Antibiotic resistance and tolerance: What can drug delivery do against this global threat?

Antimicrobial resistance and tolerance (AMR&T) are urgent global health concerns, with alarmingly increasing numbers of antimicrobial drugs failing and a corresponding rise in related deaths. Several reasons for this situation can be cited, such as the misuse of traditional antibiotics, the massive use of sanitizing measures, and the overuse of antibiotics in agriculture, fisheries, and cattle. AMR&T management requires a multifaceted approach involving various strategies at different levels, such as increasing the patient's awareness of the situation and measures to reduce new resistances, reduction of current misuse or abuse, and improvement of selectivity of treatments. Also, the identification of new antibiotics, including small molecules and more complex approaches, is a key factor. Among these, novel DNA- or RNA-based approaches, the use of phages, or CRISPR technologies are some potent strategies under development. In this perspective article, emerging and experienced leaders in drug delivery discuss the most important biological barriers for drugs to reach infectious bacteria (bacterial bioavailability). They explore how overcoming these barriers is crucial for producing the desired effects and discuss the ways in which drug delivery systems can facilitate this process.

Latest advances in glucose-responsive microneedle-based systems for transdermal insulin delivery

The development of a self-regulated minimally invasive system for insulin delivery can be considered as the holy grail in the field of diabetes mellitus. A delivery system capable of releasing insulin in response to blood glucose levels would significantly improve the quality of life of diabetic patients, eliminating the need for frequent finger-prick tests and providing better glycaemic control with lower risk of hypoglycaemia. In this context, the latest advances in glucose-responsive microneedle-based transdermal insulin delivery are here compiled with a thorough analysis of the delivery mechanisms and challenges lying ahead in their clinical translation. Two main groups of microneedle-based systems have been developed so far: glucose oxidase-containing and phenylboronic acid-containing systems. Both strategies in combination have also been tested and two other novel strategies are under development, namely electronic closed-loop and glucose transporter-based systems. Results from preclinical studies conducted using these different types of glucose-triggered release systems are comprehensively discussed. Altogether, this analysis from both a mechanistic and translational perspective will provide rationale and/or guidance for future trends in the research hotspot of glucose-responsive microneedle-based insulin delivery systems.

Cyclosporin A-loaded dissolving microneedles for dermatitis therapy: Development, characterisation and efficacy in a delayed-type hypersensitivity in vivo model

Several drugs can be used for treating inflammatory skin pathologies like dermatitis and psoriasis. However, for the management of chronic and long-term cases, topical administration is preferred over oral delivery since it prevents certain issues due to systemic side effects from occurring. Cyclosporin A (CsA) has been used for this purpose; however, its high molecular weight (1202 Da) restricts the diffusion through the skin structure. Here, we developed a nano-in-micro device combining lipid vesicles (LVs) and dissolving microneedle array patches (DMAPs) for targeted skin delivery. CsA-LVs allowed the effective incorporation of CsA in the hydrophilic DMAP matrix despite the hydrophobicity of the drug. Polymeric matrix composed of poly (vinyl alcohol) (5% w/v), poly (vinyl pyrrolidine) (15% w/v) and CsA-LV dispersion (10% v/v) led to the formation of CsA-LVs@DMAPs with adequate mechanical properties to penetrate the stratum corneum barrier. The safety and biocompatibility were ensured in an in vitro viability test using HaCaT keratinocytes and L929 fibroblast cell lines. Ex vivo permeability studies in a Franz-diffusion cell setup showed effective drug retention in the skin structure. Finally, CsA-LVs@DMAPs were challenged in an in vivo murine model of delayed-type hypersensitivity to corroborate their potential to ameliorate skin inflammatory conditions. Different findings like photon emission reduction in bioluminescence study, normalisation of histological damage and decrease of inflammatory cytokines point out the effectivity of CsA-LVs@DMAPs to treat these conditions. Overall, our study demonstrates that CsA-LVs@DMAPs can downregulate the skin inflammatory environment which paves the way for their clinical translation and their use as an alternative to corticosteroid-based therapies.

Nanotechnology-based techniques for hair follicle regeneration

The hair follicle (HF) is a multicellular complex structure of the skin that contains a reservoir of multipotent stem cells. Traditional hair repair methods such as drug therapies, hair transplantation, and stem cell therapy have limitations. Advances in nanotechnology offer new approaches for HF regeneration, including controlled drug release and HF-specific targeting. Until recently, embryogenesis was thought to be the only mechanism for forming hair follicles. However, in recent years, the phenomenon of wound-induced hair neogenesis (WIHN) or de novo HF regeneration has gained attention as it can occur under certain conditions in wound beds. This review covers HF-specific targeting strategies, with particular emphasis on currently used nanotechnology-based strategies for both hair loss-related diseases and HF regeneration. HF regeneration is discussed in several modalities: modulation of the hair cycle, stimulation of progenitor cells and signaling pathways, tissue engineering, WIHN, and gene therapy. The HF has been identified as an ideal target for nanotechnology-based strategies for hair regeneration. However, some regulatory challenges may delay the development of HF regeneration nanotechnology based-strategies, which will be lastly discussed.

Radioprotective Effects from Propolis: A Review

Propolis is a natural bee-produced substance with antimicrobial, anti-inflammatory, and wound-healing properties, containing some components from the leaves, buds and resins of plants. It has been used for centuries for various health benefits. In this manuscript, our group reviewed the radioprotective effect of propolis using PubMed and Embase, and our review was conducted according to the PRISMA statement. Finally, 27 articles were included in this review, which includes the radioprotective effect of propolis from cell-based studies (n = 8), animal models (n = 14), and human trials (n = 5). Results reflected that the dosage forms of propolis extracted in the scientific literature were ethanolic extracts of propolis, a water-soluble derivate of propolis, or capsules. The efficacy of the radioprotective properties from propolis is extracted from the bibliography, as several compounds of this resinous mixture individually or synergistically are possible candidates that have the radioprotective effect. In fact, studies prior to 2011 lacked a comprehensive characterization of propolis due to the variability in active compounds among different batches of propolis and were limited to analytical techniques. Furthermore, in this manuscript, we have selected studies to include primarily propolis types from Brazil, Croatia, Egypt, European countries, and those commercialized in Spain. They all contained ethanolic extract of propolis (EEP) and were influenced by different dosage forms. EEP showed a significant presence of lipophilic bioactive compounds like flavones, flavonols, and flavanones.

A Narrative Review of the Herbal Preparation of Ayurvedic, Traditional Chinese, and Kampō Medicines Applied as Radioprotectors

In recent years, there has been growing scientific interest in the search for natural radioprotectors that can be used to mitigate the effects of radiation on patients, healthcare personnel, and even for space travel. This narrative review covers the past fifty years and focuses on herbal preparations of Ayurvedic, Traditional Chinese, and Kampō Medicines that have the potential to reduce or eliminate the harmful effects of radiation. Our findings highlight ten herbal preparations, namely Abana, Amalakyadi Churna, Amritaprasham, Brahma, Bu-zhong-yi-qi-tang (BZYQT), Chyavanaprasha, Cystone, Geriforte, Mentat, and Triphala, which have demonstrated potential radioprotective effects. This review examines their composition, properties, and possible mechanisms of action in relation to their radioprotective properties. Exploring the ethnobotany of traditional Asian medicine is particularly interesting as it may lead to the discovery of new active compounds with radioprotective properties.

Microneedle-assisted transdermal delivery of nanoparticles: Recent insights and prospects

Transdermal delivery of drugs offers an interesting alternative for the administration of molecules that present certain troubles when delivered by the oral route. It can produce systemic effects or perform a local action when the formulation exerts an optimal controlled drug release or a targeted delivery to the specific cell type or site. It also avoids several inconveniences of the oral administration such as the hepatic first pass effect, gastric pH-induced hydrolysis, drug malabsorption because of certain diseases or surgeries, and unpleasant organoleptic properties. Nanomedicine and microneedle array patches (MAPs) are two of the trendiest delivery systems applied to transdermal research nowadays. However, the skin is a protective barrier and nanoparticles (NPs) cannot pass through the intact stratum corneum. The association of NPs and MAPs (NPs@MAPs) work synergistically, since MAPs assist NPs to bypass the outer skin layers, and NPs contribute to the system providing controlled drug release and targeted delivery. Vaccination and tailored therapies have been proposed as fields where both NPs and MAPs have great potential due to inherent characteristics. MAPs conception and easy use could allow self-administration and therefore facilitate mass vaccination campaigns in undeveloped areas with weak healthcare services. Additionally, nanomedicine is being explored as a platform to personalize therapies in such an important field as oncology. In this work we show recent insights that prove the benefits of NPs@MAPs association and analyze the prospects and the discrete interest of the industry in NPs@MAPs, evaluating different limiting steps that restricts NPs@MAPs translation to the clinical practice. This article is categorized under: Nanotechnology Approaches to Biology > NA Therapeutic Approaches and Drug Discovery > NA.

Skin drug delivery using lipid vesicles: A starting guideline for their development

Lipid vesicles can provide a cost-effective enhancement of skin drug absorption when vesicle production process is optimised. It is an important challenge to design the ideal vesicle, since their properties and features are related, as changes in one affect the others. Here, we review the main components, preparation and characterization methods commonly used, and the key properties that lead to highly efficient vesicles for transdermal drug delivery purposes. We stand by size, deformability degree and drug loading, as the most important vesicle features that determine the further transdermal drug absorption. The interest in this technology is increasing, as demonstrated by the exponential growth of publications on the topic. Although long-term preservation and scalability issues have limited the commercialization of lipid vesicle products, freeze-drying and modern escalation methods overcome these difficulties, thus predicting a higher use of these technologies in the market and clinical practice.

Vitamins and Radioprotective Effect: A Review

The radioprotective effect ex vivo, in vitro and in vivo of vitamins was reviewed using PubMed and Embase and conducted according to the PRISMA statement. A total of 38 articles were included in this review, which includes the radioprotective effect of vitamins from ex vivo, in vitro and in vivo studies. Vitamins A, C, D and E were used alone, in combination or with other nutritional and non-nutritional compounds. The use of vitamins in natural form or supplementation can be useful to reduce the radiation effect in the body, organs and/or cells. Only four (A, C, D and E) out of thirteen vitamins have been detected with radioprotective properties being mainly vitamin E followed by vitamin C, A and D.

In Vitro Skin Co-Delivery and Antibacterial Properties of Chitosan-Based Microparticles Containing Ascorbic Acid and Nicotinamide

Vitamins are widely found in nature, for example, in plants and fruits. Ascorbic acid and nicotinamide are examples of these compounds that have potent antioxidant properties, besides stimulating collagen production and depigmenting properties that protect the skin from premature aging. To overcome the skin barrier and reduce the instability of antioxidant compounds, alternative systems have been developed to facilitate the delivery of antioxidants, making them efficiently available to the tissue for an extended time without causing damage or toxicity. The objective of this study was to obtain chitosan biodegradable microparticles containing ascorbic acid and nicotinamide for topical delivery. The microparticles were obtained by spray drying and characterized chemically by means of scanning electron microscopy, infrared spectroscopy, X-ray diffraction, and differential exploratory calorimetry. The drugs were successfully encapsulated and the microparticles showed positive zeta potential. In vitro release assays showed a sustained release profile. The evaluation of ex vivo skin permeation and retention demonstrated low permeation and adequate retention of the compounds in the epidermis/dermis, suggesting the efficient delivery from the obtained microparticles. Antibacterial assays have shown that microparticles can inhibit the growth of microorganisms in a time- and dose-dependent manner, corroborating their use in cosmetic products for application on the skin.

Cholinergic Senescence in the Ts65Dn Mouse Model for Down Syndrome

Down syndrome (DS) induces a variable phenotype including intellectual disabilities and early development of Alzheimer’s disease (AD). Moreover, individuals with DS display accelerated aging that affects diverse organs, among them the brain. The Ts65Dn mouse is the most widely used model to study DS. Progressive loss of cholinergic neurons is one of the hallmarks of AD present in DS and in the Ts65Dn model. In this study, we quantify the number of cholinergic neurons in control and Ts65Dn mice, observing a general reduction in their number with age but in particular, a greater loss in old Ts65Dn mice. Increased expression of the m1 muscarinic receptor in the hippocampus counteracts this loss. Cholinergic neurons in the Ts65Dn mice display overexpression of the early expression gene c-fos and an increase in the expression of β-galactosidase, a marker of senescence. A possible mechanism for senescence induction could be phosphorylation of the transcription factor FOXO1 and its retention in the cytoplasm, which we are able to confirm in the Ts65Dn model. In our study, using Ts65Dn mice, we observe increased cholinergic activity, which induces a process of early senescence that culminates in the loss of these neurons.

3D-Printed Products for Topical Skin Applications: From Personalized Dressings to Drug Delivery

3D printing has been widely used for the personalization of therapies and on-demand production of complex pharmaceutical forms. Recently, 3D printing has been explored as a tool for the development of topical dosage forms and wound dressings. Thus, this review aims to present advances related to the use of 3D printing for the development of pharmaceutical and biomedical products for topical skin applications, covering plain dressing and products for the delivery of active ingredients to the skin. Based on the data acquired, the important growth in the number of publications over the last years confirms its interest. The semisolid extrusion technique has been the most reported one, probably because it allows the use of a broad range of polymers, creating the most diverse therapeutic approaches. 3D printing has been an excellent field for customizing dressings, according to individual needs. Studies discussed here imply the use of metals, nanoparticles, drugs, natural compounds and proteins and peptides for the treatment of wound healing, acne, pain relief, and anti-wrinkle, among others. The confluence of 3D printing and topical applications has undeniable advantages, and we would like to encourage the research groups to explore this field to improve the patient's life quality, adherence and treatment efficacy.

Cyanocobalamin Ultraflexible Lipid Vesicles: Characterization and In Vitro Evaluation of Drug-Skin Depth Profiles

Atopic dermatitis (AD) and psoriasis are the most common chronic inflammatory skin disorders, which importantly affect the quality of life of patients who suffer them. Among other causes, nitric oxide has been reported as part of the triggering factors in the pathogenesis of both conditions. Cyanocobalamin (vitamin B₁₂) has shown efficacy as a nitric oxide scavenger and some clinical trials have given positive outcomes in its use for treating skin pathologies. Passive skin diffusion is possible only for drugs with low molecular weights and intermediate lipophilicity. Unfortunately, the molecular weight and hydrophilicity of vitamin B₁₂ do not predict its effective diffusion through the skin. The aim of this work was to design new lipid vesicles to encapsulate the vitamin B₁₂ to enhance its skin penetration. Nine prototypes of vesicles were generated and characterized in terms of size, polydispersity, surface charge, drug encapsulation, flexibility, and stability with positive results. Additionally, their ability to release the drug content in a controlled manner was demonstrated. Finally, we found that these lipid vesicle formulations facilitated the penetration of cyanocobalamin to the deeper layers of the skin. The present work shows a promising system to effectively administer vitamin B₁₂ topically, which could be of interest in the treatment of skin diseases such as AD and psoriasis.

Cranioplasty with Autologous Bone Flaps Cryopreserved with Dimethylsulphoxide: Does Tissue Processing Matter

OBJECTIVE

The aim of this article was to study the outcome of patients who underwent cranioplasty with cryopreserved autologous bone after decompressive craniectomy.

METHODS

Data from 74 patients were retrospectively analyzed. They were divided into groups according to the storage time and the age at cranioplasty. To assess the predictive potential for complication, factors were related to successive stages (preoperative, craniectomy, tissue processing, cranioplasty, and postoperative). Cooling and warming rates applied on bone flap were calculated. The ability to inhibit microbial growth was determined exposing bone fragments to a panel of microorganisms. The concentration of antibiotics eluted from the bone was also determined. A bone explant culture method was used to detect living cells in the thawed cranial bone.

RESULTS

Hydrocephalus was significantly more frequent in pediatric patients (26.7%) than in adults (5.1%). The overall rate of bone flap resorption was 21.6% (43.7% of which required reoperation). Surgical site infection after cranioplasty was detected in 6.8% of patients. There was no correlation between infection as a postoperative complication and previous microbiological-positive culture during processing. The cause of craniectomy did not influence the risk of bone flap contamination. Vancomycin was the only antibiotic detected in the supernatant where the bone was incubated. Outgrowth from bone explants was observed in 36.8% of thawed skulls. An early start of bone flap processing at the tissue bank had a positive effect on cell viability.

CONCLUSIONS

The outcome after autologous cranioplasty is a multifactorial process, which is modulated by patient-related, surgery-related, and bone-related factors.

Microneedle-Based Delivery: An Overview of Current Applications and Trends

Microneedle arrays (MNA) are considered as one of the most promising resources to achieve systemic effects by transdermal delivery of drugs. They are designed as a minimally invasive, painless system which can bypass the stratum corneum, overcoming the potential drawbacks of subcutaneous injections and other transdermal delivery systems such as chemical enhancers, nano and microparticles, or physical treatments. As a trendy field in pharmaceutical and biomedical research, its applications are constantly evolving, even though they are based on very well-established techniques. The number of molecules administered by MNA are also increasing, with insulin and vaccines administration being the most investigated. Furthermore, MNA are being used to deliver cells and applied in other organs and tissues like the eyes and buccal mucosae. This review intends to offer a general overview of the current state of MNA research, focusing on the strategies, applications, and types of molecules delivered recently by these systems. In addition, some information about the materials and manufacturing processes is presented and safety data is discussed.

Cubic Microcontainers Improve In Situ Colonic Mucoadhesion and Absorption of Amoxicillin in Rats

An increased interest in colonic drug delivery has led to a higher focus on the design of delivery devices targeting this part of the gastrointestinal tract. Microcontainers have previously facilitated an increase in oral bioavailability of drugs. The surface texture and shape of microcontainers have proven to influence the mucoadhesion ex vivo. In the present work, these findings were further investigated using an in situ closed-loop perfusion technique in the rat colon, which allowed for simultaneous evaluation of mucoadhesion of the microcontainers as well as drug absorption. Cylindrical, triangular and cubic microcontainers, with the same exterior surface area, were evaluated based on in vitro release, in situ mucoadhesion and in situ absorption of amoxicillin. Additionally, the mucoadhesion of empty cylindrical microcontainers with and without pillars on the top surface was investigated. From the microscopy analysis of the colon sections after the in situ study, it was evident that a significantly higher percentage of cubic microcontainers than cylindrical microcontainers adhered to the intestinal mucus. Furthermore, the absorption rate constants and blood samples indicated that amoxicillin in cubic microcontainers was absorbed more readily than when cylindrical or triangular microcontainers were dosed. This could be due to a higher degree of mucoadhesion for these particular microcontainers.

Caffeic acid skin absorption: Delivery of microparticles to hair follicles

Caffeic acid (CA) is a polyphenol that can be found in a wide range of vegetal dietary sources. It presents a remarkable antioxidant potential, but what is more interesting from the therapeutic point of view is, that it has demonstrated in vitro antimicrobial properties. Folliculitis is a common skin condition, usually caused by a bacterial or fungal infection, in which hair follicles become inflamed. A typical challenge in dermal application when the actives diffuse passively through the skin in a quick manner, as it is the case of CA, is to provide the effective concentration of the compound at the target site for the sufficient time to finalize the treatment adequately and reduce the possibility to trigger systemic side effects. To achieve this goal, it is necessary to appropriately design the drug delivery system. In this case, we leverage the ability of microparticles to accumulate into the hair follicles to design O/W-emulsions containing CA-loaded controlled-release microparticles. Two different emulsion types containing CA were prepared, one containing free CA and the other containing microencapsulated CA. Traditional and differential tape stripping techniques were performed to investigate drug distribution within the different skin layers and into the hair follicles. The Tape stripping results demonstrated that the tapes S3-S5 and S6-S10 presented a higher total amount of CA. The strips are collected and extracted in groups to assure the extraction of quantifiable amounts of drug. Samples S11-15 and S16-20 show a decrease in the amount of quantified CA, as it was expected. Thus, it can be seen that the amount of active decreases while the stratum corneum depth increases. The retention studies demonstrated that, the microparticles tend to produce a more homogeneous distribution of CA, within the stratum corneum and a higher retention into the hair follicle, which can be attributed to their size and uniformity. Besides, MPs present an additional advantage because they guarantee a continuous release of CA in the target for a prolonged period, allowing the treatment of folliculitis with a single dose until the MPs are removed from the hair follicle by its natural regeneration process or particle depletion of CA.

Calcifediol-loaded liposomes for local treatment of pulmonary bacterial infections

The influence of vitamin D3 and its metabolites calcifediol (25(OH)D) and calcitriol on immune regulation and inflammation is well described, and raises the question of potential benefit against bacterial infections. In the current study, 25(OH)D was encapsulated in liposomes to enable aerosolisation, and tested for the ability to prevent pulmonary infection by Pseudomonas aeruginosa. Prepared 25(OH)D-loaded liposomes were nanosized and monodisperse, with a negative surface charge and a 25(OH)D entrapment efficiency of approximately 23%. Jet nebulisation of liposomes was seen to yield an aerosol suitable for tracheo-bronchial deposition. Interestingly, 25(OH)D in either liposomes or ethanolic solution had no effect on the release of the proinflammatory cytokine KC from Pseudomonas-infected murine epithelial cells (LA-4); treatment of infected, human bronchial 16-HBE cells with 25(OH)D liposomes however resulted in a significant reduction in bacterial survival. Together with the importance of selecting an application-appropriate in vitro model, the current study illustrates the feasibility and practicality of employing liposomes as a means to achieve 25(OH)D lung deposition. 25(OH)D-loaded liposomes further demonstrated promising effects regarding prevention of Pseudomonas infection in human bronchial epithelial cells.

Improved photostability and reduced skin permeation of tretinoin: development of a semisolid nanomedicine

The aims of this work were to increase the photostability and to reduce the skin permeation of tretinoin through nanoencapsulation. Tretinoin is widely used in the topical treatment of various dermatological diseases such as acne, psoriasis, skin cancer, and photoaging. Tretinoin-loaded lipid-core polymeric nanocapsules were prepared by interfacial deposition of a preformed polymer. Carbopol hydrogels containing nanoencapsulated tretinoin presented a pH value of 6.08±0.14, a drug content of 0.52±0.01 mg g(-1), pseudoplastic rheological behavior, and higher spreadability than a marketed formulation. Hydrogels containing nanoencapsulated tretinoin demonstrated a lower photodegradation (24.17±3.49%) than the formulation containing the non-encapsulated drug (68.64±2.92%) after 8h of ultraviolet A irradiation. The half-life of the former was seven times higher than the latter. There was a decrease in the skin permeability coefficient of the drug by nanoencapsulation, independently of the dosage form. The liquid suspension and the semisolid form provided K(p)=0.31±0.15 and K(p)=0.33±0.01 cm s(-1), respectively (p≤0.05), while the samples containing non-encapsulated tretinoin showed K(p)=1.80±0.27 and K(p)=0.73±0.12 cm s(-1) for tretinoin solution and hydrogel, respectively. Lag time was increased two times by nanoencapsulation, meaning that the drug is retained for a longer time on the skin surface.

[Takotsubo syndrome. Usefulness of nuclear medicine studies]

Takotsubo syndrome can mimic an acute myocardial infarction. It is characterized by anginal chest pain with ST elevation in precordial leads, no coronary obstruction on angiography, and typical and reversible deformation of the left ventricular due to antero-apical ballooning with basal hyperkinesis. The pathophysiology of this syndrome is uncertain. It is probably multifactorial, cardiac adrenergic nervous dysfunction standing out in the acute phase. We report two cases performed within the diagnostic context of Takotsubo syndrome. Cardiac SPECT was performed using (123)I Metaiodobenzylguanidine (MIBG) and (99m)Tc-Tetrofosmin and the results of two cases were adrenergic denervation in the anterior wall without alterations in myocardial perfusion study. Identification of Takotsubo syndrome is of clinical importance because its management and prognosis differ significantly from that of acute myocardial infarction.

In vitro human skin segmentation and drug concentration-skin depth profiles

Highly optimized methods for skin segmentation are provided using tape stripping in combination with infrared absorption measurements for stratum corneum (SC) and cryosectioning for deeper skin layers. Furthermore, an example is calculated for demonstration of the respective procedures.

[Attention deficit disorder and hyperactivity: a pattern of evolution?]

INTRODUCTION

When the frequency of a gene in the general population exceeds 1%, is not considered a random mutation but a mutation that has been positively selected during evolution. The high prevalence of attention deficit/hyperactivity disorder (ADHD) from 5-10% and its association with the seven-repeat allele of DRD4, which is positively selected in evolution, raising the possibility that ADHD increases the reproductive fitness of the individual and/or group. One of the main characteristics of ADHD is its diversity and is a well recognized fact that diversity confers many benefits to a population (eg. immunity).

DEVELOPMENT

This article discusses the various studies that support this hypothesis and offers further explanations on the prevalence, age distribution and sex distribution of the severity and heterogeneity of ADHD.

CONCLUSION

It is possible that the presence of altered gene combinations, as in ADHD, can bring concrete benefits to society but are detrimental to the individual.

Wistar rat skin as surrogate for human skin in nortriptyline hydrochloride patch studies

Six different matrices were prepared containing nortriptyline hydrochloride (NTH) with hydroxypropyl-methyl-cellulose as polymer. A mixture of transdermal enhancers was included as part of the vehicle. Diffusion studies were carried out through Wistar rat full thickness skin using Franz cells. They were compared with previously determined human heat separated epidermis in order to test if this animal can be used as model for in vivo assays. A linear correlation was obtained between NTH diffusion coefficients through both skin types (r2=0.996).

Nortriptyline for smoking cessation: release and human skin diffusion from patches

The objective of this work was to develop a simple and inexpensive transdermal formulation containing Nortriptyline Hydrochloride (NTH) for smoking cessation support therapy. Hydroxypropyl-methyl-cellulose was chosen as polymer and a mixture of transdermal enhancers (selected from previous research) was incorporated. The formulations were characterised in terms of appearance, thickness, uniformity of NTH content, release and skin permeation. Release studies demonstrated controlled release for four formulations. Diffusion studies were performed through human heat separated epidermis (HHSE) using Franz Diffusion Cells (FDC). Patches provided different fluxes varying from 20.39+/-7.09 microg/(cm(2) h) to 256.19+/-94.62 microg/(cm(2) h). The penetration profiles of NTH within the stratum corneum (SC) and deeper skin layers (DSL) were established after three administration periods (3 h, 6 h, and 24 h). Skin changes induced by the application of the patches were observed by confocal laser scanning microscopy (CLSM). The highest flux obtained would provide the recommended doses for smoke cessation support therapy (25-75 mg per day) with a 2 cm x 2 cm patch or a 3.5 cm x 3.5 cm patch, respectively, without skin damage evidence.

[Problem-based learning in an undergraduate medical school course on anesthesiology, recovery care, and pain management]

INTRODUCTION

We describe our experience with problem-based learning (PBL) in an undergraduate course in anesthesiology and recovery care.

MATERIAL AND METHODS

The study was carried out over 5 consecutive academic years from 2000 through 2005. In total, 168 students took part. PBL was started in seminars in the first 3 years the course was given. In the last 2 years, PBL was used throughout the entire course, which consisted of 12 seminars. At the end, each student evaluated the activities overall, the tutor's intervention, the student's own participation, and the time invested in searching for information and preparing for discussions.

RESULTS

In the first 3 years, most students considered they had better assimilated the knowledge presented and that they had participated more. In the last 2 years, assessment of the course overall reached a score of 8.47 (SD, 1.24); of the instructor, 8.84 (0.98); and of student participation, 7.38 (1.29). The students used 2.11 (1.43) hours to search for information and 1.74 (1.14) hours to prepare for discussion.

CONCLUSIONS

The medical students' level of satisfaction with and acceptance of PBL in this anesthesiology course were high. The instructor's intervention and student participation were assessed highly. A large amount of time was used for study.

Estimation of peripheral dose from two linacs: Mevatron MX6700 and Mevatron KDS

An empirical calculation method for high-energy beam peripheral dose estimation is described. The peripheral dose has been measured for a Siemens Mevatron MX6700 (6 MV) and a Siemens Mevatron KDS (6 and 18 MV) linear accelerators. The dose distribution is parameterized for each beam energy as a function of depth, distance from the edge of the field, and field size. A simple algorithm has been developed for dose calculation up to 100 cm from the field central axes. Predictions by this algorithm are compared with measurements in an Alderson phantom.

[Anesthesia recovery, gas exchange and postoperative hepatic and renal function in patients with morbid obesity undergoing bariatric surgery: comparison of the effects of halothane, isoflurane and fentanyl]

OBJECTIVES

To compare the postoperative effects of three anesthetic agents, fentanyl, halothane and isoflurane, on recovery from anesthesia, changes in arterial blood gases, and tests of liver and kidney function in morbidly obese patients recovering from vertical ring gastroplasty.

MATERIAL AND METHODS

Thirty-three patients were studied, randomly distributed into three groups of 11. Induction for all was with atracurium (5 mg), 2.5% thiopentone sodium (5-6 mg.kg-1), succinylcholine (1.5 mg.kg-1) and orotracheal intubation. Anesthesia was maintained with intermittent doses of fentanyl (group F), 2% halothane (group H) or 2.5% isoflurane (group I). All patients received a 50% O2/N2O mixture at a minute volume calculated on ideal weight. Muscle relaxation was achieved by continuous perfusion of atracurium. Postoperative analgesia was by morphine chloride through a lumbar epidural catheter. Time of eye opening and time of extubation were recorded. Arterial blood gas measurements were taken and the results of liver and kidney function tests were recorded until the 7th day after surgery.

RESULTS

Eye opening after awakening was earlier in the fentanyl group (6 +/- 5 min), but no differences were found for time of extubation. Blood gas measurements for the 33 patients revealed a significant decrease in PaO2 (58 +/- 14 mmHg), a slight increase of PaCO2 (40 +/- 6 mmHg) and a lower pH (7.32 +/- 0.04) immediately after surgery. On day seven, PaO2 had not yet reached preoperative levels (p < 0.01). These results were independent of anesthetic agent used. Kidney function tests showed significant rises in SGOT (81 +/- 36 U/l), SGPT (150 +/- 110 U/l) and bilirubin (Bil: 15 +/- 5 mmol/l) and decreases in prothrombin activity (PT: 73 +/- 11%) 24 hours after surgery, with later normalization. Urea fell significantly throughout the seven-day period (3.2 +/- 1.3 mmol/l). These results were also independent of the anesthetic agent used.

CONCLUSIONS

Morbidly obese patients undergoing gastroplasty recover from anesthesia in the same way regardless of the agent used. The early postoperative period is characterized by severe hypoxemia and transitory changes in kidney function tests. Neither of these findings is dependent on the agent used.

Acid aspiration prophylaxis in morbidly obese patients: famotidine vs. ranitidine

Famotidine and ranitidine were compared as agents for the prevention of acid aspiration syndrome in 32 morbidly obese patients undergoing vertical banded gastroplasty. Single-dose oral famotidine or double-dose oral ranitidine were administered on a random basis before surgery. Gastric contents were aspirated through a gastric tube, manually aided by the surgeon with the abdomen open. Mean (SD) gastric volumes were 13.8 ml (6.7) and 12.1 ml (13.0) for the famotidine and ranitidine groups, respectively. Mean (SD) gastric pH values were 6.2 (1.5) and 6.8 (1.5), respectively. There were no significant differences between the groups and no patient was considered 'at risk' (pH less than 2.5 and gastric volume greater than 25 ml). We conclude that single-dose oral famotidine and double-dose oral ranitidine are equally effective for preventing acid aspiration syndrome in morbidly obese patients.