A Ca(2+)-mobilising carbohydrate-based polyphosphate: synthesis of 2-hydroxyethyl alpha-D-glucopyranoside 2',3,4-trisphosphate

Two routes to a glucose-based mimic of the second messenger 1D-myo-inositol 1,4,5-trisphosphate related to adenophostin A are described. Fischer glycosidation of D-glucose with allyl alcohol in the presence of a strong cation-exchange resin gave a 7:3 alpha: beta-anomeric mixture of allyl glucopyranosides (5ab) from which the pure alpha anomer 5a was isolated by crystallisation. Treatment of 5ab with 1.05 equiv of dibutyltin oxide followed by 2.1 equiv of benzoyl chloride gave allyl 2,6-di-O-benzoyl-alpha-D-glucopyranoside, which was converted in 3 steps into allyl 2,6-di-O-benzyl-3,4-O-isopropylidene-alpha-D-glucopyranoside (4). Alternatively, treatment of 5a with 2.5 equiv of dibutyltin oxide followed by benzyl bromide gave allyl 2,6-di-O-benzyl-alpha-D-glucopyranoside (9) which was also converted into 4. Compound 4 was elaborated to the phosphorylation precursor 2-hydroxyethyl 2,6-di-O-benzyl-alpha-D-glucopyranoside (12) in a convenient one-pot reaction, and 12 was phosphorylated and deblocked to afford 2-hydroxyethyl alpha-D-glucopyranoside 2',3,4-trisphosphate. The 2,6-di-O-benzyl derivative 9 was converted in high yield into 2,6-di-O-benzyl-3,4-di-O-(p-methoxybenzyl)-D-glucopyranose, a useful intermediate for the synthesis of adenophostin A and related compounds.

Human hydatidosis in New South Wales and the Australian Capital Territory, 1987-1992

OBJECTIVE

To determine the prevalence of human hydatidosis in New South Wales and the Australian Capital Territory.

METHODS

Data on human hydatid infection occurring between 1987 and 1992 were collected retrospectively from 25 hospitals and 13 health services in New South Wales and four hospitals in the Australian Capital Territory. Mean annual prevalences of human hydatidosis were determined for shires in eastern New South Wales and data on infection in immigrants and Australian-born patients were compared.

RESULTS

321 patients were diagnosed with hydatid disease, 1987-1992; 195 were new cases and 117 readmissions (nine cases were not identified as new or recurrent). Most patients lived in the eastern half of New South Wales (which includes the Australian Capital Territory), half in rural areas and half in the major coastal cities. Most Australian-born rural patients lived in 39 shires in the north-eastern and south-eastern Tablelands. Sixty per cent of the patients in major cities were born overseas.

CONCLUSIONS

Hydatid infection occurs more commonly in south-eastern Australia than the official figures suggest. In rural areas of the north-eastern and south-eastern Tablelands hydatid infection is of public health importance. The national notification system must be improved and control campaigns alerting the public to the dangers of hydatid infection promoted.

Nutrition principles and diabetes. A role for "lente carbohydrate"?

The current nutrition recommendations of the American Diabetes Association (ADA) represent a thoughtful synthesis of much current data. They depart from tradition by not advocating specific figures for total fat and carbohydrate intake. Rather, since many issues are still topics of scientific debate, they endorse the principle of individualization and set guidelines accordingly. One topic that may be worthy of further debate is the principle of "spreading the nutrient load," or lengthening the absorption time. This principle covers the effects of altered meal frequency, viscous dietary fibers, low-glycemic index foods, and inhibitors of carbohydrate absorption. In its simplest form it is illustrated by studies of altered meal frequency ("nibbling versus gorging"). Reducing the size and increasing the frequency of meals has been shown acutely to result in lower mean blood glucose and insulin levels over the day in type II diabetes and to result in reduced 24-h urinary C-peptide losses. In the longer term in nondiabetic subjects, total and low-density lipoprotein cholesterol levels are reduced, together with fasting apolipoprotein B and serum uric acid levels, as additional risk factors for coronary heart disease. These and other physiological effects make slowing carbohydrate absorption ("lente carbohydrate") a potentially useful therapeutic modality. However, of the possible ways of slowing absorption, only alteration in meal frequency was of general interest in the current ADA nutrition recommendations. Nevertheless, the effects of slowing carbohydrate absorption by various means may have beneficial metabolic effects in diabetes and may support the use of ethnic foods in diets compatible with further modifications identified more favorably in the current nutrition recommendations (e.g., increased use of monounsaturated fat).

Optimal diet for reducing the risk of arteriosclerosis

The primary objectives of current dietary advice for those at risk from coronary artery disease (CAD) focus on progressive restriction of dietary saturated (and trans) fatty acids and cholesterol intake, combined with exercise and achievement of ideal body weight. These principles are endorsed by the official bodies of most western nations concerned with reducing CAD mortality and have recently been reaffirmed by the Adult Treatment Panel of the National Cholesterol Education Program. There has been concern, however, in view of the increasing use of drug therapy, that additional strategies should supplement the primary goals to increase the palatability and effectiveness of the diet. These additional strategies include increased intake of foods high in soluble viscous fibres, vegetable proteins, possibly antioxidants such as vitamin E and the isoflavonoids, increased intake of alpha-linolenic acid and, for those with low high density lipoprotein cholesterol levels, increased monounsaturated fat intake. These strategies translate into advice to significantly increase consumption of specific plant foods such as green leafy vegetables, nuts and seeds, and dried legumes, all of which improve the overall nutritional quality of the diet and contain specific active ingredients. These changes represent a regression to a more primitive diet on the evolutionary scale.

Implications of altering the rate of carbohydrate absorption from the gastrointestinal tract

The rate of absorption of carbohydrate from the small intestine plays a major role in determining the metabolic effects of dietary carbohydrate. Factors which reduce the rate of absorption include the nature of the starch and sugars, and the presence of vegetable proteins, fats, viscous fibre, and antinutrients, including lectins and phytates. The rate of absorption can also be manipulated by the use of specific enzyme inhibitors and by increasing the number and frequency of meals while holding caloric intake constant. All these factors contribute to the creation of what may be termed slow release or "lente carbohydrate". The slowing of small intestinal absorption, as exemplified by increased meal frequency ("nibbling"), results in reduced postprandial insulin secretion and lower low-density lipoprotein (LDL) cholesterol and apolipoprotein B concentrations. A further effect of some manipulations which reduce the rate of absorption is increased delivery of carbohydrate to the colon and its absorption after bacterial fermentation to short-chain fatty acids (SCFA). These SCFA may have beneficial effects on colonic health(butyrate) or further inhibit cholesterol synthesis in the liver (propionate). Thus the absorption of "lente carbohydrate" takes place along the full length of the gastrointestinal tract with a wide variety of physiological consequences.

Physiological modulation of plasma free fatty acid concentrations by diet. Metabolic implications in nondiabetic subjects

OBJECTIVE

To determine the effect of varying the amount of carbohydrate and glycemic index (GI) of breakfast test meals on plasma free fatty acid (FFA) responses of nondiabetic subjects and to see whether the glycemic response at lunch was related to the plasma FFA response to breakfast.

RESEARCH DESIGN AND METHODS

We studied eight subjects over a 6-h period on four separate occasions using a randomized Latin-square design. They received isocaloric breakfast test meals that were either high (84 g) or low (41 g) in carbohydrate and had either a high (approximately 100) or a low (approximately 70) GI, followed by a standard lunch 4 h later.

RESULTS

The initial fall in plasma FFAs after breakfast was similar for all four test meals, but the extent of rebound differed significantly. The mean plasma FFA concentration just before the start of lunch (4 h) was highest after the low-GI, low-carbohydrate breakfast (418 +/- 42 mumol/l), followed by high-GI, low-carbohydrate (277 +/- 48 mumol/l), high-GI, high carbohydrate (227 +/- 32 mumol/l), and low-GI, high-carbohydrate (149 +/- 23 mumol/l) (P < 0.01). The concentration of plasma FFAs at 4 h was directly related to the total area under the glycemic response curve to lunch (r = 0.691, n = 32, P < 0.0001).

CONCLUSIONS

In nondiabetic subjects, the type and amount of carbohydrate eaten at breakfast influences the plasma glucose, insulin, and FFA responses to breakfast and also affects the glucose, insulin, and FFA responses to a subsequent standard lunch. The glycemic responses after lunch were closely related to the plasma FFA concentration 4 h after breakfast, which we speculate is due to the inhibitory effect of FFAs on insulin action.

Effect of nibbling versus gorging on cardiovascular risk factors: serum uric acid and blood lipids

Nibbling has been reported to decrease serum cholesterol under fasting conditions, as well as the incidence of cardiovascular disease. It has been suggested that these effects are partly attributable to reduced concentrations of serum insulin, which are also observed. However, data on the effects of nibbling on serum lipids throughout the day are not available, nor is it known how nibbling affects serum uric acid as a further insulin-related risk factor for cardiovascular disease. We have attempted to address these issues. Seven healthy men consumed identical diets in a randomized crossover design either as three meals daily (control) or as 17 meals daily (nibbling) for 2 weeks. On day 13, serum lipid levels were measured over the course of the day (12 hours) together with the 24-hour urinary excretion of mevalonic acid as an indicator of hepatic cholesterol synthesis. Concentrations of uric acid in serum and 24-hour urinary excretion of uric acid were also determined. Mean (+/- SE) percent treatment differences in day-long total, low-density lipoprotein (LDL), and non-high-density lipoprotein (HDL) cholesterol, and apolipoprotein (apo) B were significant, with lower values on the nibbling diet as compared with the control diet (8.1% +/- 1.6%, P = .002; 12.2% +/- 2.6%, P = .005; 10.1% +/- 1.6%, P < .001; and 9.9% +/- 2.6%, P = .008, respectively). No significant difference was seen in the total to HDL cholesterol ratio or in urinary mevalonic acid excretion.(ABSTRACT TRUNCATED AT 250 WORDS)

Nutritional attributes of traditional flaxseed in healthy young adults

The objective was to determine the influence of consuming 50 g flaxseed/d for 4 wk on several indexes of nutrition in young healthy adults. During flaxseed consumption, alpha-linolenate was increased significantly in adipose tissue, and n-3 polyunsaturates were increased in plasma lipids. Plasma LDL cholesterol was also reduced by up to 8%, and total urinary lignan excretion was increased more than fivefold (P < 0.05). Muffins containing 25 g flaxseed did not differ significantly from control muffins in their content of thiobarbituric acid-reactive substances, and alpha-linolenate in the muffins was not significantly reduced by baking. Antioxidant vitamins and lipid hydroperoxides in plasma were not significantly affected by flaxseed consumption. Bowel movements per week increased by 30% while flaxseed was consumed (P < 0.05). We conclude that traditional flaxseed has modest beneficial effects on several indexes of nutritional status without compromising antioxidant status.

Use of Two Humane Leg-Hold Traps for Catching Pest Species

This technical note comments on the use of Victor 'Soft Catch' No. 3 traps and Treadle snare throwers, two leg-hold devices that have been developed to minimise injuries to captured animals. Both types of traps were evaluated during more than 1000 nights of use. The numbers of animals caught in each trap type, and the degree of injury sustained by the trapped animals were recorded. Both these traps were found to be humane alternatives to the steel-jawed trap currently in common use in Australia. However, the 'Victor' traps were the more convenient to use. They gave fewer technical problems, minimised injuries, caught more animals and allowed fewer escapes.

Effect of acute lactulose administration on serum acetate levels in cirrhosis

Lactulose has been used successfully in the treatment of portal-systemic encephalopathy but its exact mechanism of action is not known. The aim of this study was to observe the systemic effects of the colonic fermentation of an acute lactulose dose in cirrhotics and normal subjects. Six cirrhotic patients and 6 normal subjects were placed on 2 identical 2-d metabolic diets, 1 of which was supplemented with lactulose (1 g/100 kcals to a maximum of 28 g/d). Lactulose increased colonic fermentation in cirrhotic and normal subjects as evidenced by higher breath hydrogen and serum acetate levels. The increase in serum acetate levels after lactulose compared to control was similar in cirrhotic compared to normal subjects. However, the mean serum acetate concentration in the cirrhotics was significantly greater than that in the control subjects (p = 0.039), indicating increased endogenous production, or decreased peripheral utilization of acetate by the cirrhotic liver, or both. No change was observed in blood ammonia, glucose, insulin, or free fatty acid levels with lactulose.

Method of administration influences the serum cholesterol-lowering effect of psyllium

To determine whether psyllium must be mixed with food to lower serum cholesterol, 18 modestly hypercholesterolemic subjects were studied for three 2-wk periods, in random order, separated by a 2-wk return to a National Cholesterol Education Program Step 2 diet. Compared with values for subjects consuming control wheat-bran cereal (63 g/d), after 2 wk of 54 g psyllium-enriched cereal/d containing 7.3 g psyllium, serum total, LDL, and HDL cholesterol, respectively, were reduced by 8% (6.15 +/- 0.15 vs 6.71 +/- 0.19 mmol/L, P < 0.01), 11% (4.24 +/- 0.15 vs 4.78 +/- 0.19 mmol/L, P < 0.02), and 7% (0.99 +/- 0.05 vs 1.07 +/- 0.05 mmol/L, P < 0.01). When 7.6 g of the same type of psyllium as in the test cereal was taken between meals, serum total (6.50 +/- 0.19 mmol/L), LDL (4.50 +/- 0.21 mmol/L), and HDL (1.06 +/- 0.06 mmol/L) cholesterol were no different from control values, and total cholesterol was greater than after psyllium cereal (P < 0.05). We conclude that psyllium must be mixed with foods to have the maximum effect on serum cholesterol.

Psyllium reduces blood lipids in men and women with hyperlipidemia

To see if a modest amount of soluble fiber reduced blood lipids in subjects with hyperlipidemia who were on a low-fat diet, 42 subjects (21 men, 21 women) consuming an American Heart Association step 2 diet took two servings of breakfast cereal daily for two 2-week periods in a randomized crossover trial. There were two types of test cereals, each providing 6.7 g psyllium fiber daily, and two types of wheat bran control cereals, matched for available carbohydrate and total fiber. Half the subjects tested each type of cereal, and the results were pooled because the psyllium cereals had similar effects on serum cholesterol levels. Comparing values at the end of 2 weeks, psyllium reduced serum total (6.33 +/- 0.12 mmol/L versus 6.76 +/- 0.12 mmol/L, p < 0.001), low-density lipoprotein (LDL; 4.36 +/- 0.11 mmol/L versus 4.73 +/- 0.12 mmol/L, p < 0.001) and high-density lipoprotein cholesterol levels (HDL; 1.10 +/- 0.05 mmol/L versus 1.14 +/- 0.05 mmol/L, p < 0.05) and the LDL/HDL cholesterol ratio (4.27 +/- 0.20 versus 4.48 +/- 0.22, p < 0.02) with no effect on triglycerides. There was no significant interaction between the effects of treatment and sex for any of the blood lipid variables. Women tended to have greater decreases in total, LDL, and HDL cholesterol levels than men, but the percent decrease in LDL/HDL ratio on psyllium was similar in men, 4.9%, and women, 4.7%. It is concluded that 6.7 g of psyllium fiber daily, with a low-fat diet, reduces serum cholesterol levels in both men and women with hyperlipidemia.

Low glycemic index: lente carbohydrates and physiological effects of altered food frequency

Many factors influence carbohydrate absorption. Slower rates of absorption may have advantages in reducing postprandial glycemia and insulinemia and, in time, reduce serum low-density-lipoprotein (LDL) cholesterol and apolipoprotein B concentrations. Foods high in viscous fiber or antinutrients, or foods that are resistant to gelatinization, show slower rates of digestion and absorption and may be called low glycemic index or lente carbohydrate foods. Specific enzyme inhibitors may also cause lente effects. Certain small-intestinal effects of lente carbohydrate may be mimicked by altering feeding frequency (eg, nibbling vs gorging). Increased meal frequency reduces post-prandial insulin and glucose responses in people with non-insulin-dependent diabetes and in nondiabetic volunteers and lowers serum concentrations of LDL cholesterol and apolipoprotein B. Reduced hepatic cholesterol synthesis has been reported. Increased meal frequency may also slow small-intestinal absorption in the treatment of conditions such as diabetes, hyperlipidemia, and possibly obesity.

Genetic variation associated with differences in the response of plasma apolipoprotein B levels to dietary fibre

1. We hypothesized that differences within genes whose protein products are involved in apolipoprotein B metabolism could influence the response of plasma apolipoprotein B-containing lipoprotein concentrations to increases in dietary fibre. 2. We studied 67 subjects (43 men and 24 women) who had taken part in parallel 2 week metabolic dietary studies involving either wheat bran or oat bran supplementation. Fasting blood lipid, lipoprotein and apolipoprotein concentrations were measured at the start and end of the 2 week metabolic period. Genotypes were determined using DNA markers for the low-density lipoprotein receptor, apolipoprotein B, apolipoprotein CIII and hepatic lipase gene loci. 3. Reductions in plasma concentrations of apolipoprotein B were significantly different depending on genotype determined with a low-density lipoprotein receptor DNA marker (P = 0.03). There was no significant variation in the reduction of plasma total cholesterol, low-density lipoprotein cholesterol or apolipoprotein B concentrations for alleles of other genes tested. 4. Thus, genetic variability is associated with interindividual differences in the fibre-related reduction in plasma apolipoprotein B and apolipoprotein B-containing lipoprotein concentrations. Implementation of current dietary recommendations to reduce plasma lipoprotein levels with fibre may have variable effects in different individuals in part because of structural differences in candidate genes whose products are involved in lipoprotein metabolism.

Response of individual serum free fatty acids to oral and intravenous glucose: relation to adipose tissue composition

The rate of oral glucose delivery determines whether serum total free fatty acids remain low (glucose sipping over 210 min) or rebound 120-180 min after initial suppression (via glucose bolus), but the response of individual serum free fatty acids to glucose ingestion is largely unknown. In this study, we measured the changes over 240 min in the levels of individual serum free and esterified fatty acids after bolus or sipped glucose ingestion and determined the extent to which the changes are related to abdominal subcutaneous adipose tissue composition. In eight healthy volunteers, 74% of the prolonged suppression of total serum free fatty acids resulting from sipping 50 g glucose over 210 min was caused by a decrease in free linoleic and oleic acids, whereas 92% of the rebound in total free fatty acids 240 min after consuming 50 g of glucose as a bolus was caused by increases in free oleic and linoleic acids. Two hundred forty minutes after the oral glucose, slower intravenous clearance of 5 g glucose was directly correlated to higher total serum free fatty acids and free stearic acid and higher oleic but lower linoleic acid in adipose tissue. We conclude that the net response of serum free fatty acids to an oral glucose load is mediated primarily by oleic and linoleic acids in a manner largely unrelated to adipose tissue composition.

Serum antibodies in canine echinococcosis

Specific IgG, IgA and IgE antibodies against E. granulosus protoscolex antigen were detected by enzyme-linked immunosorbent assay (ELISA) in sera from dogs experimentally or naturally infected with E. granulosus. The specificities of the IgG, IgA and IgE ELISAs were 100, 100 and 97.3%, respectively. Sera from 626 dogs of different categories and geographic regions in Australia, Uruguay and Kenya were tested. There were distinct differences in antibody responses in experimentally infected canids and in the number of naturally infected dogs found seropositive, depending on geographic region. The overall sensitivities of the ELISA (IgG, IgA and IgE) ranged between 73 and 84%, except for one geographic region where it was 54%. Genetic differences of the dogs and/or antigenic variations of the parasite appear to be responsible for the variations in specific antibody levels in infected dogs. In average, approximately one third of dogs from hyperendemic hydatid regions, without E. granulosus worms at autopsy or negative for E. granulosus infection by arecoline testing, were seropositive for anti-E. granulosus antibodies, suggesting previous infection with or exposure to the parasite. The results of this study demonstrate that, although the diagnosis of current intestinal E. granulosus infection on an individual dog basis is not always reliable by serology, serum antibody ELISA is useful as an epidemiological/educational tool for seroprevalence studies on canine echinococcosis.