Bioorthogonal Radiolabeling of Azide-Modified Bacteria Using [18F]FB-sulfo-DBCO.

Purpose: This study was motivated by the need for better positron emission tomography (PET)-compatible tools to image bacterial infection. Our previous efforts have targeted bacteria-specific metabolism via assimilation of carbon-11 labeled d-amino acids into the bacterial cell wall. Since the chemical determinants of this incorporation are not fully understood, we sought a high-throughput method to label d-amino acid derived structures with fluorine-18. Our strategy employed a chemical biology approach, whereby an azide (-N3) bearing d-amino acid is incorporated into peptidoglycan muropeptides, with subsequent "click" cycloaddition with an 18F-labeled strained cyclooctyne partner. Procedures: A water-soluble, 18F-labeled and dibenzocyclooctyne (DBCO)-derived radiotracer ([18F]FB-sulfo-DBCO) was synthesized. This tracer was incubated with pathogenic bacteria treated with azide-bearing d-amino acids, and incorporated 18F was determined via gamma counting. In vitro uptake in bacteria previously treated with azide-modified d-amino acids was compared to that in cultures treated with amino acid controls. The biodistribution of [18F]FB-sulfo-DBCO was studied in a cohort of healthy mice with implications for future in vivo imaging. Results: The new strain-promoted azide-alkyne cycloaddition (SPAAC) radiotracer [18F]FB-sulfo-DBCO was synthesized with high radiochemical yield and purity via N-succinimidyl 4-[18F]fluorobenzoate ([18F]SFB). Accumulation of [18F]FB-sulfo-DBCO was significantly higher in several bacteria treated with azide-modified d-amino acids than in controls; for example, we observed 7 times greater [18F]FB-sulfo-DBCO ligation in Staphylococcus aureus cultures incubated with 3-azido-d-alanine versus those incubated with d-alanine. Conclusions: The SPAAC radiotracer [18F]FB-sulfo-DBCO was validated in vitro via metabolic labeling of azide-bearing peptidoglycan muropeptides. d-Amino acid-derived PET radiotracers may be more efficiently screened via [18F]FB-sulfo-DBCO modification.

Determining Factors in the Success of Direct Pulp Capping: A Systematic Review.

AIM: To elucidate the factors that determine the success of direct pulp capping (DPC) in permanent teeth with pulp exposure due to dental caries. MATERIALS AND METHODS: A comprehensive electronic search from 1980 to 2023 across PubMed, Scopus, and ISI Web databases was conducted using specific keywords and MeSH terms in Q1 or Q2 journals. Only prospective/retrospective clinical studies in English on 15 or more human permanent teeth with carious pulpal exposure treated with DPC agents-mineral trioxide aggregate (MTA), Biodentine, or calcium hydroxide with a rubber dam and minimum 1-year follow-up, were considered. The factors retrieved and analyzed were based on study design, patient age, sample size, type of cavity, exposure size and location, pulp diagnosis, solutions to achieve hemostasis, hemostasis time, capping material, restoration type, follow-up period, methods of evaluation, and overall success. REVIEW RESULTS: Out of 680 articles, only 16 articles were selected for the present systematic review on application of the selection criteria. A wide age range of patients from 6 to 88 years were considered among these studies with sample sizes ranging from 15 to 245 teeth with reversible pulpitis being the predominant diagnosis of the cases. Mineral trioxide aggregate as a capping material was evaluated in 4 studies as a lone agent, while compared with other capping agents such as biodentine or calcium hydroxide in 7 studies. The follow-up period ranged from 9 days to nearly 80 months. While both clinical and radiographic evaluation was carried out in all studies, cold testing dominated the clinical tests while IOPR was the common radiograph considered. Mineral trioxide aggregate success rate was higher and similar to biodentine than calcium hydroxide. CONCLUSION: Direct pulp capping has a high and predictable success rate in permanent teeth with carious exposure to reversible and irreversible pulpitis. Currently, mineral trioxide aggregate and biodentine have better long-term results in DPC than calcium hydroxide, hence, they should be used as an alternative to calcium hydroxide. Definitive restoration within a short period improves long-term prognosis. CLINICAL SIGNIFICANCE: The significance of this review lies in its provision of evidence-based information on the effectiveness of DPC and the factors that influence its success. By considering these factors, clinicians can optimize treatment outcomes and improve the long-term prognosis of the treated teeth. This systematic review serves as a valuable resource for clinicians and researchers in the field of endodontics. How to cite this article: Gomez-Sosa JF, Granone-Ricella M, Rosciano-Alvarez M, et al. Determining Factors in the Success of Direct Pulp Capping: A Systematic Review. J Contemp Dent Pract 2024;25(4):392-401.

Imaging the Granzyme Mediated Host Immune Response to Viral and Bacterial Pathogens In Vivo Using Positron Emission Tomography.

Understanding how the host immune system engages complex pathogens is essential to developing therapeutic strategies to overcome their virulence. While granzymes are well understood to trigger apoptosis in infected host cells or bacteria, less is known about how the immune system mobilizes individual granzyme species in vivo to combat diverse pathogens. Toward the goal of studying individual granzyme function directly in vivo, we previously developed a new class of radiopharmaceuticals termed "restricted interaction peptides (RIPs)" that detect biochemically active endoproteases using positron emission tomography (PET). In this study, we showed that secreted granzyme B proteolysis in response to diverse viral and bacterial pathogens could be imaged with [64Cu]Cu-GRIP B, a RIP that specifically targets granzyme B. Wild-type or germline granzyme B knockout mice were instilled intranasally with the A/PR/8/34 H1N1 influenza A strain to generate pneumonia, and granzyme B production within the lungs was measured using [64Cu]Cu-GRIP B PET/CT. Murine myositis models of acute bacterial (E. coli, P. aeruginosa, K. pneumoniae, and L. monocytogenes) infection were also developed and imaged using [64Cu]Cu-GRIP B. In all cases, the mice were studied in vivo using mPET/CT and ex vivo via tissue-harvesting, gamma counting, and immunohistochemistry. [64Cu]Cu-GRIP B uptake was significantly higher in the lungs of wild-type mice that received A/PR/8/34 H1N1 influenza A strain compared to mice that received sham or granzyme B knockout mice that received either treatment. In wild-type mice, [64Cu]Cu-GRIP B uptake was significantly higher in the infected triceps muscle versus normal muscle and the contralateral triceps inoculated with heat killed bacteria. In granzyme B knockout mice, [64Cu]Cu-GRIP B uptake above the background was not observed in the infected triceps muscle. Interestingly, live L. monocytogenes did not induce detectable granzyme B on PET, despite prior in vitro data, suggesting a role for granzyme B in suppressing their pathogenicity. In summary, these data show that the granzyme response elicited by diverse human pathogens can be imaged using PET. These results and data generated via additional RIPs specific for other granzyme proteases will allow for a deeper mechanistic study analysis of their complex in vivo biology.

Peptidoglycan-Targeted [18F]3,3,3-Trifluoro-d-alanine Tracer for Imaging Bacterial Infection.

Imaging is increasingly used to detect and monitor bacterial infection. Both anatomic (X-rays, computed tomography, ultrasound, and MRI) and nuclear medicine ([111In]-WBC SPECT, [18F]FDG PET) techniques are used in clinical practice but lack specificity for the causative microorganisms themselves. To meet this challenge, many groups have developed imaging methods that target pathogen-specific metabolism, including PET tracers integrated into the bacterial cell wall. We have previously reported the d-amino acid derived PET radiotracers d-methyl-[11C]-methionine, d-[3-11C]-alanine, and d-[3-11C]-alanine-d-alanine, which showed robust bacterial accumulation in vitro and in vivo. Given the clinical importance of radionuclide half-life, in the current study, we developed [18F]3,3,3-trifluoro-d-alanine (d-[18F]-CF3-ala), a fluorine-18 labeled tracer. We tested the hypothesis that d-[18F]-CF3-ala would be incorporated into bacterial peptidoglycan given its structural similarity to d-alanine itself. NMR analysis showed that the fluorine-19 parent amino acid d-[19F]-CF3-ala was stable in human and mouse serum. d-[19F]-CF3-ala was also a poor substrate for d-amino acid oxidase, the enzyme largely responsible for mammalian d-amino acid metabolism and a likely contributor to background signals using d-amino acid derived PET tracers. In addition, d-[19F]-CF3-ala showed robust incorporation into Escherichia coli peptidoglycan, as detected by HPLC/mass spectrometry. Based on these promising results, we developed a radiosynthesis of d-[18F]-CF3-ala via displacement of a bromo-precursor with [18F]fluoride followed by chiral stationary phase HPLC. Unexpectedly, the accumulation of d-[18F]-CF3-ala by bacteria in vitro was highest for Gram-negative pathogens in particular E. coli. In a murine model of acute bacterial infection, d-[18F]-CF3-ala could distinguish live from heat-killed E. coli, with low background signals. These results indicate the viability of [18F]-modified d-amino acids for infection imaging and indicate that improved specificity for bacterial metabolism can improve tracer performance.

Procesamiento de la música en el primer episodio de trastorno depresivo mayor sin tratamiento / Music processing in major depressive disorder first episode without treatment

El propósito de este estudio fue registrar diferencias durante la audición de dos tipos diferentes de música en pacientes con Trastorno Depresivo Mayor (TDM), comparados con sujetos sanos, mediante imagen por resonancia magnética funcional (IRMf). La actividad cerebral con estímulos musicales ha sido investigada ampliamente en sujetos sanos, pero son escasos los estudios del procesamiento de la música en estados de patología mental, particularmente en el TDM. Los estudios en esta área interdisciplinaria proveen una nueva perspectiva de investigación para explorar los sustratos neurobiológicos del TDM. Participaron 20 sujetos de sexo masculino: 10 pacientes con TDM (34 ± 7 años) y 10 sujetos control (33 ± 7 años). Los pacientes se seleccionaron en el servicio de pre-consulta del Instituto Nacional de Psiquiatría Ramón de la Fuente Muñiz (INPRFM) de la Ciudad de México, y los sujetos control entre los trabajadores del propio Instituto que respondieron a la invitación. Todos los participantes contestaron, con fines de confirmar el diagnóstico, las escalas de ansiedad y depresión de Hamilton, los inventarios de Beck para ansiedad y depresión y el SCL-90-R. A los pacientes se les aplicó además el MINI-mental test. Para la IRMf se usó un equipo Philips Achieva de tres Teslas en el INPRFM, el análisis se hizo con el formato SPM2 usando el sistema MRIcro. Los estímulos experimentales fueron una obra musical de JS Bach validada como tranquila y otra de J Prodromidès validada como inquietante. Los resultados muestran diferencias tanto entre los grupos de sujetos como entre los tipos de música: en todos los casos se activó el área parahipocampal, la cola del núcleo caudado y la corteza temporal auditiva. Concluimos que el procesamiento neurobiológico de la música es afectado por el TDM. Se discuten las implicaciones clínicas y cognoscitivas de estos hallazgos.

The purpose of this study is the assessment of the differences in brain activity when patients with major depressive disorder (MDD) listen to two different types of music, with healthy subjects as control, by using functional magnetic resonance imaging (fMRI). Brain activity in musical stimuli with healthy subjects has been investigated extensively, but there are few neurobiologic music studies in mental illness, particularly in MDD. Studies in this area provide a new perspective on interdisciplinary research to explore the neurobiological substrates of MDD. This study involved 20 male subjects: 10 patients (34 ± 7 years), and 10 control subjects (33 ± 7 years). The MDD :atients were selected in the pre-consultation service of the National Institute of :sychiatry Ramón de la Fuente Muñiz (IN:RFM) of Mexico City, and control subjects were selected among workers of the Institute who responded to the invitation. All participants completed the Hamilton scales for anxiety and depression, Beck inventories for depression and anxiety and, the SCL-90-R. The Mini-Mental State Examination test was also administered to patients for diagnostic purposes. The fMRI was obtained by Philips Achieva 3-Tesla in the INPRF; the analysis was done using S:M2 format MRIcro system. The experimental stimuli were two pieces of music: one by JS Bach validated as quiet and another one by J Prodromidès validated as disturbing. Results show differences between both groups of subjects and between types of music. In all cases, the parahippocampal area, the tail of the caudate nucleus and the auditory temporal cortex were activated. The neurobiological processing of music is affected by MDD. We discuss the clinical and cognitive implications of these findings.

Modelo de análise do papel das aulas práticas no ensino de bioquímica / A model of analysis of laboratory classes role in biochemical education

Aulas práticas, nesta pesquisa, säo aquelas que ocorrem no recinto do laboratório, utilizando vidraria, reagentes, equipamentos e aparelhos especializados. O problema foi como analisá-las de forma a entender suas funções, isto é, o quê elas ensinam, e descobrir seu papel no ensino da disciplina, quer dizer, para que elas ensinam. O objetivo geral deste trabalho foi propor um modelo de análise do papel de aulas práticas no ensino de Bioquímica que desse subsídios ao professor para estabelecer critérios de inclusäo e utilizaçäo dessas aulas em sua disciplina, considerando-se o contexto em que se inserem. A metodologia teve como base a pesquisa qualitativa, complementada por pesquisa quantitativa...