Can children with Type 1 diabetes and their caregivers estimate the carbohydrate content of meals and snacks?

AIMS

Carbohydrate (CHO) counting allows children with Type 1 diabetes to adjust mealtime insulin dose to carbohydrate intake. Little is known about the ability of children to count CHO and whether a particular method for assessing CHO quantity is better than others. We investigated how accurately children and their caregivers estimate carbohydrate, and whether counting in gram increments improves accuracy compared with CHO portions or exchanges.

METHODS

One hundred and two children and adolescents (age range 8.3-18.1 years) on intensive insulin therapy and 110 caregivers independently estimated the CHO content of 17 standardized meals (containing 8-90 g CHO), using whichever method of carbohydrate quantification they had been taught (gram increments, 10-g portions or 15-g exchanges).

RESULTS

Seventy-three per cent (n = 2530) of all estimates were within 10-15 g of actual CHO content. There was no relationship between the mean percentage error and method of carbohydrate counting or glycated haemoglobin (HbA(1c)) (P > 0.05). Mean gram error and meal size were negatively correlated (r = -0.70, P < 0.0001). The longer children had been CHO counting the greater the mean percentage error (r = 0.173, P = 0.014). Core foods in non-standard quantities were most frequently inaccurately estimated, while individually labelled foods were most often accurately estimated.

CONCLUSIONS

Children with Type 1 diabetes and their caregivers can estimate the carbohydrate content of meals with reasonable accuracy. Teaching CHO counting in gram increments did not improve accuracy compared with CHO portions or exchanges. Large meals tended to be underestimated and snacks overestimated. Repeated age-appropriate education appears necessary to maintain accuracy in carbohydrate estimations.

Treatment during primary HIV infection does not lower viral set point but improves CD4 lymphocytes in an observational cohort

Objective

To investigate if early treatment of primary HIV-1 infection (PHI) reduces viral set point and/or increases CD4 lymphocytes.

Methods

Analysis of two prospective multi-centre PHI cohorts. HIV-1 RNA and CD4 lymphocytes in patients with transient treatment were compared to those in untreated patients. Time to CD4 lymphocyte decrease below 350/μl after treatment stop or seroconversion was calculated using Kaplan-Meier and Cox-PH-regression analyses.

Results

156 cases of PHI were included, of which 100 had received transient HAART (median treatment time 9.5 months) and 56 remained untreated. Median viral load (563000 cop/ml vs 240000 cop/ml; p < 0.001) and median CD4 lymphocyte (449/μl vs. 613/μl; p < 0.01) differed significantly between treated and untreated patients. Median viral load was 38056 copies/ml in treated patients (12 months after treatment stop) and 52880 copies/ml in untreated patients (12 months after seroconversion; ns). Median CD4 lymphocyte change was +60/μl vs. -86/μl (p = 0.01). Median time until CD4 lymphocytes decreased to < 350/μl (including all patients with CD4 lymphocytes < 500/μl during seroconversion) was 20.7 months in treated patients after treatment stop and 8.3 months in untreated patents after seroconversion (p < 0.01). Cox-PH analyses adjusting for baseline VL, CD4 lymphocytes, stage of early infection and symptoms confirmed these differences.

Conclusions

Treatment during PHI did not lower viral set point. However, patients treated during seroconversion had an increase in CD4 lymphocytes, whereas untreated patients experienced a decrease in CD4 lymphocytes. Time until reaching CD4 lymphocytes < 350/μl was significantly shorter in untreated than in treated patients including patients with CD4 lymphocytes < 500/μl during seroconversion.

The use of ultrasound-guided wire localisation in orthopaedics

The use of ultrasound-guided wire localisation of lesions is not well described in the orthopaedic literature. We describe a case of an impalpable schwannoma of the femoral nerve and another of sacroiliitis with an associated pelvic abscess. In both, surgical localisation was difficult. Peri-operative ultrasound-guided wire localisation was used to guide surgery and minimise tissue damage, thereby optimising the results and recovery of the patient.

Children and adolescents on intensive insulin therapy maintain postprandial glycaemic control without precise carbohydrate counting

AIMS

Carbohydrate (CHO) quantification is used to adjust pre-meal insulin in intensive insulin regimens. However, the precision in CHO quantification required to maintain postprandial glycaemic control is unknown. We determined the effect of a +/-10-g variation in CHO amount, with an individually calculated insulin dose for 60 g CHO, on postprandial glycaemic control.

METHODS

Thirty-one children and adolescents (age range 9.5-16.8 years), 17 using continuous subcutaneous insulin infusion (CSII) and 14 using multiple daily injections (MDI), participated. Each subject consumed test lunches of equal macronutrient content, differing only in carbohydrate quantity (50, 60, 70 g CHO), in random order on three consecutive days. For each participant, the insulin dose was the same for each meal, based on their usual insulin : CHO ratio for 60 g CHO. Activity was standardized. Continuous glucose monitoring was used.

RESULTS

The CSII and MDI subjects demonstrated no difference in postprandial blood glucose levels (BGLs) for comparable carbohydrate loads (P > 0.05). The 10-g variations in CHO quantity resulted in no differences in BGLs or area under the glucose curves for 2.5 h (P > 0.05). Hypoglycaemic episodes were not significantly different (P = 0.32). The 70-g meal produced higher glucose excursions after 2.5 h, with a maximum difference of 1.9 mmol/l at 3 h (P = 0.01), but the BGLs remained within international postprandial targets.

CONCLUSIONS

In patients using intensive insulin therapy, an individually calculated insulin dose for 60 g of carbohydrate maintains postprandial BGLs for meals containing between 50 and 70 g of carbohydrate. A single mealtime insulin dose will cover a range in carbohydrate amounts without deterioration in postprandial control.

Inhibition of calcium-independent phospholipase A impairs agonist-induced calcium entry in keratinocytes

Background

In many cells, depletion of intracellular calcium (Ca²⁺) reservoirs triggers Ca²⁺ entry through store-operated Ca²⁺ channels in the plasma membrane. However, the mechanisms of agonist-induced calcium entry (ACE) in keratinocytes are not fully understood.

Objectives

This study was designed to determine if pharmacological inhibition of calcium-independent phospholipase A (iPLA₂) impairs ACE in normal human epidermal keratinocytes.

Methods

Confocal laser scanning microscopy was used to monitor the dynamics of Ca²⁺ signalling in keratinocytes loaded with the calcium-sensitive dye Fluo-4. Cells were stimulated with extracellular nucleotides [adenosine triphosphate (ATP) or uridine triphosphate (UTP)] or with lysophosphatidic acid (LPA), a bioactive lipid that regulates keratinocyte proliferation and differentiation.

Results

Both ATP and UTP induced Ca²⁺ release in primary human keratinocytes. This was not followed by robust Ca²⁺ influx when the experiments were performed in low Ca²⁺ (70 μmol L⁻¹) medium. Upon elevation of extracellular Ca²⁺ to 1·2 mmol L⁻¹, however, a biphasic response consisting of an initial Ca²⁺ peak followed by an elevated plateau was observed. The plateau phase was inhibited when cells were treated with bromoenol lactone, a specific pharmacological inhibitor of iPLA₂. These findings indicate that iPLA₂ activity is required for ACE in keratinocytes. LPA also evoked Ca²⁺ release in keratinocytes but failed to induce sustained Ca²⁺ entry even when extracellular Ca²⁺ was elevated to 1·2 mmol L⁻¹.

Conclusion

Our results demonstrate for the first time an important role for iPLA₂ in regulating ACE in primary human keratinocytes.

Reactive oxygen species mediate a cellular 'memory' of high glucose stress signalling

AIMS/HYPOTHESIS

A long-term 'memory' of hyperglycaemic stress, even when glycaemia is normalised, has been previously reported in endothelial cells. In this report we sought to duplicate and extend this finding.

MATERIALS AND METHODS

HUVECs and ARPE-19 retinal cells were incubated in 5 or in 30 mmol/l glucose for 3 weeks or subjected to 1 week of normal glucose after being exposed for 2 weeks to continuous high glucose. HUVECs were also treated in this last condition with several antioxidants. Similarly, four groups of rats were studied for 3 weeks: (1) normal rats; (2) diabetic rats not treated with insulin; (3) diabetic rats treated with insulin during the last week; and (4) diabetic rats treated with insulin plus alpha-lipoic acid in the last week.

RESULTS

In human endothelial cells and ARPE-19 retinal cells in culture, as well as in the retina of diabetic rats, levels of the following markers of high glucose stress remained induced for 1 week after levels of glucose had normalised: protein kinase C-beta, NAD(P)H oxidase subunit p47phox, BCL-2-associated X protein, 3-nitrotyrosine, fibronectin, poly(ADP-ribose) Blockade of reactive species using different approaches, i.e. the mitochondrial antioxidant alpha-lipoic acid, overexpression of uncoupling protein 2, oxypurinol, apocynin and the poly(ADP-ribose) polymerase inhibitor PJ34, interrupted the induction both of high glucose stress markers and of the fluorescent reactive oxygen species (ROS) probe CM-H(2)DCFDA in human endothelial cells. Similar results were obtained in the retina of diabetic rats with alpha-lipoic acid added to the last week of normalised glucose.

CONCLUSIONS/INTERPRETATION

These results provide proof-of-principle of a ROS-mediated cellular persistence of vascular stress after glucose normalisation.

Living anonymous liver donation: case report and ethical justification

Most living organ donations are from genetically or emotionally related donors. Although some transplant centers are willing to accept donations from living anonymous kidney donors (LAKDs), very few centers will accept donations from living anonymous liver donors (LALDs). The difference in acceptance rates is primarily due to the greater risk in liver donation, which is estimated to be 10-fold that of the risk in kidney donation. We present a case of donation from a LALD, the first reported in Canada. There are currently no established standards for LALDs. Our criteria for the ethical acceptability of LALDs require such donors to be physically healthy, mentally competent, altruistic, highly motivated, well-informed and able to give voluntary consent to donation. Another major ethical criterion is that the likely psychological benefit to the LALD balances the physical risks. Our case demonstrates that transplants from LALDs are medically successful and ethically justified under certain conditions.

Mercury in seafood: mechanisms of accumulation and consequences for consumer health

Mercury is a largely uncontrollable heavy metal contaminant in that it is globally ubiquitous, and environmentally persistent. The element has the potential for global mobilization following liberation from environmental stores, which can occur as a consequence of either anthropogenic activities or natural processes. Furthermore, organic forms like methylmercury accumulate in biological tissues with an exceptionally long biological half-life, facilitating the magnification of this toxin along trophic food chains. Bioaccumulation is particularly evident in aquatic environments, in which long-lived piscivorous fishes and marine mammals are reported with a mercury burden one-million times that of the surrounding water body, typically attaining mercury burdens exceeding 1 microg g(-1). Mercury levels in other seafood, however, are typically reported in the range of 0.1 to 0.2 microg g(-1) and usually less then 0.5 microg g(-1). The primary source of human exposure to environmental mercury is through seafood consumption. The dangers associated with the consumption of large amounts of methylmercury accumulated in seafood are well recognized from past poisoning incidents, in which fish with mercury burdens in the range of 9 to 24 microg g(-1) were consumed. Nevertheless, the toxicological consequence of chronic low-level mercury exposure from habitual seafood consumption is an area of contention. This review discusses the mechanisms of mercury accumulation and distribution in fish tissues and the toxicological consequences of mercury exposure from seafood consumption with regard to international safety guidelines.

Structural and functional analyses of the wheat genomes based on expressed sequence tags (ESTs) related to abiotic stresses

To gain insights into the structure and function of the wheat (Triticum aestivum L.) genomes, we identified 278 ESTs related to abiotic stress (cold, heat, drought, salinity, and aluminum) from 7671 ESTs previously mapped to wheat chromosomes. Of the 278 abiotic stress related ESTs, 259 (811 loci) were assigned to chromosome deletion bins and analyzed for their distribution pattern among the 7 homoeologous chromosome groups. Distribution of abiotic stress related EST loci were not uniform throughout the different regions of the chromosomes of the 3 wheat genomes. Both the short and long arms of group 4 chromosomes showed a higher number of loci in their distal regions compared with proximal regions. Of the 811 loci, the number of mapped loci on the A, B, and D genomes were 258, 281, and 272, respectively. The highest number of abiotic stress related loci were found in homoeologous chromosome group 2 (142 loci) and the lowest number were found in group 6 (94 loci). When considering the genome-specific ESTs, the B genome showed the highest number of unique ESTs (7 loci), while none were found in the D genome. Similarly, considering homoeologous group-specific ESTs, group 2 showed the highest number with 16 unique ESTs (58 loci), followed by group 4 with 9 unique ESTs (33 loci). Many of the classified proteins fell into the biological process categories associated with metabolism, cell growth, and cell maintenance. Most of the mapped ESTs fell into the category of enzyme activity (28%), followed by binding activity (27%). Enzymes related to abiotic stress such as β-galactosidase, peroxidase, glutathione reductase, and trehalose-6-phosphate synthase were identified. The comparison of stress-responsive ESTs with genomic sequences of rice (Oryza sativa L.) chromosomes revealed the complexities of colinearity. This bin map provides insight into the structural and functional details of wheat genomic regions in relation to abiotic stress.

Divergent mechanisms of cis 9, trans 11 ‐ and trans 10 , cis 12 ‐ conjugated linoleic acid affecting insulin resistance and inflammation in apolipoprotein E knockout mice: a proteomics approach

Conjugated linoleic acids (CLA) affect atherogenesis, but mechanisms are not well understood. We explored how two isomers of CLA, cis9, trans11-CLA and trans10, cis12-CLA, affected lipid and glucose metabolism, as well as hepatic protein expression, in apolipoprotein E knockout mice. After 12 wk of intervention, plasma triglyceride, NEFA, and glucose concentrations were significantly higher in the trans10, cis12-CLA group, whereas plasma triglyceride, NEFA, glucose, and insulin concentrations were significantly lower in the cis9, trans11-CLA group, compared with control mice consuming linoleic acid. Proteomics identified significant up- or down-regulation of 113 liver cytosolic proteins by either CLA isomer. Principal component analysis revealed that the treatment effect of cis9, trans11-CLA was mainly explained by the up-regulation of different posttranslational forms of heat shock protein 70 kD. In contrast, the treatment effect of trans10, cis12-CLA was mainly explained by up-regulation of key enzymes in the gluconeogenic, beta-oxidation, and ketogenesic pathways. Correlation analysis again emphasized the divergent effects of both CLA isomers on different pathways, but also revealed a linkage between insulin resistance and increased levels of hepatic serotransferrin. Thus, our systems biology approach provided novel insights into the mechanisms by which individual CLA isomers differentially affect pathways related to atherogenesis, such as insulin resistance and inflammation.

Construction and evaluation of cDNA libraries for large-scale expressed sequence tag sequencing in wheat (Triticum aestivum L.)

A total of 37 original cDNA libraries and 9 derivative libraries enriched for rare sequences were produced from Chinese Spring wheat (Triticum aestivum L.), five other hexaploid wheat genotypes (Cheyenne, Brevor, TAM W101, BH1146, Butte 86), tetraploid durum wheat (T. turgidum L.), diploid wheat (T. monococcum L.), and two other diploid members of the grass tribe Triticeae (Aegilops speltoides Tausch and Secale cereale L.). The emphasis in the choice of plant materials for library construction was reproductive development subjected to environmental factors that ultimately affect grain quality and yield, but roots and other tissues were also included. Partial cDNA expressed sequence tags (ESTs) were examined by various measures to assess the quality of these libraries. All ESTs were processed to remove cloning system sequences and contaminants and then assembled using CAP3. Following these processing steps, this assembly yielded 101,107 sequences derived from 89,043 clones, which defined 16,740 contigs and 33,213 singletons, a total of 49,953 "unigenes." Analysis of the distribution of these unigenes among the libraries led to the conclusion that the enrichment methods were effective in reducing the most abundant unigenes and to the observation that the most diverse libraries were from tissues exposed to environmental stresses including heat, drought, salinity, or low temperature.

Targeting the aluminum tolerance gene Alt3 region in rye, using rice/rye micro-colinearity

Characterization and manipulation of aluminum (Al) tolerance genes offers a solution to Al toxicity problems in crop cultivation on acid soil, which composes approximately 40% of all arable land. By exploiting the rice (Oryza sativa L.)/rye (Secale cereale L.) syntenic relationship, the potential for map-based cloning of genes controlling Al tolerance in rye (the most Al-tolerant cereal) was explored. An attempt to clone an Al tolerance gene (Alt3) from rye was initiated by using DNA markers flanking the rye Alt3 gene, from many cereals. Two rice-derived, PCR-based markers flanking the Alt3 gene, B1 and B4, were used to screen 1,123 plants of a rye F2 population segregating for Alt3. Fifteen recombinant plants were identified. Four additional RFLP markers developed from rice genes/putative genes, spanning 10 kb of a 160-kb rice BAC, were mapped to the Alt3 region. Two rice markers flanked the Alt3 locus at a distance of 0.05 cM, while two others co-segregated with it. The rice/rye micro-colinearity worked very well to delineate and map the Alt3 gene region in rye. A rye fragment suspected to be part of the Alt3 candidate gene was identified, but at this level, the rye/rice microsynteny relationship broke down. Because of sequence differences between rice and rye and the complexity of the rye sequence, we have been unable to clone a full-length candidate gene in rye. Further attempts to clone a full-length rye Alt3 candidate gene will necessitate the creation of a rye large-insert library.

A chromosome bin map of 2148 expressed sequence tag loci of wheat homoeologous group 7

The objectives of this study were to develop a high-density chromosome bin map of homoeologous group 7 in hexaploid wheat (Triticum aestivum L.), to identify gene distribution in these chromosomes, and to perform comparative studies of wheat with rice and barley. We mapped 2148 loci from 919 EST clones onto group 7 chromosomes of wheat. In the majority of cases the numbers of loci were significantly lower in the centromeric regions and tended to increase in the distal regions. The level of duplicated loci in this group was 24% with most of these loci being localized toward the distal regions. One hundred nineteen EST probes that hybridized to three fragments and mapped to the three group 7 chromosomes were designated landmark probes and were used to construct a consensus homoeologous group 7 map. An additional 49 probes that mapped to 7AS, 7DS, and the ancestral translocated segment involving 7BS also were designated landmarks. Landmark probe orders and comparative maps of wheat, rice, and barley were produced on the basis of corresponding rice BAC/PAC and genetic markers that mapped on chromosomes 6 and 8 of rice. Identification of landmark ESTs and development of consensus maps may provide a framework of conserved coding regions predating the evolution of wheat genomes.

Analysis of expressed sequence tag loci on wheat chromosome group 4

A total of 1918 loci, detected by the hybridization of 938 expressed sequence tag unigenes (ESTs) from 26 Triticeae cDNA libraries, were mapped to wheat (Triticum aestivum L.) homoeologous group 4 chromosomes using a set of deletion, ditelosomic, and nulli-tetrasomic lines. The 1918 EST loci were not distributed uniformly among the three group 4 chromosomes; 41, 28, and 31% mapped to chromosomes 4A, 4B, and 4D, respectively. This pattern is in contrast to the cumulative results of EST mapping in all homoeologous groups, as reported elsewhere, that found the highest proportion of loci mapped to the B genome. Sixty-five percent of these 1918 loci mapped to the long arms of homoeologous group 4 chromosomes, while 35% mapped to the short arms. The distal regions of chromosome arms showed higher numbers of loci than the proximal regions, with the exception of 4DL. This study confirmed the complex structure of chromosome 4A that contains two reciprocal translocations and two inversions, previously identified. An additional inversion in the centromeric region of 4A was revealed. A consensus map for homoeologous group 4 was developed from 119 ESTs unique to group 4. Forty-nine percent of these ESTs were found to be homoeologous to sequences on rice chromosome 3, 12% had matches with sequences on other rice chromosomes, and 39% had no matches with rice sequences at all. Limited homology (only 26 of the 119 consensus ESTs) was found between wheat ESTs on homoeologous group 4 and the Arabidopsis genome. Forty-two percent of the homoeologous group 4 ESTs could be classified into functional categories on the basis of blastX searches against all protein databases.

Melanin protects melanocytes and keratinocytes against H2O2-induced DNA strand breaks through its ability to bind Ca2+

Reactive oxygen species (ROS) such as hydrogen peroxide (H(2)O(2)) are produced in the skin under the influence of UV radiation. These compounds are highly reactive and can induce DNA lesions in epidermal cells. Melanin is considered to protect human skin against DNA damage by absorbing UV radiation. We have investigated whether melanin can, in addition, offer protection against the effects of H(2)O(2) in human melanocytes and HaCaT keratinocytes. In the present study, it was shown that 40 and 100 microM H(2)O(2) increased the number of DNA strand breaks as measured using the comet assay, in melanocytes of Caucasian origin. In melanocytes of the same origin in which melanin levels were increased by culturing in presence of 10 mM NH(4)Cl and elevated l-tyrosine, H(2)O(2)-induced DNA damage was reduced compared to that in control melanocytes. Similarly, HaCaT cells that were loaded with melanin were better protected against H(2)O(2)-induced DNA strand breaks than control HaCaT cells. These protective effects of melanin were mimicked by the intracellular Ca(2+)-chelator BAPTA. Thus, BAPTA reduced the level of H(2)O(2)-induced DNA strand breaks in melanocytes. Like BAPTA, melanin is known to be a potent chelator of Ca(2+) and this was confirmed in the present study. It was shown that melanin levels in melanocytic cells correlated directly with intracellular Ca(2+) binding capacity and, in addition, correlated inversely with H(2)O(2)-induced increases in intracellular Ca(2+). Our results show that melanin may have an important role in regulating intracellular Ca(2+) homeostasis and it is suggested that melanin protects against H(2)O(2)-induced DNA strand breaks in both melanocytes and keratinocytes and through its ability to bind Ca(2+).