Scientific Letters

MDMA and tramadol or tapentadol co-administration causes serotonin-independent neurological damage

2025-01-14T13:52:36+00:00

The simultaneous consumption and misuse of different drugs, including 3,4-methylenedioxymethamphetamine (MDMA, “ecstasy”) and opioids, raise concerns about fatal intoxications, as a result of increased serotonin levels. However, research on the simultaneous consumption of MDMA and opioids is limited. This study aimed to evaluate the toxic effect of the simultaneous exposure of the undifferentiated human SH-SY5Y neuroblastoma cell line to MDMA and tramadol or MDMA and tapentadol, focusing on serotonin toxicity. After a 48-hour exposure to the mixtures, there was a significant decrease in cell viability linked to an increase in oxidative stress, alterations in mitochondrial membrane potential, and an increase in caspase-3 activity. Additionally, increased intracellular glucose levels and changes in the expression of enzymes involved in energetic metabolism were observed. However, serotonin levels did not significantly increase compared with the exposure to MDMA alone. Tramadol or tapentadol exposure did not cause a significant increase in serotonin levels compared with non-treated cells. Then, serotonergic toxicity may not be associated with the damage observed. Further studies are needed to better understand the toxicity deriving from the simultaneous exposure to these drugs. The results additionally underlined the need for a careful prescription of tramadol and tapentadol.

Enzyme activities of brown trout liver and kidney peroxisomes after paraquat exposure

2025-01-14T09:09:06+00:00

Paraquat, a potent herbicide, can be highly toxic to fish, causing morphological and biochemical alterations in several organs, including induction of oxidative stress that may result in cellular damage. Since peroxisomes are vital regulators of reactive oxygen species, it was hypothesized that a subacute exposure of brown trout – a sensitive bioindicator – to a waterborne environmentally relevant concentration (0.3 mg L^-1) of paraquat may impact some liver and kidney peroxisomal enzyme activities. Spectrophotometric measurements of urate oxidase, catalase, and d-amino acid oxidase activities were assayed in liver and renal homogenates from immature trout, control and exposed, at 0, 7, and 15 days. In the liver, none of those enzymes showed significant differences between the control and exposed fish at 7 and 15 days. In the kidney, urate oxidase activity was not detectable, and no significant statistical difference was found for the other enzymatic activities between groups. However, an increase in catalase and a simultaneous decrease in d-amino acid oxidase activities were detected during the experiment. At the concentration tested, paraquat did not affect the targeted hepatic and renal peroxisomal enzymes. Additionally, the study revealed changes over time, warning that captivity or experimental stress influenced the enzyme activities.

Editorial Acknowledgment to Reviewers of Scientific Letters in 2024

2024-12-24T10:29:44+00:00

On behalf of the Editorial Team of Scientific Letters, I would like to express our gratitude to the dedicated reviewers who have contributed to the success of the journal throughout 2024. Their unwavering commitment to ensuring the high quality of the articles published in Scientific Letters has been invaluable. This year, as in previous ones, we have been impressed by the consistent quality of the reviews, which reflect the dedication and professionalism of our reviewers. We are particularly grateful for the fact that many reviewers submitted their evaluations within the requested timeframes, ensuring that the peer review process remains efficient and fair. We deeply appreciate the time and effort invested by each reviewer in helping authors improve their manuscripts. Their contributions are central to the continued success and growth of Scientific Letters. On behalf of the entire Editorial Team, I would like to express our sincere thanks and look forward to continued collaboration in 2025!

Alexandra Maia

Ana Isabel Carvalho Teixeira

Ana Mota

Ana Sofia Vinhas

Andrea Cunha

Arthur R. G. Cortes

Célia Fortuna Rodrigues

Cláudia Ribeiro

Daniel Barbosa

Daniel Folha

Hassan Bousbaa

José Manuel Mendes

Karl Goodkin

Luís M. C. Monteiro

Manuel Garabal

Odília Queirós

Paulo Rompante

Rita Fidalgo Pereira

Roberto Markarian

Sara Matos

Sónia Alves

Teresa Pinho

Tony Weir

Exploring Innovations and Key Insights in Healthcare

2024-12-24T11:36:00+00:00

On behalf of the Editorial Team of Scientific Letters, we are pleased to announce the publication of the third issue. The 2024 edition of Scientific Letters presents a diverse array of research that highlights significant advancements in health, dentistry, and clinical treatments.

Different approaches and effectiveness in orthodontic traction of impacted canines: An integrative systematic review

2025-02-08T20:02:32+00:00

Canines have a fundamental role in the dental arch, both aesthetically and functionally. Apart from the third molars, maxillary canines are the most frequently impacted teeth. Orthodontic traction of an impacted canine is one of the most appropriate approaches when there is a good prognosis, in growing patients and without a serious lack of space in the arch. This systematic review aims to describe the different approaches used in orthodontic traction of impacted canines and evaluate their effectiveness. PRISMA guidelines were used to perform a bibliographic search on the referenced platform PubMed. Articles published between 2014 and May 2024 were selected. Nine articles were included, and another five were added by manual search. The most studied methods were the transpalatal arch, the mini-implant, and the cantilever spring, which prove to be quite effective. Aligners, when combined with auxiliary methods, have been demonstrated to be a viable and effective alternative to conventional techniques. However, further research is required. Despite there being no consensus among authors as to which is the most effective method, choosing the correct traction approach through an accurate diagnosis and treatment planning is crucial for the successful orthodontic treatment of impacted canines.

Evaluation of the Effect of Chlorhexidine Mouthwash on Blood Pressure: A Narrative Literature Review

2025-01-10T12:55:00+00:00

This article presents a narrative review investigating the use of chlorhexidine mouthwash and its impact on blood pressure and cardiovascular health. Chlorhexidine, a widely used antimicrobial in Dentistry, has been associated with risks, such as increased blood pressure. The bibliographic research included articles published between 2014 and 2024, using the PubMed, SciELO, and the Virtual Library of the Ministry of Health databases, with keywords including “chlorhexidine”, “mouthrinse”, “mouthwash”, “nitrate” and “blood pressure”. The results indicate that chlorhexidine may disrupt nitric oxide homeostasis, essential for blood pressure regulation, by inhibiting oral microbiota bacteria that reduce nitrate to nitrite. Although effective in reducing pathogenic microorganisms, chlorhexidine should be prescribed with caution, considering its potential hypertensive effects. The study concludes that further research is needed regarding the contexts of chlorhexidine use and prescription, as well as the development of oral hygiene protocols that balance the elimination of pathogenic microorganisms with the preservation of beneficial microbiota.