Comment on "An early Miocene extinction in pelagic sharks".

Sibert and Rubin (Reports, 4 June 2021, p. 1105) report an early Miocene extinction in pelagic sharks based on the loss of shark denticle diversity in two widely separated deep-sea sediment cores. We assert that the pattern observed is not a consequence of extinction but results from shifting species ranges induced by global current reorganization.

Differential item and test functioning methodology indicated that item response bias was not a substantial cause of country differences in mental well-being.

OBJECTIVES: Establishing the cross-cultural equivalence of the mental well-being construct, as measured with the Warwick-Edinburg Mental Well-being Scale (WEMWBS), by studying potential construct validity biases in two countries with previously reported score differences. STUDY DESIGN AND SETTING: We compared the WEMWBS total scores and item responses in Scotland (N = 779) and Catalonia (N = 1,900) general population samples. To assess whether the questionnaire spuriously favored higher scores in Catalonia, we tested for differential item functioning (DIF) by applying ordinal logistic regression on Item Response Theory scores. DIF was tested with likelihood ratio tests and standard effect measures (McFadden Pseudo R(2), >0.13; relative parameter change, >5%), and differential test functioning (DTF) was tested by plotting differences between full-test and purified (i.e., without DIF items) score estimates. RESULTS: Catalonia showed higher levels of mental well-being than Scotland (Cohen d = 0.84). Three of 14 WEMWBS items showed small amounts of DIF. DIF did not accrue to DTF, as shown by intraclass correlation coefficient (ICC, 0.999) and case-by-case differences (maximum, 0.12 SD) between total and purified scores. Population differences remained mainly constant across sociodemographics and health outcomes. CONCLUSION: The WEMWBS measures a distinct well-being construct that is stable across countries, implying that Scotland and Catalonia populations are effectively different in the distribution of mental well-being. This result adds to previous psychometric information and supports WEMWBS as a valid unbiased measures for individual and cross-cultural comparisons.

Reproduction, placentation, and embryonic development of the Atlantic sharpnose shark, Rhizoprionodon terraenovae.

The Atlantic sharpnose shark Rhizoprionodon terraenovae (Richardson) is a small carcharhinid that is a common year-round resident along the southeast coast of the United States. It is viviparous and its embryos develop an epithelio-vitelline placenta. Females enter shallow water to give birth in late May and early June. Mating occurs shortly after parturition, and four to seven eggs are ovulated. Fertilized eggs attain the blastoderm stage in early June to early July. Separate compartments for each egg are formed in the uterus when the embryos reach 3-30 mm. Embryos depend on yolk for the first 8 weeks of development. When embryos reach 72 mm their yolk supply is nearly depleted and they shift to matrotrophic nutrition. When the embryos reach 40-55 mm, placental development begins with the vascularization of the yolk sac where it contacts the uterine wall. Implantation occurs at an age of 8-10 weeks by which time the embryos reach 70-85 mm. The expanding yolk sac engulfs the maternal placental villi, and its surface interdigitates with the villi to form the placenta. The rest of the lumenal surface of the uterus is covered by non-placental villi that appear shortly after implantation. Histotrophe production by the non-placental villi begins just after their formation. The placenta grows continuously during gestation. The egg envelope is present throughout gestation, separating maternal and fetal tissues. Embryos develop numerous appendiculae on the umbilical cord. Young sharks are born at 290-320 mm after a gestation period of 11 to 12 months. © 1993 Wiley-Liss, Inc.

El sangramiento rectal en el niño / Rectal bleeding in the child

Se realiza una revisión de las historias clínicas en 25 pacientes atendidos en el Servicio de Pediatría del Instituto de Gastroenterología por sangramiento rectal, en los años comprendidos de 1975 a 1980, a los cuales se les realizó radiología de doble contraste y colonoscopia como métodos diagnósticos, con el fin de precisar factores de interés clínico en los mismos, determinar cual fue la causa más frecuente del sangramiento rectal y precisar además la eficacia de los métodos diagnósticos utilizados. Se analiza que desde el punto de vista clínico, lo más significativo fue la ausencia de anemia importante, así como el hecho de que el 24% de los pacientes estaban siendo tratados por amebiasis crónica, cuando en realidad la causa del sangramiento era una colitis ulcerativa idiopática en 2 y pólipos en los otros 4 pacientes. Se expresa que la enfermedad de mayor incidencia fue la poliposis (44%), siguiéndole en orden la colitis ulcerativa (8%). Se observa que la radiología de doble contraste fue patológica en 9 pacientes y normal en 16. De estos últimos, en 11 la colonoscopia fue patológica. Igualmente de los 9 casos con estudio radiológico patológico la colonoscopia fue normal en 2 casos para el 8% de falso-positivos. Estos resultados destacan la superioridad del estudio colonoscópico sobre la radiología en el diagnóstico del sangramiento rectal