SOUTHERN JOURNAL OF SCIENCES

Background: A crucial aspect of electrochemical enzymatic biosensor development is the immobilization of the enzymes, as it directly influences the sensitivity of the bioelectrode. Among the different methods used to incorporate enzymes on the surface of the transducers, layer-by-layer (LbL) self-assembly based on electrostatic interaction with polyelectrolytes of opposite charge stands out due to its simplicity and reproducibility. Aims: The aim of the work was to develop an electrochemical glucose biosensor by LbL assembly of a new functionalized chitosan polycation and the enzyme glucose oxidase (GOx). Methods: Chitosan was chemically functionalized with glucose by the Maillard reaction. The resulting polycation, named G-Chit, is soluble in the medium compatible with the enzyme. The bioelectrode was obtained by alternating adsorption of G-Chit and GOx onto carbon paste electrodes. By selecting the number of bilayer of G-Chit/GOX, the enzyme concentration, and the pH, the electroanalytical performance of the biosensor was optimized. The electrochemical responses were characterized by cyclic voltammetry and chronoamperometry. Results: Under optimized experimental conditions, the biosensor exhibited a sensitivity of (0.81 ± 0.03) µA mM-1 in a glucose concentration range of (0.18 to 1.75) mM. Discussion: Results indicated that catalytic response increases both with the number of G-Chit/GOx bilayers and the enzyme concentration, obtaining the best responses for 3 bilayers and 2 mg mL-1, respectively, while the optimum working pH value was 7.0. Conclusions: The analytical response of the biosensor was tested in milk samples with negligible matrix effects, suggesting a potential application in other dairy products. Results show that G-Chit appears promising for the immobilization of enzymes.

Background: Dr. Miguel Fornes is a researcher at CONICET and director of the Andrological Research Laboratory of Mendoza, Argentina. His research focuses on how dietary fat excess and hypercholesterolemia affect sperm physiology and male fertility. Objectives: The primary objective of Dr. Fornes' research is to investigate the effects of a high-fat diet on sperm function, capacitation, acrosomal reaction, and fertilization. He aims to develop translational animal models to study these effects without using human subjects. Methods: Dr. Fornes and his team use rabbit models to induce hypercholesterolemia through a high-fat diet. They then study the physiology and function of sperm cells from these hypercholesterolemic rabbits. Key parameters analyzed include cholesterol content in sperm membranes, ability to undergo capacitation and acrosomal reaction, and fertilization capability. Results: The studies revealed that hypercholesterolemia caused by a high-fat diet leads to increased cholesterol levels in sperm. This interferes with the normal physiology of sperm cells. In particular, many sperm from hypercholesterolemic rabbits were unable to properly undergo the acrosomal reaction, a crucial step for successful fertilization of the oocyte. This suggests high-fat diets could contribute to male infertility. Conclusions: The research highlights the importance of diet and lifestyle on male reproductive health. Dr. Fornes recommends a balanced diet like the Mediterranean diet, rich in fruits, vegetables, and olive oil, to maintain healthy sperm function and fertility. Replacing animal fats with olive oil may help prevent hypercholesterolemia-related infertility. The findings have implications for dietary guidelines and clinical interventions to support male fertility.

Pruning methods can primarily affect grape production at various levels. Of the commonly affected features by pruning, the number of bunches has known to have a significant effect on the relation between the functions of assimilate sources and sinks. Further, fruitfulness can significantly be negatively influenced by shading. In this study, we aim to study the impact of 4, 6 and 8 buds per cane with pruning intensity as light, moderate and severely pruned and their interaction in the course two consecutive years, 2017 and 2018 in ‘Sahebi’ and ‘Halagho’ (both seeded red table grape cultivars). In 2018, lightly pruned ‘Halagho’ and having 8 buds per cane increased number of bunches by 54.00, which had the highest value. Results showed that there is apical buds bear more fruit by comparison to the buds with vegetative nature, 1 to 4 first buds. Based upon the outcomes of this study, it could be concluded that due to the stresses imposed by the pruning of the vines, therefore, the chemical compounds increases in order alleviate the negative aftermaths . In 2018, whole berry antioxidant activity in both cultivars was significantly lessened, and this decline was higher in ‘Saahebi’. The number of bunches was increased by increasing cane length or bud load/cane. Overall, the pruning program has an impactful role in bunch number as well as antioxidant activity and in the long-run on accumulated reserves, which makes choosing and applying a specific pruning method undeniably important. Thus, emphasize the importance of further research in this field.

Background: This interview covers Dr. Peter McCullough’s medical career, experience as an editor of medical journals, and his expertise in areas such as cardiomyopathy, myocarditis, and pericarditis. Aims: The primary aim is to understand Dr. McCullough’s perspectives on various medical topics, including his journey as a cardiologist, the importance of peer review, the phenomenon of Pheidippides cardiomyopathy, the differences between myocarditis and pericarditis, and the significance of ethical principles like the Nuremberg Code and the Declaration of Helsinki. Additionally, the interview aims to explore his concerns about censorship during the COVID-19 pandemic. Methods: The interview follows a question-and-answer format, with the interviewer posing questions to Dr. McCullough on various topics related to his medical career, research interests, and ethical considerations. Results: Dr. McCullough shares his insights on topics such as cardiomyopathy, myocarditis, and pericarditis, emphasizing the importance of peer review, identifying potential biases, and balancing scientific rigor with timely dissemination of findings. He also highlights the significance of the Nuremberg Code and the Declaration of Helsinki in ensuring informed consent and preventing coercion in medical research and treatment. Discussion: Dr. McCullough expresses concerns about censorship during the COVID-19 pandemic, which he believes impacted the ability of medical professionals to freely discuss and disseminate health-related information. He also discusses the potential role of COVID-19 vaccines in causing myocarditis and the need for transparent communication about treatment options and potential complications. Conclusion: The interview provides valuable insights from Dr. McCullough’s extensive medical experience and expertise, covering a range of topics from cardiovascular conditions to ethical principles and the challenges posed by censorship during the COVID-19 pandemic.

Background: The interview with Professor Dr. Fernando Luiz Pellegrini Pessoa covers his extensive career and contributions to chemical engineering, focusing on innovations and sustainability. Objectives: To explore Professor Pellegrini's experiences in various areas of chemical engineering, including teaching methods, research in supercritical extraction, biodiesel production, and process intensification. Methods: Semi-structured interview addressing topics such as academic and industrial career, teaching methods, ongoing research, and future perspectives for the chemical industry. Results: Professor Pellegrini highlighted the importance of practical application of theoretical knowledge, the development of the Water Source Diagram method, advances in supercritical extraction and biodiesel production, and the need for process intensification in the industry. Discussion: The interview revealed the importance of integration between academia and industry, the need for teaching methods that facilitate learning, and the challenges in implementing sustainable and efficient technologies in the chemical industry. Conclusion: Professor Pellegrini emphasizes the importance of process intensification and sustainability in the evolution of the chemical industry. He highlights the need for greater collaboration between academia and industry to address future challenges and implement innovative solutions.

Background: Infectious diseases are a global problem, the second human cause of death. Infectious diseases caused by pathogenic bacteria have been treated with a high degree of efficacy. However, even when the 20th century was considered the “golden age” of antibiotics, bacteria developed a different resistance mechanism to antibiotics. In 2017, the WHO issued an alert about 12 bacteria with an urgent need to develop new antibiotics. Aims: The aim of the present review is to analyze the current knowledge of the antibacterial activity of natural extract-based treatments against the pathogens listed by WHO. Methods: A systematic review of the literature in PubMed was performed to search for publications describing the use of natural extracts as antibiotics over bacteria. We focused on the Gram-Negative group. The exclusion criteria consisted of limiting papers on natural extracts tested over the bacteria culture related to eight selected bacteria, according to an alert issued by WHO in 2017, and seven plant extracts. Results: All the Gram-Negative bacteria listed in 2017 by WHO have been treated, with different degrees of advance, with some of the plant extracts and plant-based compounds reviewed. In general, the first approach is using inhibition disks applied over the bacterial biofilm in solid culture media. Discussion: While Salmonellae and P. aeruginosa have been extensively studied, over N. gonorrhoeae, A. baumannii have been tested with fewer natural extracts. Edible herbs are more often used, as well as artemisa and wine byproducts. In all cases, they are in the early stages of study, not being tested in patients at present. Conclusions: Plant extracts and plant-based compounds are effective as antibacterial, with minimal effects on the host cell. Furthermore, they are sustainable, environmentally friendly, and renewable.