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.

Laparoscopic ovariectomy in dogs: a comparison of the LigaSure™ and the SonoSurg™ systems.

OBJECTIVES: The objective of this study was to evaluate the surgical times for removal of ovaries, and the frequency of intra-operative complications with two different instruments used for canine laparoscopic ovariectomy. METHODS: A randomised prospective clinical study. Laparoscopic ovariectomy was performed under general anaesthesia on 10 healthy female dogs admitted for elective ovariectomy. Each ovary was randomly assigned to removal by use of either a SonoSurg™ ultrasonic surgical device (Olympus), or a LigaSure™ vessel-sealing system (Valleylab/Covidien). Surgical time for removal of each ovary was measured and the frequency of intra-operative complications was recorded. A follow-up was made by interview with the owners, 2·5 years after surgery. RESULTS: The two techniques did not statistically differ with regard to surgical time, or frequency of complications. All owners were very satisfied with the procedure. CLINICAL RELEVANCE: Both the SonoSurg™ and the LigaSure™ devices appear to be effective, safe and easy to use when performing laparoscopic ovariectomy in dogs.

Comparison of haemodynamic changes during two surgical methods for neutering female dogs.

The aim was to investigate if intraoperative registrations of blood pressure and heart rate could be used to estimate surgical trauma. In a prospective clinical trial, registrations in eight dogs neutered by laparoscopic ovariectomy (LOE) were compared with eight dogs subjected to open ovariohysterectomy (OHE). For comparisons phases were used: phase zero=steady state after induction of anaesthesia; phase one=opening of abdomen; phase two=severing of ovarian pedicles; and, phase three=abdominal closure. During LOE, mean systolic blood pressure increased by 7 mmHg (p=0.05) and 15 mmHg (p=0.01) from phase zero to phase one and two, respectively, and during OHE by 3 mmHg (ns) and 29 mmHg (p<0.0001), respectively. The increase from phase one to phase two differed between groups (p=0.03). Heart rate did not change. Frequent intraoperative measurements of blood pressure appear a promising method for evaluating surgical trauma.

Influence of salt on the self-assembly of two model amyloid heptapeptides.

We study the effects of NaCl on the self-assembly of AAKLVFF and betaAbetaAKLVFF in solution. Both AAKLVFF and betaAbetaAKLVFF self-assemble into twisted fibers in aqueous solution. The addition of NaCl to aqueous solutions of AAKLVFF produces large crystal-like nanotapes which eventually precipitate. In contrast, highly twisted fibrils were observed for betaAbetaAKLVFF solutions at low salt concentration, while a coexistence of highly twisted fibers and nanotubes was observed for betaAbetaAKLVFF at high salt concentration. The self-assembled structures observed for betaAbetaAKLVFF in NaCl solutions were ascribed to the progressive screening of the betaAbetaAKLVFF surface charge caused by the addition of salt.

Peptide nanotube nematic phase.

The self-assembly of the trifluoroacetate salt of the short peptide (ala)6-lys (A6K) in water has been investigated by cryo-transmission electron microscopy and small-angle X-ray scattering. For concentrations below ca. 12%, the peptide does not self-assemble but forms a molecularly dispersed solution. Above this critical concentration, however, A6K self-assembles into several-micrometer-long hollow nanotubes with a monodisperse cross-sectional radius of 26 nm. Because the peptides carry a positive charge, the nanotubes are charge-stabilized. Because of the very large aspect ratio, the tubes form an ordered phase that presumably is nematic.

Patients' subjective symptoms, quality of life and intake of food during the recovery period 3 and 12 months after upper gastrointestinal surgery.

Few studies describe patients' quality of life and their experienced symptoms during the recovery period after having undergone upper gastrointestinal surgery at 3 and 12 months. The aims of this study were to explore patients' quality of life and symptoms preoperatively and at 3 and 12 months following upper gastrointestinal surgery and to describe and compare patients' experiences of appetite, food intake, weight changes, tiredness and sleeping patterns. A descriptive and comparative quantitative design was used. Three instruments were used: the Gastrointestinal Symptom Rating Scale, the European Organisation for Research and Treatment of Cancer Quality of Life Questionnaire and the Eating Dysfunction Scale. A questionnaire was used to investigate symptoms such as mood, appetite, sleep, activities and well-being. Twenty-four patients were included in the study. The major results were that anxiety levels and global health status decreased and that patients felt more disappointed after 12 months compared with after 3 months. Four patients at 3 months after surgery and eight patients at 12 months regained their weight compared with the situation before surgery. The contribution of nursing care activities focusing on the importance of food intake and the patients' current and historical medical records in relation to their health status should continue to be examined and researched over a longer period of time.

Oil/water droplet formation by temperature change in the water/c(16)e(6)/mineral oil system.

Droplet sizes of oil/water (O/W) nanoemulsions prepared by the phase inversion temperature (PIT) method, in the water/C16E6/mineral oil system, have been compared with those given by a theoretical droplet model, which predicts a minimum droplet size. The results show that, when the phase inversion was started from either a single-phase microemulsion (D) or a two-phase W+D equilibrium, the resulting droplet sizes were close to those predicted by the model, whereas, when emulsification was started from W+D+O or from W+D+Lalpha (Lalpha = lamellar liquid crystal) equilibria, the difference between the measured and predicted values was much higher. The structural changes produced during the phase inversion process have been investigated by the 1H-PFGSE-NMR technique, monitoring the self-diffusion coefficients for each component as a function of temperature. The results have confirmed the transition from a bicontinuous D microemulsion at the hydrophile-lipophile balance (HLB) temperature to oil nanodroplet dispersion in water when it is cooled to lower temperatures.

Patients' experiences of the recovery period 3 months after gastrointestinal cancer surgery.

It is known that patients who have undergone gastrointestinal surgery as a result of a tumour experience changes in weight and intake of food and fluid. Several studies have highlighted patients' experiences owing to cancer, but there is a lack of knowledge about the recovery period from the patients' perspective. The purpose of this research is to describe patients' experiences of the recovery period 3 months after surgery. Data was collected by inviting four women and six men, between 52 and 84 years of age, to participate in an interview or dialogue 3 months after surgery. The study takes a hermeneutic approach. The framework for interpretation is the theory "Man's search for meaning" and further theories about suffering. The recovery period is characterized by feelings of being "down in the depths", lonely, abandoned and disappointed, but also feelings of support. Some patients regained strength and energy and reached a turning point, while others did not. Patients' suffering is seen as being in limbo, a fight between lack of freedom and freedom, including feelings of hope and doubts.

Microemulsion formed by alkyl polyglucoside and an alkyl glycerol ether with weakly charged films.

We have studied the effects on phase equilibria of a nonionic surfactant mixture-water-oil system when replacing small amount of surfactant molecules by ionic surfactant, sodium dodecyl sulfate (SDS). The nonionic surfactant system contains dodecyl-beta-D-maltoside (C(12)AG2) and iso-octyl glyceryl ether (i-C(8)GE) as cosurfactant, water and cyclohexane at constant water to oil ratio of 60/40 (w/w). Adding a small amount of SDS has large impact on the phase behavior. Clear liquid crystalline phase and upper microemulsion phase are added to the phase sequence at high i-C(8)GE/(C(12)AG2+i-C(8)GE) ratio. We also compare the phase equilibria of pure dodecyl maltoside system with polyglucosides mixture system.

Glycosaminoglycan-lipoprotein interaction.

Glycosaminoglycans (GAGs) bound to various proteoglycans (PGs) present in the cardiovascular system have been proposed to perform a wide range of functions. These include conferring viscoelastic properties; interacting with and modulating growth factors and enzymes; and as receptors and co-receptors in lipoprotein metabolism. Binding of apoB-100 lipoproteins, particularly low density lipoproteins (LDL), to GAGs of extracellular matrix PGs in arteries has been proposed to be an initiating event in development of atherosclerosis. This study was initiated with the aim of getting an overview of the binding patterns of different lipoprotein subclasses with individual GAG categories. We thus evaluated the interaction of lipoproteins with GAGs commonly found in the cardiovascular system using a gel mobility-shift assay developed for this purpose. The same procedure was used to measure lipoproteins binding to metabolically [(35)S]-labeled whole PGs prepared from three cell types, arterial smooth muscle cells, THP-1 macrophages and from HepG2 cells. The effect of GAG composition on PGs on lipoprotein binding was evaluated by enzymatic degradation of the carbohydrate chains. Heparan sulfate was found to bind beta very low density lipoproteins (beta-VLDL) and a chylomicron remnant model (beta-VLDL+apoE), but not LDL. Dermatan sulfate was found to bind LDL, but not beta-VLDL or the chylomicron remnant model. Chondroitin sulfate and heparin were found to bind all lipoproteins tested (LDL, beta-VLDL and beta-VLDL+apoE) although with different affinities. We can conclude that each lipoprotein subclass tested binds a specific assortment of the GAGs tested. The observations made contribute to the understanding of new and complex mechanisms by which carbohydrate and lipid metabolism may be linked.

Heating of food and haemoglobin adducts from carcinogens: possible precursor role of glycidol.

Studies of adducts from reactive compounds to haemoglobin (Hb) by gas chromatography-tandem mass spectrometry according to the N-alkyl Edman method reveals the occurrence of N-(2,3-dihydroxypropyl)valine (diHOPrVal) at levels of 1-2 pmol/g Hb, in persons without known exposure. The hypothesis that this background originates from glycidol or related compounds during heating of food was tested in experiments with rats. Animals fed fried animal feed for 30 or 72 days showed an increase of the diHOPrVal level by about 50% compared with controls. Several arguments, such as the formation of reactive oxiranes by heat-induced dehydration of glycol configurations in glycerol and sugars, support the idea that glycidol (or e.g. glycidyl esters) are precursors of the adduct. In Hb samples, reduced for stabilisation of aldehyde adducts, relatively high levels of adducts determined as diHOPrVal were found, although without significant relation to frying of the feed. There is thus no indication that reduction in vivo of, for example, the Schiff base from glyceraldehyde, is a pathway for formation of the diHOPrVal. The background level of diHOPrVal in humans Hb is low, and the cancer risk associated with exposure to the specific alkylator-probably glycidol-formed in cooking, is therefore presumably low. The result implies, however, that low-molecular mass mutagenic oxiranes formed during the heating of food should be studied further.

Effect of hormone balance on carbohydrate-deficient transferrin and gamma-glutamyltransferase in female social drinkers.

BACKGROUND: Carbohydrate-deficient transferrin (CDT) and gamma-glutamyltransferase (GGT) are the most commonly used markers for alcohol abuse, but their sensitivity and specificity are lower and have different reference values among females compared with males. In the present study, we evaluated the effect of women's hormone balance on these two alcohol markers, as well as on their mathematical combination, named gamma-CDT. METHODS: An age-stratified random sample of 3962 women, between 25-74 years old, was drawn from the normal population. Pregnancy, the use of oral contraceptives, intrauterine device for contraception, hormone replacement therapy, and hormone treatment for infertility were considered. A comparison between fertile, peri- and postmenopausal women was also done. RESULTS: Existing pregnancy increased CDT levels but decreased GGT values. Lower CDT and higher GGT levels were observed among those women using oral contraceptives and in postmenopausal women compared with women at the fertile stage. gamma-CDT was not influenced by hormone balance. CONCLUSIONS: The different hormonal status had an opposite effect on CDT and GGT. Women who were close to late menopause had levels of both markers closer to the values of men. It must be pointed out that the findings presented here are based on measurements of absolute CDT values and that no measurements of total transferrin were done. gamma-CDT, not influenced by hormone balance, indicates promising clinical utility among women.

Dose response of laboratory markers to alcohol consumption in a general population.

The dose response to alcohol use of carbohydrate-deficient transferrin (CDT), gamma-glutamyltransferase (GGT), and their combination (gamma-CDT) was studied in an age- and gender-stratified, random sample from Finland in 1997. A linear association with a threshold between alcohol consumption and the three markers was observed. Body mass index was negatively associated with CDT and positively with GGT Age was positively associated with GGT and gamma-CDT In conclusion, CDT appears to be an early phase marker of alcohol consumption. The combined marker, gamma-CDT, was less associated with factors such as body mass index but more strongly correlated with alcohol consumption than were the two markers separately.

Serum sialic acid in a random sample of the general population.

BACKGROUND: The serum sialic acid (SA) concentration has been reported to be a potentially useful but nonspecific disease marker. We wanted to study which factors influence SA concentration in a well-characterized healthy population. METHODS: SA was determined in 97 women and 96 men with a colorimetric Warren method. RESULTS: The mean +/- SD concentrations of SA were 634 +/- 109 (95% confidence interval, 612-656) and 630 +/- 106 (95% confidence interval, 608-651) mg/L for women and men, respectively. The serum SA showed a significant positive association with body mass index and with systolic and diastolic blood pressure among both women and men. SA also correlated significantly with the use of contraceptive pills and age among women and with smoking among men. CONCLUSIONS: Our study suggests that SA does not increase with age in men but appears to increase with female menopause. The strong positive association with blood pressure may explain why SA predicts cardiovascular mortality.

Lipid mediators that modulate the extracellular matrix structure and function in vascular cells.

Treatment with moderate levels of albumin-bound, nonesterified fatty acids (NEFA) induce important alterations of the structure and functionality of proteoglycans secreted by endothelial cells and arterial smooth muscle cells. In endothelial cell monolayers, the reduction on relative amount and sulfation of heparan sulfate proteoglycans is associated with an increased permeability to albumin. In smooth muscle cells, NEFA-albumin complex increased the expression of the genes for the core proteins of the proteoglycans syndecan, decorin and perlecan. This effect appears mediated by peroxisome proliferator-activated receptor gamma (PPARg). The matrix produced by the cells treated with NEFA-albumin had a higher affinity with low-density lipoproteins (LDLs). We speculate about the possibility that under dyslipidemias associated with increased exposure of vascular cells to NEFA, like in type 2 diabetes, similar alterations may contribute to associated macrovascular and microvascular complications.

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.

Glutathione-dependent and ketone body-related enzymes in the selenium-deficient rat.

Male rats, born of selenium (Se)-depleted dams and continuously fed a Se-deficient diet regimen or Se-repleted for 11 weeks, were used for some enzymatic determinations in samples from liver, heart, kidney and hind limb muscle. The Se-dependent GSH-Px activity in liver and kidney of the Se-deficient group was less than 0.5% of Se-repleted controls, whereas a 3-fold increase in liver and kidney GSH S-transferase activity was found in these Se-deficient rats. The Se-deficient group excreted 3 times more acetoacetate via the urine than their Se-repleted siblings. The activity of the key enzymes of ketone body utilization was similar in tissues from Se-repleted and Se-deficient rats. It is suggested that longlasting or even Se-unresponsive changes in enzymes of ketone body metabolism might have developed in these rats born of Se-depleted dams.

Effect of dietary selenium on biotransformation and excretion of mutagenic metabolites of N-nitrosodimethylamine and 1,1-dimethylhydrazine in the liver perfusion/cell culture system.

The mutagenicity of N-nitrosodimethylamine (NDMA) and 1,1-dimethylhydrazine (UDMH) has been studied in an isolated liver perfusion/cell culture system. The liver donors, male Wistar rats, were either selenium (Se)-deficient or had a physiologically adequate Se status (Se-supplemented). Mutagenicity was measured in perfusate and bile with Chinese hamster V79 cells as the genetic target. Se deficiency increased the mutagenic effect of NDMA in the perfusate, whereas no mutagenicity was detected in the bile of either Se-deficient or Se-supplemented livers. No significant increase in the mutagenicity of UDMH was seen in the perfusate with Se deficiency, but the bile became mutagenic. Se deficiency thus increased the mutagenicity of both NDMA and UDMH: with NDMA, the effect was observed in the perfusate, and with UDMH, in the bile.

Selenium deficiency and detoxication functions in the rat: short-term effects of cadmium.

Weanling rats were fed a Torula yeast-based selenium-deficient diet with or without supplementation of sodium selenite (0.2 ppm selenium) in the drinking water. After 5-6 weeks on the diet regimens, the liver glutathione peroxidase activity of the selenium-deficient groups had decreased to about 1% of the supplemented groups, and the rats were then used in experiments. Cadmium-induced effects on the drug-metabolizing system of the liver were measured as the microsomal capacity to perform N- and C-oxygenation of N, N-dimethylaniline. Cadmium in vitro caused a decrease of the cytochrome P-450-dependent C-oxygenation. This effect tended to be more prominent in the selenium-deficient groups. On the other hand, N-oxygenation was increased when cadmium was added in vitro, and no significant difference was found between selenium-deficient and -supplemented groups. However, as was found for the capacity to perform C-oxygenation, there was a tendency for lower N-oxygenation in the selenium-deficient rat. Lipid peroxidation, measured as thiobarbituric acid reactive substances in liver homogenates, was higher in selenium-deficient groups after in vivo treatment or in vitro addition of cadmium, and preincubation or phenobarbital induction enhanced this selenium-dependent difference. Although, the selenium-deficient rat seems more susceptible to cadmium-induced disturbances, 5-6 weeks of selenium deficiency was not enough to cause prominent impairment on the drug-metabolizing system as measured here and with the doses used in the present study.

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.