Effect of propionate on in vivo carbohydrate metabolism in streptozocin-induced diabetic rats

Undigested carbohydrates and some dietary fibers are fermented in the large intestine to form short-chain fatty acids (SCFA), including acetate, propionate, and butyrate. It has been suggested that some of the beneficial effects of high-carbohydrate, high-fiber diets on carbohydrate and lipid metabolism are mediated by the metabolism of SCFA in the liver. Propionate has been shown in vitro to decrease glucose production in rat hepatocytes. The aim of the present study was to investigate the effects of propionate on carbohydrate metabolism in normal and streptozocin (STZ)-induced diabetic male Sprague-Dawley rats. Rats were fed a high-fat diet with or without sodium propionate supplementation (either 0.5% or 5% wt/wt) for 4 weeks. At the completion of the feeding period, body weight and liver glycogen concentrations were significantly decreased in STZ-diabetic rats and were unaffected by propionate supplementation. Although STZ-diabetic animals had elevated fasting plasma glucose, cholesterol, and triglyceride levels relative to nondiabetic rats, propionate supplementation had no significant effect on these parameters in either group. Basal and insulin-stimulated carbohydrate metabolism were assessed using the euglycemic clamp technique in overnight-fasted animals with 3(H)-6-glucose infusion. As expected, basal hepatic glucose production (HGP) was higher and the metabolic clearance rate of glucose (MCR) was lower in STZ-diabetic rats. High-dose insulin infusion (3 mU.kg-1.min-1) suppressed HGP in nondiabetic and diabetic animals and increased the MCR in nondiabetic animals. However, propionate supplementation did not alter basal or insulin-stimulated HGP or the MCR in either nondiabetic or diabetic animals.(ABSTRACT TRUNCATED AT 250 WORDS)

Apparent dietary intake in remote aboriginal communities

Apparent per capita food and nutrient intake in six remote Australian Aboriginal communities using the 'store-turnover' method is described. The method is based on the analysis of community-store food invoices. The face validity of the method supports the notion that, under the unique circumstances of remote Aboriginal communities, the turnover of foodstuffs from the community store is a useful measure of apparent dietary intake for the community as a whole. In all Aboriginal communities studied, the apparent intake of energy, sugars and fat was excessive, while the apparent intake of dietary fibre and several nutrients, including folic acid, was low. White sugar, flour, bread and meat provided in excess of 50 per cent of the apparent total energy intake. Of the apparent high fat intake, fatty meats contributed nearly 40 per cent in northern coastal communities and over 60 per cent in central desert communities. Sixty per cent of the apparent high intake of sugars was derived from sugar per se in both regions. Compared with national Australian apparent consumption data, intakes of sugar, white flour and sweetened carbonated beverages were much higher in Aboriginal communities, and intakes of wholemeal bread, fruit and vegetables were much lower. Results of the store-turnover method have important implications for community-based nutrition intervention programs.

Letters

THE IMPORTANCE OF PRESSURE RELIEF PATIENT CONFIDENTIALITY RELIABLE PRESSURE DAMAGE DATA.

Diets rich in lean beef increase arachidonic acid and long-chain omega 3 polyunsaturated fatty acid levels in plasma phospholipids

Diets rich in meat are claimed to contribute to the high tissue arachidonic acid (20:4 omega 6) content in people in Westernized societies, but there are very few direct data to substantiate this assertion. Because meat contains a variety of long-chain polyunsaturated fatty acids (PUFA) that are susceptible to oxidation, we initially examined the effect of cooking on the long-chain PUFA content of beef, and then determined the effect of ingestion of lean beef on the concentration of long-chain PUFA in plasma phospholipids (PL). First, we examined the effect of grilling (5-15 min) and frying (10 min) different cuts of fat-trimmed lean beef on the long-chain PUFA content. Second, we investigated the effect of including 500 g lean beef daily (raw weight) for 4 wk on the fatty acid content and composition of plasma PL in 33 healthy volunteers. This study was part of a larger trial investigating the effect of lean beef on plasma cholesterol levels. In the first two weeks, the subjects ate a very low-fat diet (10% energy) followed by an increase in the dietary fat by 10% each week for the next 2 wk. The added fat consisted of beef fat, or olive oil (as the oil or a margarine) or safflower oil (as the oil or a margarine). This quantity of beef provided 60, 230, 125, 140 and 20 mg/d, respectively, of eicosatrienoic acid (20:3 omega 6), 20:4 omega 6, eicosapentaenoic acid (20:5 omega 3), docosapentaenoic acid (22:5 omega 3) and docosahexaenoic acid (22:6 omega 3).(ABSTRACT TRUNCATED AT 250 WORDS)

n-3 fatty acids reduce in vitro thromboxane production while having little effect on in vitro prostacyclin production in the rat

Male Sprague-Dawley rats were fed diets with 50% of the energy from fat over a 20-day period. The fats used were hydrogenated beef-fat (HBF), or HBF supplemented with ethyl arachidonate A, safflower oil (SO), or a mixture of SO and linseed oil (LO). For comparative purposes, another group of animals was fed a diet providing 50% of the energy as butter-fat. In vitro aortic prostacyclin (PGI2) and serum thromboxane (TXA2) levels (from clotting blood) were determined by radioimmunoassay of 6-keto PGF1 alpha and TXB2, respectively. The HBF diet had similar AA levels relative to the butter-fed rats but significantly reduced tissue levels of eicosapentaenoic acid (EPA) and this was associated with an increased production of serum TXB2. Supplementing the HBF diet with AA increased tissue levels of AA while maintaining low levels of n-3 fatty acids. These changes were accompanied by significant increases of both TXB2 and 6-keto-PGF1 alpha. LO supplementation to the HBF diet (with constant SO) led to elevated levels of EPA and relatively constant AA levels and this was associated with reduced production of TXB2. These results highlight the responsiveness of TXA2 to n-3 fatty acids in contrast to PGI2 which was more influenced by the level of AA in the tissue phospholipids in the rat.

Energy intake, anthropometry and blood pressure of expeditioners in the Antarctic

The energy intakes, anthropometry and blood pressure of 62 expeditioners at one Australian sub-Antarctic (Macquarie Island) and two Antarctic stations (Davis and Casey) were examined over a 12 month period. High mean energy intakes were found at all stations (approximately 16,000 kJ/subject/day). Mean subject body weight tended to rise during the winter months (midway during the study) and fall during the spring, although there were no significant changes (p < 0.05) seen at any of the stations over the year. Subjects were generally leaner at the end of 12 months as evidenced by significant falls (p < 0.01) in mean sum of skinfold thickness at two stations over the year. At all stations, blood pressure trended downwards during the year, with significant rises (p < 0.01) seen at one station during the spring. Two 12-week dietary intervention periods were introduced during the year at one of the Antarctic stations to investigate the effects of low-cholesterol (< 300 mg/day), low-fat (< 30% of energy) and high-fibre (> 30 g/day) diets. The average energy intake/day during these two periods (14,973 kJ and 14,515 kJ) was slightly less than during the baseline diet (average of 16,228 kJ). This was reflected in the anthropometric measurements with the mean body weight, sum of skinfold thickness and waist/hip ratios trending down during the diet periods. The study confirms earlier reports of high mean energy intake in Antarctica and suggests that the techniques of measuring intake may have been more accurate than those used in large population studies where intake may have been under-estimated. The results indicate seasonal fluctuations in blood pressure and anthropometric parameters and demonstrate that these anthropometric parameters were affected by the balance of energy intake and activity.

Effect of soluble dietary fibre on the viscosity of gastrointestinal contents and the acute glycaemic response in the rat

The postprandial glycaemic response following a meal is reduced with the addition of soluble dietary fibre. The reductions in the glycaemia are thought to be due largely to increased viscosity of the gastrointestinal (GI) contents retarding digestion and absorption. The aims of the present study were to determine the effect that the GI tract has on the viscosity of meals containing different soluble fibres and to determine whether the glycaemic response of a meal (containing the soluble fibre) was predicted by the viscosity of the digesta in the small intestine. High carbohydrate diets containing 70 g soluble fibre guar gum, xanthan gum or methylcellulose)/kg or 70 g insoluble fibre (wheat bran)/kg were diluted in water to a final fibre concentration of 18 g/kg. Following dilution the wheat bran diet had no measurable viscosity, while the viscosities of the soluble fibre diets were elevated. When the diets were fed to male Sprague-Dawley rats for 2 weeks the viscosities of the stomach and small intestinal digesta were not predicted by the viscosity of the diets measured before ingestion. The action of the GI tract on the viscosity of the soluble fibres was investigated in vitro by dilution of the diets with acidic and neutralizing solutions, mimicking gastric and duodenal secretions. Dilution of diets with either acidic and neutralizing solutions or saline control significantly lowered the viscosity of all diets, while alterations in the pH of the diets had little impact on the resultant viscosity.(ABSTRACT TRUNCATED AT 250 WORDS)

Development of the Melbourne FFQ: a food frequency questionnaire for use in an Australian prospective study involving an ethnically diverse cohort

Objective. To develop an optically scannable food frequency questionnaire (FFQ), 'The Melbourne FFQ', suitable for classifying Australian-, Greek- and Italian-born individuals into quantiles of intake for a range of foods and nutrients. The FFQ would provide the primary measure of dietary exposure in a prospective cohort study. Design. The FFQ was modelled on that used for the (US) Nurses' Health Study. Food items were chosen on the basis of their relative contribution to the intake of a range of nutrients computed from weighed food records. Setting. Metropolitan Melbourne, Australia, a city of 3 million people, of whom 75.5% were born in Australia, 2.7% were born in Italy and 1.7% were born in Greece. Participants. Weighed Food Survey (1987-1989): A volunteer sample of 810 healthy middle-aged (40-69 years) men and women of whom 35% were born in Greece, 33% were born in Italy, and 32% were born in Australia. Melbourne Collaborative Cohort Study (1990-1993): A volunteer sample of 17 949 healthy men and women aged between 40 and 69 years of whom 61% were born in Australia, 21% were born in Italy and 17% were born in Greece. Results. A 121 item FFQ was developed, together with a customized nutrient database. The optical scanning format was generally well received with the majority of subjects requiring no assistance. The FFQ appeared to overestimate the consumption of fruit and vegetables. Conclusions. The Melbourne FFQ provides a convenient method of measuring habitual dietary intake in a large population setting. A separate study is required to assess how well the instrument characterizes diet at the level of the individual.

Blood pressure, lipids and other risk factors for cardiovascular disease in Aborigines and persons of European descent of southeastern Australia

Based on a survey in two country towns of southeastern Australia, cardiovascular risk-factor prevalence data from Aborigines and persons of European descent are presented. The mean diastolic blood pressure in 123 Aboriginal males was 83.2 mmHg, compared with 79.2 mmHg in 272 European males (P = 0.005). In 178 Aboriginal females, mean diastolic pressure was 79.2 mmHg, compared with 76.3 mmHg in 281 European females (P = 0.006). Mean plasma total cholesterol was higher in Europeans (both males and females: 5.7 mmol/L) than in Aborigines (in males 5.2 and females 5.0 mmol/L) (male comparison, P = 0.02, female comparison, P < 0.001). The prevalence in participants aged 25 to 64 years of at least one major risk factor (diastolic blood pressure 95 mmHg or higher, plasma cholesterol 6.5 mmol/L or higher, or smoking more than one cigarette daily) was higher in both these samples of Aborigines (94 per cent in males, 89 per cent in females) and Europeans (70 per cent in males, 59 per cent in females) than in the 1989 urban sample of the National Heart Foundation (47 per cent in males, 36 per cent in females). Multivariate analyses showed statistically significant independent contributions of body mass index and the variable 'ethnicity' (unidentified genetic and environmental differences between the groups) to blood pressure and other risk factors. The higher cardiovascular mortality of Aborigines may be explained partly by the higher prevalence of risk factors in this group compared with other Australians. Further, the risk-factor profile may be worse among rural compared with urban Europeans.

The effect of linoleic, arachidonic and eicosapentaenoic acid supplementation on prostacyclin production in rats

We examined the effect of dietary supplementation of linoleic acid (LA), arachidonic acid (AA) or eicosapentaenoic acid (EPA) to rats fed a diet low in linoleic acid on in vitro and in vivo production of prostacyclin. Male Sprague Dawley rats were fed a high-fat diet (50% energy as fat, 1.5% linoleic acid) for two weeks. Three of the groups were then supplemented orally with either 90 mg/d of LA, AA or EPA, all as the ethyl esters, for a further two weeks while remaining on the high-fat diet. Forty-eight hour urine samples were collected at the end of the second and fourth weeks. In vivo prostacyclin production was determined by a stable isotope dilution, gas chromatography/mass spectrometry assay for the major urinary metabolite of prostacyclins (2,3-dinor-6-keto-PGF1 alpha or PGI2-M and delta 17-2,3-dinor-6-keto-PGF1 alpha or PGI3-M). In vitro prostacyclin production was determined by radioimmunoassay of the stable metabolite (6-keto-PGF 1 alpha) following incubation of arterial tissue. Oral supplementation with AA resulted in a rise in plasma and aorta 20:4n-6, and increased in vitro prostacyclin and urinary PGI2-M production. EPA supplementation resulted in a rise in plasma and aorta 20:5n-3 and 22:5n-3, and a decline in plasma 20:4n-6, but not in the aorta. In the EPA-supplemented group, the in vitro prostacyclin and the urinary PGI3-M increased, but urinary PGI2-M decreased. The increase in in vitro prostacyclin production in the EPA-supplemented rats was unexpected and without obvious explanation.(ABSTRACT TRUNCATED AT 250 WORDS)

The effect of dietary fat level and quality on plasma lipoprotein lipids and plasma fatty acids in normocholesterolemic subjects

This study examined the effect on the plasma lipids and plasma phospholipid and cholesteryl ester fatty acids of changing froma typical western diet to a very low fat (VLF) vegetarian diet containing one egg/day. The effect of the addition of saturated, monounsaturated or polyunsaturated fat (PUFA) to the VLF diet was also examined. Three groups of 10 subjects (6 women, 4 men) were fed the VLF diet (10% energy as fat) for two weeks, and then in the next two weeks the dietary fat in each group was increased by 10% energy/week using butter, olive oil or safflower oil. The fat replaced dietary carbohydrate. The VLF diet reduced both the low density lipoprotein (LDL)- and high density lipoprotein (HDL)-cholesterol levels; addition of the monounsaturated fats and PUFA increased the HDL-cholesterol levels, whereas butter increased the cholesterol levels in both the LDL- and HDL-fractions. The VLF diet led to significant reductions in the proportion of linoleic acid (18:2 omega 6) and eicosapentaenoic acid (20:5 omega 3) and to increases in palmitoleic (16:1), eicosatrienoic (20:3 omega 6) and arachidonic acids (20:4 omega 6) in both phospholipids and cholesteryl esters. Addition of butter reversed the changes seen on the VLF diet, with the exception of 16:1, which remained elevated. Addition of olive oil resulted in a significant rise in the proportion of 18:1 and significant decreases in all omega 3 PUFA except 22:6 compared with the usual diet. The addition of safflower oil resulted in significant increases in 18:2 and 20:4 omega 6 and significant decreases in 18:1, 20:5 omega 3 and 22:5 omega 3. These results indicate that the reduction of saturated fat content of the diet (< 6% dietary energy), either by reducing the total fat content of the diet or by exchanging saturated fat with unsaturated fat, reduced the total plasma cholesterol levels by approximately 12% in normocholesterolemic subjects. Although the VLF vegetarian diet reduced both LDL- and HDL-cholesterol levels, the long-term effects of VLF diets are unlikely to be deleterious since populations which habitually consume these diets have low rates of coronary heart disease. The addition of safflower oil or olive oil to a VLF diet produced favorable changes in the lipoprotein lipid profile compared with the addition of butter. The VLF diets and diets rich in butter, olive oil or safflower oil had different effects on the 20 carbon eicosanoid precursor fatty acids in the plasma.(ABSTRACT TRUNCATED AT 400 WORDS)

Food habits in Aborigines and persons of European descent of southeastern Australia

As part of a study of risk factors for glucose intolerance and heart disease in Australian Aborigines and persons of European descent, we elicited the prevalence of food habits that may be associated with high fat and high salt intakes. Interview data were gathered from population-based samples in country towns and visitors to an Aboriginal health service in a state capital city, all in southeastern Australia. Among persons aged 13 years and over, the frequency of eating takeaway food as a meal was categorised as monthly or less, weekly, more than once per week, and daily or more often. The prevalence of eating such meals was higher among city Aborigines than those living in the country town; the prevalence was lowest among the country-town Europeans (chi 2 = 184, 6 df, P < 0.001). The prevalence of adding salt during cooking and food consumption was higher among Aborigines compared with Europeans. Among country-town Aboriginal males aged 35 or under, 25 of 40 (63 per cent) added salt to cooked food 'most of the time', compared with 66 of 185 (36 per cent) Europeans (chi 2 = 9.8, P = 0.002). Among Aboriginal females, 47 of 64 (64 per cent) were in the highest category of salt use, compared with 35 of 190 (18 per cent) of Europeans (chi 2 = 66.3, P < 0.001). About one-third of country-town Aboriginal males used dripping to fry food, but in the other ethnicity, gender and location groups, vegetable oil was the most frequent choice. The main differences in food habits were associated with ethnicity, rather than location.(ABSTRACT TRUNCATED AT 250 WORDS)

Nucleotide sequence analysis and epitope mapping of the merozoite surface protein 1 from Plasmodium chabaudi chabaudi AS

The complete nucleotide sequence of the gene encoding the merozoite surface protein 1 (MSP-1) from the rodent malaria parasite Plasmodium chabaudi chabaudi AS has been determined by direct sequencing of overlapping PCR derived fragments. Comparison of the P. c. chabaudi AS nucleotide sequence with the previously published P. c. chabaudi IP-PC1 sequence indicates that although the MSP-1 gene of these two P. c. chabaudi strains is highly conserved, with sequence identity often approaching 100%, interspersed throughout the molecule are 5 regions of divergence. This is at variance with published data which suggested that the P. c. chabaudi AS and P. c. chabaudi IP-PC1 MSP-1 sequences are largely identical. Epitope mapping studies with a panel of anti-P. c. chabaudi AS MSP-1 monoclonal antibodies demonstrate that whilst most of these mAbs recognise epitopes at the N-terminus of the MSP-1 molecule, two mAbs, including one capable of inhibiting challenge infections in mice in an in vivo passive transfer assay, recognise epitopes which map to the C-terminus.

A single amino acid determines the specificity of a monoclonal antibody which inhibits Plasmodium chabaudi AS in vivo

The in vivo inhibitory action of NIMP23, a monoclonal antibody raised against the rodent parasite Plasmodium chabaudi chabaudi AS, has previously been shown to be strain-specific, capable of delaying significantly the onset of P. c. chabaudi AS but not a P. c. chabaudi CB challenge parasitaemia. The epitope to which this mAb binds has been mapped to the second of two epidermal growth factor-like domains located at the C-terminus of the merozoite surface protein 1 (MSP-1) of P. c. chabaudi AS. The C-terminus region of the MSP-1 of P. c. chabaudi is a region of heterogeneity with AS and CB strain parasites showing only 78% identity at the amino acid level. The critical amino acid substitution which accounts for the strain specificity of the NIMP23 monoclonal antibody has now been identified. Polymerase chain reaction directed mutagenesis experiments demonstrate that a single proline to asparagine substitution at position 1722 in the primary amino acid sequence is sufficient to convert NIMP23-negative P. c. chabaudi CB expression constructs into NIMP23-positive clones whilst the converse substitution of an asparagine for a proline residue converts P. c. chabaudi AS expression constructs into NIMP23-negative clones.

Forearm arterial vascular responsiveness in insulin-dependent diabetic subjects

The vascular reactivity of forearm arterioles was measured in 16 control subjects (C) and 30 insulin-dependent diabetic (IDDM) subjects, 16 of whom were shown to have microvascular and/or neuropathic complications (DC) including 8 with autonomic neuropathy (DCa) and 14 were shown to be free of complications (DNC). Forearm blood flow was measured by strain gauge plethysmography basally, following a cold pressor stress and following a period of arterial occlusion (reactive hyperaemia). The tests were repeated 24 h later following aspirin treatment. Both C and DNC showed a significant reduction in blood flow in the cold pressor test (C 0.64 +/- 0.12, DNC 0.89 +/- 0.22 ml/100 ml forearm tissue/min reduction in flow P < 0.005), while DC showed no significant response. Reactive hyperaemia was significantly greater in C than in DNC or DC (8.37 +/- 1.14, 5.51 +/- 1.27 and 4.95 +/- 0.75 ml/100 ml tissue/min, respectively, P < 0.02). In the DC group, DCa had significantly less response than those without autonomic neuropathy. Aspirin treatment restored the response of DNC but not DC to normal, suggesting that the abnormality in the former group may have been due to overproduction of a vasoconstrictive cyclooxygenase product (such as thromboxane A2). It is concluded that the abnormalities of vasomotor responses in diabetic subjects are complex and are apparently dependent on autonomic neuropathy, humoral and perhaps structural changes.

Prevalence of pressure damage in hospital patients in the UK

This paper describes a method of determining the prevalence of pressure damage in hospital patients and gives some preliminary results. The same method and data collection systems were applied to seven different hospitals in the UK, and involved over 3 000 patients. The approach allows comparisons between hospitals and permits some interpretation of the national data. The methodology can be shown to be valid, reliable and reproducable, enabling it to be used to measure the effectiveness of policies and protocols. The cost of treating full-thickness pressure sores, and the resulting increase in patient length of stay has made it vital for hospitals to develop effective strategies both for prevention and treatment. Such a survey is an excellent tool for identifying opportunities to improve both these strategies. Such a survey is, ideally, part of a 'total quality outcome management' approach to the issue of pressure damage.

Obesity, diabetes, and hyperlipidemia in a central Australian aboriginal community with a long history of acculturation

OBJECTIVE

To determine the age- and sex-specific prevalence of diabetes and to examine associations between related anthropometric and metabolic abnormalities in an Aboriginal community in central Australia with a long history of acculturation.

RESEARCH DESIGN AND METHODS

We used a cross-sectional survey of 353 adults > 15 yr of age (87% response rate) and measured the following parameters: weight, height, circumferences of waist and hips; glucose, insulin, cholesterol, triglyceride, and high-density lipoprotein cholesterol in fasting plasma; and plasma glucose and insulin 2 h after 75 g oral glucose.

RESULTS

The prevalence of diabetes was 29.6% in survey participants > 35 yr of age and 5.3% in those < 35 yr of age. Impaired glucose tolerance also occurred with higher frequency in those > 35 yr of age (14.8 vs. 4.7%). Of those > 35 yr of age, 75% of the women and 51% of the men were overweight or obese, with a body mass index > or = 25 kg/m2. A large insulin response to oral glucose was evident, with the upper tertile of the 2-h insulin response six times higher than the lower tertile (113 +/- 43 vs. 19 +/- 8 mU/L). Hyperinsulinemia showed a strong, positive association with impaired glucose tolerance, body mass index, waist-to-hip ratio, cholesterol, and triglyceride levels and a negative association with high-density lipoprotein cholesterol levels. Cholesterol levels were on average 0.5 mM higher in men than in women. Deteriorations in carbohydrate and lipid metabolism occurred before 40 yr of age: diabetes, body mass index, waist-to-hip ratio, and fasting triglycerides and cholesterol concentrations peaked and high-density lipoprotein cholesterol concentrations reached their nadir at the end of the fourth decade.

CONCLUSIONS

These data suggest that any intervention programs developed to prevent or reduce diabetes prevalence in this population should be targeted at adolescents and young adults.

Effect on serum lipids of addition of safflower oil or olive oil to very-low-fat diets rich in lean beef

The cholesterol-lowering effect of very-low-fat diets rich in lean beef has previously been shown to be reversed with the addition of beef fat. The aim of this study was to determine the effect on serum lipid levels of the addition of safflower oil or olive oil to a very-low-fat diet rich in lean beef. Subjects were assigned to either the safflower oil or the olive oil group. In the first week the subjects ate their usual diet; in the second and third weeks all subjects ate a very-low-fat (9% of energy) diet rich in lean beef. In the fourth and fifth weeks the fat content of the diet was increased in a stepwise fashion to 20% and 30% of energy, respectively, by substituting safflower oil or olive oil for carbohydrate. Low-density lipoprotein cholesterol (LDL-C) concentrations decreased by 13% to 14%, and high-density lipoprotein cholesterol (HDL-C) concentrations decreased by 20% to 25% in subjects after 2 weeks of the very-low-fat, lean-beef diet. The LDL-C concentrations remained low after the addition of safflower oil or olive oil to the very-low-fat diet. These results indicate that a reduction in saturated fat, not total fat, is required to reduce serum total cholesterol and LDL-C levels. Provided that the total diet is low in saturated fat, these serum lipid responses can be achieved even when the diet is rich in fat-trimmed lean beef.

Hyperinsulinaemia and obesity in aborigines of south-eastern Australia, with comparisons from rural and urban Europid populations

Diabetes is more common in Aborigines than in other Australian populations, even in groups that have lived in contact with Europids for 150 years. Prevalence data on hyperinsulinaemia and obesity from urbanized south eastern Australian Aborigines are presented with Europid comparisons. Aborigines had higher mean insulin levels than Europids. In females, mean fasting insulin was 15.5 mU/l in Aborigines, compared with 9.5 mU/l in Europids (P < 0.001). The means for males were 15.1 mU/l (Aborigines) and 8.3 (Europids) (P < 0.005). Obesity was more prevalent in Aborigines. In Aboriginal females aged 25-64 years, 41/108 (38%) had BMI > 30.0, compared with 37/208 (18%) Europids (P < 0.001). In males, the difference in the prevalence of obesity in Aborigines (17/69, 25%) and Europids (34/195, 17%) was not statistically significant. Waist-hip ratio was significantly greater among Aboriginal females (mean 0.87 in persons aged 25-64 years) than among Europids (mean 0.81, P < 0.001). In males, the mean ratio in Aborigines and Europids was the same (0.94). Abdominal obesity was most prevalent among Aboriginal females. For females aged 20-49 years, 83/110 (75%) Aborigines had a waist-hip ratio > 0.80, compared with 71/165 (43%) Europids (P < 0.001). Being overweight or obese is perceived with least accuracy by Aboriginal males of the four ethnicity/gender groups. Comparisons with national data suggest a gradient in the prevalence of obesity, lowest in urban groups, more in the country, and higher still among Aborigines, which is in reciprocal order to socio-economic status. In multivariate analyses, the association of BMI with insulin was highly significant. Hyperinsulinaemia in an Aboriginal group after many years of contact with Europids may result from environmental as well as genetic influences. Relative hyperinsulinaemia is not found among those Aborigines who have developed glucose intolerance, which could be explained by earlier pancreatic exhaustion in this group.

Validation of an in vitro assay for predicting the amount of starch that escapes digestion in the small intestine of humans

The aim of the present study was to validate an in vitro assay for quantifying resistant starch (RS) in foods against an in vivo model. The amount of starch escaping digestion in the small intestine of ileostomates was compared with that observed by using the in vitro assay. Subjects with ileostomies were fed five foods containing different types and amounts of RS (baked beans, pearl barley, cornflakes, and whole and ground rice). The total amount of starch escaping digestion and recovered in the effluent (ranging from 5.7% in baked beans to 0.7% in ground rice) was compared with results obtained by using the in vitro assay with an incubation time of 6 h. The assay was found to be a good qualitative predictor (r = 0.90, P < 0.05), but a poor quantitative predictor of RS amounts. Increasing the duration of incubation with alpha-amylase and amyloglucosidase to 15 h resulted in a very close agreement between results from the in vitro technique and the in vivo model. These data indicate that for a variety of foods the in vitro assay produced an excellent estimate of starch escaping digestion in the small intestine of humans.

Arachidonic acid supplementation dose-dependently reverses the effects of a butter-enriched diet in rats

Male Sprague Dawley rats were fed a butter-enriched diet (50% fat) for 2 weeks which was supplemented orally with 9, 18, 36, or 72 mg/day of ethyl arachidonate for a further 2 weeks. The control group of animals were fed a 5% fat diet for 4 weeks. Aortic prostacyclin (PGI2) production, platelet aggregation and thromboxane A2 (TXA2) production and plasma and aortic phospholipid (PL) fatty acids were measured. 50% butter-feeding resulted in a significant reduction in aortic PGI2 production and collagen-induced platelet aggregation and TXA2 production. These changes were accompanied by a reduction in plasma and aortic PL arachidonic acid levels and an increase in eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA), 5,8,11-eicosatrienoic acid (ETA) and dihomo-gamma-linolenic acid (DGLA). These changes in prostanoid production, platelet aggregation and PL fatty acid composition were dose-dependently reversed by the daily oral administration of ethyl arachidonate (9, 18, 36, or 72 mg). The threshold dose being as little as 9 mg of ethyl arachidonate/rat/day for reversal of PL fatty acid composition, collagen-induced platelet aggregation and TXA2 production, and 18 mg of ethyl arachidonate/rat/day for reversal of aortic PGI2 production. Full reversal was seen generally with 36 or 72 mg of ethyl arachidonate/rat/day. The data highlight the responsiveness of tissue eicosanoid production to small quantities (ppm) of dietary eicosanoid precursors.

Low-dose acarbose improves glycemic control in NIDDM patients without changes in insulin sensitivity

OBJECTIVE

To examine the impact on metabolic control in NIDDM patients of the alpha-glucosidase inhibitor, acarbose, when administered at a low dose in powdered form.

RESEARCH DESIGN AND METHODS

Six subjects were recruited for a double-blind cross-over trial using 25 mg powdered acarbose and a placebo 3 times a day with meals for 3 mo. In addition to parameters of diabetes control and body weight, glucose turnover and insulin sensitivity were measured with the hyperinsulinemic/euglycemic clamp technique combined with tracer kinetics.

RESULTS

None of the subjects showed significant changes in FPG levels or body weight either on the 3-mo course of acarbose or placebo. HbA1c fell significantly from 10.6 +/- 1.0 to 9.4 +/- 1.3% (P = 0.05) during treatment with acarbose but failed to change on placebo (10.1 +/- 1.0 to 11.1 +/- 2.0%; P = 0.36). Basal HGP and glucose utilization were unchanged during either of the treatment periods, and hyperinsulinemia produced a similar degree of suppression of HGP before and after each treatment. At a physiological concentration, insulin failed to stimulate glucose clearance in these diabetic patients, and no improvement was seen with acarbose treatment. No changes in plasma lipids or lipoprotein profiles were demonstrated after 3 mo on acarbose. In acute studies, it was shown that administration of acarbose at a dose of 25 mg powder per meal significantly decreased the postprandial glycemic excursion.

CONCLUSIONS

When administered in the powdered form at the low dose of 25 mg 3 times/day with meals over 3 mo, acarbose was well tolerated by the NIDDM patients and was without side effects. It improved glycemic control by reducing postprandial hyperglycemia, but had no effect on glucose turnover, insulin sensitivity, or lipid profile.

Effect of fatty acid oxidation inhibition on glucose metabolism in diabetic rats

Inhibition of fatty acid (FA) oxidation has been shown previously to lower blood glucose levels acutely in diabetic rats. However, the longer term effects of FA oxidation inhibition have not been determined. This study examines the effect of inhibition of (FA) oxidation for 3 weeks on carbohydrate metabolism in rats rendered diabetic with streptozotocin (STZ). STZ treated rats (50 mg/kg) were randomized into 3 groups: a non-treated diabetic group and 2 groups treated with either 12.5 or 25 mg/kg/day Etomoxir (a specific carnitine palmitoyl transferase inhibitor) for 3 weeks. The 3 groups of rats had ad libitum access to a high fat diet (50% energy fat, 30% carbohydrate and 20% protein) throughout the study. After 3 weeks hepatic glucose production (HGP) was estimated using a constant infusion of (3H)-6-glucose in-vivo after an overnight fast. Inhibition of FA oxidation in diabetic rats resulted in a significant reduction in fasting glucose levels and hepatic glucose production. In addition, experiments with adipocytes isolated from diabetic rats treated with etomoxir demonstrated an increase in sensitivity and responsiveness to insulin of glucose utilization and pyruvate dehydrogenase (PDH) activity. It is important to note that these improvements in carbohydrate metabolism were not accompanied by increases in circulating FFA or triglyceride levels which were unchanged or lower after inhibition of FA oxidation.

Smoking in aborigines and persons of European descent in southeastern Australia: prevalence and associations with food habits, body fat distribution and other cardiovascular risk factors

As part of a population-base study of risk factors for heart disease, we aimed to establish the prevalence of smoking and to identify associations between smoking and other risk factors in Australian Aborigines (n = 306) and persons of European descent (n = 553) in two country towns. Smoking prevalence was first analysed as a dichotomy (current smokers compared with nonsmokers), and according to three levels of exposure (< 10, 10-20 and > 20 cigarettes per day), and two levels of nonexposure (never and former smoker). Other behavioural, biochemical and physical variables were included in multivariable analyses. Of the Aborigines, 64.4 per cent (95 per cent confidence interval (CI) 59.0 per cent to 69.8 per cent) were current cigarette smokers, compared with 22.8 per cent of non-Aborigines (CI 19.3 per cent to 26.3 per cent). For persons aged 13 to 54 years, using the five categories of exposure, smoking in Aborigines again far exceeded that in non-Aborigines in all age groups (for males chi 2 = 72.8, for females chi 2 = 94.6, 4 df, P = < 0.0001 for both sexes). In non-Aboriginal females, the highest prevalence was in the youngest group (56 per cent of those aged 13 to 17 years). Food habit was associated with smoking. Subjects who ate meat without trimming the fat were more likely to smoke. In Australian country towns, Aborigines and all young women need smoking cessation programs. The nutritional status of smokers requires further study.