Relationship between serum prolactin levels and protein composition of breast secretions in nonlactating women

En esta interesante se describe la relación entre los niveles séricos de prolactina (PRL) basales y tras estimulación con hormona liberadora de tirotropina (TRH), y la composición proteica de la secreción del pezón en 54 mujeres premenopáusicas y no lactantes durante la fase lútea de su ciclo menstrual. Las mujeres incluidas en este estudio se clasificaron en cuatro grupos teniendo en cuenta la presencia o ausencia de patología mamaria y el patrón proteico de sus secreciones mamarias. Los fluidos mamarios tipo I contenían Zn-α2-glicoproteina, apolipoproteina D y la proteína 15 de la enfermedad macroquistica mamaria; mientras que los fluidos tipo II se caracterizaron por la presencia de algunas proteínas de la leche como la lactoferrina, lisozima y α-lactoalbumina. Los niveles basales de PRL, progesterona, LH, FSH, T3 y T4 estuvieron dentro de rangos normales y no se identificó ninguna diferencia entre los grupos de mujeres incluidas en el estudio. Sin embargo, después de una prueba de estimulación con TRH si se objetivaron diferencias entre los grupos. En ausencia de patología mamaria, el aumento de PRL fue significativamente superior en mujeres con secreciones tipo II frente a las que tenían secreción tipo I (64 ± 6.8 µg/L vs. 7 ± 3.9 µg/L, p<0.02). De manera similar, cuando se consideraron las concentraciones de PRL en pacientes con enfermedad mamaria benigna, aquellas con fluidos mamarios tipo II tuvieron un aumento de la PRL significativamente superior en comparación con las que tenían fluidos a las que les faltaban estas proteínas (77.1 ± 6.2 µg/L vs. 58.8 ± 5.1 µg/L; P<0.05). Estos resultados muestran que la presencia de proteínas de la leche en la secreción del pezón de mujeres no lactantes se asocia con un incremento de la PRL en el suero tras la estimulación con TRH. Con ello, se abre la posibilidad de utilizar este análisis como un procedimiento no invasivo para el estudio en el efecto putativo de la PRL en el desarrollo de enfermedades mamarias benignas y malignas.Comisión Interministerial de Ciencia y Tecnología, Plan Nacional de I

Utjecaj trajanja in vitro sazrijevanja i inkubacije s aktivirajućim čimbenikom na kapacitet izlijeganja goveđih partenota - kratko priopćenje

The period of both in vitro maturation (IVM) and incubation with oocyte activators affects the blastocyst yield following parthenogenetic activation (PA). Nevertheless, it is still unknown how these conditions impact the expansion and hatching rates of bovine parthenogenetic blastocysts. The objective of this study was to assess the influence of the duration of IVM and exposure to the activating agent, 6-dimethylaminopurine (6-DMAP), on a number of developmental parameters in bovine parthenotes, including: Cleavage, blastocyst formation, expansion, and hatching. Slaughterhouse oocytes were subjected to different periods of IVM. Subsequently, eggs were first parthenogenetically activated for five minutes with ionomycin and then incubated for distinct lengths of time with a second activator, 6-DMAP. The treatments were: a) Control: 22 h IVM/4 h 6-DMAP; b) 22 h IVM/5 h 6-DMAP; c) 24 h IVM/4 h 6-DMAP; and d) 24 h IVM/5 h 6-DMAP. Developmental stages were evaluated at day 4 and day 8 of in vitro culture (IVC). No differences were detected in most developmental parameters. However, the duration of IVM and incubation with 6-DMAP significantly affected (P<0.05) hatching capacity considering the number of blastocysts (Hatch./Blast.). Also, this same variable was higher (P<0.05) in group b) 22 h IVM/5 h 6-DMAP (45.89 ± 12.59%), as compared to c) 24 h IVM/4 h 6-DMAP (6.67 ± 6.67%). In conclusion, the length of IVM and incubation with 6-DMAP influenced parthenogenetic development, where 22 h IVM/5 h 6-DMAP was the condition producing the highest Hatch./Blast. rate in bovine parthenotes.Vrijeme in vitro sazrijevanja (IVM) i vrijeme inkubacije s aktivatorima oocista utječu na stvaranje blastocista nakon partenogenetske aktivacije (PA). Ipak, još uvijek se ne zna kako navedeno utječe na ekspanziju i stopu izlijeganja goveđih partenogenetskih blastocista. Cilj rada bio je istražiti utjecaj trajanja IVM i izloženosti aktivirajućem čimbeniku 6-dimethylaminopurinu (6-DMAP) na više razvojnih parametara u goveđih partenota, uključujući diobu, formiranje blastociste, ekspanziju i izlijeganje. Oocite prikupljene u klaonicama bile su podvrgnute različitom trajanju IVM. Nakon toga jajašca su prvo partenogenetski aktivirana s ionomicinom kroz 5 minuta i nakon toga inkubirana tijekom određenih vremenskih razdoblja sa drugim aktivatorom, 6-DMAP. Protokoli po istraženim skupinama bili su sljedeći: a) kontrolna skupina 22 h IVM/4 h 6-DMAP, b) skupina 22 h IVM/5 h 6-DMAP, c) skupina 24 h IVM/4 h 6-DMAP i d) skupina 24 h IVM/5 h 6-DMAP. Razvojni stadiji in vitro kulture (IVC) procijenjivani su 4. i 8. dan. Za većinu razvojnih parametara nisu utvrđene razlike između istraženih skupina. Ipak, trajanja IVM i inkubacije sa 6-DMAP znakovito su utjecali (P<0,05) na kapacitet izlijeganja kad se u obzir uzme broj blastocista (izlijeganja/ blasociste). Također, isti pokazatelji bili su viši (P<0,05) u skupini b) 22 h IVM/5 h 6-DMAP (45,89 ± 12,59 %) u odnosu na skupinu c) 24 h IVM/4 h 6-DMAP (6,67 ± 6,67 %). Zaključno, trajanje IVM i inkubacije sa 6-DMAP utjecali su na partenogenetski razvoj, pri čemu je 22 h IVM/5 h 6-DMAP kombinacija koja u goveđih partenota proizvodi najvišu stopu za pokazetelj izlijeganje/blasociste

Students' Models of Newton's Second Law in Mechanics and Electromagnetism

We investigated students' use of Newton's second law in mechanics and electromagnetism contexts by interviewing students in a two-semester calculus-based physics course. We observed that students' responses are consistent with three mental models. These models appeard in mechanics contexts and were transferred to electromagnetism contexts. We developed an inventory to help instructors identify these models and direct students towards the correct one.Comment: 15 pages, 3 figues and 4 table