Molecular mimicry is an essential part of the development of drugs and molecular probes. In the chemical glycobiology field, although many glycomimetics have been developed in the past years, it has ...been considered that many failures in their use are related to the lack of the anomeric effects in these analogues. Additionally, the origin of the anomeric effects is still the subject of virulent scientific debates. Herein, by combining chemical synthesis, NMR methods, and theoretical calculations, we show that it is possible to restore the anomeric effect for an acetal when replacing one of the oxygen atoms by a CF2 group. This result provides key findings in chemical sciences. On the one hand, it strongly suggests the key relevance of the stereoelectronic component of the anomeric effect. On the other hand, the CF2 analogue adopts the natural glycoside conformation, which might provide new avenues for sugar‐based drug design.
Taking effect: The combination of chemical synthesis, NMR methods, and calculations show that it is possible to restore the anomeric effect for an acetal when replacing one of the oxygen atoms by a CF2 group. This result provides key findings as it strongly suggests the importance of the stereoelectronic component for the anomeric effect, and may open new avenues for sugar‐based drug design.
Protein-glycosaminoglycan interactions are essential in many biological processes and human diseases, yet how their recognition occurs is poorly understood. Eosinophil cationic protein (ECP) is a ...cytotoxic ribonuclease that interacts with glycosaminoglycans at the cell surface; this promotes the destabilization of the cellular membrane and triggers ECP’s toxic activity. To understand this membrane destabilization event and the differences in the toxicity of ECP and its homologues, the high resolution solution structure of the complex between full length folded ECP and a heparin-derived trisaccharide (O-iPr-α-d-GlcNS6S-α(1–4)-l-IdoA2S-α(1–4)-d-GlcNS6S) has been solved by NMR methods and molecular dynamics simulations. The bound protein retains the tertiary structure of the free protein. The 2S0 conformation of the IdoA ring is preferably recognized by the protein. We have identified the precise location of the heparin binding site, dissected the specific interactions responsible for molecular recognition, and defined the structural requirements for this interaction. The structure reveals the contribution of Arg7, Gln14, and His15 in helix α1, Gln40 in strand β1, His64 in loop 4, and His128 in strand β6 in the recognition event and corroborates the previously reported participation of residues Arg34–Asn39. The participation of the catalytic triad (His15, Lys38, His128) in recognizing the heparin mimetic reveals, at atomic resolution, the mechanism of heparin’s inhibition of ECP’s ribonucleolytic activity. We have integrated all the available data to propose a molecular model for the membrane interaction process. The solved NMR complex provides the structural model necessary to design inhibitors to block ECP’s toxicity implicated in eosinophil pathologies.
Sugar function, structure and dynamics are intricately correlated. Ring flexibility is intrinsically related to biological activity; actually plasticity in L‐iduronic rings modulates their ...interactions with biological receptors. However, the access to the experimental values of the energy barriers and free‐energy difference for conformer interconversion in water solution has been elusive. Here, a new generation of fluorine‐containing glycomimetics is presented. We have applied a combination of organic synthesis, NMR spectroscopy and computational methods to investigate the conformational behaviour of idose‐ and glucose‐like rings. We have used low‐temperature NMR spectroscopic experiments to slow down the conformational exchange of the idose‐like rings. Under these conditions, the exchange rate becomes slow in the 19F NMR spectroscopic chemical shift timescale and allows shedding light on the thermodynamic and kinetic features of the equilibrium. Despite the minimal structural differences between these compounds, a remarkable difference in their dynamic behaviour indeed occurs. The importance of introducing fluorine atoms in these sugars mimics is also highlighted. Only the use of 19F NMR spectroscopic experiments has permitted the unveiling of key features of the conformational equilibrium that would have otherwise remained unobserved.
Sweet chemistry: The combination of chemical synthesis, NMR methods, and calculations demonstrate that a new generation of gem‐difluoro‐containing molecules is able to mimic the conformational behaviour of their parent moieties. A detailed description is also provided of the conformational exchange process in which the use of 19F NMR spectroscopy has been essential (see figure).
The effects of lysine N ε-trimethylation at selected positions of the antimicrobial cecropin A−melittin hybrid peptide KWKLFKKIGAVLKVL-amide have been studied. All five monotrimethylated, four ...bis-trimethylated plus the per-trimethylated analogues have been synthesized and tested for antimicrobial activity on Leishmania parasites and on Gram-positive and -negative bacteria, as well as for hemolysis of sheep erythrocytes as a measure of cytotoxicity. The impact of trimethylation on the solution conformation of selected analogues has been evaluated by NMR, which indicates a slight decrease in the α-helical content of the modified peptides, particularly in the N-terminal region. Trimethylation also enhances the proteolytic stability of mono- and bis-trimethylated analogues by 2−3-fold. Although it tends to lower antimicrobial activity in absolute terms, trimethylation causes an even higher decrease in hemolytic activity and therefore results in improved selectivity for several analogues. The monotrimethylated analogue at position 6 shows the overall best selectivity against both the Leishmania donovani protozoan and Acinetobacter baumannii, a Gram-negative bacterium of increasing clinical concern.
In this paper, we describe the evaluation of an automated
in vitro micronucleus assay using CHO-K1 cells in 96-well plates. CHO-K1 cells were pre-loaded with a cell dye that stains the cytoplasm, ...after which the cells were treated with the test compounds for either 3
h (for the +S9 condition) or 24
h (for the −S9 condition). A total of 10 concentrations were tested, of which the top five concentrations were scored (limited by either cytotoxicity or solubility). At the end of the incubation period the cells were fixed and their DNA was stained with Hoechst. The visualization and scoring of the cells was done using an automated fluorescent microscope coupled with proprietary automated image analysis software provided by Cellomics (Pittsburg, PA). A total of 46 compounds were used in this evaluation, including 8 aneugens and 25 clastogens with varied mechanisms of action. Thirteen non-genotoxic compounds were also included. The automated scoring had a sensitivity of 88% and a specificity of 100%, with a predictive value positive of 100% and a predictive value negative of 76%, compared to data from the literature that was obtained with manual scoring. We also describe the incorporation of a metabolic activation system using rat liver S9 homogenates, and the use of cell number counts as a cytotoxicity index which is complementary to the CBPI- (cytokinesis-block proliferation index) based index. Finally, we also discuss the potential for artefactual findings due to fluorescent precipitate, which should be carefully monitored to prevent false positive results. In conclusion, the automated
in vitro micronucleus scoring is a valid alternative to the manual scoring of slides, and it has the advantage of generating data in a rapid and consistent manner, and with low compound requirements, which makes it well suited as a screening assay in the early stages of compound development.
This paper studies the effects of teenage motherhood on later educational and labor market achievement of the mothers. We construct a pseudo panel from the Brazilian Household Surveys (the 1992–2004 ...PNADs) and from the Health Ministry data (DATASUS 1981–1992) by state of birth and cohort. We find that the effects of teenage pregnancy are much stronger for high school completion and labor market participation than for schooling or wages. A reduction in teenage pregnancy by one standard deviation explains (i) 9.2% of the increase in high school completion and (ii) 5.4% of the increase in women's labor market participation, as observed over 10 cohort years. Lifecycle results show that the gains in terms of high school education are greater for younger than for older women, suggesting that women who give birth as teenagers tend to catch up with high school education while young but not as they become older. The results on labor market participation show persistent teenage motherhood effects.
Este artigo analisa os efeitos da maternidade na adolescência sobre os níveis de escolaridade e resultados no mercado de trabalho dessas mães. Foi construído um pseudo painel a partir das Pesquisas Nacionais por Amostra de Domicílios (PNADs 1992-2004) e dos dados do Ministério da Saúde (DATASUS 1981-1992) por Estado de nascimento e coorte. Os resultados indicam que os efeitos da gravidez precoce são muito mais fortes para a conclusão do ensino médio e participação no mercado de trabalho do que para anos de estudo ou salários. Um redução na gravidez na adolescência de um desvio-padrão explica (i) 9,2% do aumento na conclusão do ensino médio e (ii) 5,4% do aumento na participação feminina no mercado de trabalho, como observado ao longo de 10 anos de coortes. Resultados da análise do ciclo de vida mostram que os ganhos em termos de conclusão do ensino médio são maiores para adolescentes mais jovens do que para as mais velhas, o que sugere que as mulheres que são mães na adolescência tendem a concluir o ensino médio, quando são mais jovens, mas não quando são mais velhas. Os resultados sobre a participação no mercado de trabalho mostram que os efeitos da maternidade na adolescência são persistentes.
The interactions of simple carbohydrates with aromatic moieties have been investigated experimentally by NMR spectroscopy. The analysis of the changes in the chemical shifts of the sugar proton ...signals induced upon addition of aromatic entities has been interpreted in terms of interaction geometries. Phenol and aromatic amino acids (phenylalanine, tyrosine, tryptophan) have been used. The observed sugar–aromatic interactions depend on the chemical nature of the sugar, and thus on the stereochemistries of the different carbon atoms, and also on the solvent. A preliminary study of the solvation state of a model monosaccharide (methyl β‐galactopyranoside) in aqueous solution, both alone and in the presence of benzene and phenol, has also been carried out by monitoring of intermolecular homonuclear solvent–sugar and aromatic–sugar NOEs. These experimental results have been compared with those obtained by density functional theory methods and molecular mechanics calculations.
Recognition of simple sugars, with different stereochemistries, by aromatic entities (such as depicted), including phenol and the aromatic amino acids, has been studied by NMR (chemical shift perturbations, NOE experiments) assisted by molecular mechanics and DFT calculations, as model systems for naturally occurring protein–carbohydrate interactions.
Purpose
Although uveitis‐glaucoma‐hyphema (UGH) syndrome was described as a postoperative complication associated with intraocular lenses (IOL) in the anterior chamber, cases with IOL in the ...posterior chamber have also been described in both into capsular bag, in sulcus as well as lenses anchored to the iris. The physiopathology is not clear but it seems that the mechanical friction produced by the IOL haptics, in contact with different structures, produces erosion, pigment dispersion and consequently anterior uveitis accompanied by elevated intraocular pressure (IOP) and hyphema. Different treatments have been proposed: topical or systemic drugs, YAG laser iridectomies, capsular tension rings, anti‐VEGF or IOL explantion.
Methods
We present the case of a 40‐year‐old man who came to our emergency department with painful red left eye and blurred vision since several hours. He had a history of left congenital cataract surgery when he was 14. The patient presented uveitis with elevated IOP that did not yield with topical treatment with mydriatics, corticoids, antihypertensive drugs and oral diuretic agent. 24 hours later, he showed hyphema, deciding to enter the hospital IV for treatment. Symptomatic control was achieved, being discharged with topical treatment. 15 days later he returned to A&E at the same clinic. He was treated in the same way and ultrasonic biomicroscopy (UBM) was performed.
Results
UBM demostrated a poorly positioned IOL.Then, we diagnosed him with UGH syndrome. After presenting a third episode a week after discharge, explantation exchange was decided. Since then it is in follow‐up and has not submitted incidents.
Conclusion
The increase in cataract surgeries implies that a growth of the possible associated complications.UGH syndrome must be taken into account in all those patients who present their characteristic triad. Before suspicion a UBM should be performed.
Long‐term evolution of juvenile X‐linked retinoschisis Boned‐Murillo, Ana; Dolores Diaz, Maria; El Bakkali, Ismael Bakkali ...
Acta ophthalmologica,
January 2022, 2022-01-00, 20220101, Letnik:
100, Številka:
S267
Journal Article
Recenzirano
Odprti dostop
Purpose
To present long‐term evolution of congenital retinoschisis, also called juvenile or X‐linked retinoschisis (CXLRS), is a very rare disease with a prevalence of approximately 1: 120 000 and ...usually unknown, being one of the most common causes of macular degeneration in young men. It is a consequence of the mutation in the RS1 gene that encodes retinoschisis, manifesting with visual deficit, strabismus and nystagmus. In general, its evolution is rapid during the first five years of life, secondary to an increase in schisis, and later it slows down, in some cases the retinoschisis area may return partially spontaneously.
Methods
We report the case of a 32‐year‐old man diagnosed with X‐linked juvenile retinoschisis at 22 years of age in context of a possible convergent strabismus associated with hyperopia of +5.50 Right Eye (RE) and +6.50 Left Eye (LE).
Results
At the time of diagnosis of his disease, his corrected visual acuity (BCVA) was 20/40 in RE and 20/32 in LE. Radial distribution to the fovea macular cysts was observed in both eyes (OC), associated to macular area and the supero‐temporal quadrant RE retinoschisis and LE macula and the superior and temporal quadrants of the peripheral retina retinoschisis. Optical coherence tomography (OCT) reveals macular schisis that extends from the outer nuclear layer (NEC) to the outer plexiform layer (EPC) as well as a certain cystic component in OC. There was also an increased foveal autofluorescence. Ten Years follow‐up was performed and nowadays his BCVA is 20/50 in OC, with almost total regression of the macular cysts. Examination reveals the regression with foveal atrophy in OCT and an increase in the Foveal Avascular Zone (FAZ) AO in the OCT‐A.
Conclusions
Juvenile X‐linked retinoschisis is a slowly progressive condition. Optical coherence tomography (OCT) allows the study of retinoschisis in real time, being useful in the follow‐up and disease evolution. Although there is no current treatment, gene therapy could be a therapeutic option in the future.
Purpose
Sclerochoroidal calcification (SCC) is an unusual and poorly recognized ocular condition which is usually presented as an incidental finding in asymptomatic individuals. An exhaustive ...diagnosis is required as it may be commonly misdiagnosed such as choroidal osteoma, choroidal metastasis, amelanotic choroidal nevus, or lymphoma. It is commonly idiopathic but ophthalmologists should be aware of the possible association with severe ocular trauma and chronic intraocular inflammation, or with abnormal calcium‐phosphorus metabolism
Methods
We report the case of a 78‐year‐old woman with a medical history of breast cancer treated with quadrantectomy followed by adjuvant chemotherapy and radiotherapy, and Letrozole (aromatase inhibitors) for 3 years, which was discontinued when a hypercalcaemia and primary hyperparathyroidism (PHPT) related to a parathyroid adenoma. Oncological follow‐up was negative until during a routine examination prior to a right eye cataract intervention, dilated fundus examination revealed bilateral multiple asymptomatic yellow placoid lesions
Results
The patient's best‐corrected visual acuity (BCVA) was 20/20 in the right and left eye. Tomography–computed tomography (OCT‐scan), Magnetic resonance imaging (MRI) and Positron emission tomography–computed tomography (18‐FDG PET‐TC) revealed diffuse calcification in the choroid plexus bilaterally as well as calcification in the posterior aspect of both globes with no changes in metabolism at these levels. A SCC secondary to hypercalcaemia and PHPT related to a parathyroid adenoma was diagnosed. She was referred to endocrinology specialist to rule out systemic conditions. As the patient stills refusing surgery, she was treated with Cinacalcet (a calcimimetic) with regular follow‐up in the endocrinology clinic. Dilated fundus examination and OCT are performed periodically. For the time being, the patient remains asymptomatic and the lesion stays stable.
Conclusions
All patients with SCC should be tested for underlying systemic disorders involving abnormal calcium‐phosphorus metabolism to avoid complication or unwarranted intervention resulting from the misdiagnosed as a malignant tumor. Periodic ophthalmology studies are required as well to rule out possible complications.
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