A peptide from human semenogelin I self-assembles into a pH-responsive hydrogel.

The peptide GSFSIQYTYHV derived from human semenogelin I forms a transparent hydrogel through spontaneous self-assembly in water at neutral pH. Linear rheology measurements demonstrate that the gel shows a dominating elastic response over a large frequency interval. CD, fluorescence and FTIR spectroscopy and cryo-TEM studies imply long fibrillar aggregates of extended ß-sheet. Dynamic light scattering data indicate that the fibril lengths are of the order of micrometers. Time-dependent thioflavin T fluorescence shows that fibril formation by GSFSIQYTYHV is a nucleated reaction. The peptide may serve as basis for development of smart biomaterials of low immunogenicity suitable for biomedical applications, including drug delivery and wound healing.

Probing cellulose-solvent interactions with self-diffusion NMR: Onium hydroxide concentration and co-solvent effects.

The molecular self-diffusion coefficients were accessed, for the first time, in solutions of microcrystalline cellulose, dissolved in 30 wt% and 55 wt% aqueous tetrabutylammonium hydroxide, TBAH (aq), and in mixtures of 40 wt% TBAH (aq) with an organic co-solvent, dimethylsulfoxide (DMSO), through pulsed field gradient stimulated echo NMR measurements. A two-state model was applied to estimate α (i.e., average number of ions that "bind" to each anhydroglucose unit) and Pb (i.e., fraction of "bound" molecules of DMSO, TBAH or H2O to cellulose) parameters. The α values suggest that TBA+ ions can bind to cellulose within 0.5 TBA+ to 2.3 TBA+/AGU. On the other hand, the Pb parameter increases when raising cellulose concentration for TBA+, DMSO and water in all solvent systems. Data suggests that TBAH interacts with the ionized OH groups from cellulose forming a sheath of bulky TBA+ counterions which consequently leads to steric hindrance between cellulose chains.

Single origin of human commensalism in the house sparrow.

The current, virtually worldwide distribution of the house sparrow (Passer domesticus) is a result of its commensal relationship with humans. It has been suggested that long before the advent of agriculture, an early glacial advance resulted in two disjunct ranges of ancestral house sparrows - one in the Middle East and another on the Indian subcontinent. Differentiation during this period of isolation resulted in two major groups of subspecies: the domesticus group and the indicus group. According to this hypothesis, commensalism with humans would have evolved independently in the two regions and at least twice. An alternative hypothesis is that morphological differences between the subspecies represent very recent differentiation, following expansions from a single source. To test between these hypotheses, we analysed genetic variation at the mitochondrial DNA control region and at three nuclear loci from several house sparrow populations in Europe, Asia and North Africa. No differentiation between the indicus and domesticus groups was found, supporting the single origin hypothesis. One of the subspecies in the indicus group, P. d. bactrianus, differs ecologically from other house sparrows in being migratory and in preferentially breeding in natural habitat. We suggest that bactrianus represents a relict population of the ancestral, noncommensal house sparrow. When agricultural societies developed in the Middle East about 10 000 years ago, a local house sparrow population of the bactrianus type adapted to the novel environment and eventually became a sedentary, human commensal. As agriculture and human civilizations expanded, house sparrows experienced a correlated and massive expansion in range and numbers. The pattern of genetic variation analysed here is consistent with this scenario.

Agreement between child and parent reports of 10- to 12-year-old children's meal pattern and intake of snack foods.

BACKGROUND: Dietary assessment in children is associated with misreporting, which is a problem with both child and parent reports. Therefore, it is of interest to study how children and parents report children's eating, respectively, although comparative studies are rare. The aim of the present article was to study the meal patterns and intake of certain snack foods of 10- to 12-year-old children as reported by the children and their parents, respectively, and to determine whether there was agreement between the child and parent reports. An additional aim was to study what factors might influence rater agreement. METHODS: School children aged 10-12years and their parents were given parallel questionnaires regarding the children's meal pattern. Matched pairs (n=147) were analysed for agreement. Descriptive statistics were used to study all variables. Rater agreement and whether agreement depends on the age and the sex of the child, the sex of the parent and household type were analysed using ordinal regression models. Correlations between the child and parent assessments were estimated as polychoric correlations. RESULTS: There was a general agreement between child and parent reports, except with respect to sweets and chocolate, where children reported less frequent consumption than the parents did (P= 0.0001). The sex of the child was a significant factor regarding consumption of in-between meals (P=0.0001) and soft drinks (P=0.01). Most children had breakfast, school lunch and dinner every day, whereas it was less common to report daily consumption of in-between meals. CONCLUSIONS: There was a general agreement between children's and parents' reports, and most children were reported to have a regular meal pattern.

Serum concentration of mineralocorticoids, glucocorticoids, and sex steroids in peripartum bitches.

The aim of the work was to describe the profile of steroid hormones in the peripartum period of the bitch. Twenty-five healthy pregnant bitches presented for pregnancy monitoring and parturition assistance were included in the study. A blood sample was collected for routine progesterone assay, and serum was stored at -20°C. The day of parturition and the number of delivered puppies were registered. Concentrations of corticosteroids, androgens, progestogens, estrogens, for a total number of 17 different hormones, were measured using ultra-performance supercritical fluid chromatography-tandem mass spectrometry. Data were analyzed using a repeated measure, mixed-model approach, taking into account day (from day -4 to day +2 from parturition), age, parity (primiparous vs pluriparous), number of delivered puppies (<4 vs 4-8 vs > 8), and interactions between factors. Day related to parturition significantly affected the concentration of progesterone (P < 0.001), testosterone (P < 0.001), 17α-hydroxyprogesterone (P = 0.0002), and cortisone (P = 0.006). Estrogen concentration did not show any significant variation over time. Testosterone and androstenedione showed an abrupt decline on the day of parturition. The concentration of all glucocorticoids increased the day before parturition. Age or parity was not significantly associated with any of the steroids. Litter size significantly affected concentrations of aldosterone (P = 0.02) and etiocholanolone (P = 0.01). Aldosterone concentrations were higher in litters with 4 to 8 pups than in litters with more than 8 pups (P = 0.02). None of the steroids measured in our study, with the already known exception of progesterone, shows potential to be clinically useful in predicting the onset of parturition in the bitch.

Size determination of shear-induced multilamellar vesicles by rheo-NMR spectroscopy.

A model for analyzing the deuterium ((2)H) NMR line shapes of D(2)O in surfactant multilamellar vesicle (MLV, "onion") systems is proposed. The assumption of the slow exchange of water molecules between adjacent layers implies that the (2)H NMR line shape is simply given by a sum of Lorentzians if the condition of motional narrowing is also fulfilled. Using the classical two-step model for the NMR relaxation in structured fluids allows us to calculate how the NMR line shape depends on the MLV size. The model is tested on two different MLV systems for which the NMR line shapes are measured as a function of the applied shear rate using rheo-NMR. The MLV sizes obtained are in good agreement with previous data from rheo-small-angle light scattering.

PEGylated amyloid peptide nanocontainer delivery and release system.

A micellar nanocontainer delivery and release system is designed on the basis of a peptide-polymer conjugate. The hybrid molecules self-assemble into micelles comprising a modified amyloid peptide core surrounded by a PEG corona. The modified amyloid peptide previously studied in our group forms helical ribbons based on a beta-sheet motif and contains beta-amino acids that are excluded from the beta-sheet structure, thus being potentially useful as fibrillization inhibitors. In the model peptide-PEG hybrid system studied, enzymatic degradation using alpha-chymotrypsin leads to selective cleavage close to the PEG-peptide linkage, break up of the micelles, and release of peptides in unassociated form. The release of monomeric peptide is useful because aggregation of the released peptide into beta-sheet amyloid fibrils is not observed. This concept has considerable potential in the targeted delivery of peptides for therapeutic applications.

Shear-induced defect formation in a nonionic lamellar phase.

(2)H NMR experiments on a nonionic oriented lamellar phase demonstrate that shear flow induces structural defects in the lamellar structure. These substantial structural changes give rise to a transition from a viscous to a solidlike behavior; the elastic modulus of presheared samples was found to increase, reversibly, with the applied preshear rate. A similar behavior was found when step-cycling the temperature toward the layer-to-multilamellar-vesicle transition and back at constant shear rate. However, while shear rate controls the defect density, the temperature is found to control the defect rigidity. The lamellar phase exhibits a shear-thinning behavior under steady shear conditions, following the power law eta approximately gamma(n), with n approximately -0.4. Both the shear thinning and the elastic behavior are in agreement with the available theoretical models. The observed shear-induced structural defects are reversible and can be regarded as a pretransition prior to the shear-induced formation of multilamellar vesicles.

Ordering fluctuations in a shear-banding wormlike micellar system.

We present a first investigation about the non-linear flow properties and transient orientational-order fluctuations observed in the shear-thinning lecithin-water-cyclohexane wormlike micellar system at a concentration near to the zero-shear isotropic-nematic phase transition. From rheological measurements the stress plateau was found shifted to very low values of the applied shear rate gamma, compared to most of the concentrated living polymer systems reported in the literature. Rheo-small angle neutron scattering (Rheo-SANS) experiments performed in the flow-vorticity plane revealed periodical fluctuations of both the order parameter P(2) and the angular deviation phi from the vorticity axis as determined from the scattering peaks. The periods of the oscillations were not found to depend on imposed gamma. A theoretical model was also developed to explain the oscillatory dynamics of the shear-induced nematic order parameter in terms of the presence of standing waves of the director orientation profile along the circumference of the Couette cell. The experimental results of the periodic order parameter fluctuations together with their theoretical modelling shed significant new insights on the shear banding phenomenon, particularly its microscopic mechanism.

A new small-angle X-ray scattering set-up on the crystallography beamline I711 at MAX-lab.

A small-angle X-ray scattering (SAXS) set-up has recently been developed at beamline I711 at the MAX II storage ring in Lund (Sweden). An overview of the required modifications is presented here together with a number of application examples. The accessible q range in a SAXS experiment is 0.009-0.3 A(-1) for the standard set-up but depends on the sample-to-detector distance, detector offset, beamstop size and wavelength. The SAXS camera has been designed to have a low background and has three collinear slit sets for collimating the incident beam. The standard beam size is about 0.37 mm x 0.37 mm (full width at half-maximum) at the sample position, with a flux of 4 x 10(10) photons s(-1) and lambda = 1.1 A. The vacuum is of the order of 0.05 mbar in the unbroken beam path from the first slits until the exit window in front of the detector. A large sample chamber with a number of lead-throughs allows different sample environments to be mounted. This station is used for measurements on weakly scattering proteins in solutions and also for colloids, polymers and other nanoscale structures. A special application supported by the beamline is the effort to establish a micro-fluidic sample environment for structural analysis of samples that are only available in limited quantities. Overall, this work demonstrates how a cost-effective SAXS station can be constructed on a multipurpose beamline.

Influence of the solvent on the self-assembly of a modified amyloid beta peptide fragment. I. Morphological investigation.

The solvent-induced transition between self-assembled structures formed by the peptide AAKLVFF is studied via electron microscopy, light scattering, and spectroscopic techniques. The peptide is based on a core fragment of the amyloid beta-peptide, KLVFF, extended by two alanine residues. AAKLVFF exhibits distinct structures of twisted fibrils in water or nanotubes in methanol. For intermediate water/methanol compositions, these structures are disrupted and replaced by wide filamentous tapes that appear to be lateral aggregates of thin protofilaments. The orientation of the beta-strands in the twisted tapes or nanotubes can be deduced from X-ray diffraction on aligned stalks, as well as FT-IR experiments in transmission compared to attenuated total reflection. Strands are aligned perpendicular to the axis of the twisted fibrils or the nanotubes. The results are interpreted in light of recent results on the effect of competitive hydrogen bonding upon self-assembly in soft materials in water/methanol mixtures.

On the concentration-induced growth of nonionic wormlike micelles.

We present a comprehensive study of the concentration-induced growth of nonionic wormlike micelles in dilute solutions, below the overlap concentration, where we combine static and dynamic light scattering and NMR self-diffusion. The data are analyzed in detail in terms of the number-averaged contour length, assuming an exponential size distribution, as predicted by theory, and that the micellar flexibility can be described by the wormlike chain model with a certain persistence length. A very good agreement between the different experimental methods is obtained. The number-averaged contour length increases with increasing micelle volume fraction. The data are consistent with a power law, where the power law exponent is in the range 0.5-0.8, depending on the system. The result is in reasonable agreement with the theory of living polymers.

Molecular parameters that control the association of low density lipoprotein apo B-100 with chondroitin sulphate.

The association of low density lipoprotein (LDL) with proteoglycans of the arterial intima, in particular chondroitin 6-sulphate proteoglycans, may contribute to LDL accumulation during atherogenesis. We studied the interactions of apolipoprotein B-100 (apo B-100) peptide segments and model peptides with chondroitin 6-sulphate. The ability of these peptides to inhibit complex formation between LDL and chondroitin 6-sulphate was used as a measurement of the interaction. Results from earlier studies suggest that surface located segments of apo B-100 are responsible for the interaction of LDL with heparin and chondroitin sulphate-rich arterial proteoglycans. Therefore 16 hydrophilic apo B-100 peptides were selected for studies and synthesized with a peptide synthesizer. These synthetic peptides were 7 to 26 amino acids long. Four of the peptides inhibited the association of LDL with chondroitin 6-sulphate, namely apo B segments 4230-4254, 3359-3377, 3145-3157 and 2106-2121. The 3359-3377 segment was the most efficient. A common feature between the interacting peptides was an excess of positively charged side chains and based on these results we synthesized nine model peptides that shared sequence characteristics with the interacting apo B-100 peptides. Five of these: RSGRKRSGK, RSSRKRSGK, RGGRKRGGK, RSRSRSRSR and RGRGRGRGR were shown to block the LDL-chondroitin-6-sulphate association, RSRSRSRSR being the most effective. The results suggest that the optimal association of the peptides with chondroitin 6-sulphate is obtained with a minimal chain length of nine amino acids and a minimum of five positive charges and that flexibility in the binding region is important.

Fatty acids modulate the composition of extracellular matrix in cultured human arterial smooth muscle cells by altering the expression of genes for proteoglycan core proteins.

In diabetes-associated microangiopathies and atherosclerosis, there are alterations of the extracellular matrix (ECM) in the intima of small and large arteries. High levels of circulating nonesterified fatty acids (NEFAs) are present in insulin resistance and type 2 diabetes. High concentrations of NEFAs might alter the basement membrane composition of endothelial cells. In arteries, smooth muscle cells (SMCs) are the major producers of proteoglycans and glycoproteins in the intima, and this is the site of lipoprotein deposition and modification, key events in atherogenesis. We found that exposure of human arterial SMCs to 100-300 micromol/albumin-bound linoleic acid lowered their proliferation rate and altered cell morphology. SMCs expressed 2-10 times more mRNA for the core proteins of the proteoglycans versican, decorin, and syndecan 4 compared with control cells. There was no change in expression of fibronectin and perlecan. The decorin glycosaminoglycan chains increased in size after exposure to linoleic acid. The ECM produced by cells grown in the presence of linoleic acid bound 125I-labeled LDL more tightly than that of control cells. Darglitazone, a peroxisome proliferator-activated receptor (PPAR)-gamma ligand, neutralized the NEFA-mediated induction of the decorin gene. This suggests that some of the NEFA effects are mediated by PPAR-gamma. These actions of NEFAs, if present in vivo, could contribute to changes of the matrix of the arterial intima associated with micro- and macroangiopathies.

Changes in matrix proteoglycans induced by insulin and fatty acids in hepatic cells may contribute to dyslipidemia of insulin resistance.

Insulin resistance and type 2 diabetes are associated with elevated circulating levels of insulin, nonesterified fatty acids (NEFAs), and lipoprotein remnants. Extracellular matrix proteoglycan (PG) alterations are also common in macro- and microvascular complications of type 2 diabetes. In liver, extracellular heparan sulfate (HS) PGs contribute to the uptake of triglyceride-rich lipoprotein remnants. We found that HepG2 cells cultured with 10 or 50 nmol/l insulin or 300 micromol/l albumin-bound linoleic acid changed their PG secretion. The glycosaminoglycans (GAGs) of the secreted PGs from insulin-treated HepG2 cells were enriched in chondroitin sulfate (CS) PGs. In contrast, cells exposed to linoleic acid secreted PGs with decreased content of CS. Insulin caused a moderate increase in mRNA for versican (secreted CS PG), whereas linoleic acid markedly decreased mRNA for versican in HepG2 cells, as did the peroxisomal proliferator-activated receptor-alpha agonist bezafibrate. The effects of insulin or linoleic acid on syndecan 1, a cell surface HS PG, were similar to those on versican, but less pronounced. The livers of obese Zucker fa/fa rats, which are insulin-resistant and have high levels of insulin, NEFAs, and triglyceride-rich remnants, showed increased expression of CS PGs when compared with lean littermates. These changes in PG composition decreased the affinity of remnant beta-VLDL particles to PGs isolated from insulin-treated HepG2 cells and obese rat livers. The results indicated that insulin and NEFAs modulate the expression of PGs in hepatic cells. We speculate that in vivo this exchange of CS for HS may reduce the clearance of remnant beta-VLDLs and contribute to the dyslipidemia of insulin resistance.

Binding parameters and concentration modulate formation of complexes between LDL and arterial proteoglycans in serum.

The interactions of LDL with extracellular matrix proteoglycans apparently contribute to the accumulation of apo B-lipoproteins in atherogenesis. Serum LDL forms insoluble complexes with human arterial chondroitin sulfate proteoglycans (CSPG). While the amount of insolubilized LDL varies, serum from survivors of myocardial infarcts and ischaemic subjects shows higher values of CSPG-insolubilized LDL than serum from controls. In this study, we explored the relationship between the formation of LDL-CSPG complexes in serum and some LDL properties, using binding isotherms and characterization of isolated LDL from 12 healthy controls and 12 young myocardial infarct survivors. The amount of LDL insolubilized in serum from solutions of CSPG was found to be a function of the product Bt (total binding) x the amount of serum LDL-cholesterol. Furthermore, the Bt values for the isolated LDL from controls and patients could be predicted with more than 70% certainty by using a multiple regression model which included the cholesterol/protein ratio, protein/triglyceride ratio, isoelectric point and the affinity coefficient of the lipoprotein for CSPG. The results indicate that LDL-CSPG measurements in serum are dependent upon both LDL concentration and structural properties which are related to its tendency to form complexes with arterial CSPG.

Further studies on the involvement of selenium in peroxisome proliferation in rat liver. Comparison of effects with clofibric acid and perfluorooctanoic acid and the pharmacokinetics of [14C]clofibrate.

Most effects of the peroxisome proliferator clofibrate on rat liver are marginal or absent in selenium (Se) deficiency. The purpose of the present study was to determine whether the uptake or distribution of clofibrate is altered by Se deficiency. Rats were fed a Se-adequate or -deficient diet for 10-11 weeks and then these same diets with 0.5% (w/w) clofibric acid (the direct acting hydrolysis product of clofibrate) or 0.02% (w/w) perfluorooctanoic acid (PFOA) for 10 days. Other groups of rats received radiolabeled clofibrate by intubation. Clofibric acid was an ineffective as clofibrate in producing effects (i.e. decreased body weight gain, increases in liver somatic index and protein content of the mitochondrial fraction, and increased activities of catalase and peroxisomal fatty acid beta-oxidation) in the liver of Se-deficient rats. Microsomal omega-hydroxylation was, however, equally induced in both dietary groups. In contrast to clofibric acid, the biological effects of PFOA were not affected by Se status. Furthermore, neither the tissue distribution (plasma, liver and kidney) nor the urinary excretion of 14C was affected by Se deficiency. These results demonstrate that the hydrolysis of clofibrate to clofibric acid is not impaired in the Se-deficient rat. In addition, the involvement of Se in the effects of peroxisome proliferators differs for different members of this structurally heterogeneous group of compounds. It is concluded that the Se-deficient rat may provide valuable information concerning the biochemical mechanism(s) underlying peroxisome proliferation.

Impaired ketone body metabolism in the selenium deficient rat. Possible implications.

Male rats were fed a selenium-deficient Torula yeast diet with or without 0.2 ppm selenium (as sodium selenite) in the drinking water. Selenium deficiency caused a significant increase of urinary acetoacetate excretion in fed rats, and 24 or 48 hours of starvation enhanced this effect. Two days of selenium supplementation decreased the amount of urinary acetoacetate and 3-hydroxybutyrate to 50% of the deficiency value, indicating an enzymatic impairment in the selenium-deficient rat. No selenium-dependent effect was found for the following: (1) urinary pH, amount of nitrite, glucose (negative), hemoglobin or protein, and the urine was negative for phenylketones; (2) blood content of glucose, acetoacetate, or 3-hydroxybutyrate; or (3) liver content of glycogen, glucose, acetoacetate, or 3-hydroxybutyrate. On the other hand, the liver content of triglycerides was significantly lower in selenium deficiency. Indications for a higher content of ketone bodies (acetoacetate plus 3-hydroxybutyrate) in the kidneys from selenium-deficient rats were found. The increased urinary excretion of ketone bodies on selenium deficiency may indicate an impairment of lipid and ketone body turnover (in the kidney), or a decreased kidney reabsorption rate. Possible implications of these results in connection with protective roles of selenium in atherosclerosis and carcinogenesis are suggested.

Inheritance of type-III hyperlipoproteinemia. Lipoprotein patterns in first-degree relatives.

The lipoprotein (LP) patterns were studied in the families of 19 index cases with type-III hyperlipoproteinemia (HLP). Seventy adult first-degree relatives (93% ascertainment) to the 19 probands were analyzed. The diagnosis of HLP type III among the first-degree relatives was based on three criteria, all of which had to be fulfilled to make the diagnosis: (1) presence of a slow-moving band in very-low-density LP (VLDL) on agarose gel electrophoresis migrating in beta or close to beta position; (2) A cholesterol/triglyceride ratio (mg/100 ml: mmoles/liter) in VLDL greater than 29.0; and (3) A "III-index" [cholesterol/triglycerides in VLDL x 10 divided by cholesterol/triglycerides in low-density LP (LDL)] greater than 1.30. When defined according to these criteria there was a marked over-representation of HLP type III among the relatives (27%). There was also an increased frequency of hypertriglyceridemia (28% against expected 15%), mainly because of a high prevalence of HLP type IV (24%). On agarose gel electrophoresis a "late pre-beta" band, probably indicative of an increased amount of intermediary LP particles, was frequently present (47%) among relatives not classified as HLP type III. Type-III patients with hypertriglyceridemia were characterized by a significantly higher body weight than those with normotriglyceridemic type III. However, there was no qualitative difference in the composition of the lipoproteins in normotriglyceridemic and hypertriglyceridemic type-III patients. A genetic analysis of the LP patterns within the families showed several examples of vertical transmission of HLP type III. There was no sex linkage. Six of thirteen analyzed parents showed LP patterns classified as HLP type III. Another two parents were most probably carriers of the gene. Of the siblings to the probands, 23% showed a type-III pattern and another four (7%) showed LP patterns very similar to type III, fulfilling two of three criteria for HLP type III. The data support the concept that HLP type III is inherited as an autosomal dominant gene. It was indicated that HLP type IV with a late pre-beta band in VLDL may represent another expression of the gene for HLP type III. It is suggested that HLP type III may be a pathogenetically heterogenous group of lipid disorders. A separation of type III into two subgroups with low or normal and high LDL cholesterol concentration, respectively, may facilitate the understanding of the inheritance of type III as well as of the pathogenesis behind this LP abnormality.

Effects of starvation on the urinary contents of primary thromboxane and prostacyclin metabolites and a possible selenium-dependent role of prostacyclin in the renal handling of ketone bodies.

The aim of this study was to investigate whether urinary prostanoids, as an index of renal synthesis of these compounds, are affected in selenium (Se) deficiency and, if so, whether such changes could add to our understanding of the high excretion of ketone bodies in Se-deficient rats (p < 0.005 vs Se-adequate rats). Male rats were fed a Se-deficient diet with less than 0.01 mg Se/kg or the same diet supplemented with 0.2 mg Se/kg. The urinary contents of prostaglandin E2 (PGE2), PGF2 alpha and 6-keto PGF1 alpha were not significantly affected by the Se status. However, there was a positive correlation between the urinary contents of ketone bodies and 6-keto PGF1 alpha in Se deficiency (with p < 0.02 for acetaoacetate and p < 0.05 for 3-hydroxybutyrate). In contrast, only negative (nonsignificant) relationships were observed between these same parameters in Se-adequate rats. No correlations between urinary contents of ketone bodies and PGE2, PGF2 alpha or thromboxane B2 (TXB2) were obtained. Compared to fed rats, starvation caused a 4-fold increase in the urinary TXB2 content in Se-adequate, as well as in Se-deficient rats (p < 0.001). Starvation had an opposite effect on the content of 6-keto PGF1 alpha, which decreased (to 64% that of fed animals p < 0.001) in Se-adequate rats and, nonsignificantly (to 93% that of fed animals) in the Se-deficient group. It is concluded that starvation profoundly affects the urinary contents (and thus, probably renal synthesis) of TX and prostacycline (PGI2).(ABSTRACT TRUNCATED AT 250 WORDS)