The calcium (Ca) metabolism of established human lactation was studied in 40 adult women (mean age 32.4 years) who had been breast-feeding for 6 months (Lac) and in 40 age-matched controls (Con) using fasting urine and blood biochemistry and forearm single-photon bone mineral densitometry (BMD). Serial studies were performed up to 6 months after weaning in Lac women and repeated once in Con women. During lactation the significant findings were (1) a selective reduction (7.1%, P less than 0.03) in BMD at the ultradistal site containing 60% trabecular bone, but not at two more proximal, chiefly cortical bone sites; (2) increased bone turnover affecting bone resorption [fasting hydroxyproline excretion, Lac 2.22 +/- 0.12 mumol/liter GF (mean +/- SEM), Con 1.19 +/- 0.04, P less than 0.001] and affecting bone formation (plasma alkaline phosphatase, Lac 81.9 +/- 2.5 IU/liter, Con 53.5 +/- 2.7, P less than 0.001, and serum osteocalcin, Lac 14.0 +/- 0.7 microgram/liter, Con 7.3 +/- 0.4, P less than 0.001); and (3) renal conservation in the fasting state of both Ca and inorganic phosphate (Pi) with a resultant moderate increase in plasma Pi but not in plasma Ca (total or ionized). There were no differences between the groups in serum parathyroid hormone (PTH, intact and midmolecule assays), 25-hydroxy- and 1,25-dihydroxyvitamin D, nephrogenous cyclic AMP production, or plasma creatinine.(ABSTRACT TRUNCATED AT 250 WORDS)

Background: DAT activity is regulated by protein kinases. Results: We identify Thr 53 as a DAT phosphorylation site in rat striatum by mass spectrometry and a phospho-specific antibody; Thr 53 mutation reduced dopamine influx and ablated transporter-mediated efflux. Conclusion: Phosphorylation of DAT Thr 53 is involved in transport activity. Significance: These results identify Thr 53 phosphorylation of DAT in vivo and elucidate associated functional properties.

Nonpoint‐source pollution has been linked to agricultural practices; however, there is a need for quantitative information describing the effect of specific farming practices on ground and surface water quality. Lack of information at the watershed scale limits our ability to make decisions about the effect of potential changes in either farming practices or landscape management that would enhance water quality. A multidisciplinary study was designed to evaluate the effect of farming practices on subsurface drainage, surface runoff, stream discharge, groundwater, volatilization, and soil processes that influence water quality. Walnut Creek watershed is a 5130‐ha intensively cropped area in central Iowa on the Des Moines Lobe landform region. Soils within the watershed are in the Clarion‐Nicollet‐Webster (Typic Hapludoll‐Aquic Hapludoll‐Typic Haplaquoll) soil association, and the underlying surficial material is glacial till. Land use is predominantly corn (Zea mays L.)‐soybean [Glycine max (L.) Merr.] rotation. Fertilizer use, herbicide application, tillage practices, and crop selection were obtained through surveys of each field operator. Atrazine [6‐chloro‐N‐ethyl‐N′‐(1‐methylethyl)‐1,3,5‐triazine‐2,4‐diamine], cyanazine [2‐[[4‐chloro‐6‐(ethylamino)‐1,3,5‐triazin‐2‐yl]amino]‐2‐methylpropanenitrile], EPTC [S‐ethyl dipropyl carbamothioatel, and metolachlor [2‐chloro‐N‐(2‐ethyl‐6‐methyiphenyl)‐N‐(2‐methoxy‐1‐methylethyl)acetamide] are the primary herbicides used within the watershed at rates similar to those for the state. Nitrogen fertilizer was applied as anhydrous ammonia on 60% of the corn fields at an average rate of 153 kg ha−1 for the 1991–1994 period, but the frequency of corn fields receiving <112 kg ha−1 has increased.

The apparatus responsible for translocation of proteins across bacterial membranes is the conserved SecY complex, consisting of SecY, SecE, and SecG. Prior genetic analysis provided insight into the mechanisms of protein export, as well as the interactions between the component proteins. In particular, the prl suppressor alleles of secE and secY, which allow export of secretory proteins with defective signal sequences, have proven particularly useful. Here, we report the isolation of novel mutations in secE and secY, as well as the phenotypic effects of combinations of prl mutations. These new alleles, as well as previously characterized prl mutations, were analyzed in light of the recently published crystal structure of the archaeal SecY complex. Our results support and expand a model of Prl suppressor activity that proposes that all of the prlA and prlG alleles either destabilize the closed state of the channel or stabilize the open form. These mutants thus allow channel opening to occur without the triggering event of signal sequence binding that is required in a wild-type complex.

Our data suggests that leptin is markedly increased in some patients with chronic renal failure. The association of increased leptin with low protein intake and loss of lean tissue is consistent with leptin contributing to malnutrition but a definitive role cannot be substantiated by this study.