A frustrated three-dimensional antiferromagnet: stacked J1-J2 layers.

We study a frustrated 3D antiferromagnet of stacked J(1)-J(2) layers. The intermediate 'quantum spin liquid' phase, present in the 2D case, narrows with increasing interlayer coupling and vanishes at a triple point. Beyond this, there is a direct first-order transition from Néel to columnar order. Possible applications to real materials are discussed.

Critical behaviour of structure factors at a quantum phase transition.

We review the theoretical behaviour of the total and one-particle structure factors at a quantum phase transition for temperature T = 0. The predictions are compared with exact or numerical results for the transverse Ising model, the alternating Heisenberg chain, and the bilayer Heisenberg model. At the critical wavevector, the results are generally in accord with theoretical expectations. Away from the critical wavevector, however, different models display quite different behaviours for the one-particle residues and structure factors.

The impact of combination therapy with peginterferon alpha-2a and ribavirin on the energy intake and body weight of adult hepatitis C patients.

BACKGROUND: It is recognized that interferon therapy has an adverse effect on the appetite and nutritional status of children with hepatitis B and C. No similar studies have been undertaken in adults. The aim of the present study was to determine if and how combination therapy with peginterferon alpha-2a and ribavirin affects energy intake and body weight in adult hepatitis C patients. A secondary aim was to investigate whether any changes are related to the presence of perceived side effects of treatment. METHODS: The energy intake of 15 adult hepatitis C patients was measured using a 3-day food diary. A visual analogue scale (VAS) was used to investigate patients' perception of fatigue, appetite and nausea. These measurements and body weight were taken before the start of treatment and at weeks 1, 3, 11, 24 and 28 in order to assess changes at intervals throughout interferon therapy. RESULTS: Fourteen patients (93%) lost weight during therapy. The greatest rate of mean [95% confidence interval (CI)] weight loss occurred at week 1 [1.64% (0.95-2.33)]. Weight loss continued until week 24. The greatest decrease in mean (95% CI) energy intake occurred at week 1 [9.74% (0.78-18.70)]. Mean VAS scores for fatigue, loss of appetite and nausea increased at week 1 and remained above pretreatment levels throughout the study period. CONCLUSION: Adult hepatitis C patients treated with a combination of peginterferon alpha-2a and ribavirin are likely to experience decreased energy intake and weight loss during treatment. This may be related to the impact of side effects of treatment and may require dietetic intervention.

Dietetic guidelines: diet in secondary prevention of cardiovascular disease (first update, June 2003).

AIM: To update dietetic guidelines summarizing the systematic review evidence on dietary advice to prevent further events in people with existing cardiovascular disease (CVD) (secondary prevention). METHODS: The Cochrane Library, MEDLINE and EMBASE were comprehensively searched to November 2002 for systematic reviews on aspects of diet and heart health. Reviews were included if they searched systematically for randomised controlled trials relating to diet and secondary prevention of CVD. Two members of the UK Heart Health and Thoracic Dietitians Group critically appraised each review. The quality and results of each review were discussed and summarized in a meeting of the whole group. RESULTS: Providing evidence-based dietary information (including increasing omega-3 fat intake) to all people who have had a myocardial infarction will save more lives than concentrating dietary advice on just those in need of weight loss or lipid lowering. The practice of prioritizing dietetic time in secondary prevention to those with raised lipids is out of date since the advent of statin therapy. However, effective dietary advice for those with angina, stroke, peripheral vascular disease or heart failure is less clear. CONCLUSION: There is good systematic review evidence that dietary advice to those with coronary heart disease can reduce mortality and morbidity as well as modify some risk factors. Dietary advice that does this most effectively should be prioritized.

Detection of severe protein-energy malnutrition by nurses in The Gambia.

AIM: To test whether nurses can use the WHO integrated management of childhood illness (IMCI) nutrition algorithm to identify reliably severe protein-energy malnutrition in children. METHODS: Nurses were trained to identify severe protein-energy malnutrition using IMCI training materials. They identified visible severe wasting and bipedal oedema, and categorised weight-for-age using a growth chart, in consecutive children attending outpatient clinics. Their findings were compared with weight for height Z (WHZ) score, bipedal oedema assessed by a trained observer, and weight-for-age Z score. RESULTS: A total of 352 children were recruited, of whom 34 (9.7%) were severely wasted (WHZ score <-3) and 18 (5.1%) had bipedal oedema. In the detection of severe wasting, the nurses' assessments showed 56% sensitivity, 95% specificity, and 56% positive predictive value (PPV), and for bipedal oedema 22%, 99%, and 57% respectively. Overall, the nurses identified only half of 50 children with severe wasting and/or bipedal oedema and wrongly identified a further 13 children as severely malnourished. Plotting weight for age by the nurses showed 62% sensitivity, 99% specificity, and 89% PPV for the detection of children with very low weight. CONCLUSIONS: Severe malnutrition was both under-diagnosed and wrongly diagnosed by nurses trained in the use of the IMCI nutrition algorithm in a clinic setting in The Gambia. These guidelines for health workers and the training materials, particularly with respect to calculation of age, need further development to improve the detection of malnourished children.

Symmetry breaking in the collinear phase of the J1-J2 Heisenberg model.

The large J2 limit of the square-lattice J1-J2 Heisenberg antiferromagnet is a classic example of order by disorder where quantum fluctuations select a collinear ground state. Here, we use series expansion methods and a mean-field spin-wave theory to study the excitation spectra in this phase and look for a finite-temperature Ising-like transition, corresponding to a broken symmetry of the square lattice, as first proposed by Chandra et al. [Phys. Rev. Lett. 64, 88 (1990)]]. We find that the spectra reveal the symmetries of the ordered phase. However, we do not find evidence for a finite-T transition. We suggest a scenario for a T=0 transition based on quantum fluctuations.

A stronger policy of organ retrieval from cadaveric donors: some ethical considerations.

Taking organs from dead people seems, prima facie, to raise fewer ethical complications than taking organs from other sources. There are, however, serious ethical problems in taking organs from the dead unless there is premortem evidence that this is what the deceased would have wanted, or at least, not have objected to. In this paper we will look at a "strong" opting out policy as proposed by John Harris. We will argue that people can be harmed after their death and that the posthumous removal of organs against their expressed wishes is one form that such harm might take. We also argue that Harris's claim that we show "equality of concern" between the donor and recipient requires too much.

Physical and transcript map of the dominant optic atrophy (OPA1) gene critical region at 3q28-q29.

The dominant optic atrophy gene (OPA1) has previously been mapped to chromosome 3q28-q29. We have now constructed a physical and transcriptional map across the OPA1 critical region between markers D3S3557 and D3S3346. It comprises 21 sequence-tagged sites (STSs), 4 single nucleotide polymorphisms, 29 expressed sequence tags, 2 known genes, and 12 newly generated STSs anchored onto 21 yeast artificial chromosome, 22 bacterial artificial chromosome, 48 P1 phage artificial chromosome, and 42 cosmid overlapping clones spanning 2.5 Mb. The map has allowed us to order many of the markers hitherto only roughly defined and to exclude 23 of the putative candidate genes assigned to the region. We found the OPA1 critical interval to be 450-550 kb. It contains 2 known genes, RPL35a and SDHA, which thus constitute candidate genes.

The value of methods to determine zinc deficiency in patients with Crohn's disease.

BACKGROUND: The serum zinc concentration is frequently applied for the assessment of zinc deficiency, but this concentration is also influenced by other factors. The aim of this study was to compare various methods of assessing the zinc status in patients with Crohn' s disease. METHODS: Serum levels of zinc, serum alkaline phosphatase activity, and zinc in various types of cells were related to factors potentially inducing zinc deficiency: the number of liquid stools, weight loss, bowel resection, and the extent and severity of inflammation. RESULTS: Thirty-one patients with more or less active Crohn's disease were included. In 68% of these patients the serum zinc concentration was less than the reference level, and it was correlated with the extent of bowel resection and the van Hees Index but not with the Crohn's Disease Activity Index. Serum alkaline phosphatase activity was correlated with bowel resection. Zinc in blood cells was poorly correlated with factors inducing zinc deficiency. CONCLUSION: A decrease of serum zinc concentration is frequently seen in active Crohn's disease. This study suggests that the determination of zinc in blood cells is not superior to the determination of the serum zinc concentration and serum alkaline phosphatase activity.

Serum alkaline phosphatase activity during zinc deficiency and long-term inflammatory stress.

A decrease in serum zinc can be caused by a real zinc deficiency but can also be caused by an apparent zinc deficiency, e.g. in inflammatory stress. The aim of this study was to evaluate the diagnostic power of serum alkaline phosphatase (AP) activity in the discrimination between pathophysiologic states of "real" and "apparent" zinc deficiency. A decrease in serum zinc was induced in growing and adult rats, by providing a diet low in zinc and by causing inflammatory stress. AP activity was determined using reagents low or enriched in zinc. Serum AP was decreased in zinc-deficient adult rats (P < 0.01). In zinc-deficient growing rats AP activity was not different from normal rats but AP activity decreased rapidly. In the same growing rats a significant difference was found in AP activities determined using buffers low and enriched in zinc (P < 0.001) between both groups of rats. After inducing inflammatory stress a decrease in AP activity (P < 0.01) and serum zinc (P < 0.001) was seen during the first few days. After the initial phase of inflammation AP activity normalized, serum zinc showed a rise which after correction for the decrease in serum albumin reached the level of the control rats. A difference in AP activity in buffers low and enriched in zinc was observed only during the first few days after induction of inflammatory stress (P < 0.001). Probably the method of measurement of the difference in enzyme activity, using buffers low and enriched in zinc, can be used as an indication for zinc deficiency in situations with changing AP enzyme concentrations. AP activity is decreased during the initial phase of inflammatory stress due to a decrease in serum zinc.

Zinc exchange by blood cells in nearly physiologic standard conditions.

Determination of zinc concentrations in white blood cells has been used to establish zinc deficiency. During pathological conditions changes in zinc concentrations in these blood cells were observed. However, these investigations were hampered by the low amount of zinc in this form per mL blood. Earlier we demonstrated that, in the case of zinc deficiency, the uptake of zinc was increased, using the in vitro exchange of zinc by the various blood cells with extracellular zinc labeled with 65Zn in fairly physiologic conditions. In case of inflammation, no increase in zinc uptake by erythrocytes was seen, indicating that this method probably can be used to differentiate real from apparent zinc deficiency. Only during the first days of the inflammatory process, probably representing the redistribution phase during which zinc moves from the serum to the liver, a small increase in in vitro zinc uptake was seen in mononuclear cells (MNC) and polymorphonuclear cells (PMNC). Earlier papers raised some questions; e.g., is the uptake part of an exchange process and can the efflux of zinc by the cells be measured by the same method; what is the influence of time on the process of zinc uptake; what is the magnitude of the uptake of zinc by the cells compared to the zinc concentration in the cells; and, what is the influence of temperature on the uptake of zinc? In the present study, the influence of incubation time and temperature on the uptake of zinc by human and rat blood cells and on the release of zinc by rat blood cells was studied. At least three phases of uptake of zinc in the various cells were found by varying the incubation time--a fast phase during the first half hour, probably caused by an aspecific binding of zinc on or in the cell membrane; a second fast uptake between 60-330 min, probably caused by an influx of zinc in the cell as part of the exchange process of zinc; and a slow third phase after 5.5 h, in which probably the in- and efflux of the rapidly exchangeable intracellular pool is more or less equilibrated. For mononuclear cells, polymorphonuclear cells, and erythrocytes of rats, the rapidly exchangeable intracellular pool is 40%, 53%, and 10%, respectively, of the total zinc content of the cells. This study is also performed in human cells; in human cells the exchangeable pool of mononuclear cells and erythrocytes is 17 and 3.5% of the total zinc content of the cells, respectively.(ABSTRACT TRUNCATED AT 400 WORDS)

The in-vitro uptake of zinc by blood cells in rats with long-term inflammatory stress.

The aim of the present study was to investigate the in vitro uptake of zinc by blood cells, in an attempt to distinguish between those conditions in which low plasma zinc concentrations are due to inflammatory stress, and those which are due to true zinc deficiency. Inflammation induced by intramuscular injection of turpentine caused a significant reduction in plasma albumin concentrations, which persisted until the end of the study (2 weeks). It also caused a reduction in the plasma zinc concentration which was most marked during the first few days. A smaller difference persisted until the end of the study. When the serum zinc concentration was corrected for the hypoalbuminaemia, the changes in serum zinc concentration after the first 4 days of turpentine were small and mainly non-significant. The in vitro uptake of zinc by erythrocytes obtained from animals with inflammation did not increase, whereas the uptake was increased in cells obtained from animals with true zinc deficiency. Therefore this study suggests a method that can probably differentiate between an apparent zinc deficiency due to inflammatory stress and a real zinc deficiency, but additional experiments to validate this method should be performed.

Patients' perceptions of chronic leg ulcers.

Leg ulceration affects approximately 0.15% of the UK population at any point in time1, and the disease is typically one of ulceration, healing and re-ulceration. The cost of leg ulceration in both financial and human terms is large; however, human costs (pain, immobility, social isolation, embarrassment) have been largely ignored by researchers. This study aimed to explore patients' perceptions of their leg ulcer disease, and the impact of leg ulceration on quality of life. A random sample of leg ulcer patients was interviewed in the patients' own homes, and a variety of data were collected using semi-structured interviews and validated health-assessment tools. A sample of healthy elderly subjects participated by completing the health and quality of life assessment. Data analysis is currently at a preliminary stage.