High‐throughput microbial bioassays to screen potential New Zealand functional food ingredients intended to manage the growth of probiotic and pathogenic gut bacteria

A spectrophotometric bioassay was used to screen selected food ingredients intended for development of functional foods designed to influence the growth of gut bacteria. Dose–response profiles displaying Δ_growth, the magnitude of deviation from growth of controls, were generated for probiotics Lactobacillus reuteri, Lactobacillus rhamnosus, Bifidobacterium lactis and pathogens Escherichia coli, Salmonella Typhimurium and Staphylococcus aureus. Ingredients were manuka honey UMF?20+(dose‐dependently increased probiotics and decreased pathogens); bee pollen (biphasic growth effects against all); Rosehips and BroccoSprouts^® (increased all dose‐dependently); blackcurrant oil (little effect) and propolis (inhibited all strains). Ingredients were also bioassayed in pairs to assess desirable or undesirable synergistic interactions. Observed synergies included manuka honey (predominantly desirable); rosehips or BroccoSprouts® (desirable and undesirable); blackcurrant oil (desirable) and propolis (tended towards synergies reinforcing its antimicrobial effects), collectively revealing a complex web of interactions which varied by ingredient and bacterial strain. Manuka honey was particularly effective at influencing gut bacteria. The surprising frequency of undesirable synergistic interactions illustrates the importance of pre‐testing potential ingredient combinations intended for use in functional foods.     

Fabrication of Optically Transparent and Electrooptic Strontium Barium Niobate Ceramics

The tetragonal tungsten bronze (TTB) type of Sr _x Ba_{1− x} ^m Nb₂O₆ (SBN) (0.5 ≤ x ≤ 0.75) was synthesized by a mixed-oxide route. Using the two-step densification process of pressureless sintering followed by oxygen HIPing, transparent ceramics were successfully fabricated. Microstructural, dielectric, optical, and electrooptic properties were investigated. All single-phase TTB-type SBN showed the characteristics of relaxor ferroelectrics. The extinction coefficients of the sample with the highest transparency were calculated from transmission spectra to be 30.4, 5.8, and 2.4 cm⁻¹ at 600, 1450, and 2000 nm, respectively. The linear electrooptic coefficients for SBN55, r ₃₃ and r ₁₃, were 46 × 10⁻¹² and 21 × 10⁻¹² m/V at 633 nm, respectively.     

Antisense estrogen receptor RNA expression increases epidermal growth factor receptor gene expression in breast cancer cells

In human breast cancer, progression to a more malignant phenotype is often accompanied by decreased expression of estrogen receptor (ER) and increased expression of epidermal growth factor receptor (EGFR). Higher levels of this receptor tyrosine kinase are found in tumors lacking ER, and a quantitative, inverse relationship exists between the level of ER and EGFR mRNA in human breast cell lines. Antisense ER (ASER) RNA was used to evaluate the consequence of decreased ER expression in breast cancer cells, specifically to determine whether ER is involved in the regulation of EGFR gene expression. ER-positive MCF-7 human breast cancer cells were transfected with ASER, and clones constitutively expressing ASER RNA had decreased ER and up to a 3-fold increase in the expression of EGFR mRNA. To confirm that this observation was a direct consequence of ASER expression, a metal-inducible ASER expression construct was transfected into MCF-7 cells, and transfected clones were isolated and characterized. Northern analysis revealed an induction of ASER RNA within 1 h of the addition of zinc, which was followed by a 4-fold increase in EGFR mRNA levels, maximal at 6-12 h. The basal level of expression of the glucocorticoid receptor is also inversely related to that of ER among breast cancer cell lines, but neither constitutive nor inducible expression of ASER affected the expression of glucocorticoid receptor. These data support the hypothesis that the level of expression of ER specifically influences the expression of EGFR in human breast cancer cells and provides a potential link between loss of steroid sensitivity and the acquisition of autonomous growth.     

The relationship between symptoms and blood pressure during maintenance hemodialysis

Intradialytic hypotension (IDH) is a detrimental complication of maintenance hemodialysis, but how it is defined and reported varies widely in the literature. European Best Practice Guideline and Kidney Disease Outcomes Quality Initiative guidelines require symptoms and a mitigating intervention to fulfill the diagnosis, but morbidity and mortality outcomes are largely based on blood pressure alone. Furthermore, little is known about the incidence of asymptomatic hypotension, which may be an important cause of hypoperfusion injury and impaired outcome. Seventy‐seven patients were studied over 456 dialysis sessions. Blood pressure was measured at 15‐minute intervals throughout the session and compared with post‐dialysis symptom questionnaire results using mixed modeling to adjust for repeated measures in the same patient. The frequency of asymptomatic hypotension was estimated by logistic regression using a variety of commonly cited blood pressure metrics that describe IDH. In 113 sessions (25%) where symptoms were recorded on the questionnaire, these appear not to have been reported to dialysis staff. When symptoms were reported (293 sessions [64%]), an intervention invariably followed. Dizziness and cramp were strongly associated with changes in systolic blood pressure (SBP), but not diastolic blood pressure. Nausea occurred more frequently in younger patients but was not associated with falls in blood pressure. Thresholds that maximized the probability of an intervention rather than a session remaining asymptomatic were SBP <100 mmHg or a 20% reduction in SBP from baseline. The probability of SBP falling to <100 mmHg in an asymptomatic session was 0.23. Symptoms are frequently not reported by patients who are hypotensive during hemodialysis, which leads to an underestimation of IDH if symptom‐based definitions are used. A revised definition of IDH excluding patient‐reported symptoms would be in line with literature reporting morbidity and mortality outcomes and include sessions in which potentially detrimental asymptomatic hypotension occurs.     

Ways of learning in a computer-based environment: some findings of the LOGO Maths Project

Abstract  This paper is derived from the LOGO Maths Project's investigation of the potential of LOGO in the secondary school mathematics classroom (1983–1986). The main focus of the work has been to discover whether and under what conditions the computer language LOGO can be used as an aid to pupils' learning and thinking in mathematics. Longitudinal case studies were undertaken for four pairs of pupils throughout the three years of the project. In addition the research was extended for two years into another eight schools. This paper presents the findings concerned with peer collaboration and the role of the teacher in the LOGO environment. It describes how LOGO work can be used to gain insights into pupils' conceptions of mathematical ideas. It also makes reference to gender issues in the wider context of computer use in the United Kingdom.     

Insulin down-regulates the inducible nitric oxide synthase pathway: nitric oxide as cause and effect of diabetes?

Evidence in this paper indicates that insulin can down-regulate the inducible nitric oxide synthase (iNOS) pathway in vivo. The iNOS pathway is up-regulated in diabetes-prone rats and mice and is associated with an autoimmune process. However, the results presented here indicate that macrophage nitric oxide (NO) production and iNOS mRNA expression are also elevated in rats or mice made diabetic by streptozotocin injection in which there is no primary autoimmune component. Insulin administration reduces NO production in autoimmune-prone and streptozotocin-induced diabetic rodents. Finally, insulin decreases macrophage NO production in normal hosts. These results indicate that the autoimmune paradigm is inadequate to explain increased NO in diabetes. As a potential mechanism to explain insulin-mediated regulation of NO production, TGF-1 may be involved because 1) macrophages from diabetic mice produce less TGF-beta1 than macrophages from normal hosts; 2) the circulating TGF-beta1 level is lower in diabetic mice; and 3) insulin administration increases circulating TGF-beta1 in normal mice. Together, these results provide evidence that increased NO in diabetes is not only a cause but also an effect of beta-cell destruction and results in part from a heretofore unrecognized immunomodulatory activity of insulin.     

Variation between hosts in the developmental success of the free-living stages of trichostrongyle infections of sheep

Variation between hosts of different ages and genotypes in the developmental success of trichostrongylid parasite eggs from sheep was investigated in two trials. The percentage development to infective third-stage larvae of eggs collected from lambs and adult ewes infected with Ostertagia circumcincta was compared in an indoor trial. In addition, sheep previously bred for either high or low faecal egg count and grazed outdoors on parasite contaminated pasture were sampled; egg development, faecal egg count, generic profile and faecal dry matter were measured. In both trials, development to L3 was significantly lower in eggs derived from adult ewes than from lambs and, in the field trial, from animals selected for low faecal egg count. The observed differences could not be accounted for by variations in faecal egg count, faecal dry matter content nor by differences in the generic composition of worm egg output. Although not shown conclusively, the results are consistent with an immune mechanism influencing the development of free-living stages of gastrointestinal nematodes outside the host. These results have significant implications for our understanding of parasite epidemiology, particularly as it relates to sources of pasture contamination.