Sulfonamide as amide isostere for fine-tuning the gelation properties of physical gels

(S)-2-Stearamidopentanedioic acid (C₁₈-Glu) is a known LMW gelator that forms supramolecular gels in a variety of solvents. In this work, we have carried out the isosteric substitution of the amide group by a sulfonamide moiety yielding the new isosteric gelator (S)-2-(octadecylsulfonamido)pentanedioic acid (Sulfo-Glu). The gelation ability and the key properties of the corresponding gels were compared in terms of gelation concentration, gel-to-sol transition temperature, mechanical properties, morphology, and gelation kinetics in several organic solvents and water. This comparison was also extended to (S)-2-(4-hexadecyl-1H-1,2,3-triazol-4-yl)pentanedioic acid (Click-Glu), which also constitutes an isostere of C₁₈-Glu. The stabilizing interactions were explored through computational calculations. In general, Sulfo-Glu enabled the formation of non-toxic gels at lower concentrations, faster, and with higher thermal-mechanical stabilities than those obtained with the other isosteres in most solvents. Furthermore, the amide-sulfonamide isosteric substitution also influenced the morphology of the gel networks as well as the release rate of an embedded antibiotic (vancomycin) leading to antibacterial activity in vitro against Staphylococcus aureus.

Amide–sulfonamide isosteric substitution in a low-molecular-weight gelator enables fine-tuning of its gelation ability and the properties of the corresponding supramolecular gels.     

Kinematical Comparison of the 200 m Backstroke Turns between National and Regional Level Swimmers

The aims of this investigation were to determine the evolution of selected turn variables during competitive backstroke races and to compare these kinematic variables between two different levels of swimmers. Sixteen national and regional level male swimmers participant in the 200 m backstroke event at the Spanish Swimming Championships in short course (25 m) were selected to analyze their turn performances. The individual distances method with two-dimensional Direct Linear Transformation (2D-DLT) algorithms was used to perform race analyses. National level swimmers presented a shorter “turn time”, a longer “distance in”, a faster “underwater velocity” and “normalized underwater velocity”, and a faster “stroking velocity” than regional level swimmers, whereas no significant differences were detected between levels for the “underwater distance”. National level swimmers maintained similar “turn times” over the event and increased “underwater velocity” and “normalized underwater velocity” in the last (seventh) turn segment, whereas regional level swimmers increased “turn time” in the last half of the race. For both national and regional level swimmers, turn “underwater distance” during the last three turns of the race was significantly shorter while no significant differences in distance into the wall occurred throughout the race. The skill level of the swimmers has an impact on the competitive backstroke turn segments. In a 200 m event, the underwater velocity should be maximized to maintain turn proficiency, whereas turn distance must be subordinated to the average velocity.

Key Points

• The underwater turn velocity is as a critical variable related to the swimmers’ level of skill in a 200 m backstroke event.
• Best swimmers perform faster but no longer turn segments during a 200 m backstroke event.
• Best swimmers maintain their turn performance throughout the 200 m backstroke event by increasing the underwater velocity during the final part of the race.
• The turn distance out seems to be subordinated in order to maximize the average velocity during a 200 m backstroke event.

Key words: Swimming, biomechanics, motor skills, repeated measures     

Importance of Genetic Studies in Consanguineous Populations for the Characterization of Novel Human Gene Functions

Consanguineous offspring have elevated levels of homozygosity. Autozygous stretches within their genome are likely to harbour loss of function (LoF) mutations which will lead to complete inactivation or dysfunction of genes. Studying consanguineous offspring with clinical phenotypes has been very useful for identifying disease causal mutations. However, at present, most of the genes in the human genome have no disorder associated with them or have unknown function. This is presumably mostly due to the fact that homozygous LoF variants are not observed in outbred populations which are the main focus of large sequencing projects. However, another reason may be that many genes in the genome—even when completely “knocked out,” do not cause a distinct or defined phenotype. Here, we discuss the benefits and implications of studying consanguineous populations, as opposed to the traditional approach of analysing a subset of consanguineous families or individuals with disease. We suggest that studying consanguineous populations “as a whole” can speed up the characterisation of novel gene functions as well as indicating nonessential genes and/or regions in the human genome. We also suggest designing a single nucleotide variant (SNV) array to make the process more efficient.     

Progressive facial hemiatrophy with associated osseous lesions

Progressive facial hemiatrophy (PFH) is a rare condition characterized by the slow, progressive appearance of a unilateral facial atrophy that affects the skin, subcutaneous tissue, muscle and bone. We report the case of a 60-year-old female patient whose cutaneous symptoms commenced in 1987 in the form of a purplish erythema on the left side of her face and neck, which subsequently remitted giving rise to an indurated region in the left maxillary region. Since 1995 until the present day, she has developed facial hemiatrophy on the left side accompanied by progressive osseous reabsorption of the upper maxilla and left mandible with atrophy of soft tissue. The association of the onset of PFH with progressive osteolysis of the maxilla has not been previously reported in an adult patient.