No abstract

Clinical and pathologic findings were compared in 43 postmenopausal endometrial carcinoma patients who had received exogenous estrogens prior to diagnosis and 79 similar patients unexposed to estrogens. Estrogen non-users were more likely to manifest lower parity, later menopause, obesity, hypertension, and diabetes, all of which have been considered to be constitutional risk factors for the development of endometrial carcinoma. Although estrogen users and non-users had similar extent of disease as judged by clinical stage, there was a tendency to more myometrial invasion in hysterectomy specimens from non-users, as well as greater frequency of unfavorable histologic types and grades of tumor. At short-term follow-up, more recurrences occurred in non-users, and this tendency appeared to be independent of clinical stage, histologic type, histologic grade, or modality of treatment. The significance of these and other observation to the determination of the risk-benefit ratio for estrogen administration is discussed.

No abstract

This study was conducted to examine the role of intraspecific competition in size-specific habitat segregation by longnose dace (Rhinichthys cataractae). Previous studies indicate that adults use faster velocity areas and larger substrates than juveniles. An instream maze containing fast-(40-50 cm/s), medium-(25-35 cm/s), and slow-velocity (0-10 cm/s) habitats was used to examine the habitat preferences of both size classes. Cages provided with a single shelter were used to examine the effect of the presence of adults on shelter use by juveniles, and adults were removed from an enclosed riffle to examine the response of juveniles. Both adults and juveniles used the fast-and medium-velocity habitats within the maze and avoided the slow-velocity habitat. Juveniles reduced their use of the shelters in the presence of adults, and expanded their niches to include faster velocity areas of the riffle when adults were removed from the enclosed riffle. However, juveniles did not increase their use of larger substrates in the absence of adults. These results suggest that segregation of juvenile and adult longnose dace according to velocity is due to intraspecific competition for faster velocity areas within the riffle, while segregation according to substrate size may be due simply to an increasing preference for larger substrates as fish grow.Résumé : Cette étude a été entreprise dans le but de déterminer le rôle de la compétition intraspécifique dans le choix d'un habitat en fonction de la taille corporelle chez le Naseux des rapides (Rhinichthys cataractae). Les études antérieures ont démontré que les adultes utilisent des eaux plus rapides et des substrats plus étendus que les poissons juvéniles. Des habitats différents, courant rapide (40-50 cm/s), courant moyen (25-35 cm/s) et courant lent (0-10 cm/s), ont été aménagés directement dans un ruisseau pour étudier les préférences des poissons des deux classes de taille. Des cages offrant un seul abri ont servi à examiner l'effet des adultes sur l'utilisation des abris par les jeunes et les adultes ont été enlevés d'une zone d'eau rapide clôturée pour examiner la réaction des juvéniles. Les poissons des deux groupes préféraient les zones de courant rapide et moyen dans l'espace aménagé et évitaient la zone d'eau lente. Les poissons juvéniles réduisaient leur utilisation des zones protégées en présence des adultes et étendaient leurs niches jusque dans les rapides dans la zone rapide d'où les adultes avaient été enlevés. Cependant, les juvéniles n'utilisaient pas les substrats plus étendus en l'absence d'adultes. Ces résultats indiquent que la ségrégation des naseux en fonction de la vitesse du courant est due à la compétition intraspécifique pour les zones plus rapides des courants, alors que la ségrégation en fonction de la taille des substrats semble résulter d'une préférence pour les substrats plus grands à mesure que les poissons grandissent. [Traduit par la Rédaction]

No abstract

Summary Whereas lake sturgeon Acipenser fulvescens stocking began in the Cumberland River system in 2006, reservoir‐specific data are needed to assess restoration efforts as well as provide information to support sturgeon management decisions. The purpose of this study was to (i) assess dam passage and emigration rates of tagged hatchery‐reared juvenile lake sturgeon through the Cheatham and Old Hickory locks and dams, (ii) estimate reservoir section use and movement by tagged hatchery‐reared juvenile lake sturgeon within Cheatham Reservoir, and (iii) estimate the minimum annual stocking rate for Cheatham Reservoir from model parameters. To quantify emigration from Cheatham Reservoir, hatchery‐raised juvenile lake sturgeon were surgically implanted with acoustic transmitters and passively tracked with archival submersible ultrasonic receivers. Annual section usage was estimated by actively tracking juvenile lake sturgeon at a minimum of once quarterly. Matrix projection models were used to create simple life tables from demographic data (age specific mortality, growth and fecundity), varying emigration rates (0.0, 0.01, and 0.10) and spawning fractions (0.10, 0.15 and 0.20) to estimate the annual stocking rate necessary to achieve an adult population of 750 individuals after 40 years. Percent downstream passage of tagged lake sturgeon through Cheatham Lock and Dam (CLD) was 32% (n = 11) in 2011 and 9% (n = 3) in 2012. Percent upstream passage of tagged lake sturgeon through Old Hickory Lock and Dam (OHLD) was 32% (n = 11) in 2011 and 28% (n = 9) in 2012. The total emigration rate for Cheatham Lake was 65% in 2011 and 38% in 2012. Upstream movement was high for each cohort as 75% (n = 25) in 2011 and 81% (n = 26) in 2012 of tagged lake sturgeon that moved upstream to a position just below OHLD within five days post‐stocking. Average upstream distance traveled post‐stocking in 2011 was 25.2 river km (rkm), and downstream 3.6 rkm. Average upstream distance traveled in 2012 post‐stocking was 35.6 rkm, and downstream 16.1 rkm. The estimated minimum annual stocking rates would be 1,770, 2,456 and 48,778 at 0%, 1% and 10% emigration rates when applied equally over 40 years of stocking.

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Autochthonous energy input, in the form of periphyton production and growth, was studied before and after partial logging of the watershed surrounding School Brook, a small tributary of the Aroostook River, Maine. Due to infection by the spruce budworm (Chiristoneura fumiferana), the buffer strip on one bank of the stream was logged and only limited riparian vegetation was left. Though impacts in subsequent years are unknown, the effect of the logging on the periphyton community was insignificant during the nine months following cutting, seemingly due to several factors. Because only 5 percent of the canopy was actually removed, the intensity of available light changed little. Small springs in the area helped maintain a stable thermal regime, and only a small portion of the low gradient watershed was actually logged. Consequently, the nutrients reaching the stream did not change. The relatively low concentrations of nitrates (< 0.3 mg/l) and phosphates (< 10 μg/l), both before and in the first nine months after logging, reflect the limited autochthonous input, thereby reducing the effect of this limited cutting on the stream community.