Monkeypox virus genomic accordion strategies.

The 2023 monkeypox (mpox) epidemic was caused by a subclade IIb descendant of a monkeypox virus (MPXV) lineage traced back to Nigeria in 1971. Person-to-person transmission appears higher than for clade I or subclade IIa MPXV, possibly caused by genomic changes in subclade IIb MPXV. Key genomic changes could occur in the genome's low-complexity regions (LCRs), which are challenging to sequence and are often dismissed as uninformative. Here, using a combination of highly sensitive techniques, we determine a high-quality MPXV genome sequence of a representative of the current epidemic with LCRs resolved at unprecedented accuracy. This reveals significant variation in short tandem repeats within LCRs. We demonstrate that LCR entropy in the MPXV genome is significantly higher than that of single-nucleotide polymorphisms (SNPs) and that LCRs are not randomly distributed. In silico analyses indicate that expression, translation, stability, or function of MPXV orthologous poxvirus genes (OPGs), including OPG153, OPG204, and OPG208, could be affected in a manner consistent with the established "genomic accordion" evolutionary strategies of orthopoxviruses. We posit that genomic studies focusing on phenotypic MPXV differences should consider LCR variability.

Facultative endosymbionts modulate the aphid reproductive performance on wheat cultivars differing in contents of benzoxazinoids.

BACKGROUND: Facultative bacterial endosymbionts have the potential to influence the interactions between aphids, their natural enemies, and host plants. Among the facultative symbionts found in populations of the grain aphid Sitobion avenae in central Chile, the bacterium Regiella insecticola is the most prevalent. In this study, we aimed to investigate whether infected and cured aphid lineages exhibit differential responses to wheat cultivars containing varying levels of the benzoxazinoid DIMBOA (2,4-dihydroxy-7-methoxy-2H-1,4-benzoxazin-3(4H)-one), which is a xenobiotic compound produced by plants. Specifically, we examined the reproductive performance responses of the most frequently encountered genotypes of Sitobion avenae when reared on wheat seedlings expressing low, medium, and high concentrations of DIMBOA. RESULTS: Our findings reveal that the intrinsic rate of population increase (rm ) in cured lineages of Sitobion avenae genotypes exhibits a biphasic pattern, characterized by the lowest rm and an extended time to first reproduction on wheat seedlings with medium levels of DIMBOA. In contrast, the aphid genotypes harbouring Regiella insecticola display idiosyncratic responses, with the two most prevalent genotypes demonstrating improved performance on seedlings featuring an intermediate content of DIMBOA compared to their cured counterparts. CONCLUSION: This study represents the first investigation into the mediating impact of facultative endosymbionts on aphid performance in plants exhibiting varying DIMBOA contents. These findings present exciting prospects for identifying novel targets for aphid control by manipulating the presence of aphid symbionts. © 2023 Society of Chemical Industry.

Early administration of tecovirimat shortens the time to mpox clearance in a model of human infection.

Despite use of tecovirimat since the beginning of the 2022 outbreak, few data have been published on its antiviral effect in humans. We here predict tecovirimat efficacy using a unique set of data in nonhuman primates (NHPs) and humans. We analyzed tecovirimat antiviral activity on viral kinetics in NHP to characterize its concentration-effect relationship in vivo. Next, we used a pharmacological model developed in healthy volunteers to project its antiviral efficacy in humans. Finally, a viral dynamic model was applied to characterize mpox kinetics in skin lesions from 54 untreated patients, and we used this modeling framework to predict the impact of tecovirimat on viral clearance in skin lesions. At human-recommended doses, tecovirimat could inhibit viral replication from infected cells by more than 90% after 3 to 5 days of drug administration and achieved over 97% efficacy at drug steady state. With an estimated mpox within-host basic reproduction number, R0, equal to 5.6, tecovirimat could therefore shorten the time to viral clearance if given before viral peak. We predicted that initiating treatment at symptom onset, which on average occurred 2 days before viral peak, could reduce the time to viral clearance by about 6 days. Immediate postexposure prophylaxis could not only reduce time to clearance but also lower peak viral load by more than 1.0 log10 copies/mL and shorten the duration of positive viral culture by about 7 to 10 days. These findings support the early administration of tecovirimat against mpox infection, ideally starting from the infection day as a postexposure prophylaxis.

The Surprising Dynamics of Electrochemical Coupling at Membrane Sandwiches in Plants.

Transport processes across membranes play central roles in any biological system. They are essential for homeostasis, cell nutrition, and signaling. Fluxes across membranes are governed by fundamental thermodynamic rules and are influenced by electrical potentials and concentration gradients. Transmembrane transport processes have been largely studied on single membranes. However, several important cellular or subcellular structures consist of two closely spaced membranes that form a membrane sandwich. Such a dual membrane structure results in remarkable properties for the transport processes that are not present in isolated membranes. At the core of membrane sandwich properties, a small intermembrane volume is responsible for efficient coupling between the transport systems at the two otherwise independent membranes. Here, we present the physicochemical principles of transport coupling at two adjacent membranes and illustrate this concept with three examples. In the supplementary material, we provide animated PowerPoint presentations that visualize the relationships. They could be used for teaching purposes, as has already been completed successfully at the University of Talca.

Viral dynamics in patients with monkeypox infection: a prospective cohort study in Spain.

BACKGROUND: Monkeypox DNA has been detected in skin lesions, saliva, oropharynx, urine, semen, and stool of patients infected during the 2022 clade IIb outbreak; however, the viral dynamics within these compartments remain unknown. We aimed to characterise the viral load kinetics over time in various parts of the body. METHODS: This was an observational, prospective, multicentre study of outpatients diagnosed with monkeypox in two hospitals and two sexual health clinics in Spain between June 28, 2022, and Sept 22, 2022. Men and women aged over 18 years were eligible if they reported having symptom onset within the previous 10 days of presentation, and were ineligible if disease was severe enough to be admitted to hospital. Samples were collected from five body locations (skin lesions, oropharynx, rectum, semen or vagina, and a dried blood spot) at six time points up to 57 days after the screening visit. Samples were analysed by quantitative PCR and a subset by cell culture. The primary endpoint was time from symptom onset to viral DNA clearance. FINDINGS: Overall, 1663 samples were collected from 77 study participants. 75 (97%) participants were men, the median age was 35·0 years (IQR 29·0-46·0), and 39 (51%) participants were living with HIV. The median time from symptom onset to viral clearance was 25 days (95% CI 23-28) in the skin lesions, 16 days (13-19) in the oropharynx, 16 days (13-23) in the rectum, 13 days in semen (9-18), and 1 day in blood (0-5). The time from symptom onset to viral clearance for 90% of cases was 41 days (95% CI 34-47) in skin lesions and 39 days (27-56) in semen. The median viral load in skin lesions was 7·3 log10 copies per mL (IQR 6·5-8·2) at baseline, compared with 4·6 log10 copies per mL (2·9-5·8) in oropharyngeal samples, 5·0 log10 copies per mL (2·9-7·5) in rectal samples, 3·5 log10 copies per mL (2·9-4·7) in semen samples, and 4·0 log10 copies per mL (4·0-4·0) in blood specimens. Replication-competent viruses were isolated in samples with high DNA levels (>6·5 log10 copies per mL). INTERPRETATION: In immunocompetent patients with mild monkeypox disease, PCR data alone would suggest a contact isolation period of 3 to 6 weeks but, based on detection of replication-competent virus, this time could be reduced. Based on findings from this cohort of patients, semen testing and prolonged use of condoms after recovery from monkeypox might not be necessary. FUNDING: University Hospital Germans Trias i Pujol and the YoMeCorono. TRANSLATION: For the Spanish translation of the abstract see Supplementary Materials section.

Evaluating the Accuracy of Self-Collected Swabs for the Diagnosis of Mpox.

We evaluated the accuracy of patient-collected skin lesions, oropharyngeal, and rectal swabs among 50 individuals enrolled in a study of mpox viral dynamics. We found that the performance of self-collected samples was similar to that of physician-collected samples, suggesting that self-sampling is a reliable strategy for diagnosing mpox.

TPC1-Type Channels in Physcomitrium patens: Interaction between EF-Hands and Ca2.

Two-pore channels (TPCs) are members of the superfamily of ligand-gated and voltage-sensitive ion channels in the membranes of intracellular organelles of eukaryotic cells. The evolution of ordinary plant TPC1 essentially followed a very conservative pattern, with no changes in the characteristic structural footprints of these channels, such as the cytosolic and luminal regions involved in Ca2+ sensing. In contrast, the genomes of mosses and liverworts encode also TPC1-like channels with larger variations at these sites (TPC1b channels). In the genome of the model plant Physcomitrium patens we identified nine non-redundant sequences belonging to the TPC1 channel family, two ordinary TPC1-type, and seven TPC1b-type channels. The latter show variations in critical amino acids in their EF-hands essential for Ca2+ sensing. To investigate the impact of these differences between TPC1 and TPC1b channels, we generated structural models of the EF-hands of PpTPC1 and PpTPC1b channels. These models were used in molecular dynamics simulations to determine the frequency with which calcium ions were present in a coordination site and also to estimate the average distance of the ions from the center of this site. Our analyses indicate that the EF-hand domains of PpTPC1b-type channels have a lower capacity to coordinate calcium ions compared with those of common TPC1-like channels.

Clinical presentation and virological assessment of confirmed human monkeypox virus cases in Spain: a prospective observational cohort study.

BACKGROUND: In May, 2022, several European countries reported autochthonous cases of monkeypox, which rapidly spread globally. Early reports suggest atypical presentations. We aimed to investigate clinical and virological characteristics of cases of human monkeypox in Spain. METHODS: This multicentre, prospective, observational cohort study was done in three sexual health clinics in Madrid and Barcelona, Spain. We enrolled all consecutive patients with laboratory-confirmed monkeypox from May 11 to June 29, 2022. Participants were offered lesion, anal, and oropharynx swabs for PCR testing. Participant data were collected by means of interviews conducted by dermatologists or specialists in sexually transmitted infections and were recorded using a standard case report form. Outcomes assessed in all participants with a confirmed diagnosis were demographics, smallpox vaccination, HIV status, exposure to someone with monkeypox, travel, mass gathering attendance, risk factors for sexually transmitted infections, sexual behaviour, signs and symptoms on first presentation, virological results at multiple body sites, co-infection with other sexually transmitted pathogens, and clinical outcomes 14 days after the initial presentation. Clinical outcomes were followed up until July 13, 2022. FINDINGS: 181 patients had a confirmed monkeypox diagnosis and were enrolled in the study. 166 (92%) identified as gay men, bisexual men, or other men who have sex with men (MSM) and 15 (8%) identified as heterosexual men or heterosexual women. Median age was 37·0 years (IQR 31·0-42·0). 32 (18%) patients reported previous smallpox vaccination, 72 (40%) were HIV-positive, eight (11%) had a CD4 cell count less than 500 cells per µL, and 31 (17%) were diagnosed with a concurrent sexually transmitted infection. Median incubation was 7·0 days (IQR 5·0-10·0). All participants presented with skin lesions; 141 (78%) participants had lesions in the anogenital region, and 78 (43%) in the oral and perioral region. 70 (39%) participants had complications requiring treatment: 45 (25%) had a proctitis, 19 (10%) had tonsillitis, 15 (8%) had penile oedema, six (3%) an abscess, and eight (4%) had an exanthem. Three (2%) patients required hospital admission. 178 (99%) of 180 swabs from skin lesions collected tested positive, as did 82 (70%) of 117 throat swabs. Viral load was higher in lesion swabs than in pharyngeal specimens (mean cycle threshold value 23 [SD 4] vs 32 [6], absolute difference 9 [95% CI 8-10]; p<0·0001). 108 (65%) of 166 MSM reported anal-receptive sex. MSM who engaged in anal-receptive sex presented with proctitis (41 [38%] of 108 vs four [7%] of 58, absolute difference 31% [95% CI 19-44]; p<0·0001) and systemic symptoms before the rash (67 [62%] vs 16 [28%], absolute difference 34% [28-62]; p<0·0001) more frequently than MSM who did not engage in anal-receptive sex. 18 (95%) of 19 participants with tonsillitis reported practising oral-receptive sex. The median time from onset of lesions to formation of a dry crust was 10 days (IQR 7-13). INTERPRETATION: In our cohort, monkeypox caused genital, perianal, and oral lesions and complications including proctitis and tonsillitis. Because of the variability of presentations, clinicians should have a low threshold for suspicion of monkeypox. Lesion swabs showed the highest viral loads, which, combined with the history of sexual exposure and the distribution of lesions, suggests close contact is probably the dominant transmission route in the current outbreak. FUNDING: None.

Standards for practical intravenous rapid drug desensitization & delabeling: A WAO committee statement.

Drug hypersensitivity reactions (DHRs) to intravenous drugs can be severe and might leave patients and doctors in a difficult position where an essential treatment or intervention has to be suspended. Even if virtually any intravenous medication can potentially trigger a life-threatening DHR, chemotherapeutics, biologics, and antibiotics are amongst the intravenous drugs most frequently involved in these reactions. Admittedly, suspending such treatments may negatively impact the survival outcomes or the quality of life of affected patients. Delabeling pathways and rapid drug desensitization (RDD) can help reactive patients stay on first-choice therapies instead of turning to less efficacious, less cost-effective, or more toxic alternatives. However, these are high-complexity and high-risk techniques, which usually need expert teams and allergy-specific techniques (skin testing, in vitro testing, drug provocation testing) to ensure safety, an accurate diagnosis, and personalized management. Unfortunately, there are significant inequalities within and among countries in access to allergy departments with the necessary expertise and resources to offer these techniques and tackle these DHRs optimally. The main objective of this consensus document is to create a great benefit for patients worldwide by aiding allergists to expand the scope of their practice and support them with evidence, data, and experience from leading groups from around the globe. This statement of the Drug Hypersensitivity Committee of the World Allergy Organization (WAO) aims to be a comprehensive practical guide on the technical aspects of implementing acute-onset intravenous hypersensitivity delabeling and RDD for a wide range of drugs. Thus, the manuscript does not only focus on clinical pathways. Instead, it also provides guidance on topics usually left unaddressed, namely, internal validation, continuous quality improvement, creating a healthy multidisciplinary environment, and redesigning care (including a specific supplemental section on a real-life example of how to design a dedicated space that can combine basic and complex diagnostic and therapeutic techniques in allergy).

Drug allergy desensitization is not a unique recipe.

PURPOSE OF REVIEW: Drug desensitization is the only therapeutic option for patients with drug allergies who need to receive the drugs they are allergic to, and it is especially critical in patients with an urgent need for chemotherapy, biologics, or antibiotics, where equally effective alternatives might not be available. However, drug desensitization is not a cookbook where anyone with no experience or specific training can find a general recipe. This review article will approach the singularities that make personalized and highly specialized care essential in this field. RECENT FINDINGS: Drug desensitization needs to be personalized for each individual patient bearing in mind countless factors. Recent articles have tried to define the optimal resources and the most important factors to account for in personalization. However, drug desensitization is only a tool within the wider management pathway, and we will discuss recent findings in allergy delabelling in chemotherapy, biologics, and antibiotics. SUMMARY: Risk-assessment, delabelling, and desensitization protocols, as a part of wider management pathways, can be adapted locally along with comprehensive and multifactorial risk-management strategies. These high-complexity and high-risk procedures, such as drug desensitization, need to be managed by expert allergists who can provide personalization, innovation, continuous improvement, research, and teaching in expert centres.

Changes in the genetic composition of Myzus persicae nicotianae populations in Chile and frequency of insecticide resistance mutations.

Myzus persicae is a cosmopolitan aphid that is highly polyphagous and an important agricultural pest. The subspecies M. persicae nicotianae has been described for highly specialized phenotypes adapted to tobacco (Nicotiana tabacum). In Chile, the population of M. persicae nicotianae was originally composed of a single red genotype that did not possess insecticide resistance mutations. However, in the last decade, variation in the colour of tobacco aphids has been observed in the field. To determine whether this variation stems from the presence of new genotypes, sampling was carried out across the entire distribution of tobacco cultivation regions in Chile. The aphids collected were genotyped, and the frequency of kdr (L1014F), super-kdr (M918T), modification of acetylcholinesterase (MACE) and nicotinic acetylcholine receptor ß subunit (nAChRß) mutations associated with insecticide resistance was determined. A total of 16 new genotypes of M. persicae nicotianae were detected in Chile: four of them possessed the MACE mutation, and none of them possessed the kdr, super-kdr or nAChRß mutation. The previously described red genotype was not detected in any of the sampled fields over two seasons. These results raise questions about the mechanisms underlying changes in the genetic structure of M. persicae nicotianae populations in Chile. Future research aimed at addressing these questions could provide new insight into aphid evolution and agricultural practices.

Current situation of allergy education in Mexico and other parts of Latin America.

Allergic diseases are one of the most frequent chronic diseases in the world. It has been established that there is a worldwide epidemic of allergic diseases; therefore, the treatment of allergies should be acknowledged as a worldwide priority and the specialty of allergy should be considered an important field in medicine. Due to the fact that allergic diseases involve many organs, and Allergy and Clinical Immunology is one of the specialties in which physicians may be trained to treat patients of all ages, the subject in medical schools is not always taught as an individual specialty but often as part of another subject such as internal medicine or pediatrics. Certified allergists are an important contribution to health systems, providing the necessary care for patients who have allergic diseases. Undergraduate programs in many universities do not include allergy as a subject, contributing to a lack of knowledge regarding the correct management of allergic diseases. World Health Organization (WHO) recommends 1 allergist per 50,000 people; however, there is an uneven distribution of allergy and clinical immunology specialists. Most practitioners are localized mainly in larger cities and state capitals, while in other regions, specialists are still greatly needed. Support and training systems are required for allergy and clinical immunology specialists to promote continuing education and keep their clinical competence up to date, which will lead to better care for their patients. Increased exposure to the concepts of allergy and clinical immunology diagnosis and treatment in undergraduate education may also potentially lead to an increase in interest in the field of allergy and clinical immunology among physicians in training. This review will approach allergy education in Mexico and other parts of Latin America.

Streptococcus gallolyticus subsp. pasteurianus: un agente inusual ocasionando una infección común / Streptococcus gallolyticus subsp. pasteurianus: a common infection caused by an unusual agent

Resumen Introducción: Streptococcus gallolyticus subsp. pasteurianus es un coco grampositivo, catalasa negativo, perteneciente al grupo D de Lancefield, que se encuentra relacionado con cuadros de sepsis neonatal, específicamente con meningitis. Caso clínico: Se reporta el caso de un paciente de 2 meses con un cuadro de meningitis por S. gallolyticus subsp. pasteurianus. Se describen la sintomatología y el abordaje diagnóstico y terapéutico. Asimismo, se realiza una revisión de la literatura que evidencia el subdiagnóstico de este agente como causa de meningitis en pediatría. Conclusiones: Este caso representa el primer aislamiento de este agente en el Hospital Nacional de Niños de Costa Rica, de la Caja Costarricense de Seguro Social.

Abstract Background: Streptococcus gallolyticus subsp. pasteurianus is a positive Gram stain, catalase negative coccus that belongs to the Lancefield group D. It is associated with clinical manifestations such as neonatal sepsis and meningitis. Case report: The case of a 2-month-old male patient with meningitis caused by S. gallolyticus subsp. pasteurianus is described. Moreover, the symptoms, diagnosis, and management of the patient are discussed. Also, a review of the literature was conducted showing the sub-diagnosis of this agent as a cause of meningitis in pediatrics. Conclusions: This case represents the first detection of this agent in the National Children's Hospital of Costa Rica, which is part of the Caja Costarricense de Seguro Social.

[Streptococcus gallolyticus subsp. pasteurianus: a common infection caused by an unusual agent]. / Streptococcus gallolyticus subsp. pasteurianus: un agente inusual ocasionando una infección común.

Introducción: Streptococcus gallolyticus subsp. pasteurianus es un coco grampositivo, catalasa negativo, perteneciente al grupo D de Lancefield, que se encuentra relacionado con cuadros de sepsis neonatal, específicamente con meningitis. Caso clínico: Se reporta el caso de un paciente de 2 meses con un cuadro de meningitis por S. gallolyticus subsp. pasteurianus. Se describen la sintomatología y el abordaje diagnóstico y terapéutico. Asimismo, se realiza una revisión de la literatura que evidencia el subdiagnóstico de este agente como causa de meningitis en pediatría. Conclusiones: Este caso representa el primer aislamiento de este agente en el Hospital Nacional de Niños de Costa Rica, de la Caja Costarricense de Seguro Social.

Asexual reproduction of a few genotypes favored the invasion of the cereal aphid Rhopalosiphum padi in Chile.

BACKGROUND: Aphids (Hemiptera: Aphididae) are insects with one of the highest potentials for invasion. Several aphid species are present globally due to introduction events; they represent important pests of agroecosystems. The bird cherry-oat aphid Rhopalosiphum padi (Linnaeus) is a major pest of cereals and pasture grasses worldwide. Here, we report the genetic features of populations of R. padi that colonize different cereal crops in central Chile. METHODS: Rhopalosiphum padi individuals were collected in central Chile and genotyped at six microsatellite loci. The most frequent multilocus genotype (MLG) was then studied further to assess its reproductive performance across cereal hosts under laboratory conditions. RESULTS: Populations of R. padi in Chile are characterized by a low clonal diversity (G/N = 62/377 = 0.16) and the overrepresentation of a few widely distributed MLGs. One of the MLGs constituted roughly half of the sample and was observed in all sampled populations at high frequencies. Furthermore, this putative aphid "superclone" exhibited variations in its reproductive performance on cereals most commonly cultivated in Chile. The sampled populations also exhibited weak signs of genetic differentiation among hosts and localities. Our findings suggest that (1) obligate parthenogenesis is the primary reproductive mode of R. padi in Chile in the sampled range and (2) its introduction involved the arrival of a few genotypes that multiplied asexually.

Sex- and tissue-specific expression of odorant-binding proteins and chemosensory proteins in adults of the scarab beetle Hylamorpha elegans (Burmeister) (Coleoptera: Scarabaeidae).

In this study, we addressed the sex- and tissue-specific expression patterns of odorant-binding proteins (OBPs) and chemosensory proteins (CSPs) in Hylamorpha elegans (Burmeister), an important native scarab beetle pest species from Chile. Similar to other members of its family, this scarab beetle exhibit habits that make difficult to control the pest by conventional methods. Hence, alternative ways to manage the pest populations based on chemical communication and signaling (such as disrupting mating or host finding process) are highly desirable. However, developing pest-control methods based on chemical communication requires to understand the molecular basis for pheromone recognition/chemical perception in this species. Thus, with the aim of discovering olfaction-related genes, we obtained the first reference transcriptome assembly of H. elegans. We used different tissues of adult beetles from males and females: antennae and maxillary palps, which are well known for embedded sensory organs. Then, the expression of predicted odorant-binding proteins (OBPs) and chemosensory proteins (CSPs) was analyzed by qRT-PCR. In total, 165 transcripts related to chemoperception were predicted. Of these, 16 OBPs, including one pheromone-binding protein (PBP), and four CSPs were successfully amplified by qRT-PCR. All of these genes were differentially expressed in the sensory tissues with respect to the tibial tissue that was used as a control. The single predicted PBP found was highly expressed in the antennal tissues, particularly in males, while several OBPs and one CSP showed male-biased expression patterns, suggesting that these proteins may participate in sexual recognition process. In addition, a single CSP was expressed at higher levels in female palps than in any other studied condition, suggesting that this CSP would participate in oviposition process. Finally, all four CSPs exhibited palp-biased expression while mixed results were obtained for the expression of the OBPs, which were more abundant in the palps than in the antennae. These results suggest that these chemoperception proteins would be interesting novel targets for control of H. elegans, thus providing a theoretical basis for further studies involving new pest control methods.

Nutrient exchange in arbuscular mycorrhizal symbiosis from a thermodynamic point of view.

To obtain insights into the dynamics of nutrient exchange in arbuscular mycorrhizal (AM) symbiosis, we modelled mathematically the two-membrane system at the plant-fungus interface and simulated its dynamics. In computational cell biology experiments, the full range of nutrient transport pathways was tested for their ability to exchange phosphorus (P)/carbon (C)/nitrogen (N) sources. As a result, we obtained a thermodynamically justified, independent and comprehensive model of the dynamics of the nutrient exchange at the plant-fungus contact zone. The predicted optimal transporter network coincides with the transporter set independently confirmed in wet-laboratory experiments previously, indicating that all essential transporter types have been discovered. The thermodynamic analyses suggest that phosphate is released from the fungus via proton-coupled phosphate transporters rather than anion channels. Optimal transport pathways, such as cation channels or proton-coupled symporters, shuttle nutrients together with a positive charge across the membranes. Only in exceptional cases does electroneutral transport via diffusion facilitators appear to be plausible. The thermodynamic models presented here can be generalized and adapted to other forms of mycorrhiza and open the door for future studies combining wet-laboratory experiments with computational simulations to obtain a deeper understanding of the investigated phenomena.

Presencia del cuarto molar. Revisión de la literatura / Presence of the fourth molar. Literature review

Resumen: El cuarto molar, también llamado distomolar, es una variante de número y forma que se presenta como una alteración durante la odontogénesis, pueden ser eumórfico o dismórfico, único o múltiple, erupcionado o retenido, de forma unilateral o bilateral y se puede presentar en ambos maxilares. La etiología es desconocida, pero existen varias teorías que justifican el desarrollo de esta alteración dentaria como la duplicación de la lámina dental, su proliferación horizontal o hiperactividad de ésta; otros factores pueden ser los hereditarios, la división completa del germen dentario o regresión filogenética. El cuarto molar se encuentra en un espacio muy importante, que al desconocer su existencia o técnica adecuada para su extracción, las posibilidades de tener severas complicaciones transy postoperatorias son altas. Se realiza una revisión bibliográfica de diferentes artículos y textos en diferentes años para determinar de forma más clara el origen y formación de este diente supernumerario.

Abstract: Fourth molars, also called distomolars, are a variant in shape and number appearing as alterations during odontogenesis. They can be eumorphic or dismorphic, single or multiple, erupted or impacted, unilateral or bilateral, and can appear in both jaws. They are of unknown etiology, but there are several theories to justify these tooth alterations such as dental lamina duplication, its horizontal proliferation or its hyperactivity. Other factors can be hereditary factors, full division of tooth bud or phylogenetic regression. Fourth molars are found in a very important space, and when their own existence or the suitable extraction techniques are unknown, severe complications can frequently occur during and after surgery. A literature review was undertaken, examining different articles and texts of different years, in order to better determine the origins and formation of this supernumerary tooth.

Evaluation of a Freezer Mill for Bone Pulverization prior to DNA Extraction: An Improved Workflow for STR Analysis.

Traditional methods for bone pulverization typically generate heat, risking stability of DNA sample. SPEX™ has developed cryogenic grinders which introduce liquid nitrogen to cool the sample and aid in the grinding process. In this study, the Freezer Mill 6970 EFM was used with two DNA extraction methods and routine downstream STR analysis procedures. DNA from as little as 0.1 g of bone powder was used to develop full STR profiles after freezer mill pulverization, and the method was reproducible. Further, no contamination was detected upon cleaning/reuse of the sample vials. There were no significant differences in DNA yield, STR alleles detected, or peak heights using the freezer mill as compared to traditional grinding, and successful DNA profiles were achieved from as low as 0.1 g of bone powder with this method. Overall, this work indicates that this cryogenic mill method may be used as a viable alternative to traditional tissue grinders.