Ultrasensitive Label-Free Detection of Protein-Membrane Interaction Exemplified by Toxin-Liposome Insertion.

Measuring the high-affinity binding of proteins to liposome membranes remains a challenge. Here, we show an ultrasensitive and direct detection of protein binding to liposome membranes using high throughput second harmonic scattering (SHS). Perfringolysin O (PFO), a pore-forming toxin, with a highly membrane selective insertion into cholesterol-rich membranes is used. PFO inserts only into liposomes with a cholesterol concentration >30%. Twenty mole-percent cholesterol results in neither SHS-signal deviation nor pore formation as seen by cryo-electron microscopy of PFO and liposomes. PFO inserts into cholesterol-rich membranes of large unilamellar vesicles in an aqueous solution with Kd = (1.5 ± 0.2) × 10-12 M. Our results demonstrate a promising approach to probe protein-membrane interactions below sub-picomolar concentrations in a label-free and noninvasive manner on 3D systems. More importantly, the volume of protein sample is ultrasmall (<10 µL). These findings enable the detection of low-abundance proteins and their interaction with membranes.

Hyaluronan orders water molecules in its nanoscale extended hydration shells.

Hyaluronan (HA) is an anionic, highly hydrated bio-polyelectrolyte found in the extracellular environment, like the synovial fluid between joints. We explore the extended hydration shell structure of HA in water using femtosecond elastic second-harmonic scattering (fs-ESHS). HA enhances orientational water-water correlations. Angle-resolved fs-ESHS measurements and nonlinear optical modeling show that HA behaves like a flexible chain surrounded by extended shells of orientationally correlated water. We describe several ways to determine the concentration-dependent size and shape of a polyelectrolyte in water, using the amount of water oriented by the polyelectrolyte charges as a contrast agent. The spatial extent of the hydration shell is determined via temperature-dependent measurements and can reach up to 475 nm, corresponding to a length of 1600 water molecules. A strong isotope effect, stemming from nuclear quantum effects, is observed when light water (H2O) is replaced by heavy water (D2O), amounting to a factor of 4.3 in the scattered SH intensity.

Preliminary report of in vitro and in vivo effectiveness of dornase alfa on SARS-CoV-2 infection.

Dornase alfa, the recombinant form of the human DNase I enzyme, breaks down neutrophil extracellular traps (NET) that include a vast amount of DNA fragments, histones, microbicidal proteins and oxidant enzymes released from necrotic neutrophils in the highly viscous mucus of cystic fibrosis patients. Dornase alfa has been used for decades in patients with cystic fibrosis to reduce the viscoelasticity of respiratory tract secretions, to decrease the severity of respiratory tract infections, and to improve lung function. Previous studies have linked abnormal NET formations to lung diseases, especially to acute respiratory distress syndrome (ARDS). It is well known that novel coronavirus disease 2019 (COVID-19) pneumonia progresses to ARDS and even multiple organ failure. High blood neutrophil levels are an early indicator of COVID-19 and predict severe respiratory diseases. Also it is reported that mucus structure in COVID-19 is very similar to that in cystic fibrosis due to the accumulation of excessive NET in the lungs. In this study, we showed the recovery of three individuals with COVID-19 after including dornase alfa in their treatment. We followed clinical improvement in the radiological analysis (two of three cases), oxygen saturation (Spo2), respiratory rate, disappearance of dyspnoea, coughing and a decrease in NET formation and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) viral load after the treatment. Also here, we share our preliminary results suggesting that dornase alfa has an anti-viral effect against SARS-CoV-2 infection in a green monkey kidney cell line, Vero, and a bovine kidney cell line, MDBK, without determined cytotoxicity on healthy peripheral blood mononuclear cells.

On the stability and necessary electrophoretic mobility of bare oil nanodroplets in water.

Hydrophobic oil droplets, particles, and air bubbles can be dispersed in water as kinetically stabilized dispersions. It has been established since the 19th century that such objects harbor a negative electrostatic potential roughly twice larger than the thermal energy. The source of this charge continues to be one of the core observations in relation to hydrophobicity, and its molecular explanation is still debated. What is clear though is that the stabilizing interaction in these systems is understood in terms of electrostatic repulsion via Derjaguin, Landau, Verwey, and Overbeek theory. Recent work [A. P. Carpenter et al., Proc. Natl. Acad. Sci. U. S. A. 116, 9214 (2019)] has added another element into the discussion, reporting the creation of bare near-zero charged droplets of oil in neat water that are stable for several days. Key to the creation of the droplets is a rigorous glassware cleaning procedure. Here, we investigate these conclusions and show that the cleaning procedure of glassware has no influence on the electrophoretic mobility of the droplets and that oil droplets with near-zero charge are unstable. We provide an alternative possible explanation for the observations involving glass surface chemistry.

Pressure-Induced Charge Disorder-Order Transition in the Cs4O6 Sesquioxide.

Cs4O6 adopts two distinct crystal structures at ambient pressure. At temperatures below ∼200 K, its ground state structure is tetragonal, incorporating two symmetry-distinct dioxygen anions, diamagnetic peroxide, O22-, and paramagnetic superoxide, O2-, units in a 1:2 ratio, consistent with the presence of charge and orbital order. At high temperatures, its ground state structure is cubic, comprising symmetry-equivalent dioxygen units with an average oxidation state of -4/3, consistent with the adoption of a charge-disordered state. The pressure dependence of the structure of solid Cs4O6 at 300 K and at 13.4 K was followed up to ∼12 GPa by synchrotron X-ray powder diffraction. When a pressure of ∼2 GPa is reached at ambient temperature, an incomplete phase transition that is accompanied by a significant volume reduction (∼2%) to a more densely packed highly anisotropic tetragonal structure, isostructural with the low-temperature ambient-pressure phase of Cs4O6, is encountered. A complete transformation of the cubic (charge-disordered) to the tetragonal (charge-ordered) phase of Cs4O6 is achieved when the hydrostatic pressure exceeds 6 GPa. In contrast, the pressure response of the Cs4O6 cubic/tetragonal phase assemblage at 13.4 K is distinctly different with the cubic and tetragonal phases coexisting over the entire pressure range (to ∼12 GPa) accessed in the present experiments and with only a small fraction of the cubic phase converting to tetragonal. Pressure turns out to be an inefficient stimulus to drive the charge disorder-order transition in Cs4O6 at cryogenic temperatures, presumably due to the high activation barriers (much larger than the thermal energy at 13.4 K) associated with the severe steric hindrance for a rotation of the molecular oxygen units necessitated in the course of the structural transformation.

Transient domains of ordered water induced by divalent ions lead to lipid membrane curvature fluctuations.

Cell membranes are composed of a hydrated lipid bilayer that is molecularly complex and diverse, and the link between molecular hydration structure and membrane macroscopic properties is not well understood, due to a lack of technology that can probe and relate molecular level hydration information to micro- and macroscopic properties. Here, we demonstrate a direct link between lipid hydration structure and macroscopic dynamic curvature fluctuations. Using high-throughput wide-field second harmonic (SH) microscopy, we observe the formation of transient domains of ordered water at the interface of freestanding lipid membranes. These domains are induced by the binding of divalent ions and their structure is ion specific. Using nonlinear optical theory, we convert the spatiotemporal SH intensity into maps of membrane potential, surface charge density, and binding free energy. Using an electromechanical theory of membrane bending, we show that transient electric field gradients across the membrane induce spatiotemporal membrane curvature fluctuations.

Elusive Valence Transition in Mixed-Valence Sesquioxide Cs4O6.

Cs4O6 is a mixed-valence molecular oxide with a cubic structure, comprising valency-delocalized O24/3- units and with properties highly sensitive to cooling protocols. Here we use neutron powder diffraction to authenticate that, while upon deep quenching the cubic phase is kinetically arrested down to cryogenic temperatures, ultraslow cooling results in an incomplete structural transition to a contracted tetragonal phase. Two dioxygen anions in a 1:2 ratio are identified, providing evidence that the transition is accompanied by charge and orbital order and stabilizes a Robin-Day Class II mixed-valence state, comprising O22- and O2- anions. The phenomenology of the phase change is consistent with that of a martensitic transition. The response of the low-temperature phase assemblage to heating is complex, involving a series of successive interconversions between the coexisting phases. Notably, a broad interconversion plateau is present near 260 K, signifying reentrant kinetic arrest of the tetragonal phase upon heating because of the combined effects of increased steric hindrance for molecular rotation and melting of charge and orbital order. The geometrically frustrated pyrochlore lattice adopted by the paramagnetic S = 1/2 O2- units provides an intimate link between the crystal and magnetic properties of charge-ordered Cs4O6, naturally accounting for the absence of magnetic order.

Polyelectrolytes induce water-water correlations that result in dramatic viscosity changes and nuclear quantum effects.

Ions interact with water via short-ranged ion-dipole interactions. Recently, an additional unexpected long-ranged interaction was found: The total electric field of ions influences water-water correlations over tens of hydration shells, leading to the Jones Ray effect, a 0.3% surface tension depression. Here, we report such long-range interactions contributing substantially to both molecular and macroscopic properties. Femtosecond elastic second harmonic scattering (fs-ESHS) shows that long-range electrostatic interactions are remarkably strong in aqueous polyelectrolyte solutions, leading to an increase in water-water correlations. This increase plays a role in the reduced viscosity, which changes more than two orders of magnitude with polyelectrolyte concentration. Using D2O instead of H2O shifts both the fs-ESHS and the viscosity curve by a factor of ~10 and reduces the maximum viscosity value by 20 to 300%, depending on the polyelectrolyte. These phenomena cannot be explained using a mean-field approximation of the solvent and point to nuclear quantum effects.

Comment on "Water-water correlations in electrolyte solutions probed by hyper-Rayleigh scattering" [J. Chem. Phys. 147, 214505 (2017)].

The work by Shelton [J. Chem. Phys. 147, 214505 (2017)] discussed and interpreted differences with a previous study by Chen et al. [Sci. Adv. 2, e1501891 (2016)] regarding the influence of electrolytes on the structure of water. It is argued by Shelton [J. Chem. Phys. 147, 214505 (2017)] that impurities and hyper-Raman scattering contributions are the reasons for differences in the measured second harmonic intensity between the above two studies. Here, we show that these proposed effects are not relevant and discuss the influence of pulse parameters, focusing on pulse duration, since these two sets of experiments are performed with substantially different pulse durations, 100 ns and 190 fs, respectively. We show that inelastic higher-order effects play a role in the experiment with 100 ns laser pulses (the probed structure is that of the electrolyte solution that is modified by a laser pulse), while in the experiment with 190 fs laser pulses, only the elastic second-order response is measured (probing the unperturbed water structure).

Central nervous system involvement in a case of familial hemophagocytic lymphohistiocytosis with perforin mutation.

Familial hemophagocytic lymphohistiocytosis (FHL) is a rare autosomal recessive lethal condition characterized by fever, cytopenia, hepatosplenomegaly and hemophagocytosis. The presence of central nervous system involvement has a profound impact on the prognosis, treatment, and clinical outcome of the disease. Therefore, the identification of the clinical manifestations of the disease and the characterization of the accompanying neurological symptoms are of prime importance for the rapid diagnosis and subsequent clinical management of the disease. Herein, we report a case of FHL with homozygosity for perforin gene mutation, who presented with central nervous system involvement in the absence of systemic findings.

Three cases of intrathoracic gossypiboma with varying morbidities depending on the time of detection.

An intrathoracic gossypiboma (surgical sponge retained within the thoracic cavity during surgery) is rare but causes serious surgical complications and presents with difficulties in the differential diagnosis. In this article, we describe three cases of intrathoracic gossypiboma identified with the help of exploratory surgery 22, 10 and 3 years after they had been retained after surgery. The radiological findings varied in these cases and were insufficient for an accurate preoperative diagnosis. Marked deterioration in the neighboring lung tissue was observed over time, and the patients who had gossypibomas for 22, 10 and 3 years required pneumonectomy, lobectomy and partial decortication, respectively.

High cystine in platelets from patients with nephropathic cystinosis: a chemical, ultrastructural, and functional evaluation.

AIM: To investigate the morphology and function of platelets in nephropathic cystinosis (NC). METHODS: Seven patients (mean age, 6.5 years; SD, 20 months) with NC were investigated. Their platelets were examined by transmission electron microscopy (TEM) and the characteristics of the dense granules (DGs) were determined by mepacrine labelling and the uranaffin reaction. Bleeding time, turbidometric aggregation, and luminescence aggregation were studied and intraplatelet cystine was measured. RESULTS: Increased intraplatelet cystine, primary and secondary aggregation defects, and the absence of ATP release were demonstrated. TEM revealed DGs of various shapes and sizes and lamellary or amorphous cytoplasmic inclusions. Viscous material had been released into the vacuolar spaces and enlarged open canalicular system. Mepacrine labelling revealed that the numbers of DGs/platelet were comparable between the patients and the controls (mean, 2.9 (SD, 0.22) v 3.32 (0.18); p = 0.34). The uranaffin reaction revealed that the numbers of type 1, 3, and 4 DGs were comparable between the patients and the controls, but that there were fewer type 2 DGs in the patients (mean, 8.5 (SD, 1.95) v 17.22 (1.58); p = 0.01). TEM for platelet aggregation revealed a lack of induction and/or defective execution and/or delayed transmission. The patients' intraplatelet cystine concentrations were higher than the controls (mean, 1.56 (SD, 0.84) v 0.08 (0.01) nmol/mg protein; p = 0.009). CONCLUSIONS: This is the first report to demonstrate raised intraplatelet cystine, abnormal platelet ultrastructural findings, and defective aggregation in NC.

The effects of orchidopexy and orchidectomy on testes of rats subjected to ipsilateral abdominal testis with vas deferens obstruction.

An experimental study was planned to evaluate and compare the effects of orchidopexy and orchidectomy on the testes of rats subjected to unilateral abdominal testis with vas deferens obstruction. Four groups were established. Rats in the control group underwent a sham procedure. While the testis was maintained in the abdomen with the vas deferens ligated for 8 weeks in group 2, rats in groups 3 and 4 underwent orchidopexy or orchidectomy after 4 weeks. Remaining testes were harvested at the end of the 8-week period. Testis and body weights were obtained during harvest. Samples were evaluated through DNA flow cytometry, and percentages of haploid cells were determined. Groups were compared through unpaired t-test, and p-values less than 0.05 were considered significant. All three treatments had decreased testis weight over body weight values of ipsilateral testes. Ipsilateral orchidectomy increased the value among contralateral testes. However, none of the groups had a contralateral testicular value less than the sham-operated group. All three treatments decreased the percentage of haploid cells among ipsilateral testes, but only an abdominal testis was associated with a decrease in the percentage of haploid cells among contralateral testes. Maintaining a testis with an obstructed vas deferens in the abdomen for 8 weeks damages both ipsilateral and contralateral testes. Orchidopexy, while showing amelioration of the ipsilateral testis, spares the contralateral testis as well as orchidectomy. Orchidopexy for an undescended testis with vas deferens obstruction is a rational approach.

Autonomic nervous system appears to play a role in obliteration of processus vaginalis.

BACKGROUND: Failed obliteration of processus vaginalis (PV) has recently been proposed to be due to persistence of the smooth muscle (SM), which is transiently present to generate the physical force to descend the testis. Sacs from hernia, hydrocele, or undescended testis reveal alterations in Ca(2+) contents. Since Ca(2+) signaling and some regulatory proteins are involved in programmed cell death (PCD), a flow cytometric evaluation was planned to evaluate the expression of inducers or inhibitors of PCD in sacs from different diagnostic sources. METHODS: Sacs associated with male hernia ( n=16), female hernia ( n=11), undescended testis ( n=9), and hydrocele ( n=11) were evaluated for binding of annexin and expressions of Bcl-2, Bax, Fas, Fas-ligand (Fas-L), and Fas+Fas-L. The binding and expressions in cells that express alpha-smooth muscle actin (alpha-SMA) were also determined. Expressions according to the groups were compared through unpaired t-test, and P values less than 0.05 were considered to be significant. RESULTS: Sacs associated with undescended testis that contain the least SM revealed the most annexin binding, and sacs associated with hernia that contain the most SM binded the least annexin. However, expressions of Bcl-2, Bax, Fas, Fas-L and Fas+Fas-L have not revealed a significant difference. On the other hand, Bax and Fas expressions of cells that express alpha-SMA have been significantly higher in sacs associated with undescended testis. CONCLUSIONS: Since increase of Bax and Fas in cells that express alpha-SMA are encountered in sacs with the least SM content, Bax and Fas appear to play roles in the amount of persisting SM. The necessities of initial depletion of Ca(2+) stores through inositol 1,4,5-trisphosphate receptors and subsequent increase of Bax and Fas levels in the mitochondrial pathway of PCD, together with the role of the sympathetic system in maintenance of SM, suggest a determinative role of the autonomic nervous system for obliteration of PV.

Testicular blood flow alterations and flow cytometric analysis in prepubertal rats with experimentally induced unilateral varicocele.

Unilateral testicular pathologies have been accused of causing contralateral damage through a decrease in testicular blood flow. However, the contralateral testicular blood flow in unilateral varicocele has not been studied in detail. Therefore, the present study has been designed to evaluate the effects of a unilateral varicocele on the ipsilateral and on the contralateral testicular blood flow and the flow cytometric alterations in prepubertal rats. Experimental stenosis of the left renal vein in prepubertal rats causes dilation of the testicular vessels after puberty. Partial stenosis of the ipsilateral renal vein during the prepubertal period has no effect on ipsilateral or contralateral testicular blood flow, but does induce significant testicular damage, as determined by flow cytometry.

The effects of high dose methylprednisolone on apoptosis in children with acute lymphoblastic leukemia.

Rapid leukemic cell kill at initial diagnosis of patients with acute lymphoblastic leukemia (ALL) has been shown to be associated with a favorable outcome. The aim of the present study was to investigate the effect of high dose methylprednisolone (HDMP) on in vivo blast cell apoptosis in children with ALL. Annexin V-binding and Fas (CD95), Fas ligand (FasL; CD95L), and Bcl-2 expression in PB blasts were determined in newly diagnosed children with ALL before and 4, 24, 96 h after initiation of HDMP treatment (n=20) or conventional dose steroids (CDS) (n=10) as the control group. A decrease in absolute blast count (from 40.8 x 09 to 21.4 x 109/l) associated with an increase in apoptosis (14.2 to 26.9%) (P < 0.05) was detected 4 h after initiation of HDMP. A significant increase in Fas and FasL expression was detected 96 h after HDMP. There was no significant change in apoptosis, Fas and FasL expression from baseline in the control group treated with CDS. The changes in Bcl-2 expression after treatment was not significant in both groups. The results of this preliminary study have shown that HDMP treatment was effective in inducing immediate (within 4 h) blast cell apoptosis. The contribution of Fas/FasL interaction in the rapid component of cell kill remains to be determined, as the increase in the expression of these molecules was evident later.

Increased neutrophil apoptosis during attacks of familial Mediterranean fever.

AIM: Apoptosis is a programmed form of cell death. Recently much attention has been devoted to the role of apoptosis in rheumatological diseases. We have aimed to analyze apoptosis in the inflammatory pathway of familial Mediterranean fever (FMF). METHODS: 26 FMF patients and 12 age and sex matched controls were the subject of the study. Twelve of the patients were analyzed during an FMF attack whereas samples were obtained at least a week after an attack in 14. Four of the patients had renal amyloidosis. Whole blood was treated with ammonium chloride for RBC lysis. Subsequently the cells were stained with propidium iodide and annexin. Neutrophils and lymphocytes were gated separately for analysis by flow cytometry. We have also analyzed cellular Fas and Fas-ligand expression in these cells. RESULTS: The mean age of the patients was 12.00 +/- 3.17, and was not different than the control subjects. Erythrocyte sedimentation rate and CRP levels were significantly elevated in the attack group as compared to the attack-free group. The mean levels of neutrophil apoptosis in the FMF patients with an attack, attack-free and controls were 12.94 +/- 11.78, 6.60 +/- 7.83 and 3.98 +/- 4.27, respectively. Lymphocyte apoptosis in the same groups were 7.84 +/- 8.63, 2.75 +/- 2.33, and 1.22 +/- 0.93, respectively. Neutrophil and monocyte apoptosis was significantly increased during the attack as compared to the controls (p < 0.05). However lymphocyte apoptosis was not different between the aforementioned groups. On the other hand, lymphocyte apoptosis was significantly increased in the SLE patients (p < 0.05), whereas neutrophil apoptosis was not. Fas staining of neutrophils were not different between the groups (p > 0.05). On the other hand the difference between the groups for FasL was significant (p < 0.05). CONCLUSION: Neutrophil and monocyte but not lymphocyte apoptosis was significantly increased during FMF attacks reminding us that FMF is an autoinflammation of certain peripheral cells. The increased apoptosis in these patients maybe regarded as a response to clear the unwanted inflammatory cells. On the other hand the increased apoptosis maybe the explanation of the self-limited nature of the FMF attacks. Future studies will enlighten us on the significance of this increased apoptosis in the process of inflammation.

Impact of stress, gender and menstrual cycle on immune system: possible role of nitric oxide.

Stress is a factor found to be involved in the etiology of many diseases. Gender and menstrual cycle phases are other factors affecting the predisposition of individuals for certain diseases. Results from animal and human studies suggest that the distribution of immune system cells may change at different phases of the menstrual cycle. Acute mental stress in humans alters immune variables, too. The increase in the number of natural killer (NK) cells is the most consistent finding among the immune variables, though there are controversies for the other lymphocyte groups. Nitric oxide (NO) as an immune mediator has an unsettled role whether it causes the redistribution of the immune cells, or is an end product of lymphocyte activation. This study was planned to investigate the effect of mental stress on lymphocyte subtypes and the role of NO, for men and women at different phases of the cycle. For this purpose, healthy men (n = 10) and women (n = 10), during the follicular and luteal phases underwent Stroop colour-word interference and cold pressor tests. The immune system responses before and after the tests were determined by cell counts with the flowcytometer. Menstrual cycle phase was ascertained by plasma estrogen and progesterone measurements. Stress response was evaluated by blood pressure (BP) and heart rate (HR) measurements throughout the tests and plasma cortisol and urinary metanephrine and vanillylmandelic acid (VMA) measurements before and after the tests. Plasma and urinary NO determinations were performed before and after the test was completed. All the results were analysed with the appropriate statistical methods. The luteal phase differed from the other groups due to the presence of suppressed immune response to acute stress, including decreased CD4/CD8 ratio and NK cell percentage. On the other hand, acute stress caused a shift from cellular to humoral immunity in men. As indicated by these results, individual reaction towards stress is affected by gender and menstrual cycle phase. NO appears to be a possible effector molecule for these differences.

Corrosive injuries of the esophagus in newborns.

To evaluate the morbidity and mortality of corrosive esophageal injuries (CEI) in the neonatal period, the records of 184 children hospitalized following caustic ingestion over a 10-year period from January 1987 to November 1997 were reviewed. Eight (4.3%) were newborns (5 boys and 3 girls). The mean age of the newborns was 12 days (range 1-28). The ingested caustic materials were benzalkonium chloride in six patients and trichloroacetic acid in two. Oropharyngeal examination and esophagoscopy were performed for diagnosis. Hyperemia and fibrin plaques were present in the oropharynx in all patients. The management consisted of endotracheal intubation, antibiotics, corticosteroids, and total parenteral nutrition. Pneumonia and sepsis developed in three patients and one died of sepsis. Stenosis developed in two patients, who were treated three times with antegrade dilatations. The morbidity was 62.5% (five patients) and the mortality was 12.5% (one) in newborns with CEI. These results indicate that ingestion of a caustic substance results in high morbidity and mortality in newborns. Parents and nurses should be warned about this risk.