Declines in health service use during the Coronavirus Disease 2019 (COVID-19) pandemic could have important effects on population health. In this study, we used an interrupted time series design to assess the immediate effect of the pandemic on 31 health services in two low-income (Ethiopia and Haiti), six middle-income (Ghana, Lao People’s Democratic Republic, Mexico, Nepal, South Africa and Thailand) and high-income (Chile and South Korea) countries. Despite efforts to maintain health services, disruptions of varying magnitude and duration were found in every country, with no clear patterns by country income group or pandemic intensity. Disruptions in health services often preceded COVID-19 waves. Cancer screenings, TB screening and detection and HIV testing were most affected (26–96% declines). Total outpatient visits declined by 9–40% at national levels and remained lower than predicted by the end of 2020. Maternal health services were disrupted in approximately half of the countries, with declines ranging from 5% to 33%. Child vaccinations were disrupted for shorter periods, but we estimate that catch-up campaigns might not have reached all children missed. By contrast, provision of antiretrovirals for HIV was not affected. By the end of 2020, substantial disruptions remained in half of the countries. Preliminary data for 2021 indicate that disruptions likely persisted. Although a portion of the declines observed might result from decreased needs during lockdowns (from fewer infectious illnesses or injuries), a larger share likely reflects a shortfall of health system resilience. Countries must plan to compensate for missed healthcare during the current pandemic and invest in strategies for better health system resilience for future emergencies.

Antes del surgimiento de la epigenética, la relación genes-ambiente era explicado bajo la visión de un "determinismo genético". Ambas concepciones, epigenética y determinismo genético, tienen sus ancestros en los conceptos de epigénesis y preformismo que surgieron en los siglos XVII y XIX 3 . Posteriormente, prevaleció la concepción de que tanto el desarrollo como el fenotipo estaban definidos casi exclusivamente por los genes. A comienzos del siglo XX la Genética era considerada la ciencia de la herencia y la Embriología la del desarrollo 4 . Waddington trató de demostrar que ambas disciplinas estaban estrechamente ligadas entre sí y con la evolución, de manera que la explicación del desarrollo desde el genotipo al fenotipo tendrían que necesariamente integrar el conocimiento de ambas ciencias.En las últimas décadas, sus planteamientos se han retomado en una nueva perspectiva. Actualmente se reconoce el papel fundamental que el ambiente extranuclear, extracelular y social ejerce en la modulación de la actividad genética 5 . Los modelos simples aditivos que sugieren que el fenotipo es la suma de los efectos de los genes y del ambiente, no dan respuesta a la realidad 6 . Se propone que los sistemas genéticos son dinámicos o cibernéticos 7 . Al respecto, investigadores 8 han demostrado cómo el nivel socioeconómico modifica la heredabilidad del coeficiente intelectual (CI) de manera no lineal. Estos autores, a diferencia

To determine if the egg provides any clues for the regulation of ovum transport in the hamster, oocyte and embryo transport were compared. On the evening preceding ovulation, the animals were randomly assigned to one of five groups. They were caged overnight with a male of proven fertility (Group 1) or they were isolated (Group 2). Other females were artificially inseminated in both uterine horns at 2200 h either with fertile epididymal spermatozoa (Group 3), spermatozoa rendered infertile by freezing and thawing (Group 4), or with fertile spermatozoa in one uterine horn and infertile spermatozoa in the contralateral horn (Group 5). The number, condition, and distribution of ova in the genital tract were assessed at various intervals during the next 4 days. The rate of fertilization and normal development in females or sides inseminated with fertile or infertile spermatozoa was over 90% and 0% respectively. Embryos in Groups 1 and 3 reached the uterus 1 day earlier than unfertilized oocytes in Groups 2 and 4. In group 5, the transport of embryos resulting from insemination with fertile spermatozoa followed a pattern similar to those in Groups 1 and 3; the oocytes in the contralateral tract resembled those of Groups 2 and 4. The different transport rates of embryos and oocytes were not associated with the reproductive state of the female but with the condition of the ova. Moreover, the different transport rates were observed in animals transporting the two types of eggs simultaneously on different sides indicating that there is a local recognition of some unidentified factor unequally present in fertilized and unfertilized eggs.

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Congenital hypothyroidism (CH) is the most common cause of preventable cognitive disability worldwide. Generally, it is produced by an alteration in the embryogenesis of the thyroid gland or by an alteration in the synthesis of thyroid hormones, which determine that affected patients have low or absent thyroid hormone concentrations. The importance of this fact is that brain development during the first three years of life is highly dependent on thyroid hormones. Prior to the implementation of national neonatal screening programs around the world, 8 to 27% of children with CH had an IQ lower than 70. Nowadays, this percentage is close to 0 in countries that have implemented the program. In Chile, CH neonatal screening program achieved national coverage in 1996. Currently, the incidence of the disease in our country is 1: 3163. The degree of disability produced by CH not only depends on the time of detection of the disease and the prompt start of therapy, but also on an adequate monitoring. Despite screening programs, neurocognitive impairment in schoolchildren and teenagers with CH is still observed, reflected in lower scores in cognitive, language and gross motor assessments, receptive communication, expressive communication, fine motor and gross motor skills compared to healthy children. Also, lesser achievements in learning and language disorders are observed. The objective of this review is to update the information available on neurodevelopment of patients with CH.

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This paper experimentally estimates medium term impacts of a large-scale and lowcost parenting program targeting poor families in Chile. Households in 162 public health centers were randomly assigned to three groups: a control group, a second group that was offered eight weekly group parenting sessions, and a third group that was offered the same eight group sessions plus two sessions of guided interactions between parents and children focused on responsive play and dialogic reading. In spite of its short duration and intensity, three years after the end of the intervention, the receptive vocabulary and the socio-emotional development of children of families participating in either of the treatment arms improved (by 0.43 and 0.54 standard deviation, respectively) relative to children of nonparticipating families. The treatments also led to improvements in home environments and parenting behaviors of comparable magnitudes, which far outlasted the short duration of the intervention. H43, I10, I20, I38 parenting, early childhood development JEL Classification:

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