Feasibility Assessment of Microwave Ablation for Treating Esophageal Varices

Esophageal varices are a significant complication of portal hypertension. Endoscopic variceal ligation (EVL) is one of the clinical standards for treating these varices and preventing their hemorrhage. Limitations of EVL include the risk of stricture formation and postband ulcer bleeding due to the damage caused to the esophageal mucosa, as well as the need for multiple endoscopic treatment sessions to eradicate the varices. The goal of this study is to develop a device and evaluate the technical feasibility of microwave ablation to seal esophageal varices, while preventing thermal damage to the surface mucosal tissue. A microwave applicator with a directional radiation pattern was developed for endoscopic ablation of esophageal varices. Electromagnetic and bioheat transfer computational models were employed to optimize the design of the microwave applicator and evaluate energy delivery strategies for this application. Experiments in ex vivo and in vivo tissue were employed to verify simulation results. Simulations predicted enhanced heating performance of the antenna using an angled monopole radiating element. Further, simulations indicate that while the endoscopic cap attenuated electric fields in tissue, it also enhanced surface cooling of tissue, increasing the likelihood of preserving mucosal tissue. Experiments in ex vivo tissue indicated the feasibility of sealing veins with 77 W microwave power delivered for 30 s. In vivo experiments demonstrated the ability to seal veins, while preserving surface tissue. This study demonstrated the technical feasibility of microwave thermal ablation for treating esophageal varices using a 2.45 GHz water-cooled directional microwave applicator.

Assessment of 25-hydroxyvitamin D and 1,25-dihydroxyvitamin D3 concentrations in male and female multiple sclerosis patients and control volunteers

Populations with insufficient ultraviolet exposure and who consume diets low in vitamin D have low vitamin D status (plasma 25-hydroxyvitamin D (25(OH)D) concentrations) and a reported higher incidence of multiple sclerosis (MS). The active form of vitamin D, 1,25-dihydroxyvitamin D3 (1,25(OH)2D3), is an effective anti-inflammatory molecule. No research to date has assessed 1,25(OH)2D3 concentrations in individuals with MS. In this study, plasma concentrations of 25(OH)D, 1,25(OH)2D3 and parathyroid hormone (PTH) were measured in 29 individuals with MS and 22 age- and sex-matched control volunteers. There were no significant differences in plasma PTH, 25(OH)D and 1,25(OH)2D3 concentrations between individuals with MS and control volunteers. Women with MS had significantly higher 25(OH)D and 1,25(OH)2D3 concentrations than men with MS (79.1+/-45.4 versus 50.2+/-15.3 nmol/L, P=0.019 and 103.8+/-36.8 versus 70.4+/-28.7 pmol/L, P=0.019, respectively). There was a significant positive correlation between 25(OH)D and 1,25(OH)2D3 concentrations in all subjects (r=0.564, P=0.000), but secondary analysis revealed that the correlation was driven by women with MS (r=0.677, P=0.001). Significant sex differences in vitamin D metabolism were observed and were most marked in individuals with MS, suggesting that vitamin D requirements may differ between the sexes, as well as by underlying disease state.

Thermoelastic Analysis of High-Pressure Angioplasty Balloons

Failures in angioplasty balloons are investigated using typical destructive techniques. The material properties of moulded balloons are derived from tensile tests and used to establish the reasons for failure of the balloons. Thermoelastic stress analysis is used to determine the stress distribution in the balloons, and a means of interpreting the data to derive actual stresses is described. The departure from linear elastic behaviour in the angioplasty balloons is identified using thermoelastic analysis. The results from the thermoelastic analysis are discussed and compared with those from the destructive tests, and the thermoelastic technique is shown to be a potential new means for non-destructive analysis of angioplasty balloons.

Growth study of cri du chat syndrome

We compared the growth of children with cri du chat (5p-) syndrome with the 1990 UK growth curves. Most subjects had impaired growth, particularly of head circumference. The more emaciated the child the more pronounced the microcephaly, showing the need for growth and nutrition monitoring.

Growth charts for cri-du-chat syndrome: an international collaborative study

Low birth weight and slow growth are frequently observed in the patients with cri-du-chat syndrome. To provide a growth reference standard for children with cri-du-chat syndrome, syndrome-specific growth charts have been developed from a combination of cross-sectional and longitudinal measurements on 374 patients from North America, Italy, Australia, and the British Isles. The data were obtained from pediatric records, parent reporting, and personal examinations at national 5p- parent support group meetings in the U.S., Italy, U.K., and Australia. The growth curves include height and weight measurements for patients ages 0 to 18 years and head circumference measurements for patients ages 0 to 15 years. Birth weight was above the 5th percentile of general population in 50% of cases: mean weight 2.8 kg +/- 1.85 SD for males and 2.6 kg +/- 1.51 SD for females. Growth curve medians were usually at or below the 5th centile of reference populations throughout life. The median head circumference falls below the 2nd centile, and this change increases with age. The charts show that compared with the standard population, most children with cri-du-chat syndrome are small at birth and as they grow most, but not all, have significant microcephaly and compromised weight for age, and to a lesser extent, compromised height for age. Am. J. Med. Genet. 94:153-162, 2000.

Riboflavin and vitamin B-6 intakes and status and biochemical response to riboflavin supplementation in free-living elderly people

Free-living elderly people aged > or = 65 y were recruited to assess riboflavin and vitamin B-6 intakes and status and the effect of riboflavin supplementation on biochemical indicators of these 2 vitamins. The status of riboflavin (erythrocyte glutathione reductase activation coefficient; EGRAC) and vitamin B-6 (plasma pyridoxal-5'-phosphate; PLP) were determined in a total sample of 92 subjects, from whom dietary intake data were obtained by using the diet history method (n = 83). Although dietary intakes of both vitamins were considered to be adequate according to current reference values, abnormal EGRAC and plasma PLP values were identified in 49% and 38% of subjects, respectively, with 21% having suboptimal status for both nutrients. A subgroup of subjects from the initial sample (n = 45) was assigned in a double-blind manner to receive either 1.6 or 25 mg riboflavin or placebo daily for 12 wk. In those subjects with a baseline EGRAC or plasma PLP value falling outside the currently accepted threshold value for adequacy, low-dose riboflavin supplementation improved status of the limiting nutrient significantly (P<0.0001 and P = 0.020 for EGRAC and plasma PLP responses, respectively). We conclude that a high proportion of healthy elderly people may have suboptimal status for these nutrients despite apparently adequate dietary intakes. Furthermore, we showed that riboflavin supplementation at physiologic doses corrects biochemical abnormalities of not only EGRAC, but also plasma PLP, confirming the biochemical interdependency of these vitamins and suggesting that riboflavin is the limiting nutrient.

Nutrient intakes and impact of fortified breakfast cereals in schoolchildren

OBJECTIVE

To report micronutrient intakes in Northern Ireland schoolchildren, and to establish the contribution of fortified breakfast cereal to overall nutrient intakes and achievement of current dietary recommendations.

DESIGN

Analysis of dietary intakes and physical characteristics of participants in a randomly selected 2% population sample of 1015 schoolchildren aged 12 and 15 years in Northern Ireland during the 1990/1 school year.

MAIN OUTCOME MEASURES

Dietary intakes, physical characteristics, and their association with consumption of fortified breakfast cereal.

RESULTS

Mean micronutrient intakes were generally adequate with the exception of low intakes of folate (boys and girls) and iron (girls). Fortified breakfast cereals, consumed by a high proportion (94% boys; 83% girls) of the sample, were associated with higher daily intakes of most micronutrients and fibre and with a macronutrient profile consistent with current nutritional recommendations. Appreciable proportions of subjects who did not consume fortified breakfast cereals had daily intakes that fell below the lower reference nutrient intake for riboflavin, niacin, folate, vitamin B-12, and iron (girls).

CONCLUSIONS

The results demonstrate the potential of fortification in contributing to micronutrient intakes of schoolchildren, particularly where requirements are high, or for those on marginal diets of low nutritional quality.

Osteoporosis and the role of diet

Osteoporosis, a common problem of older women in developed countries, is characterised by low bone mineral density or low bone mineral content, both measures of bone quantity. However, with osteoporosis there is also a loss of bone micro-architecture--that is, a loss of bone quality. Dietary factors thought to be important in maintaining bone quantity include calcium, vitamin D, protein and salt. Trace minerals may be important in maintaining bone quality through their role as metallo-enzymes in the synthesis of collagen and other proteins that form the structure of bone. Other substances like flavonoids may also have a role in preventing osteoporosis.

The effect of lactation and other factors on post-partum changes in body-weight and triceps skinfold thickness

1. Mothers were followed from 1 month post-partum up to 12 months post-partum to measure changes in their body-weight and triceps skinfold thickness. 2. Overall there was a significant weight loss in the first few months but this levelled off by 7 months. 3. The triceps skinfold increased significantly up to 5 months post-partum and then decreased. 4. These changes in body-weight and skinfold were not affected by the duration of lactation, smoking or the educational achievement of the mothers, but were influenced by the initial body mass index and the desire to lose weight.

Sleep patterns of infants in the first year of life

A prospective study of 132 infants aged from 1 month to 1 year found that infants who were breast fed or breast plus bottle fed were significantly more likely to wake at night throughout the first year. Social class of the family, parity of the mother, and the weight gain of the infant had no consistent effects. This increased waking was not due to mothers of wakeful infants prolonging breast feeding to soothe their infants.

Effects of feeding and social factors on diarrhoea and vomiting in infants

In a prospective study of infants and their feeding in south east Queensland, Australia, the incidences of reported diarrhoea and/or vomiting in breast, bottle, and mixed (breast and bottle) fed infants were compared from birth to 1 year. Up to 6 months infants who were given breast feeds, with or without other milks, had less diarrhoea and/or vomiting than those given bottle feeds only. Breast feeding seemed to protect the infant against possible introduced infections even when other milks were given along with the breast milk. After 6 months breast feeding did not reduce the incidence of gastrointestinal infection. In both upper and lower social class families infants given solids before 3 months had less diarrhoea and/or vomiting than those given solids later. Bottle fed infants aged 3-6 months in upper social class families had fewer gastrointestinal problems than those of lower social class families. This study suggests that up to the age of 6 months, in this population, breast feeding protects the infant against diarrhoea and/or vomiting, but other milks and solids can safely be given to supplement the breast milk. Breast feeding conferred no significant protection after 6 months.

Recall by mothers of the birth weights and feeding of their children

We have tested mothers' abilities to remember at a later date, the birth weight, duration of breastfeeding and time of introduction of other milks to their previous children, by comparing their recall with the information recorded by the nursing sisters at maternal and child health clinics at the time. Data were available for 81 children with present ages from 1 to 10 years. Birth weight and the duration of breast feeding were generally remembered accurately, but there were large discrepancies on the time of starting other milk feeds. This could pose diagnostic difficulties in some paediatric conditions, particularly milk allergies and intolerance.

Growth of Aboriginal infants

Aboriginal infants at Cherbourg Aboriginal Settlement in Queensland now have growth rates which are similar to those of white Australian infants. The proportion of children under 90% of the standard weight-for-age appears to be the same as for white Australian children and meets the international standards. Apart from premature infants, no children have been found in the accepted "at risk" categories.