Is there a diurnal variation in the susceptibility of mouse skin to the tumorigenic action of methylcholanthrene? A study of tumour yield with special reference to the variation between cages

Skin tumour development was studied in groups of mice painted once with 125 mug of 3-methylcholanthrene (MCA) either at 12:00 or at 24:00 MET. Eight animals were kept in each box. The animals were observed weekly for 20 months and all tumours were registered. There was no difference between the two groups of mice as regards tumour induction time or number of papilloma-bearing mice. In the groups of mice treated at 24:00 the number of skin tumours to develop was 9 per cent higher than in groups of mice treated at 12:00. This difference in papilloma yields is not statistically significant. Among female mice painted at 24:00 carcinoma-bearing animals were significantly more numerous (50 per cent) than among those painted at 12:00, whereas there was no difference between the groups of male mice. Considering the groups collectively (males + females), the intergroup difference (17 per cent) in advantage of painting at 24:00 was barely significant (0.5 less than p less than 0.10). There was no difference between the groups as regards the total number of carcinomas to occur. When the tumour yields in individual boxes were found to vary greatly. The slight increase in tumour yield after night painting correlates with the circadian variation in proliferative activity of the epidermidis. Previous reports in the literature have shown similar differences. Further investigations and better methods seem necessary before a definite conclusion can be drawn concerning a possible diurnal variation in the susceptibility of mouse skin to chemical carcinogenesis. It is also emphasized that it is necessary to exercise great caution when the results of classical epidermal chemical carcinogenesis experiments are to be interpreted. It seems necessary to observe animals for at least 15 months before any conclusion can be drawn.     

Muscle lipids, vitamins E and A, and lipid oxidation as affected by diet and RN genotype in female and castrated male Hampshire crossbreed pigs

The objectives of this study were to investigate the polar and neutral lipid fatty acid composition, content of retinol, -tocopherol, γ-tocopherol and level of oxidation of the pig muscle (M. longissimus dorsi). Female and castrated male Hampshire crossbreeds were produced in two systems. One group was raised indoors with a more polyunsaturated diet and the other raised outdoors with a more saturated diet. The level of polyunsaturated fatty acids in muscle was higher in the indoor females compared with the outdoor females, indoor castrated males and outdoor castrated males. The increased level of polyunsaturated fatty acids in the muscle, which was accompanied by a relatively low content of -tocopherol, increased the susceptibility to lipid oxidation in the form of MDA (malondialdehyde) in the indoor female pigs. Finally, the level of polyunsaturated fatty acids in the polar lipids was affected by the RN genotype, and this difference was dependent on sex. In conclusion, diet has a major effect on the fatty acid composition and oxidation stability in pork muscle, but additional factors such as sex and RN genotype might also contribute.     

Species identification by genotyping and determination of antibiotic resistance in Campylobacter jejuni and Campylobacter coli from humans and chickens in Sweden

Campylobacter is today the most common cause of human bacterial enteritis in Sweden, as well as in most other industrialized countries. Common sources of infection are undercooked chicken meat, unpasteurized milk and contaminated drinking water. One aim with our present study was to identify the species Campylobacter jejuni and Campylobacter coli strains from humans and chickens using a polymerase chain reaction/restriction enzyme analysis (PCR/REA) method, as well as traditional hippurate hydrolysis test. Another aim was to investigate the antibiotic resistance pattern of the human domestic C. jejuni/C. coli isolates from infected patients and isolates from healthy Swedish chicken, as well as isolates from humans infected abroad. If discrimination between C. jejuni and C. coli was based on testing for hippurate hydrolysis, 95% of the human domestic strains and 88% of the chicken strains were identified as C. jejuni. Based on genotyping by PCR/REA, 100% of the human domestic strains and 98% of the chicken strains were attributed to C. jejuni. The E-test and disc diffusion methods were used for phenotypic antibiotic resistance studies. The two methods gave similar results. Most Swedish C. jejuni/C. coli isolates both from humans and chickens were sensitive to doxycycline and erythromycin, which are antibiotics used to treat human infection. Only 7% of the human domestic strains and 2% of the chicken strains were resistant to the quinolones tested. As a comparison, more than 94% of strains isolated from travelers to Asia and southern Europe showed antibiotic resistance to one or more drugs.     

Accumulation of polybrominated diphenyl ethers, hexabromobenzene, and 1,2-dibromo-4-(1,2-dibromoethyl)cyclohexane in earthworm (Eisenia fetida). Effects of soil type and aging

In the present study the accumulation potentials in earthworms (Eisenia fetida) of selected brominated flame retardants (BFRs) were investigated. The tested BFRs, including polybrominated diphenyl ethers (PBDEs), hexabromobenzene (HBB), and 1,2-dibromo-4-(1,2-dibromoethyl)cyclohexane (TBECH), were found to be bioavailable to Eisenia fetida, and they accumulated in the earthworms. To our knowledge, this is the first published study to address the bioaccumulation potential of TBECH in terrestrial biota. Aging the soil resulted in decreased accumulation of TBECH, HBB, and PBDEs with six or less bromine atoms. However, no effect of soil aging was seen for BDEs 183 or 209, possibly due to their low mobility in soil. The use of different soils (artificial OECD soil and two natural Swedish soils) also affected the degree of accumulation in the worms. The results indicate that use of the generally accepted standard OECD soil may overestimate accumulation of organic contaminants by earthworms, due to high bioavailability of the contaminants and/or weight loss of the worms in it. Further, the accumulation of selected PBDEs and HBB was compared to the accumulation of their chlorinated analogues. Brominated compounds accumulated to the same or a lesser extent than their chlorinated counterparts.     

Effects of feed composition,protein denaturation and storage of milk serum protein/lactose powders on lactosylation

During whey powder production, the feed is subjected to several heat treatments which can cause lactosylation of proteins. In this study, lactosylation of whey proteins was evaluated in spray-dried powders before and after storage by varying the native protein fraction as well as the serum protein/lactose ratio in the powders. The lactosylation of native α-lactalbumin and β-lactoglobulin in the powders before storage was not affected to a large extent by the protein denaturation or if the feed had been heat treated in a high or low lactose environment. After storage (relative humidity of 23.5%, 30 °C, 25 days), the kinetic of lactosylation tended to increase with increasing native protein fraction and bulk protein content in the powders. An explanation could be that proteins dissolved in the lactose glassy structure might have a lower reactivity, while proteins present in the protein glassy structure with dissolved lactose may display higher lactosylation reactivity.     

Photochemical formation of polybrominated dibenzo-p-dioxins from environmentally abundant hydroxylated polybrominated diphenyl ethers

High levels of polybrominated dibenzo-p-dioxins (PBDDs) have been found in Baltic Sea biota, where the toxic load owing to, for example, polychlorinated dibenzo-p-dioxins and other organic pollutants is already high. The levels and geographic pattern of PBDDs suggest biogenic rather than anthropogenic origin, and both biotic and abiotic formation pathways have been proposed. Photochemical formation from hydroxylated polybrominated diphenyl ethers (OH-PBDE) is a proposed pathway for PBDDs in marine environments. Ultraviolet radiation-initiated transformations of OH-BDEs 47, 68, 85, 90, 99, and 123, which all are abundant in the environment, were investigated. It was shown that the most abundant PBDDs in the environment (1,3,7-triBDD and 1,3,8-triBDD) can be formed from the most abundant OH-BDEs (OH-BDE 47 and OH-BDE 68) at high rates and with percentage yields. In fact, most of the PBDDs that have been identified in the Baltic Sea environment were formed with high yield from the six studied OH-PBDE, through initial cyclization and subsequent debromination reactions. The high formation yields point to this route as an important source of PBDDs in biota. However, congeners showing relatively high retention in fish, specifically 1,3,6,8- and 1,3,7,9-tetraBDD, were not formed. These are likely formed by enzymatic coupling of brominated phenols.     

Effect of preheating on potato texture

Preheating potatoes at 50 to 80°C has a firming effect on the cooked potato tissue. This effect is particularly pronounced at a preheating temperature of 60 to 70°C followed by cooling. Several theories have been presented in the literature to explain this firming effect: retrogradation of starch, leaching of amylose, stabilization of the middle lamellae and cell walls by the activation of the pectin methylesterase (PME) enzyme, and by the release of calcium from gelatinized starch and the formation of calcium bridges between pectin molecules. Most probably, none of these theories alone can explain the phenomenon and more than one mechanism seems to be involved. Some of these mechanisms seem to be interdependent. As an example, calcium could be considered as a link all the way through release after starch gelatinization to cross‐linking pectin substances in the cell wall and the middle lamellae, which has been demethylated by the PME enzyme. More research and “clear cut” experiments are needed in order to elucidate the role of each mechanism, especially which of them is the main contributor to the process of firming. Most probably, the calcium‐pectin‐PME mechanism plays a secondary role, that is, it only retards the collapse of the tissue structure that would otherwise occur during the final heating without preheating, and it is not the main factor of firmness.     

Gene expression of syndecans and betaglycan in isolated rat liver cells

Competence as communication skills and as skilled practice of asepsis were studied by observing four nurses while interacting with patients and performing intravenous procedures. Nurses were observed using sterile equipment for methods of intravenous therapy. Asepsis is performed frequently, but through misunderstanding in the learning of asepsis or improper model learning the nurses may establish incorrect routines. When performing procedures, unexpected factors can distract both the expert and the inexperienced, resulting in a failure to apply basic aseptic techniques. The nurses showed an interest in the patient by listening and giving responses. Nurses may control interactions with the patient by using undesirable communication skills which include incomplete sentences, incomplete explanations and closed questions. Asked to evaluate their own behavior, the nurses did not estimate whether or not the appropriate skills were applied in observed situations. To improve the quality of nursing care performance it is recommended to further develop and apply skill training programs.     

Mechanisms of diarrhoea in myotonic dystrophy

BACKGROUND: Gastrointestinal (GI) symptoms are common in myotonic dystrophy (MD). Diarrhoea is one of the more disabling of these GI complaints. The mechanisms behind diarrhoea in MD have not previously been investigated systematically. OBJECTIVE: To elucidate the mechanisms behind diarrhoea in MD. METHODS: Twenty patients with MD and suffering from diarrhoea were investigated in order to detect malabsorption (blood tests and faecal fat excretion) and bile acid malabsorption ([75Se]selenahomocholic acid-taurine (SeHCAT) retention) and to study intestinal morphology (duodenal and rectal biopsies). RESULTS: Two patients had deficiency of folic acid and four showed reduced levels of pancreatic isoamylase, but none of them had steatorrhoea. Two out of eight patients had abnormal bile acid breath tests with normal SeHCAT, indicating small bowel bacterial overgrowth and 12 displayed reduced SeHCAT retention. Duodenal biopsies were normal in eight patients and five out of nine rectal biopsies displayed slight inflammation. CONCLUSIONS: A possible mechanism of diarrhoea in MD could be identified in most of the patients. Bile acid malabsorption seems to be a frequent cause and can be treated successfully.     

Leukotriene A4 Hydrolase and Hepatocyte Growth Factor Are Risk Factors of Sudden Cardiac Death Due to First-Ever Myocardial Infarction

Patients at a high risk for sudden cardiac death (SCD) without previous history of cardiovascular disease remain a challenge to identify. Atherosclerosis and prothrombotic states involve inflammation and non-cardiac tissue damage that may play active roles in SCD development. Therefore, we hypothesized that circulating proteins implicated in inflammation and tissue damage are linked to the future risk of SCD. We conducted a prospective nested case–control study of SCD cases with verified myocardial infarction (N = 224) and matched controls without myocardial infarction (N = 224), aged 60 ± 10 years time and median time to event was 8 years. Protein concentrations (N = 122) were measured using a proximity extension immunoassay. The analyses revealed 14 proteins significantly associated with an increased risk of SCD, from which two remained significant after adjusting for smoking status, systolic blood pressure, BMI, cholesterol, and glucose levels. We identified leukotriene A4 hydrolase (LTA4H, odds ratio 1.80, corrected confidence interval (CI_corr) 1.02–3.17) and hepatocyte growth factor (HGF; odds ratio 1.81, CI_corr 1.06–3.11) as independent risk markers of SCD. Elevated LTA4H may reflect increased systemic and pulmonary neutrophilic inflammatory processes that can contribute to atherosclerotic plaque instability. Increased HGF levels are linked to obesity-related metabolic disturbances that are more prevalent in SCD cases than the controls.