preferred site of cation binding to helices may be the C-terminus end, where three free CO groups are available for chelation. Ab initio and DFT calculations at several levels have been carried out for the binding of H+, Li+, Na+, and K+ to CHO-(Gly)3)-OMe. The results reveal that metallation in helices is favoured by chelation to carbonyl groups at the C-terminus, while protonation involved two carbonyl groups and thus favour a 10-membered cyclic hydrogen-bonded structure. In -strands, metallation/protonation occurs at isolated carbonyl groups. Collision induced fragmentation of hydrophobic peptides under ESI conditions reveals that helix fragmentation occurs predominantly from the C-terminus, while in -hairpins cleavage occurs simultaneously at multiple sites.

The 4,4'-dipyridyl disulfide-induced formation of GroEL monomers is cooperative and leads to increased hydrophobic exposure

The molecular chaperone, GroEL, is completely disassembled into monomers by the addition of 4,4'-dipyridyl disulfide. The dissociation leads to monomers in a kinetically controlled process. The additions of functional ligands of GroEL such as Mg(2+) or adenine nucleotides produced differences in the observed rates, but at the end of the kinetics, the dissociation was complete. In addition to the information obtained from native gels, the fluorescent probe bis-ANS was utilized to follow the monomer formation. The results demonstrate that the formation of monomers was associated with the exposure of hydrophobic surfaces. This assessment was possible without the use of added chaotropes, such as urea, to dissociate GroEL. Dissociation kinetics were also followed by light scattering. The kinetics of dissociation of the 14mer are cooperative with respect to the concentration of 4,4'-DPDS. Thermodynamic parameters for the kinetic process gave a free energy of activation (DeltaG) of 19.3 +/- 1.2 kcal mol(-1), which was decomposed to an enthalpy of activation (DeltaH) of 19.30 +/- 1.2 kcal mol(-1) and an entropy of activation (DeltaS) of -8.2 +/- 3.9 cal mol(-1) K(-1). We conclude that the dissociation of GroEL observed in this investigation is an enthalpy-controlled process.

The binding of bis-ANS to the isolated GroEL apical domain fragment induces the formation of a folding intermediate with increased hydrophobic surface not observed in tetradecameric GroEL

The extent of hydrophobic exposure upon bis-ANS binding to the functional apical domain fragment of GroEL, or minichaperone (residues 191-345), was investigated and compared with that of the GroEL tetradecamer. Although a total of seven molecules of bis-ANS bind cooperatively to this minichaperone, most of the hydrophobic sites were induced following initial binding of one to two molecules of probe. From the equilibrium and kinetics studies at low bis-ANS concentrations, it is evident that the native apical domain is converted to an intermediate conformation with increased hydrophobic surfaces. This intermediate binds additional bis-ANS molecules. Tyrosine fluorescence detected denaturation demonstrated that bis-ANS can destabilize the apical domain. The results from (i) bis-ANS titrations, (ii) urea denaturation studies in the presence and absence of bis-ANS, and (iii) intrinsic tyrosine fluorescence studies of the apical domain are consistent with a model in which bis-ANS binds tightly to the intermediate state, relatively weakly to the native state, and little to the denatured state. The results suggest that the conformational changes seen in apical domain fragments are not seen in the intact GroEL oligomer due to restrictions imposed by connections of the apical domain to the intermediate domain and suppression of movement due to quaternary structure.

High hydrostatic pressure can probe the effects of functionally related ligands on the quaternary structures of the chaperonins GroEL and GroES

We investigated the effects of high hydrostatic pressure in the range of 1--3 kilobars on tetradecameric GroEL, heptameric GroES, and the GroEL-GroES complex. Unlike GroEL monomers formed by urea dissociation, which can be reassembled back to the tetradecamer, the pressure-dissociated monomers do not reassemble readily. This indicates an alteration of their native structures, an example of conformational drift. Pressure versus time profiles and kinetics of the dissociation of both GroEL and GroES at fixed pressures were monitored by light scattering. Unlike GroEL, GroES monomers do reassociate readily. Reaction conditions were varied by adding ATP, Mg(2+), ADP, AMP-PNP, and KCl. At any individual pressure, the dissociation process is governed by both thermodynamics and kinetics. This leads to the decrease in the yield of monomers at lower pressures. In the presence of Mg(2+) and KCl, GroEL is stable up to 3 kilobars. The presence of either ATP or ADP but not AMP-PNP leads to GroEL dissociation at lower pressures. Interestingly, the GroEL-GroES complex is very stable in the range of 1--2.5 kilobars. However, the addition of ADP destabilizes the complex, which dissociates completely at 1.5 kilobars. The results are rationalized in terms of different degrees of cooperativity between individual monomers and heptameric rings in the GroEL tetradecamer. Such allosteric interactions leading to the alteration of quaternary structure of GroEL in the absence of chemical denaturants are important in understanding the mechanism of chaperonin-assisted protein folding by the GroEL-GroES system.

Active-site sulfhydryl chemistry plays a major role in the misfolding of urea-denatured rhodanese

Unfolded bovine rhodanese, a sulfurtransferase, does not regain full activity upon refolding due to the formation of aggregates and disulfide-linked misfolded states unless a large excess of reductant such as 200 mM beta-ME and 5 mg/ml detergent are present [Tandon and Horowitz (1990), J. Biol. Chem. 265, 5967]. Even then, refolding is incomplete. We have studied the unfolding and refolding of three rhodanese forms whose crystal structures are known: ES, containing the transferred sulfur as a persulfide; E, without the transferred sulfur, and carboxymethylated rhodanese (CMR), in which the active site was blocked by chemical modification. The X-ray structures of ES, E, and CMR are virtually the same, but their tertiary structures in solution differ somewhat as revealed by near-UV CD. Among these three, CMR is the only form of rhodanese that folds reversibly, requiring 1 mM DTT. A minimum three-state folding model of CMR (N<-->I<-->U) followed by fluorescence at 363 nm, (N<-->I) by fluorescence at 318 nm, and CD (I<-->U) is consistent with the presence of a thermodynamically stable molten globule intermediate in 5-6 M urea. We conclude that the active-site sulfhydryl group in the persulfide form is very reactive; therefore, its modification leads to the successful refolding of urea-denatured rhodanese even in the absence of a large excess of reductant and detergent. The requirement for DTT for complete reversibility of CMR suggests that oxidation among the three non-active-site SH groups can represent a minor trap for refolding through species that can be easily reduced.

Cytochrome c folds through a smooth funnel

A dominant feature of folding of cytochrome c is the presence of nonnative His-heme kinetic traps, which either pre-exist in the unfolded protein or are formed soon after initiation of folding. The kinetically trapped species can constitute the majority of folding species, and their breakdown limits the rate of folding to the native state. A temperature jump (T-jump) relaxation technique has been used to compare the unfolding/folding kinetics of yeast iso-2 cytochrome c and a genetically engineered double mutant that lacks His-heme kinetic traps, H33N,H39K iso-2. The results show that the thermodynamic properties of the transition states are very similar. A single relaxation time tau(obs) is observed for both proteins by absorbance changes at 287 nm, a measure of solvent exclusion from aromatic residues. At temperatures near Tm, the midpoint of the thermal unfolding transitions, tau(obs) is four to eight times faster for H33N,H39K iso-2 (tau(obs) approximately 4-10 ms) than for iso-2 (tau(obs) approximately 20-30 ms). T-jumps show that there are no kinetically unresolved (tau < 1-3 micros T-jump dead time) "burst" phases for either protein. Using a two-state model, the folding (k(f)) and unfolding (k(u)) rate constants and the thermodynamic activation parameters standard deltaGf, standard deltaGu, standard deltaHf, standard deltaHu, standard deltaSf, standard deltaSu are evaluated by fitting the data to a function describing the temperature dependence of the apparent rate constant k(obs) (= tau(obs)(-1)) = k(f) + k(u). The results show that there is a small activation enthalpy for folding, suggesting that the barrier to folding is largely entropic. In the "new view," a purely entropic kinetic barrier to folding is consistent with a smooth funnel folding landscape.

Productive and nonproductive intermediates in the folding of denatured rhodanese

The competition between protein aggregation and folding has been investigated using rhodanese (thiosulfate:cyanide sulfurtransferase, EC 2.8.1.1) as a model. During folding from a urea-denatured state, rhodanese rapidly forms associated species or intermediates, some of which are large and/or sticky. The early removal of such particles by filtration results in a decreased refolding yield. With time, a portion of the smaller aggregates can partition back first to intermediates and then to refolded protein, while a fraction of these irreversibly form unproductive higher aggregates. Dynamic light scattering measurements indicate that the average sizes of the aggregates formed during rhodanese folding increase from 225 to 325 nm over 45 min and they become increasingly heterogeneous. Glycerol addition or the application of high hydrostatic pressure improved the final refolding yields by stabilizing smaller particles. Although addition of glycerol into the refolding mixture blocks the formation of unproductive aggregates, it cannot dissociate them back to productive intermediates. The presence of 3.9 M urea keeps the aggregates small, and they can be dissociated to monomers by high hydrostatic pressure even after 1 h of incubation. These studies suggest that early associated intermediates formed during folding can be reversed to give active species.

A bile acid-induced apoptosis assay for colon cancer risk and associated quality control studies

Bile acids are important in the etiology of colorectal cancer. Bile acids induce apoptosis in colonic goblet cells at concentrations comparable to those found in fecal water after high-fat meals. Preliminary evidence indicated that cells of the normal-appearing (nontumorous) portion of the colon epithelium of colon cancer patients are more resistant to bile salt-induced apoptosis than are cells from normal individuals. In the present study, 68 patients were examined, and biopsies were taken at 20 cm from the anal verge, cecum, and descending colon. The patients included 17 individuals with a history of colorectal cancer, 37 individuals with adenomas, and 14 individuals who were neoplasia free. The mean bile salt-induced apoptotic index among normal individuals was 57.6 +/- 3.47 (SE), which differed significantly (P < 0.05) from the mean value of 36.41 +/- 3.12 in individuals with a history of colon cancer. The correlation between independent observers was 0.89 (P < 0.001), indicating good interobserver reliability. Components of variance comparing interindividual versus intraindividual sources of variation suggested that site-to-site variability, both between regions of the colon and for adjacent biopsies, was larger than the interpatient variability for individuals with a history of neoplasia. Therefore, there was "patchiness" of the susceptibility of regions of the colon to bile acid-induced apoptosis in individuals with a history of neoplasia (a patchy field effect). There was no obvious correlation of low-apoptotic index regions with regions in which previous neoplasias had been found and removed. On the other hand, for normal, i.e., neoplasia-free, individuals, there was relatively less intraindividual variation compared to interindividual variation. Our assay shows an association between resistance to bile acid-induced apoptosis, measured at 20 cm from the anal verge, and colon cancer risk. Thus, this assay may prove useful as a biomarker of colon cancer risk.

Treatment of chronic osteomyelitis using the Papineau technique

From 1984 to 1994, 41 cases of chronic osteomyelitis were treated in Kinshasa by the Papineau technique; 75.5% were men and 24.5% women. The mean age was 28 years (range: 7-77), and the average duration of the infection was 3 years (range: 1 month to 28 years). The aetiology was "trauma" in 53.5%, haematogenous in 44% and drepanocytosis in 2.5%. Infections of the femur and tibia each constituted 41.5% of the cases. Immobilisation was by external fixation in 44%, and by a cast in 39%. Wound healing was complete after an average of 3 months with spontaneous healing, and in 4.5 months after skin grafting. Control of the infection and bone healing were obtained in 89% after a period of 3-7 months. We discuss the Papineau technique and the modifications which were required in Kinshasa.