Nuclear magnetic resonance studies on the structure of the tetrapeptide tuftsin, L-threonyl-L-lysyl-L-prolyl-L-arginine, and its pentapeptide analogue L-threonyl-L-lysyl-L-prolyl-L-prolyl-L-arginine.

Nuclear magnetic resonance spectroscopy has been used to investigate the solution conformation of tuftsin, threonyllysylprolylarginine, as well as a pentapeptide inhibitor of tuftsin, threonyllysylprolylprolylarginine. Both proton and carbon-13 studies were performed. In water, neither peptide gives evidence of a preferred conformation. In dimethyl-d6 sulfoxide, tuftsin appears to prefer a particular conformation, but the inhibitor does not. The conformation of tuftsin is one in which the amide NH proton of arginine is solvent shielded. The conformation does not, however, appear to be such that a normal 4 leads to 1 beta turn exists.     

Etiology and modification of gait instability in older adults: a randomized controlled trial of exercise.

Increased gait instability is common in older adults, even in the absence of overt disease. The goal of the present study was to quantitatively investigate the factors that contribute to gait instability and its potential reversibility in functionally impaired older adults. We studied 67 older men and women with functional impairment before and after they participated in a randomized placebo-controlled, 6-mo multimodal exercise trial. We found that 1) gait instability is multifactorial; 2) stride time variability is strongly associated with functional status and performance-based measures of function that have previously been shown to predict significant clinical outcomes such as morbidity and nursing home admission; 3) neuropsychological status and health-related quality of life play important, independent roles in gait instability; and 4) improvement in physiological capacity is associated with reduced gait instability. Although the etiology of gait instability in older persons with mild-moderate functional impairment is multifactorial, interventions designed to reduce gait instability may be effective in bringing about a more consistent and more stable walking pattern.     

Environmental and Physiological Influences to Isotopic Ratios of N and Protein Status in a Montane Ungulate in Winter

Winter severity can influence large herbivore populations through a reduction in maternal proteins available for reproduction. Nitrogen (N) isotopes in blood fractions can be used to track the use of body proteins in northern and montane ungulates. We studied 113 adult female caribou for 13 years throughout a series of severe winters that reduced population size and offspring mass. After these severe winters, offspring mass increased but the size of the population remained low. We devised a conceptual model for routing of isotopic N in blood in the context of the severe environmental conditions experienced by this population. We measured δ¹⁵N in three blood fractions and predicted the relative mobilization of dietary and body proteins. The δ ¹⁵N of the body protein pool varied by 4‰ and 46% of the variance was associated with year. Annual variation in δ¹⁵N of body protein likely reflected the fall/early winter diet and winter locations, yet 15% of the isotopic variation in amino acid N was due to body proteins. Consistent isotopic differences among blood N pools indicated that animals tolerated fluxes in diet and body stores. Conservation of body protein in caribou is the result of active exchange among diet and body N pools. Adult females were robust to historically severe winter conditions and prioritized body condition and survival over early investment in offspring. For a vagile ungulate residing at low densities in a predator-rich environment, protein restrictions in winter may not be the primary limiting factor for reproduction.     

Reviews

The Family Album. A film by Alan Berliner. 16mm, 55min, b/w. Distributed by Filmmakers Library, Inc.

Beyond Words—Images from America's Concentration Camps. By Deborah Gesensway and Mindy Roseman. 1987, 176 pages, illustrated. Ithaca: Cornell University Press. Price: cloth $24.95.

The Lau (Granada Television “Disappearing World” Series). A film by Leslie Woodhead, producer‐director; Jon Woods, camera; Ray French, sound; Kimball Horton, editor; David Wasson, researcher; and Pierre Maranda, anthropological consultant. 1987, video, color, 52 minutes. Dialogues: Lau. Subtitles: English. Narration: English. Distributed by Granada TV International, Suite 3468, 1221 Avenue of the Americas, New York, NY 10020, tele. 212–242–2363. Price: on application.

Men's Lives: The Surfmen and Baymen of the South Fork. By Peter Matthiessen. 1986, New York: Random House. Price: hardcover $29.95; softcover $7.95 (Vintage Press); limited edition $200 (University of Washington Press, Seattle).

In Her Own Time. A film by Lynne Littman with Barbara Myerhoff. 1986, 16mm, color, 60 minutes. Distributed by Direct Cinema, Ltd., P.O. Box 69589, Los Angeles, CA 90060, tele. 213–652–8000. Price: 16mm—purchase $895, rental $100; video—purchase $350, rental $50 (prices quoted are for educational institutions only).

The Miracle of Intervale Avenue. A film by Irving Rappaport, producer; Ken Howard, director; and Jack Kugelmaas, associate producer. 1983, 16mm, color, 65 minutes. Catalog #430. Distributed by Ergo Media, Inc., P.O. Box 2037, Teaneck, NJ 07666, tele. 201–692–0404.

Some Babies Die. A film by Martyn Landon Down. Australia, 16mm, color, 54 minutes. Distributed by The University of California Extension Media Center, 2176 Shattuck Avenue, Berkeley, CA 94704, tele. 415–642–1340. Price: 16mm—purchase $850, rental $60; video—purchase $450, rental $60.

El Sebou’: The Egyptian Birth Ritual. A film by Fadwa El Guindi; produced by El Nil Research Project; co‐sponsored by the Office of Folklife, Smithsonian Institution. 1986, 16mm, color, 27 minutes. Distributed by El Nil Research Project, 1157 Beverwil Drive, Los Angeles, CA 90035, tele. 213–553–5645. Price: 16mm—purchase $570, rental $70; video—purchase $370. Screenings: Society for Visual Anthropology (1987 Award for Excellence); 1987 Margaret Mead Film Festival; Royal Anthropological Institute (1988 Commendation).

The Making of El Sebou‘

Classified People. Yolande Zauberman, director; produced by OBSESSION/INA/CNC/ FR3‐TOULOUSE; Dewald Aukema, camera; Tony Bensusan, sound; Jean‐François Naudon, editor. 1987, 16mm, color, 53 minutes. Distributed by TELEMONDIS, 15, rue Mesnil, 75016, Paris, tele. 47–27–03–84, telex: 649 078 TELMOND. In U.S., distributed by Filmmaker's Library, 124 E. 40th Street, New York, NY 10016, tele. 212–355–6545. Price: 16mm—rental only $150; video (½″ or ¾″)—purchase $75, rental $75. Screenings: Festival of Women's Films at Créteil (Prix de Jury); Festival of Young Directors at Belfort (Prix de Publique); Bilan du Film Ethnographique 1988 (Prix Nanook/Grand Prix); 1988 Cinéma du Réel; 1987 Margaret Mead Film Festival; U.S. Public Television.

To Cross the Border: An interview with Filmmaker Yolande Zauberman, Paris, May 1988.     

Net land gain or loss for two Mississippi River diversions: Caernarvon and Davis Pond

Coastal wetland restoration can be complex and expensive, so knowing long‐term consequences makes it important to inform decisions about if, when, and where to conduct restoration. We determined temporal changes in land gain and loss in receiving basins and adjacent reference areas for two diversions of the Mississippi River in south Louisiana (Davis Pond and Caernarvon initiated in 1991 and 2002, respectively). Water from both diversions went into receiving basins with vegetated areas as did the adjoining reference areas. The results from two different types of satellite imagery analyses demonstrate a net land loss after diversions began. The results were confirmed for the Caernarvon diversion using a before–after/control–impact analysis of independently collected data over a larger area of the estuary. These results are consistent with an analysis of land gain and loss after a natural levee break on the Mississippi River in 1973. The positive influences of adding new sediments were apparently counter‐balanced by other factors, and consistent with the conclusion from other studies indicating that increased nutrient supply and flooding are, by themselves, negative influences on marsh health. Modeling the ecosystem effects of diversions can be calibrated and tested using landscape‐scale analyses like this to understand the chronic and delayed effects, including the unintended consequences. Basing the legitimacy of river diversion on ecosystem modeling will be premature without successfully reproducing empirical results like these in ecosystem models.     

Ectopically Expressed Pro-group X Secretory Phospholipase A2 Is Proteolytically Activated in Mouse Adrenal Cells by Furin-like Proprotein Convertases: IMPLICATIONS FOR THE REGULATION OF ADRENAL STEROIDOGENESIS*

Group X secretory phospholipase A₂ (GX sPLA₂) hydrolyzes mammalian cell membranes, liberating free fatty acids and lysophospholipids. GX sPLA₂ is produced as a pro-enzyme (pro-GX sPLA₂) that contains an N-terminal 11-amino acid propeptide ending in a dibasic motif, suggesting cleavage by a furin-like proprotein convertase (PC). Although propeptide cleavage is clearly required for enzymatic activity, the protease(s) responsible for pro-GX sPLA₂ activation have not been identified. We previously reported that GX sPLA₂ negatively regulates adrenal glucocorticoid production, likely by suppressing liver X receptor-mediated activation of steroidogenic acute regulatory protein expression. In this study, using a FLAG epitope-tagged pro-GX sPLA₂ expression construct (FLAG-pro-GX sPLA₂), we determined that adrenocorticotropic hormone (ACTH) enhanced FLAG-pro-GX sPLA₂ processing and phospholipase activity secreted by Y1 adrenal cells. ACTH increased the expression of furin and PCSK6, but not other members of the PC family, in Y1 cells. Overexpression of furin and PCSK6 in HEK 293 cells significantly enhanced FLAG-pro-GX sPLA₂ processing, whereas siRNA-mediated knockdown of both PCs almost completely abolished FLAG-pro-GX sPLA₂ processing in Y1 cells. Expression of either furin or PCSK6 enhanced the ability of GX sPLA₂ to suppress liver X receptor reporter activity. The PC inhibitor decanoyl-Arg-Val-Lys-Arg-chloromethyl ketone significantly suppressed FLAG-pro-GX sPLA₂ processing and sPLA₂ activity in Y1 cells, and it significantly attenuated GX sPLA₂-dependent inhibition of steroidogenic acute regulatory protein expression and progesterone production. These findings provide strong evidence that pro-GX sPLA₂ is a substrate for furin and PCSK6 proteolytic processing and define a novel mechanism for regulating corticosteroid production in adrenal cells.