Pandemic preparedness and response: a new mechanism for expanding access to essential countermeasures.

As the world comes together through the WHO design and consultation process on a new medical counter-measures platform, we propose an enhanced APT-A (Access to Pandemic Tools Accelerator) that builds on the previous architecture but includes two new pillars - one for economic assistance and another to combat structural inequalities for future pandemic preparedness and response. As part of the APT-A, and in light of the Independent Panel on Pandemic Preparation & Response's call for an enhanced end-to-end platform for access to essential health technologies, we propose a new mechanism that we call the Pandemic Open Technology Access Accelerator (POTAX) that can be implemented through the medical countermeasures platform and the pandemic accord currently under negotiation through the World Health Assembly and supported by the High-Level Meeting review on Pandemic Prevention, Preparedness, and Response at the United Nations. This mechanism will provide (1) conditional financing for new vaccines and other essential health technologies requiring companies to vest licenses in POTAX and pool intellectual property and other data necessary to allow equitable access to the resulting technologies. It will also (2) support collective procurement as well as measures to ensure equitable distribution and uptake of these technologies.

Deficient Phagocytosis in Circulating Monocytes from Patients with COVID-19-Associated Mucormycosis.

Cases of rhino-orbital mucormycosis in patients suffering from severe coronavirus disease 2019 (COVID-19) were reported in different parts of the world, especially in India. However, specific immune mechanisms that are linked to susceptibility to COVID-19-associated mucormycosis (CAM) remain largely unexplored. We aimed to explore whether the differential regulation of circulating cytokines in CAM patients had any potential pathogenic links with myeloid phagocyte function and susceptibility to mucormycosis. A small cohort of Indian patients suffering from CAM (N = 9) as well as COVID-19 patients with no evidence of mucormycosis (N = 5) were recruited in the study. Venous blood was collected from the patients as well as from healthy volunteers (N = 8). Peripheral blood mononuclear cells and plasma were isolated. Plasma samples were used to measure a panel of 48 cytokines. CD14+ monocytes were isolated and used for a flow cytometric phagocytosis assay as well as a global transcriptome analysis via RNA-sequencing. A multiplex cytokine analysis of the plasma samples revealed reduction in a subset of cytokines in CAM patients, which is known to potentiate the activation, migration, or phagocytic activity of myeloid cells, compared to the COVID-19 patients who did not contract mucormycosis. Compared to monocytes from healthy individuals, peripheral blood CD14+ monocytes from CAM patients were significantly deficient in phagocytic function. The monocyte transcriptome also revealed that pathways related to endocytic pathways, phagosome maturation, and the cytoskeletal regulation of phagocytosis were significantly downregulated in CAM patients. Thus, the study reports a significant deficiency in the phagocytic activity of monocytes, which is a critical effector mechanism for the antifungal host defense, in patients with CAM. This result is in concordance with results regarding the specific cytokine signature and monocyte transcriptome. IMPORTANCE A number of cases of mucormycosis, often fatal, were reported among severe COVID-19 patients from India as well as from some other parts of the world. However, specific immunocellular mechanisms that underlie susceptibility to this fungal infection in COVID-19 remain largely unexplored. Our study reports a deficiency in phagocytosis by monocytes in COVID-19 patients who are concomitantly afflicted with mucormycosis, with this deficiency being linked to a characteristic monocyte transcriptome as well as a circulating cytokine signature. The functional phenotype and cytokine signature of the monocytes may provide useful biomarkers for detecting potential susceptibility to mucormycosis in COVID-19 as well as in other viral infections.

Understanding the coevolution of mask wearing and epidemics: A network perspective.

Nonpharmaceutical interventions (NPIs) such as mask wearing can be effective in mitigating the spread of infectious diseases. Therefore, understanding the behavioral dynamics of NPIs is critical for characterizing the dynamics of disease spread. Nevertheless, standard infection models tend to focus only on disease states, overlooking the dynamics of "beneficial contagions," e.g., compliance with NPIs. In this work, we investigate the concurrent spread of disease and mask-wearing behavior over multiplex networks. Our proposed framework captures both the competing and complementary relationships between the dueling contagion processes. Further, the model accounts for various behavioral mechanisms that influence mask wearing, such as peer pressure and fear of infection. Our results reveal that under the coupled disease-behavior dynamics, the attack rate of a disease-as a function of transition probability-exhibits a critical transition. Specifically, as the transmission probability exceeds a critical threshold, the attack rate decreases abruptly due to sustained mask-wearing responses. We empirically explore the causes of the critical transition and demonstrate the robustness of the observed phenomena. Our results highlight that without proper enforcement of NPIs, reductions in the disease transmission probability via other interventions may not be sufficient to reduce the final epidemic size.

Secondary distal renal tubular acidosis and sclerotic metabolic bone disease in seronegative spondyloarthropathy.

Adults with distal renal tubular acidosis (dRTA) commonly present with hypokalaemia (with/without paralysis), nephrolithiasis/nephrocalcinosis and vague musculoskeletal symptoms. All adults with dRTA should be thoroughly evaluated for systemic diseases, certain medications and toxins. The leading cause of acquired or secondary dRTA in adults is primary Sjögren syndrome (SS); however, other collagen vascular diseases (CVDs) including seronegative spondyloarthropathy (SSpA) may at times give rise to secondary dRTA. Metabolic bone disease is often encountered in adults with dRTA, and the list includes osteomalacia and secondary osteoporosis; sclerotic metabolic bone disease is an extremely rare manifestation of dRTA. Coexistence of dRTA and sclerotic bone disease is seen in primary dRTA due to mutation in CA2 gene and acquired dRTA secondary to systemic fluorosis. Primary SS and SSpA, rarely if ever, may also lead to both secondary dRTA and osteosclerosis. Circulating autoantibodies against carbonic anhydrase II and possibly calcium sensing receptor may explain both these features in patients with CVD.

Decoding enigma: Turner syndrome with ring chromosome.

Ring chromosome X is one of the rarest with some unique phenotypical features in Turner syndrome. A young female presented to us with anasarca developed over the past 2 months due to congestive cardiac failure along with jaundice and orthopnea. She had growth retardation, intellectual disability, primary amenorrhea, lack of secondary sexual character development and dysmorphic features like low posterior hairline, shield chest and cubitus valgus. She had dilated cardiomyopathy (DCM) with intracardiac thrombus on echocardiography. Skeletal survey revealed short fourth metacarpal/tarsal on limbs. Karyotyping showed a mosaic pattern, with 45, X/46, X,r(X)(p22.3q28), i.e. Turner syndrome karyotype with ring chromosome. Her heart failure with reduced ejection fraction was managed with vasopressor along with anticoagulant and given oral contraceptive pills for hormone replacement therapy. The ring chromosomal pattern of karyotype in this patient and DCM is a rare cardiological phenomenon that can be associated with Turner syndrome, making this case a unique one.

Sensitivity and specificity of ultrasonographic features of gout in intercritical and chronic phase.

AIM: This study aimed to assess the sensitivity and specificity of ultrasonographic features of gout in intercritical and chronic stages and compared ultrasonographic features of gout between patients with persistent high serum uric acid (SUA) and patients with low SUA. METHODS: Adult patients with gout confirmed by demonstration of monosodium urate crystals were recruited, if they were in intercritical or chronic stage clinically. Ultrasonographic examination of the first metatarsophalangeal joints (MTPJs) and the knee joints of both sides were done by a blinded rheumatologist trained in musculoskeletal ultrasound. RESULTS: Sixty-two patients with gout and 30 control subjects were examined. The double contour sign (DCS) was found in 71 (57.3%) first MTPJs and tophi were found in 54 (43.5%) first MTPJs. DCS was present in 43 (69.4%) gout patients but none in the control group (P < 0.001). Sensitivity and specificity (95% CI) of DCS in gout patients were 69.4% (56.4-80.4%) and 100% (88.3-100%), respectively, while of tophi they were 66.1% (53-77.7%) and 100% (88.3-100%), respectively. The sensitivity of DCS increased to 100% in high the SUA subgroup (SUA ≥ 7 mg/dL). The low SUA (SUA < 7 mg/dL) gout subgroup showed significantly higher occurrence of erosions (40%) and tophi (50%) in first MTP joints than the control group. CONCLUSION: MSUS is useful for diagnosis of gout in intercritical or chronic stages, especially in patients with persistently high SUA level.

Temporal evolution of urate crystal deposition over articular cartilage after successful urate-lowering therapy in patients with gout: An ultrasonographic perspective.

OBJECTIVE: To detect evolution of ultrasonographic signs of deposition of monosodium urate crystals (MSUC) in gouty joints by serial ultrasonography after initiation of urate-lowering therapy (ULT). METHODS: Adult gout patients were examined by serial ultrasonography after initiation of ULT with target serum uric acid (SUA) < 6 mg/dL. RESULTS: Thirty-eight male patients with gout with mean age of 50 ± 11 years, median disease duration of 48 months and baseline mean SUA level of 8.8 ± 1.5 mg/dL were recruited. Ultrasonographic evidence of MSUC deposition was detected in 89.74% of first metatarsophalangeal (MTP) joints and 27.63% of knee joints. Double contour sign (DCS), tophi, and hyperechoic spots (HES) were detected in 77.63%, 43.42%, and 19.74% of first MTPs, respectively. SUA level normalizes and plateaus after fourth month of follow-up. DCS thickness reduced significantly throughout the follow-up period. Overall, 86.25% DCS and 100% HES disappeared with median time of 6 months and 5.7 months, respectively. SUA normalization was the only significant predictor of DCS disappearance. CONCLUSIONS: Serial ultrasonographic determination of DCS, tophi, or HES during hypouricemic therapy is a noninvasive, effective method to detect the lowering of burden of urate load in gouty joints.

Ground- and excited-state proton transfer and antioxidant activity of 3-hydroxyflavone in egg yolk phosphatidylcholine liposomes: absorption and fluorescence spectroscopic studies.

Excited-state intramolecular proton transfer (ESIPT) and dual luminescence behaviour of 3-hydroxyflavone (3-HF) have been utilized to monitor its binding to liposomal membranes prepared from egg yolk phosphatydilcholine (EYPC). Additionally, absorption spectrophotometric assay has been performed to evaluate the antioxidant activity of 3-HF against lipid peroxidation in this membrane system. When 3-HF molecules are partitioned into EYPC liposomes, a weak long-wavelength absorption band with lambda(abs)(max) approximately 410 nm appears in addition to the principal absorption at approximately lambda(abs)(max) = 345 nm. Selective excitation of the 410 nm band produces the characteristic emission (lambda(em)(max) approximately 460 nm) of the ground-state anionic species, whereas excitation at the higher energy absorption band leads to dual emission with predominatly ESIPT tautomer fluorescence (lambda(em)(max) = 528 nm). Both ESIPT tautomer and the anionic species exhibit fairly high fluorescence anisotropy (r) values (r = 0.122 and 0.180, respectively). Biexponential fluorescence decay kinetics are observed for the ESIPT tautomer as well as the ground-state anionic forms, indicating heterogeneity in the microenvironments of the corresponding emitting species. Furthermore, we demonstrate that lipid peroxidation of EYPC liposomes is significantly inhibited upon 3-HF binding, suggesting that 3-HF can be potentially useful as an inhibitor of peroxidative damage of cell membranes.

Interaction of 7-hydroxyflavone with human serum albumin: a spectroscopic study.

Numerous recent investigations have revealed that various synthetic as well as therapeutically active natural flavonoids possess novel luminescence properties that can serve as highly sensitive monitors for exploring their interactions with relevant physiological targets. Here we report a detailed study on the interactions of the model flavone, 7-hydroxyflavone (7HF) with the plasma protein human serum albumin (HSA), employing electronic absorption, fluorescence (steady state and time resolved) and induced circular dichroism (ICD) spectroscopy. The spectral data indicate that in the protein matrix, the neutral 7HF molecules are predominantly transformed to a conjugate anion (7HFA) by a proton abstraction in the ground state. The protein (HSA) environment induces dramatic enhancements in the fluorescence emission intensity, anisotropy (r) and lifetime (tau) values, as well as pronounced changes in the fluorescence excitation and emission profiles of the fluorophore. Moreover, evidence for efficient Förster type resonance energy transfer (FRET, from tryptophan to 7HFA) is presented, from which we infer that the binding site of 7HF in HSA is proximal (estimated distance, R=23.6A) to the unique tryptophan - 214 residue present in the inter-domain (between IIA and IIIA domains) loop region of the protein. The binding constant (K=9.44x10(4)M(-1)) and the Gibbs free energy change (DeltaG=-28.33kJ/mol) for 7HFA-HSA interaction have been estimated from the emission data. Finally, the near-UV circular dichroism (CD) studies show that the electronic transitions of 7HF are strongly perturbed on binding to the chiral host (HSA), leading to the appearance of ICD bands. Implications of these results are discussed.

Effect of beta-cyclodextrin nanocavity confinement on the photophysics of robinetin.

We have studied the confinement of robinetin, a therapeutically active plant flavonol, in cyclodextrin (CDx) nanocavities, using steady state and time resolved fluorescence spectroscopy. Enhanced tautomer emission (arising from excited state intramolecular proton transfer (ESIPT)) as well as dramatically blue shifted (approximately 10 nm in beta-CDx and approximately 33 nm in SHP beta-CDx) normal fluorescence observed upon addition of the beta-CDxs indicate that robinetin readily enters the doughnut-shaped hydrophobic cavity of beta-CDx where the chromone moiety is well shielded from external hydrogen bonding perturbations. Detailed analyses of the fluorescence data (emission profile, anisotropy, decay times) indicate that robinetin forms 1:1 inclusion complexes with both natural and chemically modified beta-cyclodextrins (beta-CDx and SHP beta-CDx) with affinity constant values K=195+/-17 M(-1) and 1055+/-48 M(-1) respectively, indicating the prospective utility of SHP beta-CDx in particular as an effective drug carrier. Unlike beta-CDxs, alpha-CDxs do not form inclusion complexes with robinetin. To further characterize the robinetin/beta-CDxs complexes, circular dichroism (CD) spectroscopic studies have been performed, which reveal that incorporation of robinetin molecules in the chiral environment of the beta-CDxs strongly affects the electronic transitions of robinetin leading to the occurrence of positive induced circular dichroism (ICD) bands in the near ultra-violet (UV) region. Molecular mechanics calculations show that the inclusion complex with the chromone ring inserted into the beta-CDx cavity is most favorable, in agreement with our spectroscopic data.

Interaction of flavonoids with red blood cell membrane lipids and proteins: antioxidant and antihemolytic effects.

Plant flavonoids are emerging as potent therapeutic drugs effective against a wide range of free radical mediated diseases. Hence their interactions with cell membranes, which generally serve as targets for lipid peroxidation, are of enormous interest. Here we report in vitro studies, via absorption and fluorescence spectroscopy, on the effects of several flavonoids (namely fisetin, quercetin, chrysin, morin, and 3-hydroxyflavone, 3-HF) in goat RBC membranes. Owing to the presence of functionally relevant membrane protein components embedded in the lipid bilayer RBC ghosts provide a more realistic system for exploring drug actions in biomembranes than simpler membrane models like phosphatidylcholine liposomes used in our previous studies [e.g. B. Sengupta, A. Banerjee, P.K. Sengupta, FEBS Lett. 570 (2004) 77-81]. Here, we demonstrate that binding of the flavonoids to the RBC membranes significantly inhibits lipid peroxidation, and at the same time enhances their integrity against hypotonic lysis. Interestingly, the antioxidant and antihemolytic activities are found to be crucially dependent on the locations of the flavonoids in the membrane matrix as revealed by fluorescence studies. Furthermore, we observe that FRET (from membrane protein tryptophans to flavonoids) occurs with significant efficiency indicating that the flavonoid binding sites lie in close proximity to the tryptophan residues in the ghost membrane proteins.