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Biomedical subjects

K L Webb

Publications and source records attributed to K L Webb.

16 recordsLinked to original sources
PubMed2001

Folate fortification: potential impact on folate intake in an older population.

OBJECTIVE: To examine the potential impact of different models of folate fortification of Australian foods on the folate intakes of older Australians. DESIGN: Dietary data were collected using a food frequency questionnaire from people attending a population-based health study. SETTING: Two postcode areas west of Sydney, Australia. SUBJECTS: A total of 2895 people aged over 49 y, obtained from a door knock census (79% of 3654 subjects examined). MAIN OUTCOME MEASURES: The folate intake in this population was estimated using four different models: (1) pre-fortification folate values; (2) current voluntary folate fortification in Australia; (3) universal fortification of all foods permitted to add folate, at 25% recommended dietary intake (RDI) per reference serve; and (4) universal fortification of all foods permitted to add folate, at 50% RDI per reference serve. The increased bioavailability of synthetic folic acid (SFA) was included in the analysis. RESULTS: At current voluntary folate fortification, approximately 65% of this population consume 320 microg dietary folate equivalents (DFE) or more per day from diet and supplements, and 0.4% (n=10) consume greater than the recommended upper safety level of 1000 microg from SFA. More than 95% of this older population would be expected to consume more than 320 microg DFE from diet and supplements with universal fortification at 50% of the RDI, and 0.5% (n=14) may consume greater than 1000 microg/day of SFA. CONCLUSIONS: There is unlikely to be a large increase in the proportion of older persons who are likely to consume more than the upper safety level of intake with universal folate fortification. As most of those who currently or are predicted to consume over 1000 microg SFA take supplements containing folic acid, it is highly recommended that vitamin B12 be included in any vitamin supplements containing folate. SPONSORSHIP: This study was supported by the Australian National Health and Medical Research Council (NHMRC).

Aged↗
PubMed1999

Prevalence and socio-demographic predictors of dietary goal attainment in an older population.

OBJECTIVE: To describe the measured dietary intakes and anthropometry of a large, free-living population of middle-aged and older Australians who participated in the Australian Blue Mountains Eye Study (BMES), and to identify the socio-demographic characteristics associated with attainment or non-attainment of dietary goals. METHOD: Anthropometry and dietary intakes were compared with current population dietary goals and Recommended Dietary Intakes for 2,873 people (79% of eligible residents) aged > or = 49 years who participated in the BMES. Nutrient intakes were measured by a validated food frequency questionnaire. RESULTS: Nutrients for which mean intakes deviated most from nutrition goals included: percentages of energy from total and saturated fat, carbohydrate and alcohol (men), as well as absolute intakes of calcium, zinc and fibre. More than half the men (60%) and women (54%) were overweight or obese. Several micro-nutrient goals were more likely to be met in households where the respondents and/or their spouses were independent. Married men were more likely to meet goals for fibre and iron, but less likely to meet the goal for cholesterol. Several goals were more likely to be met by men and women who had qualifications after leaving school, those with higher job status and non-pensioners, suggesting an socio-economic status dimension. CONCLUSIONS AND IMPLICATIONS: These results indicate that over- rather than under-nutrition is more prevalent among community-dwelling older people, although under-nutrition should not be overlooked. Particular sub-groups that are less likely to meet some dietary goals may require targeting in community nutrition interventions.

Age Distribution↗
PubMed1995

A comparison of amitriptyline, vasopressin and amitriptyline with vasopressin in nocturnal enuresis.

Forty-five children aged 6-14 years with primary nocturnal enuresis were randomised to determine whether desmopressin is more effective than amitriptyline and whether the combination of amitriptyline/desmopressin is more effective than amitriptyline or desmopressin alone. Amitriptyline dosage was 25 mg for children 6-10 years and 50 mg for children aged 10-14 years. Desmopressin (20 micrograms) was given in the same dosage for all age groups. After a run-in period of 2 weeks, children were treated for 16 weeks and then observed for 12 weeks. In the amitriptyline group mean wet nights per week decreased from 5.8 +/- 0.9 to 3.3 +/- 1.9 (P < 0.0005); in the desmopressin group mean wet nights per week decreased from 6.0 +/- 0.9 to 4.7 +/- 1.7 (P < 0.02); in the amitriptyline/desmopressin group mean wet nights per week decreased from 6.3 +/- 0.9 to 3.3 +/- 2.5 (P < 0.0006). When comparing the groups, amitriptyline/desmopressin and amitriptyline were statistically more effective than desmopressin in week 6 (P < 0.009), week 8 (P < 0.03) and week 10 (P < 0.04). No significant side effects occurred. At this dose amitriptyline was more effective than desmopressin and the combination of desmopressin and amitriptyline did not confer any additional benefit.

Adolescent↗
PubMed1994

The implications of underreporting in dietary studies.

Dietary data from the Western Sydney Dietary Survey 1989-90 (n = 512) was used to investigate: 1. the prevalence and predictors of underreporting of energy intake, 2. the effects on results of excluding data from underreporters for analysis of mean nutrient intakes, and 3. the proportion of energy intake supplied by macronutrients and proportions of subjects who met dietary goals. The proportion whose measured energy intakes from a Food Frequency Questionnaire (FFQ) were below cutpoints for biologic plausibility was 28.5 per cent; it was higher for subjects who had BMI > 25 and were female. Point estimates for mean intakes of energy and nutrients were all greater when data from underreporters were excluded, but nutrient intakes expressed as percentages of energy intake remained largely unchanged. Increases in estimated mean population intake for each nutrient ranged from 7 per cent to 14 per cent for males, and 12 per cent to 17 per cent for females. Estimates of the percentages of the sample who did not meet dietary goals were significantly lower for a number of nutrients when underreporters were excluded. We conclude that: 1. results expressed as a percentage of energy intake are not affected by the exclusion of energy underreporters, and 2. estimates of the proportion of populations meeting some nutrient goals and associations between diet and disease are likely to change meaningfully and significantly with the exclusion of data from underreporters.

Adult↗
PubMed1993

Cyclosporin therapy in steroid-dependent nephrotic syndrome.

Five children with multiple relapsing steroid-dependent nephrotic syndrome were treated with continuous cyclosporin for periods ranging from 18 to 48 months. Renal biopsy showed mild mesangial proliferation in three of the children and minimal change in two. All children previously had been treated with cyclophosphamide. Cyclosporin was started during remission at 5 mg/kg per day. If a relapse occurred the dose was increased until a trough blood level of 100-250 ng/mL (HPLC) was achieved. In the initial 12 months of treatment, the mean number of relapses decreased from 6.4 +/- 0.54 (s.d.) per annum to 1.6 +/- 1.3 per annum (P < 0.01). Cyclosporin was effective in maintaining long-term remission in four of the five patients. Side effects included hypertrichosis (5) and gum hyperplasia (1). The mean creatinine clearance decreased from 126 +/- 16 to 97 +/- 22 mL/min per 1.73 m2 (P = NS). A renal biopsy in all five patients after 12 months therapy showed no nephrotoxicity. A further biopsy in one patient after 4 years therapy showed interstitial fibrosis. Cyclosporin should be considered in children with steroid-dependent nephrotic syndrome who show signs of steroid toxicity and have only a short remission period after cyclophosphamide. Serial renal biopsies are recommended if prolonged therapy is used.

Adolescent↗
PubMed1989

Algorithm to estimate cell biovolume using image analyzed microscopy.

This paper describes an algorithm for calculating the biovolume of cells with simple shapes, such as bacteria, flagellates, and simple ciliates, from a 2-dimensional digital image. The method can be adapted to any image analysis system which allows access to the binary cell image--(i.e., the pixels, or (x,y) points, composing the cell. The cell image is rotated to a standard orientation (horizontal), and a solid of revolution is calculated by digital integration. Verification and a critical assessment of the method are presented. The algorithm accounts for irregularities in cell shape that conventional methods based on length, width, and geometrical formulas do not.

Algorithms↗
PubMed1989

Evaluation of automated threshold selection methods for accurately sizing microscopic fluorescent cells by image analysis.

The accurate measurement of bacterial and protistan cell biomass is necessary for understanding their population and trophic dynamics in nature. Direct measurement of fluorescently stained cells is often the method of choice. The tedium of making such measurements visually on the large numbers of cells required has prompted the use of automatic image analysis for this purpose. Accurate measurements by image analysis require an accurate, reliable method of segmenting the image, that is, distinguishing the brightly fluorescing cells from a dark background. This is commonly done by visually choosing a threshold intensity value which most closely coincides with the outline of the cells as perceived by the operator. Ideally, an automated method based on the cell image characteristics should be used. Since the optical nature of edges in images of light-emitting, microscopic fluorescent objects is different from that of images generated by transmitted or reflected light, it seemed that automatic segmentation of such images may require special considerations. We tested nine automated threshold selection methods using standard fluorescent microspheres ranging in size and fluorescence intensity and fluorochrome-stained samples of cells from cultures of cyanobacteria, flagellates, and ciliates. The methods included several variations based on the maximum intensity gradient of the sphere profile (first derivative), the minimum in the second derivative of the sphere profile, the minimum of the image histogram, and the midpoint intensity. Our results indicated that thresholds determined visually and by first-derivative methods tended to overestimate the threshold, causing an underestimation of microsphere size. The method based on the minimum of the second derivative of the profile yielded the most accurate area estimates for spheres of different sizes and brightnesses and for four of the five cell types tested. A simple model of the optical properties of fluorescing objects and the video acquisition system is described which explains how the second derivative best approximates the position of the edge.

Cyanobacteria↗
PubMed1984

Dietary compliance among insulin-dependent diabetics.

An education program to improve dietary compliance in insulin-dependent diabetics was evaluated from 1978 to 1980 at the Royal North Shore Hospital of Sydney. Dietary intake, biochemical status, health beliefs, knowledge, anthropometric and other measurements were made on 140 diabetics and their family members before and, where possible, 6 months after the program. Four aspects of compliance were assessed: dietary composition, body weight, carbohydrate spacing among meal periods and carbohydrate variation between days. There was a significant increase in the proportion of subjects who achieved the recommended goal of a high carbohydrate/low fat diet. Diabetics who complied with this recommendation were significantly more likely to have adequate glycemic control. Most of the participants were initially near ideal weight and there were few substantial weight changes. The proportions of diabetics with acceptable scores for carbohydrate spacing and variation did not change significantly. Subjects who complied with one aspect of the dietary regimen did not necessarily comply with other aspects. Dietary compliance was related to initial patterns of dietary intake but could not be predicted from any other factors such as demographic characteristics, duration of disease, knowledge or health beliefs, although this could have been due to small sample sizes.

Adolescent↗
PubMed1982

Evaluation of a diabetes education programme.

An education programme was evaluated for 140 insulin-dependent diabetics and their family members from 1978 to 1980. Dietary, biochemical and other assessments were made before and 6 months after the programme. As a group, the diabetics were initially in good metabolic control and this was maintained, or improved, over the study period. The programme recommended a diet in which complex carbohydrate constituted at least 45% of energy intake and fat was limited to 30%. The diabetics and their family members significantly increased their consumption of complex carbohydrate and decreased fat intake. On this regimen, diabetics did not gain weight and their relatives lost weight. There were also improvements in knowledge of the disorder and in perceptions of susceptibility to complications and barriers to compliance.

Attitude to Health↗
PubMed1981

Ultrastructure of a marine Synechococcus possessing spinae.

Two Chesapeake Bay isolates of unicellular cyanobacteria belonging to the genus Synechococcus are described. Unicellular cyanobacteria are suspected to be important primary producers in estuarine and marine waters. One isolate (P-11-16) fluoresces red and forms green colonies. The other isolate (P-11-17) fluoresces orange and forms red colonies. Their ultrastructure is very similar to other isolates of Synechococcus except that spinae are formed and are attached to an outer wall layer not found in previously described species. The spinae are straight-walled cylinders, not flared at the base, are 44.0-65.0 nm in diameter, and range up to 2.7 micrometer in length. Substructure of the spinae wall consists of either material organized into stacks of rings or a strand of material helically coiled at a low (1-6 degrees) angle. Such material yielded a 6.0-9.2 nm cross-banding periodicity. Substructure of the rings or strand appeared to consist of bar-shaped, repeating units as seen in negatively stained material. Other procaryotic cell types with spinae, which were isolated from unincubated, natural seawater, are described.

Cell Wall↗
PubMed1975

Nitrification on a coral reef.

We report that the algal pavement just behind the reef crest at Enewetak Atoll produces nitrate at measurable rates. In situ and in vitro incubations with N-Serve indicate that the autotrophic pathway involving two separate organisms is effective in this oxidation of ammonia to nitrate. Significant nitrification is indicated throughout the reef environment; Nitrobacter agilis has specifically been identified as at least one of the organisms responsible for the terminal oxidation of nitrite to nitrate.

Ammonia↗
PubMed1968

Amino acid flux in an estuary.

Dissolved organic matter in York River estuary included 38 micrograms of free amino acids per liter. The highest concentrations were of glycine, serine, and ornithine. Of the 14 amino acids studied for uptake by planktonic bacteria, glycine, methionine, and serine had the greatest flux rates. The total amino acid flux represented from 1 to 10 percent of the daily photosynthetic carbon fixation.

Amino Acids↗