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With the prosperity of the development of carbon nanorings, certain topologically or functionally unique units-embedded carbon nanorings have sprung up in the past decade. Herein, we report the facile and efficient synthesis of three cyclooctatetraene-embedded carbon nanorings (COTCNRs) that contain three (COTCNR1 and COTCNR2) and four (COTCNR3) COT units in a one-pot Yamamoto coupling. These nanorings feature hoop-shaped segments of Gyroid (G-), Diamond (D-), and Primitive (P-) type carbon schwarzites. The conformations of the trimeric nanorings COTCNR1 and COTCNR2 are shape-persistent, whereas the tetrameric COTCNR3 possesses a flexible carbon skeleton which undergoes conformational changes upon forming host-guest complexes with fullerenes (C 60 and C 70 ), whose co-crystals may potentially serve as fullerene-based semiconducting supramolecular wires with electrical conductivities on the order of 10 -7  S cm -1 (for C 60 ⊂COTCNR3) and 10 -8  S cm -1 (for C 70 ⊂COTCNR3) under ambient conditions. This research not only describes highly efficient one-step syntheses of three cyclooctatetraene-embedded carbon nanorings which feature hoop-shaped segments of distinctive topological carbon schwarzites, but also demonstrates the potential application in electronics of the one-dimensional fullerene arrays secured by COTCNR3., (© 2024 Wiley-VCH GmbH.)

Objective This report on the third round of the Research and Development Survey (RANDS 3) provides a general description of RANDS 3 and presents percentage estimates of selected demographic and health-related variables from the overall sample and by one set of experimental groups embedded in the survey. Statistical tests comparing estimates for the two randomized groups were conducted to evaluate the randomization. Methods NORC at the University of Chicago conducted RANDS 3 for the National Center of Health Statistics in 2019 using its AmeriSpeak Panel in web-only mode. To assess question-response patterns, probe questions and four sets of experiments were embedded in RANDS 3, with panelists randomized into two groups for each set of experiments. Participants in each group received questions with differences in wording, question-andresponse formats, or question order. Results Of the 4,255 people sampled, 2,646 completed RANDS 3 for a completion rate of 62.2% and a weighted cumulative response rate of 18.1%. Iterative raking was performed using demographic and selected health condition variables to calibrate the RANDS 3 sample to 2019 National Health Interview Survey (NHIS) estimates. As a result, the overall demographic distribution and percentages of asthma, diabetes, hypertension, and high cholesterol for the calibrated RANDS 3 sample aligned with the percentages estimated from the 2019 NHIS. The distributions of demographic and healthrelated variables were comparable between the two randomized groups examined except for ever-diagnosed hypertension. Conclusion As part of a research series using probability-based survey panels, RANDS 3 included health-related questions with a focus on disability and opioids. Because RANDS is an ongoing research platform, a variety of persistent and emergent research questions relating to survey methodology will continue to be examined in current and future rounds of RANDS., (All material appearing in this report is in the public domain and may be reproduced or copied without permission; citation as to source, however, is appreciated.)

Aiming at the construction of novel soft actuators through the amplified motions of molecular machines at the nanoscale, the design and synthesis of a new family of photoresponsive rotaxane-branched dendrimers through an efficient controllable divergent approach was successfully realized for the first time. In the third-generation rotaxane-branched dendrimers, up to 21 azobenzene-based rotaxane units located at each branch, thus making them the first successful synthesis of light-control integrated artificial molecular machines. Notably, upon alternative irradiation with UV and visible light, photoisomerization of the azobenzene stoppers leads to the collective and amplified motions of the precisely arranged rotaxane units, resulting in controllable and reversible dimension modulation of the integrating photoresponsive rotaxane-branched dendrimers in solution. Moreover, novel macroscopic soft actuators were further constructed based on these photoresponsive rotaxane-branched dendrimers, which revealed fast shape transformation behaviors with an actuating speed up to 21.2 ± 0.2° s -1 upon ultraviolet irradiation. More importantly, the resultant soft actuators could produce mechanical work upon light control that has been further successfully employed for weight-lifting and cargo transporting, thus laying the foundation toward the construction of novel smart materials that can perform programmed events.

Introduction: Uterine mesothelial cysts represent a diagnostic challenge because of their low incidence, with very few cases reported in the English literature., Patient Concerns: We report the case of a 27-year-old nullipara woman complaining of self-discovery of a mass in the abdomen for 1 week. Supersonic examination revealed a pelvic cystic lesion measuring 8.9 × 8.2 cm. The patient underwent exploratory single-port laparoscopic surgery and had a large uterine cystic mass located within the posterior wall of the uterus., Diagnosis: After excision of the uterine cyst, the final histopathological diagnosis was uterine mesothelial cyst., Interventions: We treated her with a single-port laparoscopic uterine cystectomy., Outcomes: Close follow-up of the case for 2 years showed that the patient was free of any symptoms, and no recurrence was noted., Lessons: Uterine mesothelial cysts are extremely rare. They are often misdiagnosed by clinicians as extrauterine masses or cystic degeneration of leiomyomas. This report aims to share a rare case of uterine mesothelial cyst and improve gynecologists' academic vision of the disease., Competing Interests: The authors have no conflicts of interest to disclose., (Copyright © 2023 the Author(s). Published by Wolters Kluwer Health, Inc.)

General access to highly valuable seven-membered rings via Büchner-type reaction remains a formidable challenge. Here we report a Cu-catalyzed intermolecular oxidation of alkynes using N-oxides as oxidants, which enables expedient preparation of valuable benzo[6,7]azepino[2,3-b]quinolines and pyridine-based diones. Importantly, in contrast to the well-established gold-catalyzed intermolecular alkyne oxidation, the dissociated pyridine or quinoline partner could be further utilized to construct N-heterocycles in this system and the reaction most likely proceeds by a Büchner-type ring expansion pathway. A mechanistic rationale for this cascade cyclization is supported by DFT calculations., (© 2023. The Author(s).)

The conversion of dinitrogen to more useful and reactive molecules has been the focus of intense research by chemists. In contrast to reductive N 2 fixation, direct oxidation of N 2 by O 2 to nitric oxide under mild conditions via a thermochemical process is extremely challenging. Herein, we report the first example of N 2 and O 2 activation and coupling under thermochemical conditions through the remarkable ability of Y 2 BO + to react with one N 2 and two O 2 molecules. Detailed mechanistic studies using mass spectrometry and quantum chemical calculations revealed that the N 2 activation by Y 2 BO + is facilitated by the double aromatic character of the Y 2 BON 2 + intermediate. Subsequent oxidation with O 2 releases NO in a dearomatization process driven by the formation of stronger Y-O bonds over the Y-N bonds. Our findings represent the first example of N 2 and O 2 activation and coupling under thermochemical conditions at room temperature, providing a novel strategy for small-molecule activation.

Background: The present study aimed to report a technically improved operation on the surgical exposure of labially impacted maxillary canine, elaborating the management of soft tissue to achieve better aesthetic results, and post-treatment periodontal health., Methods: Patients sought orthodontic treatment with unilateral labially impacted maxillary canines were selected in this study. The impacted teeth were assigned to the experimental group and contralateral unimpacted canines were assigned to the control group. The impacted canines were surgically exposed with dissected dental follicle (DF) stitching to muscle and mucosa surrounding the crowns. The gingival index (GI), probing depth (PD), the width of the keratinized gingiva (WKG), gingival scars (GS), bone loss (BL), and apical root resorption (ARR) were recorded after the removal of the fixed appliance. A two-sample t-test was used for independent samples for parametric variables., Results: A total of 24 patients with unilateral maxillary canine impaction were successfully treated. The outcomes of GI, WKG, GS, BL, and ARR did not indicate statistical significance between the experimental group and the control group., Conclusions: The preservation of DF promotes soft tissue management in combined surgical and orthodontic treatment of labially impacted maxillary canine to achieve better periodontal status. Trial Registration Chinese Clinical Trial Registry ChiCTR2000029091, 2020-01-12., (© 2021. The Author(s).)

Nucleobase mismatches can jeopardize DNA polymerization specificity, causing mutations and errors in DNA replication and detection. Herein we report the first synthesis of novel 2-Se-thymidine triphosphate (SeTTP), describe the single-selenium atom-specific modification strategy (SAM) against T/G mismatches, and demonstrate SAM-assisted polymerization and detection with much higher specificity and sensitivity. SAM can effectively suppress the formation of non-specific products in DNA polymerization and detection. Thus, SAM enhances the specificity of DNA synthesis by approximately 10 000 fold, and in turn, it allows the detection of clinical COVID-19 viral RNA in low copy numbers (single-digit copies), while the conventional RT-qPCR does not.

Mammalian cells respond to insufficient oxygen through transcriptional regulators called hypoxia-inducible factors (HIFs). Although transiently protective, prolonged HIF activity drives distinct pathological responses in different tissues. Using a model of chronic HIF1a accumulation in pluripotent-stem-cell-derived oligodendrocyte progenitors (OPCs), we demonstrate that HIF1a activates non-canonical targets to impair generation of oligodendrocytes from OPCs. HIF1a activated a unique set of genes in OPCs through interaction with the OPC-specific transcription factor OLIG2. Non-canonical targets, including Ascl2 and Dlx3, were sufficient to block differentiation through suppression of the oligodendrocyte regulator Sox10. Chemical screening revealed that inhibition of MEK/ERK signaling overcame the HIF1a-mediated block in oligodendrocyte generation by restoring Sox10 expression without affecting canonical HIF1a activity. MEK/ERK inhibition also drove oligodendrocyte formation in hypoxic regions of human oligocortical spheroids. This work defines mechanisms by which HIF1a impairs oligodendrocyte formation and establishes that cell-type-specific HIF1a targets perturb cell function in response to low oxygen., Competing Interests: Declaration of Interests P.J.T. and M.M. are listed as inventors on pending patent claims filed by CWRU covering methods of generating oligocortical spheroids. P.J.T. is a co-founder and consultant for Convelo Therapeutics, which has licensed these claims and other patents unrelated to the current study. P.J.T. and CWRU retain equity in Convelo Therapeutics. All other authors declare no competing interests., (Copyright © 2020 Elsevier Inc. All rights reserved.)

Crossbreeding is an essential way of improving herd performance. However, frequent parentage record errors appear, which results in the lower accuracy of genetic parameter estimation and genetic evaluation. This study aims to build a single nucleotide polymorphism (SNP) panel with sufficient power for parentage testing in the crossbred population of Simmental and Holstein cattle. The direct sequencing technique in PCR products of pooling DNA along with matrix-assisted laser desorption/ionization time-of-flight MS method for genotyping the individuals was applied. A panel comprising 50 highly informative SNPs for parentage analysis was developed in the crossbred population. The average minor allele frequency for SNPs was 0.43, and the cumulative probability of exclusion for single-parent and both-parent inference met 0.99797 and 0.999999, respectively. The maker-set for parentage verification was then used in a group of 81 trios with aid of the likelihood-based parentage-assignment program of Cervus software. Reconfirmation with on-farm records showed that this 50-SNP system could provide sufficient and reliable information for parentage testing with the parental errors for mother-offspring and sire-offspring being 8.6 and 18.5%, respectively. In conclusion, a set of low-cost and efficient SNPs for the paternity testing in the Simmental and Holstein crossbred population are provided., (Copyright © 2020 The Authors. Published by Elsevier B.V. All rights reserved.)

Lymphedema is mainly identified by progressive soft tissue swelling in impaired lymphatic system. Secondary lymphedema attributed to cancer therapy, parasite infection, and trauma remains a serious global disease. Patients with lymphedema suffer swelling, pain, and fatigue, with the dysfunction of the deformed extremities reducing the quality of life and increasing the risk of infection and lymphangiosarcoma. Adipose-derived stem cells (ADSCs) possess prominent regenerative potential to differentiate into multilineage cells, and produce various lymphangiogenic factors, making ADSC therapy a promising approach for lymphedema. The development of lymphedema consists of local inflammation, the fibrosis of lymphatic vessels, and the deposition of adipose fat. Existing animal models do not mimic the chronic inflammation environment, therefore suitable models are required in further studies. Some signal pathways and molecular mechanisms in physiological and pathological lymphagiogenesis remain unclear. In previous animal and human trials, ADSC therapy reduced edema in varying degrees. A larger number of trials with larger samples and longer follow-up periods are required to verify the efficiency and feasibility of ADSC therapy. ADSCs are of easy availability and immune exemption, making them a candidate for lymphedema treatment. Whether ADSCs enhance malignant characteristics or trigger the malignant change deserves further exploration and study before ADSC therapy can be made widely available., Competing Interests: Conflict-of-interest statement: The authors declare no conflict of interests for this article., (©The Author(s) 2020. Published by Baishideng Publishing Group Inc. All rights reserved.)

Obscurin is a giant cytoskeletal protein with structural and regulatory roles encoded by the OBSCN gene. Recently, mutations in OBSCN were associated with the development of different forms of cardiomyopathies, including hypertrophic cardiomyopathy (HCM). We previously reported that homozygous mice carrying the HCM-linked R4344Q obscurin mutation develop arrhythmia by 1-year of age under sedentary conditions characterized by increased heart rate, frequent incidents of premature ventricular contractions, and episodes of spontaneous ventricular tachycardia. In an effort to delineate the molecular mechanisms that contribute to the observed arrhythmic phenotype, we subjected protein lysates prepared from left ventricles of 1-year old R4344Q and wild-type mice to comparative proteomics analysis using tandem mass spectrometry; raw data are available via ProteomeXchange with identifier PXD017314. We found that the expression levels of proteins involved in cardiac function and disease, cytoskeletal organization, electropotential regulation, molecular transport and metabolism were significantly altered. Moreover, phospho-proteomic evaluation revealed changes in the phosphorylation profile of Ca 2+ cycling proteins, including sAnk1.5, a major binding partner of obscurin localized in the sarcoplasmic reticulum; notably, this is the first report indicating that sAnk1 undergoes phosphorylation. Taken together, our findings implicate obscurin in diverse cellular processes within the myocardium, which is consistent with its multiple binding partners, localization in different subcellular compartments, and disease association., (Copyright © 2020 Hu and Kontrogianni-Konstantopoulos.)

Multiple sclerosis (MS) is an autoimmune disease characterized by attack on oligodendrocytes within the central nervous system (CNS). Despite widespread use of immunomodulatory therapies, patients may still face progressive disability because of failure of myelin regeneration and loss of neurons, suggesting additional cellular pathologies. Here, we describe a general approach for identifying specific cell types in which a disease allele exerts a pathogenic effect. Applying this approach to MS risk loci, we pinpoint likely pathogenic cell types for 70%. In addition to T cell loci, we unexpectedly identified myeloid- and CNS-specific risk loci, including two sites that dysregulate transcriptional pause release in oligodendrocytes. Functional studies demonstrated inhibition of transcriptional elongation is a dominant pathway blocking oligodendrocyte maturation. Furthermore, pause release factors are frequently dysregulated in MS brain tissue. These data implicate cell-intrinsic aberrations outside of the immune system and suggest new avenues for therapeutic development. VIDEO ABSTRACT., Competing Interests: Declaration of Interests P.J.T. and D.J.A are co-founders and consultants for Convelo Therapeutics, which has licensed patents unrelated to the current study. P.J.T., D.J.A., and Case Western Reserve University retain equity in Convelo Therapeutics. D.C.F. is currently an employee and shareholder of Convelo Therapeutics., (Copyright © 2020 Elsevier Inc. All rights reserved.)

Dinitrogen activation and reduction is one of the most challenging and important subjects in chemistry. Herein, we report the N 2 binding and reduction at the well-defined Ta 3 N 3 H - and Ta 3 N 3 - gas-phase clusters by using mass spectrometry (MS), anion photoelectron spectroscopy (PES), and quantum-chemical calculations. The PES and calculation results show clear evidence that N 2 can be adsorbed and completely activated by Ta 3 N 3 H - and Ta 3 N 3 - clusters, yielding to the products Ta 3 N 5 H - and Ta 3 N 5 - , but the reactivity of Ta 3 N 3 H - is five times higher than that of the dehydrogenated Ta 3 N 3 - clusters. The detailed mechanistic investigations further indicate that a dissociative mechanism dominates the N 2 activation reactions mediated by Ta 3 N 3 H - and Ta 3 N 3 - ; two and three Ta atoms are active sites and also electron donors for the N 2 reduction, respectively. Although the hydrogen atom in Ta 3 N 3 H - is not directly involved in the reaction, its very presence modifies the charge distribution and the geometry of Ta 3 N 3 H - , which is crucial to increase the reactivity. The mechanisms revealed in this gas-phase study stress the fundamental rules for N 2 activation and the important role of transition metals as active sites as well as the new significant role of metal hydride bonds in the process of N 2 reduction, which provides molecular-level insights into the rational design of tantalum nitride-based catalysts for N 2 fixation and activation or NH 3 synthesis.

2'-Deoxynucleoside 5'-(alpha-P-seleno)-triphosphates (dNTPαSe) have been conveniently synthesized using a protection-free, one-pot strategy. One of two diastereomers of each dNTPαSe can be efficiently recognized by DNA polymerases, while the other is neither a substrate nor an inhibitor. Furthermore, this Se-atom modification can significantly inhibit non-specific DNA polymerization caused by mis-priming. Se-DNAs amplified with dNTPαSe via polymerase chain reaction have sequences identical to the corresponding native DNA. In conclusion, a simple strategy for more specific DNA polymerization has been established by replacing native dNTPs with dNTPαSe., (© 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Nucleic acids can fold into well-defined 3D structures that help determine their function. Knowing precise nucleic acid structures can also be used for the design of nucleic acid-based therapeutics. However, locations of hydrogen atoms, which are key players of nucleic acid function, are normally not determined with X-ray crystallography. Accurate determination of hydrogen atom positions can provide indispensable information on protonation states, hydrogen bonding, and water architecture in nucleic acids. Here, we used neutron crystallography in combination with X-ray diffraction to obtain joint X-ray/neutron structures at both room and cryo temperatures of a self-complementary A-DNA oligonucleotide d[GTGG(C Se )CAC] 2 containing 2'-SeCH 3 modification on Cyt5 (C Se ) at pH 5.6. We directly observed protonation of a backbone phosphate oxygen of Ade7 at room temperature. The proton is replaced with hydrated Mg 2+ upon cooling the crystal to 100 K, indicating that metal binding is favored at low temperature, whereas proton binding is dominant at room temperature., (Published by Elsevier Ltd.)

Sarcomeres consist of highly ordered arrays of thick myosin and thin actin filaments along with accessory proteins. Thick filaments occupy the center of sarcomeres where they partially overlap with thin filaments. The sliding of thick filaments past thin filaments is a highly regulated process that occurs in an ATP-dependent manner driving muscle contraction. In addition to myosin that makes up the backbone of the thick filament, four other proteins which are intimately bound to the thick filament, myosin binding protein-C, titin, myomesin, and obscurin play important structural and regulatory roles. Consistent with this, mutations in the respective genes have been associated with idiopathic and congenital forms of skeletal and cardiac myopathies. In this review, we aim to summarize our current knowledge on the molecular structure, subcellular localization, interacting partners, function, modulation via posttranslational modifications, and disease involvement of these five major proteins that comprise the thick filament of striated muscle cells. © 2018 American Physiological Society. Compr Physiol 8:631-709, 2018., (Copyright © 2018 American Physiological Society. All rights reserved.)

[This corrects the article DOI: 10.1371/journal.pone.0088162.].

Obscurins are cytoskeletal proteins with structural and regulatory roles encoded by OBSCN . Mutations in OBSCN are associated with the development of hypertrophic cardiomyopathy (HCM) and dilated cardiomyopathy (DCM). Specifically, the R4344Q mutation present in immunoglobulin domain 58 (Ig58) was the first to be linked with the development of HCM. To assess the effects of R4344Q in vivo, we generated the respective knock-in mouse model. Mutant obscurins are expressed and incorporated normally into sarcomeres. The expression patterns of sarcomeric and Ca 2+ -cycling proteins are unaltered in sedentary 1-year-old knock-in myocardia, with the exception of sarco/endoplasmic reticulum Ca 2+ adenosine triphosphatase 2 (SERCA2) and pentameric phospholamban whose levels are significantly increased and decreased, respectively. Isolated cardiomyocytes from 1-year-old knock-in hearts exhibit increased Ca 2+ -transients and Ca 2+ -load in the sarcoplasmic reticulum and faster contractility kinetics. Moreover, sedentary 1-year-old knock-in animals develop tachycardia accompanied by premature ventricular contractions, whereas 2-month-old knock-in animals subjected to pressure overload develop a DCM-like phenotype. Structural analysis revealed that the R4344Q mutation alters the distribution of electrostatic charges over the Ig58 surface, thus interfering with its binding capabilities. Consistent with this, wild-type Ig58 interacts with phospholamban modestly, and this interaction is markedly enhanced in the presence of R4344Q. Together, our studies demonstrate that under sedentary conditions, the R4344Q mutation results in Ca 2+ deregulation and spontaneous arrhythmia, whereas in the presence of chronic, pathological stress, it leads to cardiac remodeling and dilation. We postulate that enhanced binding between mutant obscurins and phospholamban leads to SERCA2 disinhibition, which may underlie the observed pathological alterations.

Gold-doped germanium clusters, AuGen(-) (n = 2-12), were investigated by using anion photoelectron spectroscopy in combination with ab initio calculations. Their geometric structures were determined by comparison of the theoretical calculations with the experimental results. The results show that the most stable isomers of AuGen(-) with n = 2-10 are all exohedral structures with the Au atom capping the vertex, edge or face of Gen clusters, while AuGe11(-) is found to be the critical size of the endohedral structure. Interestingly, AuGe12(-) has an Ih symmetric icosahedral structure with the Au atom located at the center. The molecular orbital analysis of the AuGe12(-) cluster suggests that the interactions between the 5d orbitals of the Au atom and the 4s4p hybridized orbitals of the Ge atoms may stabilize the Ih symmetric icosahedral cage and promote the Au atom to be encapsulated in the cage of Ge12. The NICS(0) and NICS(1) values are calculated to be -143.7 ppm and -36.3 ppm, respectively, indicating that the icosahedral AuGe12(-) cluster is significantly aromatic.

Tumor suppressor in lung cancer 1 (TSLC1) is a novel tumor suppressor gene whose inactivation is implicated in the occurrence, invasion, metastasis and prognosis of esophageal cancer. TSLC1 was studied by comparing the tumor formation of TSLC1 transfectant and control cells in nude mice. Compared with blank group and mock group, tumor size and infiltrating range of transfected group was less, differentiation of tumor tissue was slightly better, and differences of tumor angiogenesis was worse. There was no obvious difference between blank group and mock group. We have shown TSLC1 gene inhibited the growth proliferation, infiltration and angiogenesis of Eca109 cells.

Research on the potential impact of high salt intake on health has grown rapidly over the last decades. Recent studies have suggested that high salt intake could also be associated with adverse effects on cardiovascular system. The review evaluated the current level of epidemiologic evidence on the association between the level of habitual salt intake and stroke outcome. We also suggest further research direction. There were 21 independent samples from 12 studies, with 225,693 participants (follow-up, 3-19 years) and 8135 stroke events. High salt intake was associated with risk of stroke event (pooled odd ratio [OR], 1.34; 95% confidence interval [CI], 1.19-1.51), stroke death (1.40; 1.21-1.63) and stroke onset (1.11; 1.00-1.24), ischemic stroke death (2.15; 1.57-2.95), not associated with risk of ischemic stroke onset (1.07, 0.95-1.2), with no significant evidence of publication bias. High salt intake is associated with significantly increased risk of stroke event. Further research should be directed toward clarifying and quantifying these possible effects and generating testable hypotheses on plausible biologic mechanisms., (© 2012 Blackwell Publishing Ltd.)

Purpose: To evaluate the treatment results of 216 cracked teeth., Methods: Between May 1991 and May 2003, 208 patients with 216 cracked teeth were treated according to the stages. The patients were followed up and the final outcomes were analyzed, retrospectively., Results: The majority of the patients were between 40 and 60 years, with a predominance in males. The cracked lines were mainly located in the mesial grooves. The dominant treatment modality was binding of band, adjustment of occlusion, endodontic therapy and restoration with artificial crowns, with a success rate of 92%., Conclusion: Cracked teeth are commonly seen clinically with appropriate treatment, these teeth can be still useful. Routine extraction of these teeth are not advocated.

The design and performance of a filter holder which enables convenient preparation of volumes of up to a milliliter of large, unilamellar vesicles formed by extrusion (LUVETs) from multilamellar vesicles (MLVs) are described. The filter holder provides for back-and-forth passage of the sample between two syringes, a design that minimizes filter blockage, eliminates the need to change filters during LUVET preparation and reduces preparation time to a few minutes. Replicas of slam-frozen LUVETs in the electron microscope are unilamellar and reasonably homogeneous with an average diameter close to the pore size of the filters used to extrude them. Extrusion per se does not destabilize the vesicles, which trapped a fluorescent dye only when they were disrupted on freeze-thawing and during the first extrusion when most of the MLVs were apparently converted to LUVETs.

Destabilization of liposomes composed of phosphatidylethanolamine (PE) and purified glycophorin of human erythrocytes was studied with the release of an entrapped fluorescent dye, calcein. Proteolytic cleavage of liposomes by trypsin induced a rapid increase of turbidity and the leakage of calcein from the liposomes. Kinetic experiments indicated that the destabilization was a second order reaction, i.e. it required liposome collision. Using N-(7-nitro-2,1,3-benzoxadiazol-4-yl) PE as a fluorescent probe for the formation of hexagonal phase of PE, tryptic digestion of the liposomes resulted in a higher tendency of the PE bilayer to transform into the hexagonal phase. We propose that hexagonal (or inverted micellar) structures are involved in the trypsin induced liposome destabilization.