Inter-institutional laboratory standardization for SARS-CoV-2 surveillance through wastewater-based epidemiology applied to Mexico City.

Objectives: Wastewater-based surveillance applied to SARS-CoV-2 viral load quantification for COVID-19 has become one of the most relevant complementary tools in epidemiologic prevention programs worldwide. However, this valuable decision-making tool still requires fine-tuning to produce comparable results between laboratories, especially when applied to the surveillance of megacities. Methods: Six laboratories across Mexico and one from the United States executed an interlaboratory study to set up a singular standardized protocol considering method cost, installed infrastructure, materials available, and supply availability for SARS-CoV-2 quantification from five Mexico City sampling sites across this megacity. Results: Comparable data from processing outcomes in the Mexican laboratories and in the external international laboratory serve as a validating data source. The Bland-Altman comparison showed consistency, with cycle threshold values within ±1.96 SD of SARS-CoV-2 genetic copies for the standard curve quantification, with a mismatch of two laboratories. In addition, MS2 bacteriophage recovery rates varied between 35% and 67% among all participating laboratories. Finally, the efficiency of viral genetic material recovered from all participating laboratories varied between 65% and 93% for the participating laboratories. Conclusion: This work lays the foundation for extensive and continuous wastewater-based surveillance application across independent Mexican laboratories in a time- and resource-effective manner.

Preventing bisphosphonate induced osteonecrosis of the jaw with a polyguanidine conjugate (GuaDex): A promising new approach.

Osteonecrosis of the jaw (ONJ) is a relatively rare side effect after prolonged use of bisphosphonates, which are drugs used to treat bone resorption in osteoporosis and certain cancers. This study introduces a novel ONJ model in rats by combining exposure to bisphosphonates, oral surgery, and bacterial inoculation. Potential ONJ preventive effects of polyguanidine (GuaDex) or antibiotics were evaluated. The study consisted of twenty-four male Wistar rats were divided into four groups. Groups 1 to 3 were given weekly doses of i.v. Zoledronic acid (ZA), four weeks before and two weeks after an osteotomy procedure on their left mandibular first molar. Group 4 was a negative control. Streptococcus gordonii bacteria were introduced into the osteotomy pulp chamber and via the food for seven days. On day eight, the rats were given different treatments. Group 1 was given a GuaDex injection into the osteotomy socket, Group 2 was given an intramuscular (i.m.) injection of clindamycin, Group 3 (positive control) was given an i.m. injection of saline, and Group 4 was given an i.m. injection of saline. Blood samples were taken two weeks after the osteotomy procedure, after which the rats were euthanized. Bone healing, bone mineral density, histology, and blood status were analyzed. The results showed that Group 1 (GuaDex) had no ONJ, extensive ongoing bone regeneration, active healing activity, vascularization, and no presence of bacteria. Group 2 (clindamycin) showed early stages of ONJ, avascular areas, and bacteria. Group 3 showed stages of ONJ, inflammatory infiltrates, defective healing, and bacterial presence, and Group 4 had normal healing activity and no bacterial presence. Conclusion: ZA treatment and bacterial inoculation after tooth extraction inhibited bone remodeling/healing and induced ONJ characteristic lesions in the rats. Only GuaDex apparently prevented ONJ development, stimulated bone remodeling, and provided an antimicrobial effect.

The novel cytotoxic polybisphosphonate osteodex decreases bone resorption by enhancing cell death of mature osteoclasts without affecting osteoclastogenesis of RANKL-stimulated mouse bone marrow macrophages.

It has previously been demonstrated that the polybisphosphonate osteodex (ODX) inhibits bone resorption in organ-cultured mouse calvarial bone. In this study, we further investigate the effects by ODX on osteoclast differentiation, formation, and function in several different bone organ and cell cultures. Zoledronic acid (ZOL) was used for comparison. In retinoid-stimulated mouse calvarial organ cultures, ODX and ZOL significantly reduced the numbers of periosteal osteoclasts without affecting Tnfsf11 or Tnfrsf11b mRNA expression. ODX and ZOL also drastically reduced the numbers of osteoclasts in cell cultures isolated from the calvarial bone and in vitamin D3-stimulated mouse crude bone marrow cell cultures. These data suggest that ODX can inhibit osteoclast formation by inhibiting the differentiation of osteoclast progenitor cells or by directly targeting mature osteoclasts. We therefore assessed if osteoclast formation in purified bone marrow macrophage cultures stimulated by RANKL was inhibited by ODX and ZOL and found that the initial formation of mature osteoclasts was not affected, but that the bisphosphonates enhanced cell death of mature osteoclasts. In agreement with these findings, ODX and ZOL did not affect the mRNA expression of the osteoclastic genes Acp5 and Ctsk and the osteoclastogenic transcription factor Nfatc1. When bone marrow macrophages were incubated on bone slices, ODX and ZOL inhibited RANKL-stimulated bone resorption. In conclusion, ODX does not inhibit osteoclast formation but inhibits osteoclastic bone resorption by decreasing osteoclast numbers through enhanced cell death of mature osteoclasts.

Cytotoxicity of poly-guanidine in medulloblastoma cell lines.

Medulloblastoma (MB) is the most common pediatric brain tumor. The therapy frequently causes serious side effects, and new selective therapies are needed. MB expresses hyper sialylation, a possible target for selective therapy. The cytotoxic efficacy of a poly guanidine conjugate (GuaDex) incubated with medulloblastoma cell cultures (DAOY and MB-LU-181) was investigated. The cells were incubated with 0.05-8 µM GuaDex from 15 min to 72 h. A fluorometric cytotoxicity assay (FMCA) measured the cytotoxicity. Labeled GuaDex was used to study tumor cell interaction. FITC-label Sambucus nigra confirmed high expression of sialic acid (Sia). Immunofluorescence microscopy was used to visualize the cell F-actin and microtubules. The cell interactions were studied by confocal and fluorescence microscopy. Annexin-V assay was used to detect apoptosis. Cell cycle analysis was done by DNA content determination. A wound-healing migration assay determined the effects on the migratory ability of DAOY cells after GuaDex treatment. IC50 for GuaDex was 223.4 -281.1 nM. FMCA showed potent growth inhibition on DAOY and MB-LU-181 cells at 5 uM GuaDex after 4 h of incubation. GuaDex treatment induced G2/M phase cell cycle arrest. S. nigra FITC-label lectin confirmed high expression of Sia on DAOY medulloblastoma cells. The GuaDex treatment polymerized the cytoskeleton (actin filaments and microtubules) and bound to DNA, inducing condensation. The Annexin V assay results were negative. Cell migration was inhibited at 0.5 µM GuaDex concentration after 24 h of incubation. GuaDex showed potent cytotoxicity and invasion-inhibitory effects on medulloblastoma cells at low micromolar concentrations. GuaDex efficacy was significant and warrants further studies.

Bone mineral density changes in lactating adolescent mothers during the first postpartum year.

OBJECTIVES: This study aimed to compare changes in whole body bone mineral density (wbBMD) during the first postpartum year in adolescent mothers with those of nulliparous adolescents. METHODS: The study included 21 adolescent mothers and 16 nulliparous adolescent non-indigenous Mexican women (State of Sonora) from a low income level. All mothers were assessed at 15 days (0.5 months), 3 months, and 6 months postpartum; 16 were measured at 12 months postpartum. Nulliparous adolescents were assessed in the same periods. Multiple regression models was used to assess adjusted associations of changes in wbBMD (by DPX-MD+ densitometer) with dietary calcium and physical activity assessments (estimated using pre-tested questionnaires), post menarche years, and number of breast feedings. RESULTS: At baseline, no differences were observed between nulliparous and adolescent mothers regarding age, post-menarche years, or BMD values. Changes in wbBMD of -0.56% and 0.77% were observed in mothers and nulliparous adolescents, respectively, after the first 3 months (P = 0.006). Changes in wbBMD in mothers were associated with number of breast feedings and changes in BMI. At 12 months postpartum, the BMD of adolescent mothers was similar to that of nulliparous adolescents. CONCLUSIONS: At 1 year postpartum, adolescent mothers exhibited BMD similar to those of nulliparous adolescents. This result is likely attributable to the breastfeeding practices adopted by mothers during late adolescence.

Estudio comparativo de las destrezas en el desarrollo psicomotríz con el uso de la seda dental en la edad escolar entre dos niveles socioeconómicos a un mes y seis meses / Influence of the socioeconomical level in the psico-motional pattern to develop A technic for tHe use of the dental wax

Este estudio fué realizado para determinar y comparar la influencia del nivel socioeconómico, en el patrón de la psicomotricidad, teniendo en cuenta la edad y el sexo para el desarrollo de la técnica para el uso de la seda dental. Se tomaron 122 niños con una instrucción previa en la técnica para el uso de la seda dental hace seis meses de dos instituciones de diferente nivel socioeconómico, ambos en Santafé de Bogotá. Estos niños se dividieron en dos grupos, que a su vez se subdividieron de acuerdo a la edad en tres grupos de la siguiente forma:7 - 9 años, 10 años, 11 - 12 años; cada subgrupo estaba formado por 20 individuos, 10 niños y 10 niñas. La instrucción para el uso de la seda dental se realizó en ambas instituciones de manera individualizada y generalizada con material audiovisual, macromodelos y una cartilla didáctica de refuerzo. La técnica se evaluó paso a paso de acuerdo a un formato preestablecido. Para fines estadísticos se determinaron y compararon el número de niños capaces de realizar la técnica correcta,aceptable o deficiente, teniendo en cuenta variables de edad, sexo y nivel socioeconómico por medio de un análisis descriptivo. En este estudio no se encontraron grandes diferencias, sin embargo se pudo abservar que a los seis meses el número de niños que realizaron la técnica de manera aceptable se incrementó en ambos niveles socioeconómicos. Encontramos que el área de la boca que presenta mayor dificultad para todos los niños fué la posterior superior y el paso de la técnica más difícil fué la inserción de la seda en el espacio interproximal

Obstrucción de vía aérea superior de tipo no infeccioso / Non-infectious upper respiratory tract obstruction

Se revisaron 153 expedientes de niños de 0 a 12 años egresados entre enero de 1980 y diciembre de 1984, del Hospital Nacional de Niños "Dr. Carlos Sáenz Herrera" en San José, Costa Rica, con signos y síntomas obstructivos de vías aéreas superiores de tipo no infeccioso. Se establecen las causas de obstrucción de vía superior. Se encontró como signo más frecuente el estridor laríngeo inspiratorio, seguido por la disfonía debido a nódulos laríngeos. Se hace énfasis en que todo niño con signos y/o síntomas obstructivos de vías aéreas superiores debe ser bien evaluado, mediante una anamnesis meticulosa con información sobre aspectos que ayudarían a localizar el sitio de la obstrucción, como calidad de la voz, características del estridor, postura adoptada, la presencia de neumonía o atelectasias persistente o recurrente, dificultad para la alimetación y presencia de respiración sibilante